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13 pages, 2837 KiB

Open AccessArticle

Monitoring and Analysing Changes in Temperature and Energy in the Ground with Installed Horizontal Ground Heat Exchangers

by Pavel Pauli, Pavel Neuberger^* and Radomír Adamovský

Department of Mechanical Engineering, Faculty of Engineering, Czech University of Life Sciences Prague, Kamýcká 129, Prague-Suchdol 165 21, Czech Republic

Energies 2016, 9(8), 555; https://doi.org/10.3390/en9080555 - 28 Jul 2016

Cited by 9 | Viewed by 4175

Abstract

The objective of this work was to monitor and analyse temperature changes in the ground with installed linear and Slinky-type horizontal ground heat exchangers (HGHEs), used as low-potential heat pump energy sources. Specific heat flows and specific energies extracted from the ground during [...] Read more.

The objective of this work was to monitor and analyse temperature changes in the ground with installed linear and Slinky-type horizontal ground heat exchangers (HGHEs), used as low-potential heat pump energy sources. Specific heat flows and specific energies extracted from the ground during the heating season were also measured and compared. The verification results showed that the average daily ground temperatures with the two HGHEs are primarily affected by the temperature of the ambient environment. The ground temperatures were higher than ambient temperature during most of the heating season, were only seldom below zero, and were higher by an average 1.97 ± 0.77 K in the ground with the linear HGHE than in the ground with the Slinky-type HGHE. Additionally, the specific thermal output extracted from the ground by the HGHE was higher by 8.45 ± 16.57 W/m² with the linear system than with the Slinky system. The specific energies extracted from the ground over the whole heating season were 110.15 kWh/m² and 57.85 kWh/m² for the linear and Slinky-type HGHEs, respectively. Full article

(This article belongs to the Special Issue Advanced Heating and Cooling Techniques)

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19 pages, 2808 KiB

Open AccessArticle

A Run-Time Dynamic Reconfigurable Computing System for Lithium-Ion Battery Prognosis

by Shaojun Wang^1,2, Datong Liu^1,*, Jianbao Zhou¹, Bin Zhang³

and Yu Peng¹

¹ Department of Automatic Test and Control, Harbin Institute of Technology, Harbin 150080, China

² Department of Computing, Imperial College London, London SW7 2BZ, UK

³ College of Engineering and Computing, University of South Carolina, Columbia, SC 29208, USA

Energies 2016, 9(8), 572; https://doi.org/10.3390/en9080572 - 25 Jul 2016

Cited by 20 | Viewed by 5878

Abstract

As safety and reliability critical components, lithium-ion batteries always require real-time diagnosis and prognosis. This often involves a large amount of computation, which makes diagnosis and prognosis difficult to implement, especially in embedded or mobile applications. To address this issue, this paper proposes [...] Read more.

As safety and reliability critical components, lithium-ion batteries always require real-time diagnosis and prognosis. This often involves a large amount of computation, which makes diagnosis and prognosis difficult to implement, especially in embedded or mobile applications. To address this issue, this paper proposes a run-time Reconfigurable Computing (RC) system on Field Programmable Gate Array (FPGA) for Relevance Vector Machine (RVM) to realize real-time Remaining Useful Life (RUL) estimation. The system leverages state-of-the-art run-time dynamic partial reconfiguration technology and customized computing circuits to balance the hardware occupation and computing efficiency. Optimal hardware resource consumption is achieved by partitioning the RVM algorithm according to a multi-objective optimization. Moreover, pipelined and parallel computation circuits for kernel function and matrix inverse are proposed on FPGA to further accelerate the computation. Experimental results with two different battery data sets show that, without sacrificing the RUL prediction performance, the embedded RC platform significantly reduces the computation time and the requirement of hardware resources. This demonstrates that complex prognostic tasks can be implemented and deployed on the proposed system, and it can be extended to the embedded computation of other machine learning algorithms. Full article

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16 pages, 7932 KiB

Open AccessArticle

Optimal Cooling Load Sharing Strategies for Different Types of Absorption Chillers in Trigeneration Plants

by Benedetto Conte, Joan Carles Bruno^* and Alberto Coronas

Department of Mechanical Engineering, University Rovira i Virgili, CREVER-Research Group on Applied Thermal Engineering, Avda. Països Catalans 26, Tarragona 43007, Spain

Energies 2016, 9(8), 573; https://doi.org/10.3390/en9080573 - 25 Jul 2016

Cited by 12 | Viewed by 6140

Abstract

Trigeneration plants can use different types of chillers in the same plant, typically single effect and double effect absorption chillers, vapour compression chillers and also cooling storage systems. The highly variable cooling demand of the buildings connected to a district heating and cooling [...] Read more.

Trigeneration plants can use different types of chillers in the same plant, typically single effect and double effect absorption chillers, vapour compression chillers and also cooling storage systems. The highly variable cooling demand of the buildings connected to a district heating and cooling (DHC) network has to be distributed among these chillers to achieve lower operating costs and higher energy efficiencies. This problem is difficult to solve due to the different partial load behaviour of each chiller and the different chiller combinations that can cover a certain cooling demand using an appropriate sizing of the cooling storage. The objective of this paper is to optimize the daily plant operation of an existing trigeneration plant based on cogeneration engines and to study the optimal cooling load sharing between different types of absorption chillers using a mixed integer linear programming (MILP) model. Real data from a trigeneration plant connected to a DHC close to Barcelona (Spain) is used for the development of this model. The cooling load distribution among the different units is heavily influenced by the price of the electricity sold to the grid which rules the duration of the operation time of the engines. The main parameter to compare load distribution configurations is the primary energy saving indicator. Cooling load distribution among the different chillers changes also with the load of the whole plant because the chiller performance changes with load. Full article

(This article belongs to the Special Issue Simulation of Polygeneration Systems)

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17 pages, 3662 KiB

Open AccessArticle

Study on the Criteria for the Determination of the Road Load Correlation for Automobiles and an Analysis of Key Factors

by Charyung Kim^1,2, Hyunwoo Lee¹, Yongsung Park¹, Cha-Lee Myung² and Simsoo Park^2,*

¹ Korea Automobile Testing & Research Institute, Hwaseong-si, Gyeonggi-do 18247, Korea

² School of Mechanical Engineering, Korea University, 145, Anam-ro, Seongbuk-gu, Seoul 02841, Korea

Energies 2016, 9(8), 575; https://doi.org/10.3390/en9080575 - 25 Jul 2016

Cited by 15 | Viewed by 6212

Abstract

To determine the fuel economy and emissions of a vehicle using a chassis dynamometer, the load to which the vehicle is subjected when it actually runs on a road, or the road load specifications, must be simulated when the dynamometer is applied. The [...] Read more.

To determine the fuel economy and emissions of a vehicle using a chassis dynamometer, the load to which the vehicle is subjected when it actually runs on a road, or the road load specifications, must be simulated when the dynamometer is applied. The most commonly used method to measure road load specifications is coastdown testing. Currently, road load is measured and provided by the manufacturer of the vehicle. Verification of the accuracy of the manufacturer’s reported road load specifications by a third party may reveal that the specifications are inaccurate, possibly because of different testing locations, test drivers or test equipment. This study aims at identifying key factors that can affect a vehicle’s road load correlation by using experimental design and deriving criteria for determining the correlation based on the energy difference. Full article

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16 pages, 6568 KiB

Open AccessArticle

Analysis and Performance Improvement of WPT Systems in the Environment of Single Non-Ferromagnetic Metal Plates

by Linlin Tan^1,2,*, Jiacheng Li^1,2

, Chen Chen^1,3, Changxin Yan^1,2, Jinpeng Guo^1,2 and Xueliang Huang^1,2

¹ Department of Electrical Engineering, Southeast University, No. 2 Sipailou, Nanjing 210096, China

² Jiangsu Key Laboratory of Smart Grid Technology and Equipment, Zhenjiang 212009, China

³ State Grid Jiangsu Economic Research Institute, Nanjing 210096, China

Energies 2016, 9(8), 576; https://doi.org/10.3390/en9080576 - 25 Jul 2016

Cited by 28 | Viewed by 5790

Abstract

Wireless power transfer (WPT) is greatly affected when the transmission channel is surrounded by non-ferromagnetic metallic objects and the alternating magnetic field interacts with the metal conductor, which is more of an issue in wirelessly charged electric vehicle (EV) applications. This paper analyses [...] Read more.

Wireless power transfer (WPT) is greatly affected when the transmission channel is surrounded by non-ferromagnetic metallic objects and the alternating magnetic field interacts with the metal conductor, which is more of an issue in wirelessly charged electric vehicle (EV) applications. This paper analyses the performances of a WPT system in an environment with a non-ferromagnetic metal plate. The impedance model of the WPT system in the metal environment is established. Moreover the variation law of a coil’s equivalent inductance and resistance is deduced when the coil is surrounded by the non-ferromagnetic metal plate. Meanwhile, simulations, theory and experiments all confirm that the model is correct. Finally, since the system performance of a wireless charging system is influenced by non-ferromagnetic metals, this paper puts forward a method to improve the performance, that is, to place ferrite cores between the receiving coil and a metal plate. Experiments are carried out to verify the method, and the desired results are achieved. Full article

(This article belongs to the Special Issue Advanced Power Electronics and Control for Wireless Power Transfer Systems)

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19 pages, 5385 KiB

Open AccessArticle

Energy Simulation of a Holographic PVT Concentrating System for Building Integration Applications

by Julia Marín-Sáez¹

, Daniel Chemisana^1,*

, Álex Moreno¹, Alberto Riverola¹, Jesús Atencia²

and María-Victoria Collados²

¹ Applied Physics Section of the Environmental Science Department, Polytechnic School, University of Lleida, Lleida 25001, Spain

² Applied Physics Department, Aragon Institute of Engineering Research (I3A), University of Zaragoza, Zaragoza 50009, Spain

Energies 2016, 9(8), 577; https://doi.org/10.3390/en9080577 - 25 Jul 2016

Cited by 12 | Viewed by 5601

Abstract

A building integrated holographic concentrating photovoltaic-thermal system has been optically and energetically simulated. The system has been designed to be superimposed into a solar shading louvre; in this way the concentrating unit takes profit of the solar altitude tracking, which the shading blinds [...] Read more.

A building integrated holographic concentrating photovoltaic-thermal system has been optically and energetically simulated. The system has been designed to be superimposed into a solar shading louvre; in this way the concentrating unit takes profit of the solar altitude tracking, which the shading blinds already have, to increase system performance. A dynamic energy simulation has been conducted in two different locations—Sde Boker (Israel) and Avignon (France)—both with adequate annual irradiances for solar applications, but with different weather and energy demand characteristics. The simulation engine utilized has been TRNSYS, coupled with MATLAB (where the ray-tracing algorithm to simulate the holographic optical performance has been implemented). The concentrator achieves annual mean optical efficiencies of 30.3% for Sde Boker and 43.0% for the case of Avignon. Regarding the energy production, in both locations the thermal energy produced meets almost 100% of the domestic hot water demand as this has been considered a priority in the system control. On the other hand, the space heating demands are covered by a percentage ranging from 15% (Avignon) to 20% (Sde Boker). Finally, the electricity produced in both places covers 7.4% of the electrical demand profile for Sde Boker and 9.1% for Avignon. Full article

(This article belongs to the Special Issue Simulation of Polygeneration Systems)

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17 pages, 2948 KiB

Open AccessArticle

A High-Precision Control for a ZVT PWM Soft-Switching Inverter to Eliminate the Dead-Time Effect

by Baoquan Kou^*, Hailin Zhang

and He Zhang

Department of Electrical Engineering, Harbin Institute of Technology, Harbin 150080, China

Energies 2016, 9(8), 579; https://doi.org/10.3390/en9080579 - 25 Jul 2016

Cited by 8 | Viewed by 6229

Abstract

Attributing to the advantages of high efficiency, low electromagnetic interference (EMI) noise and closest to the pulse-width-modulation (PWM) converter counterpart, zero-voltage-transition (ZVT) PWM soft-switching inverters are very suitable for high-performance applications. However, the conventional control algorithms intended for high efficiency generally results in [...] Read more.

Attributing to the advantages of high efficiency, low electromagnetic interference (EMI) noise and closest to the pulse-width-modulation (PWM) converter counterpart, zero-voltage-transition (ZVT) PWM soft-switching inverters are very suitable for high-performance applications. However, the conventional control algorithms intended for high efficiency generally results in voltage distortion. Thus, this paper, for the first time, proposes a high-precision control method to eliminate the dead-time effect through controlling the auxiliary current in the auxiliary resonant snubber inverter (ARSI), which is a typical ZVT PWM inverter. The dead-time effect of ARSI is analyzed, which is distinguished from hard-switching inverters. The proposed high-precision control is introduced based on the investigation of dead-time effect. A prototype was developed to verify the effectiveness of the proposed control. The experimental results shows that the total harmonic distortion (THD) of the output current of the ARSI can be reduced compared with that of the hard-switching inverter, because the blanking delay error is eliminated. The quality of the output current and voltage can be further improved by utilizing the proposed control method. Full article

(This article belongs to the Special Issue Power Electronics Optimal Design and Control)

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11 pages, 5214 KiB

Open AccessArticle

Analytical Calculation of D- and Q-axis Inductance for Interior Permanent Magnet Motors Based on Winding Function Theory

by Peixin Liang^1,2, Yulong Pei², Feng Chai^1,2,* and Kui Zhao²

¹ State Key Laboratory of Robotics and System, Harbin Institute of Technology, Harbin 150001, China

² Department of Electrical Engineering, Harbin Institute of Technology, Harbin 150001, China

Energies 2016, 9(8), 580; https://doi.org/10.3390/en9080580 - 25 Jul 2016

Cited by 31 | Viewed by 19658

Abstract

Interior permanent magnet (IPM) motors are widely used in electric vehicles (EVs), benefiting from the excellent advantages of a more rational use of energy. For further improvement of energy utilization, this paper presents an analytical method of d- and q-axis inductance [...] Read more.

Interior permanent magnet (IPM) motors are widely used in electric vehicles (EVs), benefiting from the excellent advantages of a more rational use of energy. For further improvement of energy utilization, this paper presents an analytical method of d- and q-axis inductance calculation for IPM motors with V-shaped rotor in no-load condition. A lumped parameter magnetic circuit model (LPMCM) is adopted to investigate the saturation and nonlinearity of the bridge. Taking into account the influence of magnetic field distribution on inductance, the winding function theory (WFT) is employed to accurately calculate the armature reaction airgap magnetic field and d- and q-axis inductances. The validity of the analytical technique is verified by the finite element method (FEM). Full article

(This article belongs to the Special Issue Electric Machines and Drives for Renewable Energy Harvesting)

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17 pages, 9123 KiB

Open AccessArticle

Maximum Power Point Tracking Sensorless Control of an Axial-Flux Permanent Magnet Vernier Wind Power Generator

by Xiang Luo^1,2 and Shuangxia Niu^1,*

¹ Department of Electrical Engineering, The Hong Kong Polytechnic University, Hong Kong, China

² State Key Laboratory of Ocean Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

Energies 2016, 9(8), 581; https://doi.org/10.3390/en9080581 - 26 Jul 2016

Cited by 18 | Viewed by 6254

Abstract

Recently, Vernier permanent magnet (VPM) machines, one special case of magnetic flux-modulated (MFM) machines, benefiting from their compact, simple construction and low-speed/ high-torque characteristics, have been receiving increasing interest. In this paper, the Vernier structure is integrated with an axial-flux PM machine to [...] Read more.

Recently, Vernier permanent magnet (VPM) machines, one special case of magnetic flux-modulated (MFM) machines, benefiting from their compact, simple construction and low-speed/ high-torque characteristics, have been receiving increasing interest. In this paper, the Vernier structure is integrated with an axial-flux PM machine to obtain the magnetic gear effect and produce an improved torque density for direct-drive wind power generation application. Another advantage of the proposed machine is that the stator flux rotating speed can be relatively high when the shaft speed is low. With this benefit, sensorless control strategy can be easily implemented in a wide speed range. In this paper, an improved sliding mode observer (SMO) is proposed to estimate the rotor position and the speed of the proposed machine. With the estimated shaft speeds, the maximum power point tracking (MPPT) control strategy is applied to maximize the wind power extraction. The machine design and the sensorless MPPT control strategy are verified by finite element analysis and experimental verification. Full article

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12 pages, 3039 KiB

Open AccessArticle

Design of a System Substituting Today’s Inherent Inertia in the European Continental Synchronous Area

by Henning Thiesen^*, Clemens Jauch and Arne Gloe

Wind Energy Technology Institute, Center for Sustainable Energy Systems Flensburg, Flensburg University of Applied Sciences, Flensburg 24943, Germany

Energies 2016, 9(8), 582; https://doi.org/10.3390/en9080582 - 27 Jul 2016

Cited by 51 | Viewed by 6153

Abstract

In alternating current (AC) power systems the power generated by power plants has to match the power drawn by consumers plus the system losses at any time. In the case of an imbalance between generation and consumption the frequency in the system deviates [...] Read more.

In alternating current (AC) power systems the power generated by power plants has to match the power drawn by consumers plus the system losses at any time. In the case of an imbalance between generation and consumption the frequency in the system deviates from its rated value. In order to avoid an unsuitable frequency, control power plants have to step in to level out this imbalance. Control power plants need time to adjust their power, which is why the inertial behaviour of today’s AC systems is crucial for frequency control. In this paper it is discussed that the inertia in the European Continental Synchronous Area decreases due to the transition to renewable energy sources. This will become a problem for frequency control, which is why the provision of non-inherent inertia is proposed. This system consists of fast-responding energy storage. Its dimensions in terms of power and energy are determined. Since such non-inherent inertia requires investments a cost-efficient solution has to be found. Different technologies are compared in terms of the newly-introduced levelised cost of inertia. This paper concludes with the proposal that in future inertia should be traded and with the recommendation to use flywheels for this purpose, as these are the most cost-efficient solution for this task. Full article

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12 pages, 1349 KiB

Open AccessArticle

The Lebanese Electricity Woes: An Estimation of the Economical Costs of Power Interruptions

by Elie Bouri^1,*

and Joseph El Assad²

¹ USEK Business School, Holy Spirit University of Kaslik 1, Jounieh, Lebanon

² Faculty of Sciences, Holy Spirit University of Kaslik 2, Jounieh, Lebanon

Energies 2016, 9(8), 583; https://doi.org/10.3390/en9080583 - 27 Jul 2016

Cited by 25 | Viewed by 7706

Abstract

This paper contributes to the political and scientific debate surrounding the economic costs entailed by the regular power cuts in Lebanon. Examining the data on electricity consumption that was produced by onshore and offshore power plants, this paper estimates the economical costs of [...] Read more.

This paper contributes to the political and scientific debate surrounding the economic costs entailed by the regular power cuts in Lebanon. Examining the data on electricity consumption that was produced by onshore and offshore power plants, this paper estimates the economical costs of power interruptions in Lebanon over the period 2009–2014. Based on 700 USD/MWh, representing the average value of lost load (VOLL) in that period, results indicate that electricity shortages continue to render significant transfers of wealth to the detriment of economy and society as a whole. Over the period 2009–2014, the total losses for the Lebanese economy reached 23.23 billion USD. Just as importantly, some evidence suggests a sharp decline in the economical costs of power interruptions with the inception of the two floating power plants in 2013. The results are crucial for the decision makers to identify the economic efficiency of alternative measures to enhance the security of the Lebanese electricity supply. Full article

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15 pages, 3464 KiB

Open AccessArticle

Environmental and Economic Performance of an Li-Ion Battery Pack: A Multiregional Input-Output Approach

by Javier Sanfélix^1,*, Cristina De la Rúa²

, Jannick Hoejrup Schmidt³

, Maarten Messagie¹ and Joeri Van Mierlo¹

¹ Electrotechnical Engineering and Energy Technology, Mobility and Automotive Technology Research Group (MOBI), Vrije Universiteit Brussel, Pleinlaan 2, 1050 Brussels, Belgium

² Research Centre on Energy, Environment and Technologies (CIEMAT), Energy Department, Energy Systems Analysis Unit, Av. Complutense 40, 28040 Madrid, Spain

³ Department of Development and Planning, Aalborg University, Skibbrogade 5 1, 9000 Aalborg, Denmark

Energies 2016, 9(8), 584; https://doi.org/10.3390/en9080584 - 27 Jul 2016

Cited by 15 | Viewed by 6898

Abstract

In this paper, the environmental and economic impacts of the life cycle of an advanced lithium based energy storage system (ESS) for a battery electric vehicle are assessed. The methodology followed to perform the study is a Multiregional Input–Output (MRIO) analysis, with a [...] Read more.

In this paper, the environmental and economic impacts of the life cycle of an advanced lithium based energy storage system (ESS) for a battery electric vehicle are assessed. The methodology followed to perform the study is a Multiregional Input–Output (MRIO) analysis, with a world IO table that combines detailed information on national production activities and international trade data for 40 countries and a region called Rest of the World. The life cycle stages considered in the study are manufacturing, use and recycling. The functional unit is one ESS with a 150,000 km lifetime. The results of the MRIO analysis show the stimulation that the life cycle of the EES has in the economy, in terms of production of goods and services. The manufacturing is the life cycle stage with the highest environmental load for all the impact categories assessed. The geographical resolution of the results show the relevance that some countries may have in the environmental performance of the assessed product even if they are not directly involved in any of the stages of the life cycle, proving the significance of the indirect effects. Full article

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20 pages, 3235 KiB

Open AccessArticle

A Least Squares Support Vector Machine Optimized by Cloud-Based Evolutionary Algorithm for Wind Power Generation Prediction

by Qunli Wu and Chenyang Peng^*

Department of Economics and Management, North China Electric Power University, 689 Huadian Road, Baoding 071003, China

Energies 2016, 9(8), 585; https://doi.org/10.3390/en9080585 - 28 Jul 2016

Cited by 24 | Viewed by 4791

Abstract

Accurate wind power generation prediction, which has positive implications for making full use of wind energy, seems still a critical issue and a huge challenge. In this paper, a novel hybrid approach has been proposed for wind power generation forecasting in the light [...] Read more.

Accurate wind power generation prediction, which has positive implications for making full use of wind energy, seems still a critical issue and a huge challenge. In this paper, a novel hybrid approach has been proposed for wind power generation forecasting in the light of Cloud-Based Evolutionary Algorithm (CBEA) and Least Squares Support Vector Machine (LSSVM). In order to improve the forecasting precision, a two-way comparison approach is conducted to preprocess the original wind power generation data. The pertinent parameters of LSSVM are optimized by using CBEA to verify the learning and generalization abilities of the LSSVM model. The experimental results indicate that the forecasting performance of the proposed model is better than the single LSSVM model and all of the other models for comparison. Moreover, the paired-sample t-test is employed to cast light on the applicability of the developed model. Full article

(This article belongs to the Special Issue Energy Time Series Forecasting)

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17 pages, 2854 KiB

Open AccessArticle

Realizing the Intended Nationally Determined Contribution: The Role of Renewable Energies in Vietnam

by Thanh Tu Tran^1,*

, Shinichiro Fujimori²

and Toshihiko Masui²

¹ Regional Centre of Expertise on Education for Sustainable Development in Southern Vietnam, International University—Vietnam National University Ho Chi Minh City, Quarter 6, Linh Trung Ward, Thu Duc District, Ho Chi Minh City 700000, Vietnam

² National Institute for Environmental Studies, 16-2 Onogawa, Ibaraki, Tsukuba 305-8506, Japan

Energies 2016, 9(8), 587; https://doi.org/10.3390/en9080587 - 27 Jul 2016

Cited by 19 | Viewed by 8919

Abstract

This study contributes to the realization of intended nationally determined contributions (INDCs) by analyzing their implications for the energy production system and the economy, and determines the role of renewable energies (RE) in reducing the challenge of committing to the INDCs. The Asia-Pacific [...] Read more.

This study contributes to the realization of intended nationally determined contributions (INDCs) by analyzing their implications for the energy production system and the economy, and determines the role of renewable energies (RE) in reducing the challenge of committing to the INDCs. The Asia-Pacific Integrated Model/Computable General Equilibrium (AIM/CGE) model was used to assess seven scenarios having the same socioeconomic development but different shares of RE in power generation. By comparing different relative reductions caused by the emission constraints vis-a-vis the business-as-usual (BaU) scenario, the mitigation costs can be estimated. Results show that the economic impact could be reduced by around 55% in terms of welfare loss (from 6.0% to 2.7%) and by around 36% in terms of gross domestic product (GDP) loss (from 3.4% to 2.1%) through the incorporation of high levels of renewable energy. Furthermore, the additional double deployment of wind and SPV to 5.4% and 12.0%, respectively, which currently comprise 43.1% of the renewable energies used in electricity generation, could reduce the GDP loss from 2.1% to 1.9% and reduce the welfare loss from 2.7% to 1.5% in order to achieve a 25.0% GHG emissions reduction. These losses are less than those in the pricing-only scenario (2.1% and 2.3%, respectively). Full article

(This article belongs to the Special Issue Energy Policy and Climate Change 2016)

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15 pages, 4063 KiB

Open AccessArticle

Investigation of Fracturing Network Propagation in Random Naturally Fractured and Laminated Block Experiments

by Yu Wang, Xiao Li^*, Jianming He

, Zhiheng Zhao and Bo Zheng

Key Laboratory of Shale Gas and Geoengineering, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029, China

Energies 2016, 9(8), 588; https://doi.org/10.3390/en9080588 - 28 Jul 2016

Cited by 37 | Viewed by 5739

Abstract

Researchers have recently realized thatsilty laminas are very developed in naturally fractured continentalsedimentary formations in the Ordos Basin(China). Studies have shown that silty laminas are significant to improve the physical properties and gas storage capacity, and the natural fractures interact with the hydraulic [...] Read more.

Researchers have recently realized thatsilty laminas are very developed in naturally fractured continentalsedimentary formations in the Ordos Basin(China). Studies have shown that silty laminas are significant to improve the physical properties and gas storage capacity, and the natural fractures interact with the hydraulic fractures to maximize the fracture network during hydraulic fracturing. However, the influence of silty laminas withrandom fractures on the created hydraulic fracture networkis not well understood. Laboratory experiments are proposed to investigate the evolution of fracture networks in naturally fractured formations with model blocks that contain laminas and random fractures. The influence of dominating factors was studied and analyzed, with an emphasis on stress ratio, injection rate, and laminae strength. Macroscopic failure morphology descriptions combined with meso 3-D laser scanning techniques are both used to reveal the evolution of fracture networks. It is suggested that high injection rate, medium laminae strength, and low stress ratio tend to increase the stimulated reservoir volume (SRV). The interactions between the silty laminae and random natural fractures affect the effect of hydraulic fracturing effectiveness. This work strongly links the production technology and fracability evaluation in the continental shale formation. It can aid in the understanding and optimization of hydraulic fracturing simulations in silty laminae shale reservoirs. Full article

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23 pages, 12993 KiB

Open AccessArticle

Analytical Investigation of the Magnetic-Field Distribution in an Axial Magnetic-Field-Modulated Brushless Double-Rotor Machine

by Chengde Tong

, Zhiyi Song, Jingang Bai, Jiaqi Liu and Ping Zheng^*

Department of Electrical Engineering, Harbin Institute of Technology, Harbin 150080, Heilongjiang, China

Energies 2016, 9(8), 589; https://doi.org/10.3390/en9080589 - 27 Jul 2016

Cited by 7 | Viewed by 4131

Abstract

The axial magnetic-field-modulated brushless double-rotor machine (MFM-BDRM) is a novel possible alternative power-split device for hybrid electric vehicles (HEVs). This paper proposes a two-dimensional (2-D) analytical method to predict the performance of the axial MFM-BDRM to reduce computing time. The computation is based [...] Read more.

The axial magnetic-field-modulated brushless double-rotor machine (MFM-BDRM) is a novel possible alternative power-split device for hybrid electric vehicles (HEVs). This paper proposes a two-dimensional (2-D) analytical method to predict the performance of the axial MFM-BDRM to reduce computing time. The computation is based on the solution of Laplace’s or Poisson’s equation with boundary conditions for each elementary rectangular region. By taking account of the existence of modulating ring and the stator slotting effect, the proposed model is able to calculate magnetic-field distribution with high accuracy. In order to assess the proposed method, the 2-D analytical and three-dimensional (3-D) finite element analysis (FEA) results have been compared, and good agreements have been achieved. As the analytical computation is much faster and more flexible, the proposed method can be used in the preliminary design process of the axial MFM-BDRM. Full article

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17 pages, 2791 KiB

Open AccessEditor’s ChoiceArticle

Dynamic Prediction of Power Storage and Delivery by Data-Based Fractional Differential Models of a Lithium Iron Phosphate Battery

by Yunfeng Jiang^*, Xin Zhao, Amir Valibeygi and Raymond A. De Callafon

Department of Mechanical and Aerospace Engineering, University of California San Diego, 9500 Gilman Drive, La Jolla, CA 92093, USA

Energies 2016, 9(8), 590; https://doi.org/10.3390/en9080590 - 27 Jul 2016

Cited by 11 | Viewed by 5935

Abstract

A fractional derivative system identification approach for modeling battery dynamics is presented in this paper, where fractional derivatives are applied to approximate non-linear dynamic behavior of a battery system. The least squares-based state-variable filter (LSSVF) method commonly used in the identification of continuous-time [...] Read more.

A fractional derivative system identification approach for modeling battery dynamics is presented in this paper, where fractional derivatives are applied to approximate non-linear dynamic behavior of a battery system. The least squares-based state-variable filter (LSSVF) method commonly used in the identification of continuous-time models is extended to allow the estimation of fractional derivative coefficents and parameters of the battery models by monitoring a charge/discharge demand signal and a power storage/delivery signal. In particular, the model is combined by individual fractional differential models (FDMs), where the parameters can be estimated by a least-squares algorithm. Based on experimental data, it is illustrated how the fractional derivative model can be utilized to predict the dynamics of the energy storage and delivery of a lithium iron phosphate battery (LiFePO

_{4}

) in real-time. The results indicate that a FDM can accurately capture the dynamics of the energy storage and delivery of the battery over a large operating range of the battery. It is also shown that the fractional derivative model exhibits improvements on prediction performance compared to standard integer derivative model, which in beneficial for a battery management system. Full article

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24 pages, 503 KiB

Open AccessArticle

Multi-Objective Optimal Sizing for Battery Storage of PV-Based Microgrid with Demand Response

by Nan Zhou¹, Nian Liu^1,*

, Jianhua Zhang¹ and Jinyong Lei²

¹ State Key Laboratory for Alternate Electrical Power System with Renewable Energy Sources, North China Electric Power University, Changping District, Beijing 102206, China

² Electric Power Research Institute, China Southern Power Grid Co., Ltd., Guangzhou 510080, Guangdong Province, China

Energies 2016, 9(8), 591; https://doi.org/10.3390/en9080591 - 28 Jul 2016

Cited by 57 | Viewed by 7953

Abstract

In order to solve the influence of uncertain photovoltaic power (PV) on the stable operation of microgrid (MG), demand response (DR) and battery energy storage system (BESS) need to be introduced simultaneously into the operation optimal scheduling of PV-based microgrid (PV-MG). Therefore, it [...] Read more.

In order to solve the influence of uncertain photovoltaic power (PV) on the stable operation of microgrid (MG), demand response (DR) and battery energy storage system (BESS) need to be introduced simultaneously into the operation optimal scheduling of PV-based microgrid (PV-MG). Therefore, it is of great significance for commercial investment decisions of PV-MG to consider the influence of DR on BESS optimal sizing. Under the peak-valley time-of-use (TOU) price, this paper builds cross-time DR models based on price elasticity matrix. Furthermore, through the introduction of DR and BESS into PV-MG scheduling optimization, the MG investment and benefit model is proposed. Considering the constraint condition such as co-ordination of supply and demand, electricity price elasticity and energy loss of storage system, the improved non-dominated sorting genetic algorithm II (NSGA-II) is utilized to solve the multi-objective optimal allocation model of the BESS with the target of maximum PV consumptive rate and annual net profits. The optimization method was applied to a PV-MG in Guangdong. Through the regulation and control effect of demand response and BESS on load distribution, the uncertainties PV power can be suppressed so as to improve the PV system consumptive level, which is of great guiding significance for BESS optimal sizing under this situation. Full article

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21 pages, 1389 KiB

Open AccessArticle

An Integer Linear Programming Model for an Ecovat Buffer

by Gijs J. H. De Goeijen^*, Gerard J. M. Smit and Johann L. Hurink

Department of Electrical Engineering, Mathematics and Computer Science, University of Twente, Enschede 7522 NB, The Netherlands

Energies 2016, 9(8), 592; https://doi.org/10.3390/en9080592 - 28 Jul 2016

Cited by 5 | Viewed by 4178

Abstract

An increase in the number of volatile renewables in the electricity grid enhances the imbalance of supply and demand. One promising candidate to solve this problem is to improve the energy storage. The Ecovat system is a new seasonal thermal energy storage system [...] Read more.

An increase in the number of volatile renewables in the electricity grid enhances the imbalance of supply and demand. One promising candidate to solve this problem is to improve the energy storage. The Ecovat system is a new seasonal thermal energy storage system currently under development. In this paper, an integer linear programming model is developed to describe the behaviour and potential of this system. Furthermore, it is compared with a previously developed model, which is simplifying the behaviour of the Ecovat system much more, but is much less computationally expensive. It is shown that the new approach performs significantly better for several cases. For controlling a real Ecovat system in the future we may incorporate a number of improvements identified by our comparison analysis into the previously developed approach, which may help increase the quality of the obtained results without increasing the computational effort too much. Full article

(This article belongs to the Special Issue Decentralized Management of Energy Streams in Smart Grids)

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25 pages, 812 KiB

Open AccessArticle

Energy Optimization in Smart Homes Using Customer Preference and Dynamic Pricing

by Muhammad Babar Rasheed¹, Nadeem Javaid^1,*

, Ashfaq Ahmad¹

, Mohsin Jamil²

, Zahoor Ali Khan³

, Umar Qasim⁴

and Nabil Alrajeh⁵

¹ COMSATS Institute of Information Technology, Islamabad 44000, Pakistan

² School of Mechanical & Manufacturing Engineering, National University of Science and Technology, Islamabad 44000, Pakistan

³ Internetworking Program, Faculty of Engineering, Dalhousie University, Halifax, NS B3J 4R2, Canada

⁴ Cameron Library, University of Alberta, Edmonton, AB T6G 2J8, Canada

⁵ Department of Biomedical Technology, College of Applied Medical Sciences, King Saud University, Riyadh 11633, Saudi Arabia

Energies 2016, 9(8), 593; https://doi.org/10.3390/en9080593 - 27 Jul 2016

Cited by 46 | Viewed by 7523

Abstract

In this paper, we present an energy optimization technique to schedule three types of household appliances (user dependent, interactive schedulable and unschedulable) in response to the dynamic behaviours of customers, electricity prices and weather conditions. Our optimization technique schedules household appliances in real [...] Read more.

In this paper, we present an energy optimization technique to schedule three types of household appliances (user dependent, interactive schedulable and unschedulable) in response to the dynamic behaviours of customers, electricity prices and weather conditions. Our optimization technique schedules household appliances in real time to optimally control their energy consumption, such that the electricity bills of end users are reduced while not compromising on user comfort. More specifically, we use the binary multiple knapsack problem formulation technique to design an objective function, which is solved via the constraint optimization technique. Simulation results show that average aggregated energy savings with and without considering the human presence control system are 11.77% and 5.91%, respectively. Full article

(This article belongs to the Special Issue Energy Efficient City)

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16 pages, 307 KiB

Open AccessArticle

Robust Peak-Shaving for a Neighborhood with Electric Vehicles

by Marco E. T. Gerards^*

and Johann L. Hurink

Faculty of Electrical Engineering, Mathematics and Computer Science, 7500 AE Enschede, The Netherlands

Energies 2016, 9(8), 594; https://doi.org/10.3390/en9080594 - 28 Jul 2016

Cited by 19 | Viewed by 5376

Abstract

Demand Side Management (DSM) is a popular approach for grid-aware peak-shaving. The most commonly used DSM methods either have no look ahead feature and risk deploying flexibility too early, or they plan ahead using predictions, which are in general not very reliable. To [...] Read more.

Demand Side Management (DSM) is a popular approach for grid-aware peak-shaving. The most commonly used DSM methods either have no look ahead feature and risk deploying flexibility too early, or they plan ahead using predictions, which are in general not very reliable. To counter this, a DSM approach is presented that does not rely on detailed power predictions, but only uses a few easy to predict characteristics. By using these characteristics alone, near optimal results can be achieved for electric vehicle (EV) charging, and a bound on the maximal relative deviation is given. This result is extended to an algorithm that controls a group of EVs such that a transformer peak is avoided, while simultaneously keeping the individual house profiles as flat as possible to avoid cable overloading and for improved power quality. This approach is evaluated using different data sets to compare the results with the state-of-the-art research. The evaluation shows that the presented approach is capable of peak-shaving at the transformer level, while keeping the voltages well within legal bounds, keeping the cable load low and obtaining low losses. Further advantages of the methodology are a low communication overhead, low computational requirements and ease of implementation. Full article

(This article belongs to the Special Issue Decentralized Management of Energy Streams in Smart Grids)

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19 pages, 5725 KiB

Open AccessArticle

An Event-Based Resource Management Framework for Distributed Decision-Making in Decentralized Virtual Power Plants

by Jianchao Zhang, Boon-Chong Seet^*

and Tek Tjing Lie

Department of Electrical and Electronic Engineering, Auckland University of Technology, Auckland 1010, New Zealand

Energies 2016, 9(8), 595; https://doi.org/10.3390/en9080595 - 28 Jul 2016

Cited by 10 | Viewed by 4788

Abstract

The Smart Grid incorporates advanced information and communication technologies (ICTs) in power systems, and is characterized by high penetration of distributed energy resources (DERs). Whether it is the nation-wide power grid or a single residential building, the energy management involves different types of [...] Read more.

The Smart Grid incorporates advanced information and communication technologies (ICTs) in power systems, and is characterized by high penetration of distributed energy resources (DERs). Whether it is the nation-wide power grid or a single residential building, the energy management involves different types of resources that often depend on and influence each other. The concept of virtual power plant (VPP) has been proposed to represent the aggregation of energy resources in the electricity market, and distributed decision-making (DDM) plays a vital role in VPP due to its complex nature. This paper proposes a framework for managing different resource types of relevance to energy management for decentralized VPP. The framework views VPP as a hierarchical structure and abstracts energy consumption/generation as contractual resources, i.e., contractual offerings to curtail load/supply energy, from third party VPP participants for DDM. The proposed resource models, event-based approach to decision making, multi-agent system and ontology implementation of the framework are presented in detail. The effectiveness of the proposed framework is then demonstrated through an application to a simulated campus VPP with real building energy data. Full article

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18 pages, 12694 KiB

Open AccessArticle

Comparative Analysis of Voltage Control in Battery Power Converters for Inverter-Based AC Microgrids

by Woo-Kyu Chae¹, Jong-Nam Won¹, Hak-Ju Lee¹, Jae-Eon Kim² and Jaehong Kim^3,*

¹ Research Institute, Korea Electric Power Corporation, Munji-ro 105, Yuseong-gu, Daejeon 34056, Korea

² School of Electrical Engineering, Chungbuk National University, Chungbuk 361-763, Korea

³ Department of Electrical Engineering, Chosun University, Pilmun-daero 309, Dong-gu, Gwangju 61452, Korea

Energies 2016, 9(8), 596; https://doi.org/10.3390/en9080596 - 28 Jul 2016

Cited by 7 | Viewed by 5359

Abstract

A microgrid is a micro-power system composed of local distributed generators, energy storage systems, loads, and other components in a local power network. Because renewable energy sources show relatively large output power variation, the integration of distributed generators in a microgrid often requires [...] Read more.

A microgrid is a micro-power system composed of local distributed generators, energy storage systems, loads, and other components in a local power network. Because renewable energy sources show relatively large output power variation, the integration of distributed generators in a microgrid often requires the installation of a large-scale energy storage system. The energy storage system is connected to a local AC bus via the DC/AC converter with an output inductor-capacitor (LC) filter. The energy storage system power converters generally form the local AC bus voltage. This grid-forming operation requires fast and robust voltage control to properly maintain a stable energy flow and high power quality in the local AC bus. In this paper, two major voltage control schemes—double-loop control and direct voltage control—are analytically compared, and their effects on the power quality of the microgrid are illustrated. The dynamic performance is compared through simulations and experimental results. Full article

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12 pages, 5001 KiB

Open AccessArticle

A Selection Method for Power Generation Plants Used for Enhanced Geothermal Systems (EGS)

by Kaiyong Hu^1,2, Jialing Zhu^1,2, Wei Zhang^1,2 and Xinli Lu^1,2,*

¹ Tianjin Geothermal Research and Training Center, Tianjin University, Tianjin 300072, China

² Key Laboratory of Efficient Utilization of Low and Medium Grade energy, Ministry of Education of the People’s Republic of China, Tianjin University, Tianjin 300072, China

Energies 2016, 9(8), 597; https://doi.org/10.3390/en9080597 - 28 Jul 2016

Cited by 6 | Viewed by 5567

Abstract

As a promising and advanced technology, enhanced geothermal systems (EGS) can be used to generate electricity using deep geothermal energy. In order to better utilize the EGS to produce electricity, power cycles’ selection maps are generated for people to choose the best system [...] Read more.

As a promising and advanced technology, enhanced geothermal systems (EGS) can be used to generate electricity using deep geothermal energy. In order to better utilize the EGS to produce electricity, power cycles’ selection maps are generated for people to choose the best system based on the geofluids’ temperature and dryness conditions. Optimizations on double-flash system (DF), flash-organic Rankine cycle system (FORC), and double-flash-organic Rankine cycle system (DFORC) are carried out, and the single-flash (SF) system is set as a reference system. The results indicate that each upgraded system (DF, FORC, and DFORC) can produce more net power output compared with the SF system and can reach a maximum net power output under a given geofluid condition. For an organic Rankine cycle (ORC) using R245fa as working fluid, the generated selection maps indicate that using the FORC system can produce more power than using other power cycles when the heat source temperature is below 170 °C. Either DF or DFORC systems could be an option if the heat source temperature is above 170 °C, but the DF system is more attractive under a relatively lower geofluid’s dryness and a higher temperature condition. Full article

(This article belongs to the Special Issue Selected Papers from the 5th Annual Conference for the Development and Utilization of Deep Geothermal Energy)

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15 pages, 4859 KiB

Open AccessArticle

Gas-Path Health Estimation for an Aircraft Engine Based on a Sliding Mode Observer

by Xiaodong Chang

, Jinquan Huang^*, Feng Lu and Haobo Sun

College of Energy and Power Engineering, Nanjing University of Aeronautics and Astronautics, 29 Yudao Road, Nanjing 210016, China

Energies 2016, 9(8), 598; https://doi.org/10.3390/en9080598 - 29 Jul 2016

Cited by 16 | Viewed by 4049

Abstract

Aircraft engine gas-path health monitoring (GPHM) plays a critical role in engine health management (EHM). Among model-based approaches, the Kalman filter (KF) has been widely employed in GPHM. The main shortcoming of KF-based scheme lies in the lack of robustness against uncertainties. To [...] Read more.

Aircraft engine gas-path health monitoring (GPHM) plays a critical role in engine health management (EHM). Among model-based approaches, the Kalman filter (KF) has been widely employed in GPHM. The main shortcoming of KF-based scheme lies in the lack of robustness against uncertainties. To enhance robustness, this paper describes a new GPHM architecture using a sliding mode observer (SMO). The convergence of the error system in uncertainty-existing circumstances is demonstrated, and the proposed method is developed to estimate components’ performance degradations regardless of modeling uncertainties. Simulations using a nonlinear model of a turbofan engine are presented, in which health monitoring problems are handled by the KF and the SMO, respectively. Results indicate the proposed approach possesses better diagnostic performance compared to the KF-based scheme, and the SMO shows its strong robustness and great potential to be applied to GPHM. Full article

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13 pages, 3382 KiB

Open AccessArticle

On-Site Measurements of CO₂ Emissions during the Construction Phase of a Building Complex

by Min-Seop Seo¹, Taeyeon Kim^2,*, Goopyo Hong² and Hyungkeun Kim²

¹ POSCO E & C, 241 Main Street of Incheon Tower, Incheon 22009, Korea

² Department of Architectural Engineering, Yonsei University, Seoul 03722, Korea

Energies 2016, 9(8), 599; https://doi.org/10.3390/en9080599 - 28 Jul 2016

Cited by 54 | Viewed by 10677

Abstract

This study describes the environmental impact of the material production, transportation, and construction phases from the construction site perspective. CO₂ emissions for each process were determined using the Korea Life Cycle Inventory Database (LCI DB) in the material production phase, and the [...] Read more.

This study describes the environmental impact of the material production, transportation, and construction phases from the construction site perspective. CO₂ emissions for each process were determined using the Korea Life Cycle Inventory Database (LCI DB) in the material production phase, and the actual amounts of oil consumption for transportation equipment were identified in the material transportation phase. Generally, the oil and electric energy consumed during the construction was evaluated by direct monitoring. Through the construction period and cost according to work type, a correlation with CO₂ emissions was also investigated. In addition, CO₂ emissions were examined through the system capacity and gross floor area for each work type. The calculations have shown that CO₂ emissions from the material production phase constitute 93.4% of the total CO₂ emissions. In addition, CO₂ emissions from the material transportation and on-site construction account for 2.4% and 4.2% of the total CO₂ emissions, respectively. This paper concludes that it is important to select appropriate input materials and resources for the reduction of CO₂ emissions. Furthermore, the amount of CO₂ emissions arising from the construction site was reduced by finding and practicing measures to reduce CO₂ emissions for each process. Full article

(This article belongs to the Special Issue CO₂ Capture)

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21 pages, 1173 KiB

Open AccessArticle

Electricity Price Forecasting by Averaging Dynamic Factor Models

by Andrés M. Alonso^1,2

, Guadalupe Bastos^1,* and Carolina García-Martos³

¹ Department of Statistics, Universidad Carlos III de Madrid, Getafe 28903, Madrid, Spain

² Instituto Flores de Lemus, Universidad Carlos III de Madrid, Getafe 28903, Madrid, Spain

³ Escuela Técnica Superior de Ingenieros Industriales, Universidad Politécnica de Madrid, Madrid 28040, Spain

Energies 2016, 9(8), 600; https://doi.org/10.3390/en9080600 - 28 Jul 2016

Cited by 14 | Viewed by 5509

Abstract

In the context of the liberalization of electricity markets, forecasting prices is essential. With this aim, research has evolved to model the particularities of electricity prices. In particular, dynamic factor models have been quite successful in the task, both in the short and [...] Read more.

In the context of the liberalization of electricity markets, forecasting prices is essential. With this aim, research has evolved to model the particularities of electricity prices. In particular, dynamic factor models have been quite successful in the task, both in the short and long run. However, specifying a single model for the unobserved factors is difficult, and it cannot be guaranteed that such a model exists. In this paper, model averaging is employed to overcome this difficulty, with the expectation that electricity prices would be better forecast by a combination of models for the factors than by a single model. Although our procedure is applicable in other markets, it is illustrated with an application to forecasting spot prices of the Iberian Market, MIBEL (The Iberian Electricity Market). Three combinations of forecasts are successful in providing improved results for alternative forecasting horizons. Full article

(This article belongs to the Special Issue Energy Time Series Forecasting)

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15 pages, 383 KiB

Open AccessArticle

Efficient Use of Energy Resources on French Farms: An Analysis through Technical Efficiency

by Mohamed Ghali^1,*, Laure Latruffe² and Karine Daniel¹

¹ Ecole Supérieure d’Agricultures Angers-Loire (ESA), Social Sciences Laboratory, LARESS, Angers 49007, France

² Structures and Markets in Agriculture, Resources and Territories (SMART), French National Institute for Agricultural Research (INRA), Rennes 35000, France

Energies 2016, 9(8), 601; https://doi.org/10.3390/en9080601 - 29 Jul 2016

Cited by 13 | Viewed by 6327

Abstract

Integrating natural resources and ecological services in the production process is crucial to implement sustainable agriculture. However, the measurement of natural resource efficiency remains difficult. This paper aims at contributing to this issue, by investigating French farms’ use and excess (slack) of energy [...] Read more.

Integrating natural resources and ecological services in the production process is crucial to implement sustainable agriculture. However, the measurement of natural resource efficiency remains difficult. This paper aims at contributing to this issue, by investigating French farms’ use and excess (slack) of energy resources through Data Envelopment Analyses (DEA). Results show that disentangling energy resources from the rest of intermediate consumption highlights energy use excess which is masked when considering intermediate consumption as a whole. The analysis of the determinants of energy use excess and of intermediate consumption shows a discrepancy in results, which policy-makers should take into account when designing energy policies. In addition, results show that large and highly capital intensive farms perform better in terms of energy use excess, while the dependence on public subsidies is a constraint. Full article

(This article belongs to the Special Issue Energy for Agriculture)

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16 pages, 4076 KiB

Open AccessEditor’s ChoiceArticle

City Carbon Footprint Networks

by Guangwu Chen^1,*

, Thomas Wiedmann^1,2

, Michalis Hadjikakou¹

and Hazel Rowley¹

¹ Sustainability Assessment Program (SAP), Water Research Centre, School of Civil and Environmental Engineering, UNSW Australia, Sydney, NSW 2052, Australia

² Integrated Sustainability Analysis (ISA), School of Physics A28, The University of Sydney, Sydney, NSW 2006, Australia

Energies 2016, 9(8), 602; https://doi.org/10.3390/en9080602 - 29 Jul 2016

Cited by 62 | Viewed by 12191

Abstract

Progressive cities worldwide have demonstrated political leadership by initiating meaningful strategies and actions to tackle climate change. However, the lack of knowledge concerning embodied greenhouse gas (GHG) emissions of cities has hampered effective mitigation. We analyse trans-boundary GHG emission transfers between five Australian [...] Read more.

Progressive cities worldwide have demonstrated political leadership by initiating meaningful strategies and actions to tackle climate change. However, the lack of knowledge concerning embodied greenhouse gas (GHG) emissions of cities has hampered effective mitigation. We analyse trans-boundary GHG emission transfers between five Australian cities and their trading partners, with embodied emission flows broken down into major economic sectors. We examine intercity carbon footprint (CF) networks and disclose a hierarchy of responsibility for emissions between cities and regions. Allocations of emissions to households, businesses and government and the carbon efficiency of expenditure have been analysed to inform mitigation policies. Our findings indicate that final demand in the five largest cities in Australia accounts for more than half of the nation’s CF. City households are responsible for about two thirds of the cities’ CFs; the rest can be attributed to government and business consumption and investment. The city network flows highlight that over half of emissions embodied in imports (EEI) to the five cities occur overseas. However, a hierarchy of GHG emissions reveals that overseas regions also outsource emissions to Australian cities such as Perth. We finally discuss the implications of our findings on carbon neutrality, low-carbon city concepts and strategies and allocation of subnational GHG responsibility. Full article

(This article belongs to the Special Issue Energy Efficient City)

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17 pages, 8535 KiB

Open AccessArticle

A Photovoltaic-Based SEPIC Converter with Dual-Fuzzy Maximum Power Point Tracking for Optimal Buck and Boost Operations

by Tanaselan Ramalu^1,2,*, Mohd Amran Mohd Radzi^1,2

, Muhammad Ammirrul Atiqi Mohd Zainuri^1,2

, Noor Izzri Abdul Wahab^1,2

and Ribhan Zafira Abdul Rahman¹

¹ Department of Electrical and Electronic Engineering, Faculty of Engineering, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia

² Centre for Advanced Power and Energy Research, Faculty of Engineering, University Putra Malaysia, 43400 Serdang, Selangor, Malaysia

Energies 2016, 9(8), 604; https://doi.org/10.3390/en9080604 - 30 Jul 2016

Cited by 17 | Viewed by 5276

Abstract

In this paper, a photovoltaic (PV)-based single ended primary-inductor converter (SEPIC) is developed with introduction of dual-fuzzy logic controller (FLC) maximum power point tracking (MPPT) algorithm. Separate FLC parts, for the first time used for MPPT, are configured for optimal operations of both [...] Read more.

In this paper, a photovoltaic (PV)-based single ended primary-inductor converter (SEPIC) is developed with introduction of dual-fuzzy logic controller (FLC) maximum power point tracking (MPPT) algorithm. Separate FLC parts, for the first time used for MPPT, are configured for optimal operations of both buck and boost operations. During buck operation, a high overshoot voltage exists, and during boost operation, an undershoot voltage occurs, both during the initial rising period. Definitely, a single-FLC MPPT could not be able to minimize both problems, which on the other hand can be handled by the proposed MPPT algorithm. For evaluation purposes, buck operation has been conducted during high irradiance, while during low irradiance, boost operation has been conducted. The dual-FLC MPPT with SEPIC was simulated in MATLAB-Simulink, and further a laboratory prototype was implemented with a TMS320F28335 eZdsp board. Both simulation and experimental results and comparison analysis (with the single-FLC MPPT) have been presented. From the results and analysis, the dual-FLC MPPT performs better than the single-FLC MPPT in terms of faster response time, lower overshoot and undershoot, and further significant reduction of power losses. Full article

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16 pages, 6532 KiB

Open AccessArticle

Effectiveness of Using Phase Change Materials on Reducing Summer Overheating Issues in UK Residential Buildings with Identification of Influential Factors

by Marine Auzeby^1,2, Shen Wei^2,*

, Chris Underwood², Jess Tindall², Chao Chen³, Haoshu Ling³ and Richard Buswell⁴

¹ Civil Engineering and Urban Planning Department, Institut National des Sciences Appliquées de Lyon, Villeurbanne F-69621, France

² Faculty of Engineering and Environment, Newcastle Upon Tyne NE1 8ST, UK

³ College of Architecture and Civil Engineering, Beijing University of Technology, Beijing 100124, China

⁴ School of Civil and Building Engineering, Loughborough University, Loughborough LE11 3TU, UK

Energies 2016, 9(8), 605; https://doi.org/10.3390/en9080605 - 1 Aug 2016

Cited by 42 | Viewed by 6577

Abstract

The UK is currently suffering great overheating issues in summer, especially in residential buildings where no air-conditioning has been installed. This overheating will seriously affect people’s comfort and even health, especially for elderly people. Phase change materials (PCMs) have been considered as a [...] Read more.

The UK is currently suffering great overheating issues in summer, especially in residential buildings where no air-conditioning has been installed. This overheating will seriously affect people’s comfort and even health, especially for elderly people. Phase change materials (PCMs) have been considered as a useful passive method, which absorb excessive heat when the room is hot and release the stored heat when the room is cool. This research has adopted a simulation method in DesignBuilder to evaluate the effectiveness of using PCMs to reduce the overheating issues in UK residential applications and has analyzed potential factors that will influence the effectiveness of overheating. The factors include environment-related (location of the building, global warming/climate change) and construction-related (location of the PCM, insulation, heavyweight/lightweight construction). This research provides useful evidence about using PCMs in UK residential applications and the results are helpful for architects and engineers to decide when and where to use PCMs in buildings to maintain a low carbon lifestyle. Full article

(This article belongs to the Special Issue PCM Applications in Building Energy)

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15 pages, 5890 KiB

Open AccessArticle

Experimental and Numerical Analyses on the Rotary Vane Expander Operating Conditions in a Micro Organic Rankine Cycle System

by Piotr Kolasiński^*, Przemysław Błasiak and Józef Rak

Department of Thermodynamics, Theory of Machines and Thermal Systems, Faculty of Mechanical and Power Engineering, Wrocław University of Science and Technology, Wybrzeże Wyspiańskiego 27, Wrocław 50-370, Poland

Energies 2016, 9(8), 606; https://doi.org/10.3390/en9080606 - 1 Aug 2016

Cited by 42 | Viewed by 6307

Abstract

Micro (0.5–10 kW) organic Rankine cycle (ORC) power systems are nowadays considered for domestic power generation. Selection of a suitable expander is one of the most important problems connected with the domestic ORC system design. Volumetric machines or micro-turbines can be adopted as [...] Read more.

Micro (0.5–10 kW) organic Rankine cycle (ORC) power systems are nowadays considered for domestic power generation. Selection of a suitable expander is one of the most important problems connected with the domestic ORC system design. Volumetric machines or micro-turbines can be adopted as an expander in domestic ORC systems. Scroll and screw expanders are a common choice and were successfully applied in different small- and micro-power applications. However, micro-turbines as well as scroll and screw expanders are mechanically complicated and expensive. An alternative are rotary-vane machines, which are simple and cheap compared to micro-turbines. This paper documents a study providing the experimental and numerical analyses on the rotary vane expander operating conditions in a micro-ORC system. A test-stand was designed and set up and a series of experiments was performed using the test-stand. Results of these experiments were further used as an input to numerical simulations of an expander operation. In order to simulate the expander operating conditions, a three-dimensional numerical model has been prepared. The analysis presented in this paper indicates that a properly designed multi-vane expander is a cheap and mechanically simple alternative to other expansion devices proposed for domestic ORC systems. Full article

(This article belongs to the Special Issue Recent Advances in Organic Rankine Cycle Technology for Stationary Applications)

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16 pages, 1357 KiB

Open AccessArticle

Unshrouded Plate Fin Heat Sinks for Electronics Cooling: Validation of a Comprehensive Thermal Model and Cost Optimization in Semi-Active Configuration

by Luigi Ventola¹, Gabriele Curcuruto¹, Matteo Fasano¹

, Saverio Fotia², Vincenzo Pugliese², Eliodoro Chiavazzo¹

and Pietro Asinari^1,*

¹ Energy Department, Politecnico di Torino, Corso Duca degli Abruzzi 24, 10129 Torino (TO), Italy

² DENSO Thermal Systems, 10046 Poirino (TO), Italy

Energies 2016, 9(8), 608; https://doi.org/10.3390/en9080608 - 2 Aug 2016

Cited by 13 | Viewed by 9067

Abstract

Plate Fin Heat Sinks (PFHS) are among the simplest and most widespread devices for electronics cooling. Because of the many design parameters to be considered, developing both cost and thermal effective PFHS is a critical issue. Here, a novel thermal model of PFHS [...] Read more.

Plate Fin Heat Sinks (PFHS) are among the simplest and most widespread devices for electronics cooling. Because of the many design parameters to be considered, developing both cost and thermal effective PFHS is a critical issue. Here, a novel thermal model of PFHS is presented. The model has a broad field of applicability, being comprehensive of the effects of flow bypass, developing boundary layers, fin efficiency and spreading resistance. Experiments are then carried out to validate the proposed thermal model, and its good accuracy is demonstrated. Finally, an optimization methodology based on genetic algorithms is proposed for a cost-effective selection of the design parameters of PFHS, which is particularly effective with semi-active configurations. Such an optimization methodology is then tested on a commercial heat sink, resulting in a possible 53% volume reduction at fixed thermal performances. Full article

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14 pages, 2511 KiB

Open AccessArticle

Real Time Hybrid Model Predictive Control for the Current Profile of the Tokamak à Configuration Variable (TCV)

by Izaskun Garrido^1,*, Aitor J. Garrido¹, Stefano Coda², Hoang B. Le² and Jean Marc Moret²

¹ Faculty of Engineering, University of the Basque Country (UPV/EHU), Paseo Rafael Moreno 3, Bilbao 48013, Spain

² Centre de Recherches en Physique des Plasmas, École Polytechnique Fédérale de Lausanne (CRPP-EPFL), CH-1015 Lausanne, Switzerland

Energies 2016, 9(8), 609; https://doi.org/10.3390/en9080609 - 3 Aug 2016

Cited by 10 | Viewed by 5534

Abstract

Plasma stability is one of the obstacles in the path to the successful operation of fusion devices. Numerical control-oriented codes as it is the case of the widely accepted RZIp may be used within Tokamak simulations. The novelty of this article relies in [...] Read more.

Plasma stability is one of the obstacles in the path to the successful operation of fusion devices. Numerical control-oriented codes as it is the case of the widely accepted RZIp may be used within Tokamak simulations. The novelty of this article relies in the hierarchical development of a dynamic control loop. It is based on a current profile Model Predictive Control (MPC) algorithm within a multiloop structure, where a MPC is developed at each step so as to improve the Proportional Integral Derivative (PID) global scheme. The inner control loop is composed of a PID-based controller that acts over the Multiple Input Multiple Output (MIMO) system resulting from the RZIp plasma model of the Tokamak à Configuration Variable (TCV). The coefficients of this PID controller are initially tuned using an eigenmode reduction over the passive structure model. The control action corresponding to the state of interest is then optimized in the outer MPC loop. For the sake of comparison, both the traditionally used PID global controller as well as the multiloop enhanced MPC are applied to the same TCV shot. The results show that the proposed control algorithm presents a superior performance over the conventional PID algorithm in terms of convergence. Furthermore, this enhanced MPC algorithm contributes to extend the discharge length and to overcome the limited power availability restrictions that hinder the performance of advanced tokamaks. Full article

(This article belongs to the Special Issue Fusion Power)

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16 pages, 6136 KiB

Open AccessArticle

A Study of an Effective Heat-Dissipating Piezoelectric Fan for High Heat Density Devices

by Chien-Nan Lin^1,*, Jiin-Yuh Jang² and Jin-Sheng Leu³

¹ Department of Mechanical Engineering, Far East University, Tainan 74448, Taiwan

² Department of Mechanical Engineering, National Cheng-Kung University, Tainan 70101, Taiwan

³ Department of Mechanical Engineering, Air Force Institute of Technology, Kaohsiung 82047, Taiwan

Energies 2016, 9(8), 610; https://doi.org/10.3390/en9080610 - 3 Aug 2016

Cited by 15 | Viewed by 4546

Abstract

Heat dissipation per unit volume has grown rapidly, as the size of modern electronic devices has continued to decrease. The air flow induced by an oscillating cantilever blade enhances the heat transfer performance of high heat density devices. The heat transfer improvement mainly [...] Read more.

Heat dissipation per unit volume has grown rapidly, as the size of modern electronic devices has continued to decrease. The air flow induced by an oscillating cantilever blade enhances the heat transfer performance of high heat density devices. The heat transfer improvement mainly depends on the velocity magnitude and distribution of air streams induced by the vibrating blade. Accordingly, this study numerically and experimentally examines the time-varying flow characteristics of a vibrating cantilever for five blade types. The blades are rectangular or trapezoidal with various widths and actuated at various frequencies. The fluid domain is numerically discretized using a dynamic meshing scheme to model the three-dimensional time-varying vibrating blade. The experiment utilizes nine hot-wire velocity meters to measure the average velocities. The flow structure with streamlines and velocity contours of the induced air flow are determined at various section planes. The results show that a major maximum-velocity region appears around the blade tip and that four minor local-maximum-velocity regions appear at the four corners. In addition, the width and width ratio of the blade significantly affects the velocity distribution of the flow induced by the vibrating cantilever blade. Full article

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12 pages, 2497 KiB

Open AccessArticle

Environment-Friendly Heterogeneous Alkaline-Based Mixed Metal Oxide Catalysts for Biodiesel Production

by Hwei Voon Lee^1,*, Joon Ching Juan^1,2, Taufiq-Yap Yun Hin³ and Hwai Chyuan Ong^4,*

¹ Nanotechnology & Catalysis Research Centre (NanoCat), Institute of Postgraduate Studies, University Malaya, 50603 Kuala Lumpur, Malaysia

² Monash University, Sunway Campus, Jalan Lagoon Selatan, 46150 Sunway Selangor, Malaysia

³ Catalysis Science and Technology Research Centre (PutraCat), Faculty of Science, Universiti Putra Malaysia, 43400 UPM Serdang, Selangor, Malaysia

⁴ Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia

Energies 2016, 9(8), 611; https://doi.org/10.3390/en9080611 - 3 Aug 2016

Cited by 56 | Viewed by 8000

Abstract

The critical problem arising from the depletion of fossil fuels has stimulated recent interests in alternative sources for petroleum-based fuel. An alternative fuel should be technically feasible, readily available, sustainable, and techno-economically competitive. Biodiesel is considered as a potential replacement of conventional diesel [...] Read more.

The critical problem arising from the depletion of fossil fuels has stimulated recent interests in alternative sources for petroleum-based fuel. An alternative fuel should be technically feasible, readily available, sustainable, and techno-economically competitive. Biodiesel is considered as a potential replacement of conventional diesel fuel, which is prepared from non-edible and high-acid feedstock via transesterification technology. The focus of this study is to investigate the catalytic activity of mixed metal oxides (MMOs) as catalysts for biodiesel production by using non-edible jatropha oil as feedstock. Various types of MMOs (CaO-MgO, CaO-ZnO, CaO-La₂O₃, and MgO-ZnO) were synthesized via a co-precipitation method. In this study, transesterification activities are closely related to the physicochemical properties of catalysts. The presence of different active metals in the binary system greatly influenced the surface area, basicity, and the stability of catalysts. The catalytic activity of MMO catalysts was increased in the order of CaO-ZnO (94% ± 1%) > CaO ~ CaO-MgO ~ CaO-La₂O₃ (~90% ± 2%) > MgO-ZnO (83% ± 2%) > MgO (64% ± 1%) > ZnO (41% ± 2%) > La₂O₃ (23% ± 1%). In addition, the MMO catalysts, especially CaO-ZnO, demonstrated high reusability and catalyst stability for four cycles of transesterification reaction of jatropha oil. Full article

(This article belongs to the Collection Bioenergy and Biofuel)

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16 pages, 5983 KiB

Open AccessArticle

Contribution of Geothermal Resources to Energy Autonomy: Evaluation and Management Methodology

by Liliana Topliceanu^* and Gabriel Petru Puiu

Engineering Faculty, “Vasile Alecsandri” University of Bacau, 157 Calea Marasesti, 600115 Bacau, Romania

Energies 2016, 9(8), 612; https://doi.org/10.3390/en9080612 - 3 Aug 2016

Cited by 4 | Viewed by 4871

Abstract

The development of renewable energy is one of the aspirations of the European Union energy policy, being generated by the struggle against climatic changes and by the intention of achieving a high rate of energy autonomy. In this context, geothermal energy is a [...] Read more.

The development of renewable energy is one of the aspirations of the European Union energy policy, being generated by the struggle against climatic changes and by the intention of achieving a high rate of energy autonomy. In this context, geothermal energy is a viable solution which has been little exploited so far. Analysing the EU’s dependence on imported energy, the paper provides a short review of the utilization of geothermal energy, of the advantages and of the problems raised by the exploitation of this resource. It also analyzes the availability of this resource in Romania and the contribution it can have towards the energy autonomy of local communities. The paper presents a particular methodology for calculating the energy autonomy. Using this methodology, one can obtain an energetic overview of the community or the area analyzed, can calculate the degree of energy autonomy and, based on the results achieved, a sustainable development strategy can be designed. The low enthalpy case study used emphasizes the way this methodology can be deployed and, moreover, allows an analysis of the contribution of geothermal energy to the degree of autonomy of the Romanian community. Full article

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21 pages, 9643 KiB

Open AccessArticle

Numerical Study of the Aerodynamic Loads on Offshore Wind Turbines under Typhoon with Full Wind Direction

by Jijian Lian^*, Yaya Jia, Haijun Wang and Fang Liu

State Key Laboratory of Hydraulic Engineering Simulation and Safety, Tianjin University, No. 92 Weijin Road, Nankai District, Tianjin 300072, China

Energies 2016, 9(8), 613; https://doi.org/10.3390/en9080613 - 3 Aug 2016

Cited by 23 | Viewed by 6007

Abstract

Super typhoon activity is likely to make the electric power network fail, or blow the wind-measuring device off, which all lead to the yaw control system of wind turbine being inactive. Under this condition, blades can be blown by the violent side wind [...] Read more.

Super typhoon activity is likely to make the electric power network fail, or blow the wind-measuring device off, which all lead to the yaw control system of wind turbine being inactive. Under this condition, blades can be blown by the violent side wind from unfavorable directions, and the aerodynamic loads on the wind turbine will be increased by a large amount, which can lead to low-cycle fatigue damage and other catastrophic collapses. So far, not enough consideration has been given to the above problems in wind turbine design. Using the transient computational fluid dynamics (CFD), this study investigates the wind load characteristics of offshore wind turbines under typhoon condition with 360-degree full wind directions. Two primary influence factors of the aerodynamic characteristics of wind turbines are clarified: variation of the wind direction and different parking positions of the wind rotor. Using 3D-numerical simulation results, this study provides detailed references for the ultimate strength and fatigue life in wind turbine design, and presents the best parking position of the wind turbine with a free yawing strategy. Full article

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20 pages, 4048 KiB

Open AccessArticle

Comparison of Organic Rankine Cycle Systems under Varying Conditions Using Turbine and Twin-Screw Expanders

by Matthew Read^*, Ian Smith, Nikola Stosic and Ahmed Kovacevic

Department of Mechanical Engineering, City University London, London EC1V 0HB, UK

Energies 2016, 9(8), 614; https://doi.org/10.3390/en9080614 - 4 Aug 2016

Cited by 16 | Viewed by 6125

Abstract

A multi-variable optimization program has been developed to investigate the performance of Organic Rankine Cycles (ORCs) for low temperature heat recovery applications using both turbine and twin-screw expanders when account is taken of performance variation due to changes in ambient conditions. The cycle [...] Read more.

A multi-variable optimization program has been developed to investigate the performance of Organic Rankine Cycles (ORCs) for low temperature heat recovery applications using both turbine and twin-screw expanders when account is taken of performance variation due to changes in ambient conditions. The cycle simulation contains thermodynamic models of both types of expander. In the case of the twin-screw machine, the methods used to match the operation of the expander to the requirements of the cycle are described. The performance of turbine expanders in a superheated ORC has been modelled using correlations derived from operational data for single stage reaction turbines to predict the turbine efficiency at “off-design” conditions. Several turbine configurations have been considered including variable nozzle area and variable speed. The capability of the cycle model has been demonstrated for the case of heat recovery from a steady source of pressurized hot water at 120 °C. The system parameters are optimised for a typical operating condition, which determines the required size of heat exchangers and the expander characteristics. Performance at off-design conditions can then be optimized within these constraints. This allows a rigorous investigation of the effect of air temperature variation on the system performance, and the seasonal variation in net power output for the turbine and twin-screw ORC systems. A case study is presented for a low temperature heat recovery application with system electrical power output of around 100 kWe at design conditions. The results indicate that similar overall performance can be achieved for ORC systems using either type of expander. Full article

(This article belongs to the Special Issue Selected Papers from the 3rd International Seminar on ORC Power Systems)

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17 pages, 1417 KiB

Open AccessArticle

Exploring Reduction Potential of Carbon Intensity Based on Back Propagation Neural Network and Scenario Analysis: A Case of Beijing, China

by Jinying Li¹, Jianfeng Shi^1,*

and Jinchao Li²

¹ Department of Economics and Management, North China Electric Power University, Baoding 071003, China

² School of Economics and Management, North China Electric Power University, Beijing 102206, China

Energies 2016, 9(8), 615; https://doi.org/10.3390/en9080615 - 4 Aug 2016

Cited by 20 | Viewed by 4925

Abstract

Carbon emissions are the major cause of the global warming; therefore, the exploration of carbon emissions reduction potential is of great significance to reduce carbon emissions. This paper explores the potential of carbon intensity reduction in Beijing in 2020. Based on factors including [...] Read more.

Carbon emissions are the major cause of the global warming; therefore, the exploration of carbon emissions reduction potential is of great significance to reduce carbon emissions. This paper explores the potential of carbon intensity reduction in Beijing in 2020. Based on factors including economic growth, resident population growth, energy structure adjustment, industrial structure adjustment and technical progress, the paper sets 48 development scenarios during the years 2015–2020. Then, the back propagation (BP) neural network optimized by improved particle swarm optimization algorithm (IPSO) is used to calculate the carbon emissions and carbon intensity reduction potential under various scenarios for 2016 and 2020. Finally, the contribution of different factors to carbon intensity reduction is compared. The results indicate that Beijing could more than fulfill the 40%–45% reduction target for carbon intensity in 2020 in all of the scenarios. Furthermore, energy structure adjustment, industrial structure adjustment and technical progress can drive the decline in carbon intensity. However, the increase in the resident population hinders the decline in carbon intensity, and there is no clear relationship between economy and carbon intensity. On the basis of these findings, this paper puts forward relevant policy recommendations. Full article

(This article belongs to the Special Issue Energy Policy and Climate Change 2016)

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18 pages, 1446 KiB

Open AccessArticle

DG Mix and Energy Storage Units for Optimal Planning of Self-Sufficient Micro Energy Grids

by Aboelsood Zidan^1,3 and Hossam A. Gabbar^1,2,*

¹ Faculty of Energy Systems and Nuclear Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, ON L1H 7K4, Canada

² Faculty of Engineering and Applied Science, University of Ontario Institute of Technology, 2000 Simcoe Street North, Oshawa, ON L1H 7K4, Canada

³ Department of Electrical Engineering, Faculty of Engineering, Assiut University, Assiut 71515, Egypt

Energies 2016, 9(8), 616; https://doi.org/10.3390/en9080616 - 4 Aug 2016

Cited by 20 | Viewed by 4384

Abstract

Micro energy grids have many merits and promising applications under the smart grid vision. There are demanding procedures for their optimal planning and performance enhancement. One of the key features of a micro energy grid is its ability to separate and isolate itself [...] Read more.

Micro energy grids have many merits and promising applications under the smart grid vision. There are demanding procedures for their optimal planning and performance enhancement. One of the key features of a micro energy grid is its ability to separate and isolate itself from the main electrical network to continue feeding its own islanded portion. In this paper, an optimal sizing and operation strategy for micro energy grids equipped with renewable and non-renewable based distributed generation (DG) and storage are presented. The general optimization objective is to define the best DG mix and energy storage units for self-sufficient micro energy grids. A multi-objective genetic algorithm (GA) was applied to solve the planning problem at a minimum optimization goal of overall cost (including investment cost, operation and maintenance cost, and fuel cost) and carbon dioxide emission. The constraints include power and heat demands constraints, and DGs capacity limits. The candidate technologies include CHPs (combined heat and power) with different characteristics, boilers, thermal and electrical storages, and renewable generators (wind and photovoltaic). In order to assess different configuration options and components sizes, several case studies for a typical micro energy grid have been presented. Full article

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15 pages, 2064 KiB

Open AccessArticle

Some Models for Determination of Parameters of the Soil Oscillation Law during Blasting Operations

by Suzana Lutovac^1,*

, Dragan Medenica², Branko Gluščević^1,*

, Rade Tokalić¹

and Čedomir Beljić¹

¹ Faculty of Mining and Geology, Djušina 7, Belgrade 11000, Serbia

² Volmont Ltd., Ustanička 128a, Belgrade 11000, Serbia

Energies 2016, 9(8), 617; https://doi.org/10.3390/en9080617 - 4 Aug 2016

Cited by 4 | Viewed by 4429

Abstract

In order to evaluate and control the seismic effect of blasting, as well as its planning, it is required to determine the soil oscillation law, with the strike/mining facilities to be protected. One of the most commonly used equations is that of M.A. [...] Read more.

In order to evaluate and control the seismic effect of blasting, as well as its planning, it is required to determine the soil oscillation law, with the strike/mining facilities to be protected. One of the most commonly used equations is that of M.A. Sadovskii, defining the law of alteration in the oscillation velocity of the soil depending on distance, the explosive amount, and conditions of blasting and geologic characteristics of the soil; all of this being determined on the basis of test blasting for the specific work environment. In the Sadovskii equation two parameters, K and n appear and they are conditioned both by rock mass characteristics and blasting conditions. The practical part of this study includes experimental investigations performed in the Veliki Krivelj Open Pit in the Bor District located in Eastern Serbia and investigations carried out during mass mining in the Kovilovača Open Pit near Despotovac, Eastern Serbia. Thus this paper offers several modes for determination of parameters K and n in the Sadovskii equation. To determine the parameters in the Sadovskii formula, in addition to the usual least square method, two more new models were applied. In the models the parameters K and n were determined by applying the quotient of the relative growth of oscillation velocities and reduced distances for Model 2. The link between the parameters K and n is determined by applying the trapezoidal formula for finding the value of definite integral for Model 3. In doing so, it was noted that all three models can be used to calculate the oscillation velocity of the rock mass. Full article

(This article belongs to the Special Issue Selected Papers from the 5th International Symposium on Mining and Environmental Protection)

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27 pages, 30913 KiB

Open AccessArticle

A Hybrid Multi-Step Model for Forecasting Day-Ahead Electricity Price Based on Optimization, Fuzzy Logic and Model Selection

by Ping Jiang, Feng Liu^*

and Yiliao Song

School of Statistics, Dongbei University of Finance and Economics, Dalian 116025, China

Energies 2016, 9(8), 618; https://doi.org/10.3390/en9080618 - 4 Aug 2016

Cited by 10 | Viewed by 5509

Abstract

The day-ahead electricity market is closely related to other commodity markets such as the fuel and emission markets and is increasingly playing a significant role in human life. Thus, in the electricity markets, accurate electricity price forecasting plays significant role for power producers [...] Read more.

The day-ahead electricity market is closely related to other commodity markets such as the fuel and emission markets and is increasingly playing a significant role in human life. Thus, in the electricity markets, accurate electricity price forecasting plays significant role for power producers and consumers. Although many studies developing and proposing highly accurate forecasting models exist in the literature, there have been few investigations on improving the forecasting effectiveness of electricity price from the perspective of reducing the volatility of data with satisfactory accuracy. Based on reducing the volatility of the electricity price and the forecasting nature of the radial basis function network (RBFN), this paper successfully develops a two-stage model to forecast the day-ahead electricity price, of which the first stage is particle swarm optimization (PSO)-core mapping (CM) with self-organizing-map and fuzzy set (PCMwSF), and the second stage is selection rule (SR). The PCMwSF stage applies CM, fuzzy set and optimized weights to obtain the future price, and the SR stage is inspired by the forecasting nature of RBFN and effectively selects the best forecast during the test period. The proposed model, i.e., CM-PCMwSF-SR, not only overcomes the difficulty of reducing the high volatility of the electricity price but also leads to a superior forecasting effectiveness than benchmarks. Full article

(This article belongs to the Special Issue Forecasting Models of Electricity Prices)

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20 pages, 8498 KiB

Open AccessArticle

Sustainable New Brick and Thermo-Acoustic Insulation Panel from Mineralization of Stranded Driftwood Residues

by Anna Laura Pisello^1,2,*

, Claudia Fabiani², Nastaran Makaremi², Veronica Lucia Castaldo², Gianluca Cavalaglio^1,2

, Andrea Nicolini^1,2

, Marco Barbanera^1,2

and Franco Cotana^1,2

¹ Department of Engineering, University of Perugia, Via G. Duranti 93, Perugia 06125, Italy

² CIRIAF—Interuniversity Research Center on Pollution and Environment “Mauro Felli”, University of Perugia, Via G. Duranti 67, Perugia 06125, Italy

Energies 2016, 9(8), 619; https://doi.org/10.3390/en9080619 - 4 Aug 2016

Cited by 7 | Viewed by 5818

Abstract

There is considerable interest recently in by-products for application in green buildings. These materials are widely used as building envelope insulators or blocks. In this study, an experimental study was conducted to test stranded driftwood residues as raw material for possible thermo-acoustic insulation [...] Read more.

There is considerable interest recently in by-products for application in green buildings. These materials are widely used as building envelope insulators or blocks. In this study, an experimental study was conducted to test stranded driftwood residues as raw material for possible thermo-acoustic insulation panel and environmentally sustainable brick. The thermal and acoustic characteristics of such a natural by-product were examined. Part of samples were mineralized by means of cement-based additive to reinforce the material and enhance its durability as well as fire resistance. Several mixtures with different sizes of ground wood chips and different quantities of cement were investigated. The thermo-acoustic in-lab characterization was aimed at investigating the thermal conductivity, thermal diffusivity, volumetric specific heat, and acoustic transmission loss. All samples were tested before and after mineralization. Results from this study indicate that it is possible to use stranded driftwood residues as building materials with competitive thermo-acoustic properties. In fact, the thermal conductivity was shown to be always around 0.07 W/mK in the unbound samples, and around double that value for the mineralized samples, which present a much higher volumetric specific heat (1.6 MJ/m³K) and transmission loss capability. The lignin powder showed a sort of intermediate behavior between the unbound and the mineralized samples. Full article

(This article belongs to the Special Issue 16th CIRIAF National Congress – Sustainable Development, Environment and Human Health Protection)

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18 pages, 11089 KiB

Open AccessArticle

Hysteresis Characteristic in the Hump Region of a Pump-Turbine Model

by Deyou Li^1,2

, Hongjie Wang^1,*

, Jinxia Chen^1,3, Torbjørn K. Nielsen², Daqing Qin^1,3 and Xianzhu Wei^1,3

¹ School of Energy Science and Engineering, Harbin Institute of Technology, Harbin 150001, China

² Waterpower Laboratory, Norwegian University of Science and Technology, Trondheim 7491, Norway

³ State Key Laboratory of Hydro-Power Equipment, Harbin Institute of Large Electrical Machinery, Harbin 150040, China

Energies 2016, 9(8), 620; https://doi.org/10.3390/en9080620 - 5 Aug 2016

Cited by 25 | Viewed by 5079

Abstract

The hump feature is one of the major instabilities in pump-turbines. When pump-turbines operate in the hump region, strong noise and serious fluctuations can be observed, which are harmful to their safe and stable operation and can even destroy the whole unit as [...] Read more.

The hump feature is one of the major instabilities in pump-turbines. When pump-turbines operate in the hump region, strong noise and serious fluctuations can be observed, which are harmful to their safe and stable operation and can even destroy the whole unit as well as water conveyance system. In this paper, a low specific speed (n_q = 36.1 min⁻¹) pump-turbine model was experimentally investigated. Firstly, the hump characteristic was obtained under 19 mm guide vane opening conditions. More interestingly, when the hump characteristic was measured in two directions (increasing and decreasing the discharge), characteristic hysteresis was found in the hump region. The analysis of performance characteristics reveals that the hump instability is the result of Euler momentum and hydraulic losses, and different Euler momentum and hydraulic losses in the two development processes lead to the hysteresis phenomenon. Then, 12 pressure sensors were mounted in the different parts of the pump-turbine model to obtain the time and frequency characteristics. The analysis of the corresponding fast Fourier transform confirms that the hump characteristic is related to low-frequency (0.04–0.15 times rotational frequency) vortices. The occurrence and cessation of vortices depend on the operating condition and measurement direction, which contribute to the hysteresis feature. Finally, the type of the low-frequency vortices was analyzed through the cross power spectrum. Full article

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22 pages, 1015 KiB

Open AccessArticle

Automated Variable Selection and Shrinkage for Day-Ahead Electricity Price Forecasting

by Bartosz Uniejewski, Jakub Nowotarski and Rafał Weron^*

Department of Operations Research, Wrocław University of Technology, 50-370 Wrocław, Poland

Energies 2016, 9(8), 621; https://doi.org/10.3390/en9080621 - 5 Aug 2016

Cited by 97 | Viewed by 10527

Abstract

In day-ahead electricity price forecasting (EPF) variable selection is a crucial issue. Conducting an empirical study involving state-of-the-art parsimonious expert models as benchmarks, datasets from three major power markets and five classes of automated selection and shrinkage procedures (single-step elimination, stepwise regression, ridge [...] Read more.

In day-ahead electricity price forecasting (EPF) variable selection is a crucial issue. Conducting an empirical study involving state-of-the-art parsimonious expert models as benchmarks, datasets from three major power markets and five classes of automated selection and shrinkage procedures (single-step elimination, stepwise regression, ridge regression, lasso and elastic nets), we show that using the latter two classes can bring significant accuracy gains compared to commonly-used EPF models. In particular, one of the elastic nets, a class that has not been considered in EPF before, stands out as the best performing model overall. Full article

(This article belongs to the Special Issue Forecasting Models of Electricity Prices)

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13 pages, 2453 KiB

Open AccessArticle

The Energy and Environmental Performance of Ground-Mounted Photovoltaic Systems—A Timely Update

by Enrica Leccisi^1,3, Marco Raugei^2,3

and Vasilis Fthenakis^3,4,*

¹ Department of Science and Technology, Parthenope University of Naples, Centro Direzionale-Isola C4, Naples 80143, Italy

² Department of Mechanical Engineering and Mathematical Sciences, Oxford Brookes University, Wheatley OX33 1HK, UK

³ Center for Life Cycle Analysis, Columbia University, New York, NY 10027, USA

⁴ Photovoltaic Environmental Research Center, Brookhaven National Laboratory, Upton, NY 11973, USA

Energies 2016, 9(8), 622; https://doi.org/10.3390/en9080622 - 8 Aug 2016

Cited by 128 | Viewed by 13831

Abstract

Given photovoltaics’ (PVs) constant improvements in terms of material usage and energy efficiency, this paper provides a timely update on their life-cycle energy and environmental performance. Single-crystalline Si (sc-Si), multi-crystalline Si (mc-Si), cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS) systems are [...] Read more.

Given photovoltaics’ (PVs) constant improvements in terms of material usage and energy efficiency, this paper provides a timely update on their life-cycle energy and environmental performance. Single-crystalline Si (sc-Si), multi-crystalline Si (mc-Si), cadmium telluride (CdTe) and copper indium gallium diselenide (CIGS) systems are analysed, considering the actual country of production and adapting the input electricity mix accordingly. Energy pay-back time (EPBT) results for fixed-tilt ground mounted installations range from 0.5 years for CdTe PV at high-irradiation (2300 kWh/(m²·yr)) to 2.8 years for sc-Si PV at low-irradiation (1000 kWh/(m²·yr)), with corresponding quality-adjusted energy return on investment (EROI_PE-eq) values ranging from over 60 to ~10. Global warming potential (GWP) per kWh_el averages out at ~30 g(CO₂-eq), with lower values (down to ~10 g) for CdTe PV at high irradiation, and up to ~80 g for Chinese sc-Si PV at low irradiation. In general, results point to CdTe PV as the best performing technology from an environmental life-cycle perspective, also showing a remarkable improvement for current production modules in comparison with previous generations. Finally, we determined that one-axis tracking installations can improve the environmental profile of PV systems by approximately 10% for most impact metrics. Full article

(This article belongs to the Special Issue Life-Cycle Assessment of Energy Systems in Current and Evolving Grids)

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14 pages, 6613 KiB

Open AccessArticle

Partial Discharge Measurement under an Oscillating Switching Impulse: A Potential Supplement to the Conventional Insulation Examination in the Field

by Ming Ren^*, Ming Dong^*, Chongxing Zhang

and Jierui Zhou

State Key Laboratory of Electrical Insulation for Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China

Energies 2016, 9(8), 623; https://doi.org/10.3390/en9080623 - 9 Aug 2016

Cited by 1 | Viewed by 7667

Abstract

Partial discharge (PD) detection under oscillating switching impulse (OSI) voltage was performed on three types of insulation defects, including a protrusion on a conductor, a particle on an insulator surface, and a void in an insulator, which are three kinds of the common [...] Read more.

Partial discharge (PD) detection under oscillating switching impulse (OSI) voltage was performed on three types of insulation defects, including a protrusion on a conductor, a particle on an insulator surface, and a void in an insulator, which are three kinds of the common potential insulation hazards in gas insulated power apparatus. Experiment indicated that the PD sequences under OSI were composed of various combinations of the single pulse, the multiple pulses, and the reverse polarity pulse. The difference between the PD inception voltage (PDIV) and the breakdown voltage (BDV) under OSI voltage was greater than that under alternating current (AC) voltage in some cases, which can provide a more sufficient margin below the BDV for PD diagnosis. The OSI voltage also showed a better performance for exciting PDs with detectable magnitudes from small-scale defects, of which the AC voltage was incapable under our test conditions. The different PD activities with different interfaces under an impulse and a slowly varying voltage were speculated to be associated with the gradient of the background electric field and the space-charge mobility. Full article

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17 pages, 4291 KiB

Open AccessArticle

Activity-Aware Energy-Efficient Automation of Smart Buildings

by Brian L. Thomas and Diane J. Cook^*

School of Electrical Engineering and Computer Science, Washington State University, Pullman, WA 99163, USA

Energies 2016, 9(8), 624; https://doi.org/10.3390/en9080624 - 9 Aug 2016

Cited by 31 | Viewed by 6721

Abstract

This paper introduces the idea of activity-aware cyber-physical systems (CPS). Activity-aware systems allow smart city services to adapt to the needs of individual residents by being sensitive to their daily tasks. The paper first defines activity recognition and activity prediction algorithms that form [...] Read more.

This paper introduces the idea of activity-aware cyber-physical systems (CPS). Activity-aware systems allow smart city services to adapt to the needs of individual residents by being sensitive to their daily tasks. The paper first defines activity recognition and activity prediction algorithms that form the foundation of activity-aware CPS and implement a prototype activity-aware building automation system, called CASAS activity aware resource learning (CARL). Evaluation of CARL on real sensor data shows not only an accurate ability to sense and predict activities but an effective means of automation buildings that reduces energy consumption while being sensitive to user activities in the building. Our ideas are demonstrated in the context of a smart home but can be utilized in a variety of smart city settings including smart offices, smart hospitals, and smart communities. Full article

(This article belongs to the Special Issue Energy Conservation in Infrastructures 2016)

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14 pages, 5069 KiB

Open AccessArticle

Modeling of Load Bearing Characteristics of Jacket Foundation Piles for Offshore Wind Turbines in Taiwan

by Cheng-Yu Ku^*

and Lien-Kwei Chien

Department of Harbor and River Engineering, National Taiwan Ocean University, Keelung 202, Taiwan

Energies 2016, 9(8), 625; https://doi.org/10.3390/en9080625 - 9 Aug 2016

Cited by 28 | Viewed by 9539

Abstract

This paper presents a pioneering study on numerical modeling of load bearing characteristics of the jacket foundation pile for offshore wind turbines on the west coast of Taiwan. Because Taiwan is located in an earthquake prone area, there is significant interest in improving [...] Read more.

This paper presents a pioneering study on numerical modeling of load bearing characteristics of the jacket foundation pile for offshore wind turbines on the west coast of Taiwan. Because Taiwan is located in an earthquake prone area, there is significant interest in improving the prediction of the behavior of wind turbine jacket foundations subjected to seismic loading. Investigation of the bearing capacity of the jacket foundation pile for the offshore wind farm using effective stress analysis, with consideration of pore pressure generation and soil/liquid coupled analysis, was conducted. A new procedure to evaluate the design of offshore wind turbine foundation piles in the sand and clay inter-layered soil was also proposed. Static and dynamic analyses of bearing capacity of the jacket foundation pile were conducted. Results obtained demonstrate that the design process for the jacket foundation pile proposed in this study can properly reflect the interaction behavior of the foundation and the soil. In addition, the pore pressure generation model can be used to simulate soil liquefaction. The proposed method is also very useful in the evaluation of the design capabilities of offshore wind turbine jacket foundations. Full article

(This article belongs to the Collection Wind Turbines)

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18 pages, 3664 KiB

Open AccessArticle

Energy Optimization for Train Operation Based on an Improved Ant Colony Optimization Methodology

by Youneng Huang^1,2,*, Chen Yang¹ and Shaofeng Gong¹

¹ School of Electronics and Information Engineering, Beijing Jiaotong University, Haidian District, Beijing 100044, China

² National Engineering Research Center of Rail Transportation Operation and Control System, Beijing Jiaotong University, Haidian District, Beijing 100044, China

Energies 2016, 9(8), 626; https://doi.org/10.3390/en9080626 - 9 Aug 2016

Cited by 21 | Viewed by 4938

Abstract

More and more lines are using the Communication Based Train Control (CBTC) systems in urban rail transit. Trains are operated by tracking a pre-determined target speed curve in the CBTC system, so one of the most effective ways of reducing energy consumption is [...] Read more.

More and more lines are using the Communication Based Train Control (CBTC) systems in urban rail transit. Trains are operated by tracking a pre-determined target speed curve in the CBTC system, so one of the most effective ways of reducing energy consumption is to fully understand the optimum curves that should prevail under varying operating conditions. Additionally, target speed curves need to be calculated with optimum real-time performance in order to cope with changed interstation planning running time. Therefore, this paper proposes a fast and effective algorithm for optimization, based on a two-stage method to find the optimal curve using a max-min ant colony optimization system, using approximate calculations of a discrete combination optimization model. The first stage unequally discretizes the line based on static gradient and speed limit in low-density and it could conduct a comprehensive search for viable energy saving target speed curves. The second stage unequally discretizes the line based on first stage discretion results, it makes full use of first-stage optimization information as pheromone, quickly optimizing the results to satisfy real-time demands. The algorithm is improved through consideration of the experience of train drivers. Finally, the paper presents some examples based on the operation data of Beijing Changping Subway Line, which is using CBTC system. The simulation results show that the proposed approach presents good energy-efficient and real-time performance. Full article

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15 pages, 4364 KiB

Open AccessArticle

Techno-Economic Modeling and Analysis of Redox Flow Battery Systems

by Jens Noack^*, Lars Wietschel, Nataliya Roznyatovskaya, Karsten Pinkwart

and Jens Tübke

Fraunhofer-Institute for Chemical Technology, Applied Electrochemistry, Joseph-von-Fraunhofer-Str. 7, Pfinztal 76327, Germany

Energies 2016, 9(8), 627; https://doi.org/10.3390/en9080627 - 10 Aug 2016

Cited by 103 | Viewed by 14276

Abstract

A techno-economic model was developed to investigate the influence of components on the system costs of redox flow batteries. Sensitivity analyses were carried out based on an example of a 10 kW/120 kWh vanadium redox flow battery system, and the costs of the [...] Read more.

A techno-economic model was developed to investigate the influence of components on the system costs of redox flow batteries. Sensitivity analyses were carried out based on an example of a 10 kW/120 kWh vanadium redox flow battery system, and the costs of the individual components were analyzed. Particular consideration was given to the influence of the material costs and resistances of bipolar plates and energy storage media as well as voltages and electric currents. Based on the developed model, it was possible to formulate statements about the targeted optimization of a developed non-commercial vanadium redox flow battery system and general aspects for future developments of redox flow batteries. Full article

(This article belongs to the Special Issue Redox Flow Batteries)

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16 pages, 5681 KiB

Open AccessEditor’s ChoiceArticle

Perspectives on Near ZEB Renovation Projects for Residential Buildings: The Spanish Case

by Faustino Patiño-Cambeiro¹, Julia Armesto^2,*, Faustino Patiño-Barbeito³ and Guillermo Bastos³

¹ Centro de Ciências Exatas e Tecnológicas, Centro Universitário Univates, Rua Avelino Tallini 171, Lajeado/RS 95900-000, Brazil

² Mining Engineering School, University of Vigo, Campus as Lagoas Marcosende, Vigo 36310, Spain

³ Industrial Engineering School, University of Vigo, Rúa Conde de Torrecedeira 86, Vigo 36208, Spain

Energies 2016, 9(8), 628; https://doi.org/10.3390/en9080628 - 10 Aug 2016

Cited by 25 | Viewed by 6210

Abstract

EU regulations are gradually moving towards policies that reduce energy consumption and its environmental impact. To reach this goal, improving energy efficiency in residential buildings is a key action line. The European Parliament adopted the Near Zero-Energy Building (nZEB) as the energy efficiency [...] Read more.

EU regulations are gradually moving towards policies that reduce energy consumption and its environmental impact. To reach this goal, improving energy efficiency in residential buildings is a key action line. The European Parliament adopted the Near Zero-Energy Building (nZEB) as the energy efficiency paradigm through Directive 2010/31/EU, but a common technical and legislative framework for energy renovations is yet to be established. In this paper, the nZEB definition by COHERENO was adopted to evaluate several energy renovation packages in a given building, which is also representative of the Spanish building stock. Global costs are calculated for all of them following EPBD prescriptions. Two economic scenarios are analysed: with entirely private funding and with the current public financial incentives, respectively. The results show the divergence between optimum solutions in terms of costs and of minimum CO₂ footprint and maximum energy saving. Moreover, in the absence of enough incentives, some inefficient renovations could achieve a global cost close to the optimal cost. The optimum solution both in terms of energy performance and global costs was carried out and described. Full article

(This article belongs to the Special Issue Energy Efficient City)

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16 pages, 4597 KiB

Open AccessArticle

Dispatching of Wind/Battery Energy Storage Hybrid Systems Using Inner Point Method-Based Model Predictive Control

by Deyou Yang¹

, Jiaxin Wen^1,*, Ka-wing Chan²

and Guowei Cai¹

¹ School of Electrical Engineering, Northeast Dianli University, Jilin 132012, China

² Department of Electrical Engineering, Hong Kong Polytechnic University, Hong Kong, China

Energies 2016, 9(8), 629; https://doi.org/10.3390/en9080629 - 11 Aug 2016

Cited by 17 | Viewed by 5912

Abstract

The application of large scale energy storage makes wind farms more dispatchable, which lowers operating risks to the grid from interconnected large scale wind farms. In order to make full use of the flexibility and controllability of energy storage to improve the schedulability [...] Read more.

The application of large scale energy storage makes wind farms more dispatchable, which lowers operating risks to the grid from interconnected large scale wind farms. In order to make full use of the flexibility and controllability of energy storage to improve the schedulability of wind farms, this paper presents a rolling and dispatching control strategy with a battery energy storage system (BESS) based on model predictive control (MPC). The proposed control scheme firstly plans expected output, i.e., dispatching order, of a wind/battery energy storage hybrid system based on the predicted output of the wind farm, then calculates the order in the predictive horizon with the receding horizon optimization and the limitations of energy storage such as state of charge and depth of charge/discharge to maintain the combination of active output of the wind farm and the BESS to track dispatching order at the extreme. The paper shows and analyses the effectiveness of the proposed strategy with different sizes of capacity of the BESS based on the actual output of a certain actual wind farm in the northeast of China. The results show that the proposed strategy that controls the BESS could improve the schedulability of the wind farm and maintain smooth output of wind/battery energy storage hybrid system while tracking the dispatching orders. When the capacity of the BESS is 20% or the rated capacity of the wind farm, the mean dispatching error is only 0.153% of the rated capacity of the wind farm. Full article

(This article belongs to the Special Issue Optimal and Neural Network Control for Renewables and Electric Power and Energy Systems)

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14 pages, 3033 KiB

Open AccessArticle

Coordinated Scheme of Under-Frequency Load Shedding with Intelligent Appliances in a Cyber Physical Power System

by Qi Wang¹, Yi Tang^1,*, Feng Li¹, Mengya Li¹, Yang Li¹ and Ming Ni²

¹ School of Electrical Engineering, Southeast University, Nanjing 210096, Jiangsu, China

² State Grid Electric Power Research Institute, Nanjing 210003, Jiangsu, China

Energies 2016, 9(8), 630; https://doi.org/10.3390/en9080630 - 10 Aug 2016

Cited by 17 | Viewed by 8422

Abstract

The construction of a cyber physical system in a power grid provides more potential control strategies for the power grid. With the rapid employment of intelligent terminal equipment (e.g., smart meters and intelligent appliances) in the environment of a smart grid, abundant dynamic [...] Read more.

The construction of a cyber physical system in a power grid provides more potential control strategies for the power grid. With the rapid employment of intelligent terminal equipment (e.g., smart meters and intelligent appliances) in the environment of a smart grid, abundant dynamic response information could be introduced to support a secure and stable power system. Combining demand response technology with the traditional under-frequency load shedding (UFLS) scheme, a new UFLS strategy-determining method involving intelligent appliances is put forward to achieve the coordinated control of quick response resources and the traditional control resources. Based on this method, intelligent appliances can be used to meet the regulatory requirements of system operation in advance and prevent significant frequency drop, thereby improving the flexibility and stability of the system. Time-domain simulation verifies the effectiveness of the scheme, which is able to mitigate frequency drop and reduce the amount of load shedding. Full article

(This article belongs to the Special Issue Innovations in Cyber-Physical Infrastructures and Systems for Energy Sustainability in Smart Cities)

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22 pages, 3857 KiB

Open AccessArticle

Methodologies Developed for EcoCity Related Projects: New Borg El Arab, an Egyptian Case Study

by Carmen Antuña-Rozado^1,2,*, Justo García-Navarro²

, Francesco Reda¹ and Pekka Tuominen¹

¹ VTT Technical Research Centre of Finland Ltd., P.O. Box 1000, FI-02044 VTT, Finland

² Research Group on Sustainability in Construction and Industry giSCI-UPM, Universidad Politécnica de Madrid, ETSIAAB—Ciudad Universitaria, s/n, 28040 Madrid, Spain

Energies 2016, 9(8), 631; https://doi.org/10.3390/en9080631 - 11 Aug 2016

Cited by 10 | Viewed by 6462

Abstract

The aim of the methodologies described here is to propose measures and procedures for developing concepts and technological solutions, which are adapted to the local conditions, to build sustainable communities in developing countries and emerging economies. These methodologies are linked to the EcoCity [...] Read more.

The aim of the methodologies described here is to propose measures and procedures for developing concepts and technological solutions, which are adapted to the local conditions, to build sustainable communities in developing countries and emerging economies. These methodologies are linked to the EcoCity framework outlined by VTT Technical Research Centre of Finland Ltd. for sustainable community and neighbourhood regeneration and development. The framework is the result of a long experience in numerous EcoCity related projects, mainly Nordic and European in scope, which has been reformulated in recent years to respond to the local needs in the previously mentioned countries. There is also a particular emphasis on close collaboration with local partners and major stakeholders. In order to illustrate how these methodologies can support EcoCity concept development and implementation, results from a case study in Egypt will be discussed. The referred case study relates to the transformation of New Borg El Arab (NBC), near Alexandria, into an EcoCity. The viability of the idea was explored making use of different methodologies (Roadmap, Feasibility Study, and Residents Energy Survey and Building Consumption Assessment) and considering the Residential, Commercial/Public Facilities, Industrial, Services/Utilities, and Transport sectors. Full article

(This article belongs to the Special Issue Energy Efficient City)

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14 pages, 2485 KiB

Open AccessArticle

TBM/MTM for HTS-FNSF: An Innovative Testing Strategy to Qualify/Validate Fusion Technologies for U.S. DEMO

by Laila El-Guebaly^1,*, Arthur Rowcliffe²

, Jonathan Menard³

and Thomas Brown³

¹ Department of Engineering Physics, University of Wisconsin-Madison, 1500 Engineering Drive, Madison, WI 53706, USA

² Oak Ridge National Laboratory, P.O. Box 2008, Oak Ridge, TN 37831, USA

³ Princeton Plasma Physics Laboratory, 100 Stellarator Road, Princeton, NJ 08540, USA

Energies 2016, 9(8), 632; https://doi.org/10.3390/en9080632 - 11 Aug 2016

Cited by 9 | Viewed by 5956

Abstract

The qualification and validation of nuclear technologies are daunting tasks for fusion demonstration (DEMO) and power plants. This is particularly true for advanced designs that involve harsh radiation environment with 14 MeV neutrons and high-temperature operating regimes. This paper outlines the unique qualification [...] Read more.

The qualification and validation of nuclear technologies are daunting tasks for fusion demonstration (DEMO) and power plants. This is particularly true for advanced designs that involve harsh radiation environment with 14 MeV neutrons and high-temperature operating regimes. This paper outlines the unique qualification and validation processes developed in the U.S., offering the only access to the complete fusion environment, focusing on the most prominent U.S. blanket concept (the dual cooled PbLi (DCLL)) along with testing new generations of structural and functional materials in dedicated test modules. The venue for such activities is the proposed Fusion Nuclear Science Facility (FNSF), which is viewed as an essential element of the U.S. fusion roadmap. A staged blanket testing strategy has been developed to test and enhance the DCLL blanket performance during each phase of FNSF D-T operation. A materials testing module (MTM) is critically important to include in the FNSF as well to test a broad range of specimens of future, more advanced generations of materials in a relevant fusion environment. The most important attributes for MTM are the relevant He/dpa ratio (10–15) and the much larger specimen volumes compared to the 10–500 mL range available in the International Fusion Materials Irradiation Facility (IFMIF) and European DEMO-Oriented Neutron Source (DONES). Full article

(This article belongs to the Special Issue Fusion Power)

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17 pages, 11831 KiB

Open AccessArticle

Non-Vacuum Processed Polymer Composite Antireflection Coating Films for Silicon Solar Cells

by Abdullah Uzum^1,2, Masashi Kuriyama¹, Hiroyuki Kanda¹, Yutaka Kimura³, Kenji Tanimoto³ and Seigo Ito^1,*

¹ Department of Materials and Synchrotron Radiation Engineering, Graduate School of Engineering, University of Hyogo, 2167 Shosha, Himeji, Hyogo 671-2280, Japan

² Department of Electrical and Electronics Engineering, Faculty of Engineering, Karadeniz Technical University, 61080 Trabzon, Turkey

³ Specialty Materials Research Laboratory, Nissan Chemical Industries, Ltd., 11-1 Kitasode, Sodegaurashi, Chiba 299-0266, Japan

Energies 2016, 9(8), 633; https://doi.org/10.3390/en9080633 - 15 Aug 2016

Cited by 11 | Viewed by 6327

Abstract

A non-vacuum processing method for preparing polymer-based ZrO₂/TiO₂ multilayer structure antireflection coating (ARC) films for crystalline silicon solar cells by spin coating is introduced. Initially, ZrO₂, TiO₂ and surface deactivated-TiO₂ (SD-TiO₂) based films were [...] Read more.

A non-vacuum processing method for preparing polymer-based ZrO₂/TiO₂ multilayer structure antireflection coating (ARC) films for crystalline silicon solar cells by spin coating is introduced. Initially, ZrO₂, TiO₂ and surface deactivated-TiO₂ (SD-TiO₂) based films were examined separately and the effect of photocatalytic properties of TiO₂ film on the reflectivity on silicon surface was investigated. Degradation of the reflectance performance with increasing reflectivity of up to 2% in the ultraviolet region was confirmed. No significant change of the reflectance was observed when utilizing SD-TiO₂ and ZrO₂ films. Average reflectance (between 300 nm–1100 nm) of the silicon surface coated with optimized polymer-based ZrO₂ single or ZrO₂/SD-TiO₂ multilayer composite films was decreased down to 6.5% and 5.5%, respectively. Improvement of photocurrent density (Jsc) and conversion efficiency (η) of fabricated silicon solar cells owing to the ZrO₂/SD-TiO₂ multilayer ARC could be confirmed. The photovoltaic properties of Jsc, the open-circuit photo voltage (V_OC), the fill factor (FF), and the η were 31.42 mA cm⁻², 575 mV, 71.5% and 12.91%. Efficiency of the solar cells was improved by the ZrO₂-polymer/SD-TiO₂ polymer ARC composite layer by a factor of 0.8% with an increase of Jsc (2.07 mA cm⁻²) compared to those of fabricated without the ARC. Full article

(This article belongs to the Special Issue Nano-Structured Solar Cells)

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10 pages, 697 KiB

Open AccessArticle

Lignocellulosic Ethanol Production from the Recovery of Stranded Driftwood Residues

by Gianluca Cavalaglio^*

, Mattia Gelosia, Silvia D’Antonio, Andrea Nicolini

, Anna Laura Pisello

, Marco Barbanera and Franco Cotana

CIRIAF-Biomass Research Center, University of Perugia, Via G. Duranti, Perugia 06125, Italy

Energies 2016, 9(8), 634; https://doi.org/10.3390/en9080634 - 12 Aug 2016

Cited by 12 | Viewed by 4318

Abstract

This paper builds upon a research project funded by the Italian Ministry of Environment, and aims to recover stranded driftwood residues (SDRs), in order to transform a potential pollution and safety issue into valuable bio-resources. In particular, one of the experiments consisted of [...] Read more.

This paper builds upon a research project funded by the Italian Ministry of Environment, and aims to recover stranded driftwood residues (SDRs), in order to transform a potential pollution and safety issue into valuable bio-resources. In particular, one of the experiments consisted of bioethanol production from lignocellulosic residues. The SDRs were gathered from the Italian coast (Abruzzo Region, Italy) after an intense storm. The biomass recalcitrance, due to its lignocellulosic structure, was reduced by a steam explosion (SE) pretreatment process. Four different pretreatment severity factors (R₀) were tested (LogR₀ 3.65, 4.05, 4.24 and 4.64) in order to evaluate the pretreated material’s accessibility to enzymatic attack and the holocellulose (cellulose plus hemicellulose) recovery. A first enzymatic hydrolysis was performed on the pretreated materials by employing a solid/liquid (S/L) ratio of 1% (w/w) and an enzyme dosage of 30% (w enzyme/w cellulose), in order to estimate the maximum enzymatically accessible cellulose content. Since the primary goal of pretreatment and hydrolysis is to convert as much cellulose as possible into monomeric glucose and recover all the holocellulose, the two pretreated materials showing these features were selected for bioethanol production process. The pretreated materials underwent a semi-simultaneous saccharification and fermentation (SSSF). The SSSF process was performed into two lab-scale bioreactors (5 L) with an S/L ratio of 15% and an enzyme dosage of 15% for five days. The efficiency of the whole bioethanol production process was assessed as ethanol overall yields (g ethanol/100 g raw material). The best overall yield was achieved by sample BS04 (8.98 g ethanol/100 g raw material). Full article

(This article belongs to the Special Issue 16th CIRIAF National Congress – Sustainable Development, Environment and Human Health Protection)

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40 pages, 11126 KiB

Open AccessArticle

Analysis and Modeling for Short- to Medium-Term Load Forecasting Using a Hybrid Manifold Learning Principal Component Model and Comparison with Classical Statistical Models (SARIMAX, Exponential Smoothing) and Artificial Intelligence Models (ANN, SVM): The Case of Greek Electricity Market

by George P. Papaioannou^1,2, Christos Dikaiakos^1,3,*,†, Anargyros Dramountanis^3,† and Panagiotis G. Papaioannou^4,†

¹ Research, Technology & Development Department, Independent Power Transmission Operator (IPTO) S.A., 89 Dyrrachiou & Kifisou Str. Gr, Athens 10443, Greece

² Center for Research and Applications in Nonlinear Systems (CRANS), Department of Mathematics, University of Patras, Patras 26500, Greece

³ Department of Electrical and Computer Engineering, University of Patras, Patras 26500, Greece

⁴ Applied Mathematics and Physical Sciences, National Technical University of Athens, Zografou 15780, Greece

^† These authors contributed equally to this work.

Energies 2016, 9(8), 635; https://doi.org/10.3390/en9080635 - 16 Aug 2016

Cited by 35 | Viewed by 11924

Abstract

In this work we propose a new hybrid model, a combination of the manifold learning Principal Components (PC) technique and the traditional multiple regression (PC-regression), for short and medium-term forecasting of daily, aggregated, day-ahead, electricity system-wide load in the Greek Electricity Market for [...] Read more.

In this work we propose a new hybrid model, a combination of the manifold learning Principal Components (PC) technique and the traditional multiple regression (PC-regression), for short and medium-term forecasting of daily, aggregated, day-ahead, electricity system-wide load in the Greek Electricity Market for the period 2004–2014. PC-regression is shown to effectively capture the intraday, intraweek and annual patterns of load. We compare our model with a number of classical statistical approaches (Holt-Winters exponential smoothing of its generalizations Error-Trend-Seasonal, ETS models, the Seasonal Autoregressive Moving Average with exogenous variables, Seasonal Autoregressive Integrated Moving Average with eXogenous (SARIMAX) model as well as with the more sophisticated artificial intelligence models, Artificial Neural Networks (ANN) and Support Vector Machines (SVM). Using a number of criteria for measuring the quality of the generated in-and out-of-sample forecasts, we have concluded that the forecasts of our hybrid model outperforms the ones generated by the other model, with the SARMAX model being the next best performing approach, giving comparable results. Our approach contributes to studies aimed at providing more accurate and reliable load forecasting, prerequisites for an efficient management of modern power systems. Full article

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11 pages, 1279 KiB

Open AccessArticle

Design and Implementation of a Test-Bench for Efficiency Measurement of Domestic Induction Heating Appliances

by Javier Serrano^1,*,†,‡, Jesús Acero^1,‡

, Rafael Alonso^2,‡, Claudio Carretero^2,‡, Ignacio Lope^3,‡ and José Miguel Burdío^1,‡

¹ Department of Electronic Engineering and Communications, Universidad de Zaragoza, Zaragoza 50018, Spain

² Department of Applied Physics, Universidad de Zaragoza, Zaragoza 50009, Spain

³ B/S/H/ Home Appliances Group, Induction Division, Zaragoza 50016, Spain

^† Current address: Universidad de Zaragoza, Maria de Luna, 1, Zaragoza 50018, Spain.

^‡ These authors contributed equally to this work.

Energies 2016, 9(8), 636; https://doi.org/10.3390/en9080636 - 12 Aug 2016

Cited by 5 | Viewed by 4887

Abstract

The operation of a domestic induction cooktop is based on the wireless energy transfer from the inductor to the pot. In such systems, the induction efficiency is defined as the ratio between the power delivered to the pot and the consumed power from [...] Read more.

The operation of a domestic induction cooktop is based on the wireless energy transfer from the inductor to the pot. In such systems, the induction efficiency is defined as the ratio between the power delivered to the pot and the consumed power from the supplying converter. The non-transferred power is dissipated in the inductor, raising its temperature. Most efficiency-measuring methods are based on measuring the effective power (pot) and the total power (converter output). While the converter output power is directly measurable, the measurement of the power dissipation in the pot is usually a cause of inaccuracy. In this work, an alternative method to measure the system’s efficiency is proposed and implemented. The method is based on a pot with a reversible base to which the inductor is attached. In the standard configuration, the inductor is placed below the pot in such a way that the delivered power is used to boil water, and the power losses are dissipated to the air. When the pot base is flipped, the inductor is immersed into the water. In this case the losses in the inductor also contribute to heating up and boiling the water. The induction efficiency is calculated from the boiling rates in both configurations. A commercial inductor was tested under real working conditions with consistent results. Full article

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20 pages, 8914 KiB

Open AccessArticle

A Novel Dynamic Co-Simulation Analysis for Overall Closed Loop Operation Control of a Large Wind Turbine

by Ching-Sung Wang and Mao-Hsiung Chiang^*

Department of Engineering Science and Ocean Engineering, National Taiwan University, No. 1, Sec. 4, Roosevelt Rd., Taipei 10617, Taiwan

Energies 2016, 9(8), 637; https://doi.org/10.3390/en9080637 - 13 Aug 2016

Cited by 8 | Viewed by 7349

Abstract

A novel dynamic co-simulation methodology of overall wind turbine systems is presented. This methodology combines aerodynamics, mechanism dynamics, control system dynamics, and subsystems dynamics. Aerodynamics and turbine properties were modeled in FAST (Fatigue, Aerodynamic, Structures, and Turbulence), and ADAMS (Automatic Dynamic Analysis of [...] Read more.

A novel dynamic co-simulation methodology of overall wind turbine systems is presented. This methodology combines aerodynamics, mechanism dynamics, control system dynamics, and subsystems dynamics. Aerodynamics and turbine properties were modeled in FAST (Fatigue, Aerodynamic, Structures, and Turbulence), and ADAMS (Automatic Dynamic Analysis of Mechanical Systems) performed the mechanism dynamics; control system dynamics and subsystem dynamics such as generator, pitch control system, and yaw control system were modeled and built in MATLAB/SIMULINK. Thus, this comprehensive integration of methodology expands both the flexibility and controllability of wind turbines. The dynamic variations of blades, rotor dynamic response, and tower vibration can be performed under different inputs of wind profile, and the control strategies can be verified in the different closed loop simulation. Besides, the dynamic simulation results are compared with the measuring results of SCADA (Supervisory Control and Data Acquisition) of a 2 MW wind turbine for ensuring the novel dynamic co-simulation methodology. Full article

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13 pages, 3968 KiB

Open AccessArticle

Estimation of Total Transport CO₂ Emissions Generated by Medium- and Heavy-Duty Vehicles (MHDVs) in a Sector of Korea

by Jigu Seo¹

, Junhong Park², Yunjung Oh¹ and Sungwook Park^3,*

¹ Graduate School of Hanyang University, 222 Wangwimni-ro, Seongdong-gu, Seoul 04763, Korea

² National Institute of Environmental Research, Hwangyong-ro 42, Seo-gu, Incheon 22689, Korea

³ Department of Mechanical Engineering, Hanyang University, 222 Wangwimni-ro, Seongdong-gu, Seoul 04763, Korea

Energies 2016, 9(8), 638; https://doi.org/10.3390/en9080638 - 13 Aug 2016

Cited by 36 | Viewed by 7959

Abstract

In order to mitigate carbon dioxide (CO₂) emissions, policy action that addresses vehicle emissions is essential. While many previous studies have focused on light-duty vehicles (LDV), little is known about medium- and heavy-duty vehicles (MHDV). This study lays the groundwork for [...] Read more.

In order to mitigate carbon dioxide (CO₂) emissions, policy action that addresses vehicle emissions is essential. While many previous studies have focused on light-duty vehicles (LDV), little is known about medium- and heavy-duty vehicles (MHDV). This study lays the groundwork for future MHDV investigations in the Republic of Korea by developing an MHDV CO₂ emissions inventory. The bottom-up approach was used to calculate national CO₂ emissions. Simulation methods that calculated the CO₂ emissions of each vehicle and statistical data, such as vehicle miles traveled (VMT) and the number of registered vehicles were used to predict CO₂ emissions. The validity of this simulation model was examined by comparing it with the chassis dynamometer test results. The results of this study showed that the CO₂ emissions of MHDV in 2015 were 24.47 million tons, which was 25.5% of the total road transportation CO₂ emissions, despite only comprising 4.2% of the total vehicles. Trucks emitted 69.6% and buses emitted 30.4% of the total MHDV CO₂ emissions. Using the results between 2012 and 2015, the level of business-as-usual (BAU) CO₂ emissions will be 25.37 million tons in 2020. Full article

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20 pages, 1031 KiB

Open AccessArticle

Theoretical Framework of Organizational Intelligence: A Managerial Approach to Promote Renewable Energy in Rural Economies

by Nicolae Istudor¹, Minodora Ursacescu^2,*, Cleopatra Sendroiu³ and Ioan Radu²

¹ Faculty of Agro-Food and Environmental Economics, Bucharest University of Economic Studies, 6 Romana Square, Bucharest 010374, Romania

² Faculty of Management, Bucharest University of Economic Studies, 6 Romana Square, Bucharest 010374, Romania

³ Faculty of Accounting and Management Information Systems, Bucharest University of Economic Studies, 6 Romana Square, Bucharest 010374, Romania

Energies 2016, 9(8), 639; https://doi.org/10.3390/en9080639 - 12 Aug 2016

Cited by 15 | Viewed by 8938

Abstract

The companies involved in the energy sector must reinvent themselves to be innovative and adaptable to contemporary environmental changes. The promotion of renewable energy in rural communities is a great challenge for these companies. They should focus on improving the environment scanning actions [...] Read more.

The companies involved in the energy sector must reinvent themselves to be innovative and adaptable to contemporary environmental changes. The promotion of renewable energy in rural communities is a great challenge for these companies. They should focus on improving the environment scanning actions and the knowledge management (KM) system and enhancing the collective intelligence to avoid the loss of information, to foster innovation, and to maintain a competitive advantage. To achieve these goals, energy companies require appropriate management tools and practices. The purpose of this study is to propose a theoretical framework of organizational intelligence (OI) supported by a cross-perspective analysis of various aspects: economic intelligence (EI) and KM practices, entropy processes, and organizational enablers. A pilot investigation for testing the framework in the case of Transelectrica S.A. has been elaborated. The findings reveal that the elements of the OI framework are embedded in Transelectrica’s system and they need to be further developed. As an intelligent company acting in the Romanian energy market, Transelectrica has a higher potential to promote projects in the renewable energy sector. The main conclusion highlights that OI is a multidimensional construct that provides the organization the ability to deal with environmental challenges in a “new economy”. Full article

(This article belongs to the Special Issue Contemporary Environmental Paradigms and the Renewable Energy in Rural Economies)

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34 pages, 7019 KiB

Open AccessArticle

Comparative Study of Hybrid Models Based on a Series of Optimization Algorithms and Their Application in Energy System Forecasting

by Xuejiao Ma

and Dandan Liu^*

School of Statistics, Dongbei University of Finance and Economics, Dalian 116023, China

Energies 2016, 9(8), 640; https://doi.org/10.3390/en9080640 - 16 Aug 2016

Cited by 10 | Viewed by 5477

Abstract

Big data mining, analysis, and forecasting play vital roles in modern economic and industrial fields, especially in the energy system. Inaccurate forecasting may cause wastes of scarce energy or electricity shortages. However, forecasting in the energy system has proven to be a challenging [...] Read more.

Big data mining, analysis, and forecasting play vital roles in modern economic and industrial fields, especially in the energy system. Inaccurate forecasting may cause wastes of scarce energy or electricity shortages. However, forecasting in the energy system has proven to be a challenging task due to various unstable factors, such as high fluctuations, autocorrelation and stochastic volatility. To forecast time series data by using hybrid models is a feasible alternative of conventional single forecasting modelling approaches. This paper develops a group of hybrid models to solve the problems above by eliminating the noise in the original data sequence and optimizing the parameters in a back propagation neural network. One of contributions of this paper is to integrate the existing algorithms and models, which jointly show advances over the present state of the art. The results of comparative studies demonstrate that the hybrid models proposed not only satisfactorily approximate the actual value but also can be an effective tool in the planning and dispatching of smart grids. Full article

(This article belongs to the Special Issue Energy Time Series Forecasting)

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11 pages, 6909 KiB

Open AccessArticle

Effect of Photoanode Design on the Photoelectrochemical Performance of Dye-Sensitized Solar Cells Based on SnO₂ Nanocomposite

by I-Ming Hung^* and Ripon Bhattacharjee

Department of Chemical Engineering and Materials Science, Yuan Ze University, Taoyuan 32003, Taiwan

Energies 2016, 9(8), 641; https://doi.org/10.3390/en9080641 - 13 Aug 2016

Cited by 17 | Viewed by 7507

Abstract

Li-doped ZnO (LZO) aggregated nanoparticles are used as an insulating layer in SnO₂ nanocomposite (SNC) photoanodes to suppress the recombination process in dye-sensitized solar cells (DSSCs). Various weight percentages of SnO₂ nanoparticles (SNPs) and SnO₂ nanoflowers (SNFs) were used to [...] Read more.

Li-doped ZnO (LZO) aggregated nanoparticles are used as an insulating layer in SnO₂ nanocomposite (SNC) photoanodes to suppress the recombination process in dye-sensitized solar cells (DSSCs). Various weight percentages of SnO₂ nanoparticles (SNPs) and SnO₂ nanoflowers (SNFs) were used to prepare SNC photoanodes. The photocurrent-voltage characteristics showed that the incorporation of an LZO insulating layer in an SNC photoanode increased the conversion efficiency of DSSCs. This was due to an increase in the surface area, charge injection, and charge collection, and the minimization of the recombination rate of photoanodes. Electrochemical impedance spectroscopy (EIS) results showed lower series resistance, charge injection resistance, and shorter lifetimes for DSSCs based on an SNC photoanode with an LZO insulating layer. The open circuit voltage and fill factor of the DSSCs based on SNC photoanodes with an LZO insulating layer significantly increased. The DSSC based on a SNC photoanode with a SNC:SNF weight ratio of 1:1 had a high current density of 4.73 mA/cm², open circuit voltage of 630 mV, fill factor of 69%, and efficiency of 2.06%. Full article

(This article belongs to the Special Issue Dye Sensitized Solar Cells)

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24 pages, 6266 KiB

Open AccessArticle

Land Suitability Analysis for Solar Farms Exploitation Using GIS and Fuzzy Analytic Hierarchy Process (FAHP)—A Case Study of Iran

by Ehsan Noorollahi, Dawud Fadai^*, Mohsen Akbarpour Shirazi and Seyed Hassan Ghodsipour

Industrial Engineering Department, Amirkabir University of Technology, 424 Hafez Ave, Tehran 15916-34311, Iran

Energies 2016, 9(8), 643; https://doi.org/10.3390/en9080643 - 19 Aug 2016

Cited by 207 | Viewed by 21111

Abstract

Considering the geographical location and climatic conditions of Iran, solar energy can provide a considerable portion of the energy demand for the country. This study develops a two-step framework. In the first step, the map of unsuitable regions is extracted based on the [...] Read more.

Considering the geographical location and climatic conditions of Iran, solar energy can provide a considerable portion of the energy demand for the country. This study develops a two-step framework. In the first step, the map of unsuitable regions is extracted based on the defined constraints. In the next step, in order to identify the suitability of different regions, 11 defined criteria, including solar radiation, average annual temperatures, distance from power transmission lines, distance from major roads, distance from residential area, elevation, slope, land use, average annual cloudy days, average annual humidity and average annual dusty days, are identified. The relative weights of defined criteria and sub-criteria are also determined applying fuzzy analytical hierarchy process (FAHP) technique. Next, by overlaying these criteria layers, the final map of prioritization of different regions of Iran for exploiting solar photovoltaic (PV) plants is developed. Based on Iran’s political divisions, investigation and analysis of the results have been presented for a total of 1057 districts of the country, where each district stands in one of the five defined classes of excellent, good, fair, low, and poor level. The obtained data indicate that 14.7% (237,920 km²), 17.2% (278,270 km²), 19.2% (311,767 km²), 11.3% (183,057 km²), 1.8% (30,549 km²) and 35.8% (580,264 km²) of Iran’s area are positioned as excellent, good, fair, low, poor and unsuitable areas, respectively. Moreover, Kerman, Yazd, Fars, Sisitan and Baluchestan, Southern Khorasan and Isfahan are included in the regions as the most excellent suitable provinces for exploiting solar PV plants. Full article

(This article belongs to the Special Issue Solar Photovoltaics Trilemma: Efficiency, Stability and Cost Reduction 2017)

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15 pages, 5899 KiB

Open AccessArticle

A New Switching Impulse Generator Based on Transformer Boosting and Insulated Gate Bipolar Transistor Trigger Control

by Ming Ren¹, Chongxing Zhang¹

, Ming Dong^1,*, Rixin Ye¹

and Ricardo Albarracín²

¹ State Key Laboratory of Electrical Insulation and Power Equipment, Xi’an Jiaotong University, Xi’an 710049, China

² Department of Electrical, Electronics and Automation Engineering and Applied Physics, Polytechnic University of Madrid, Ronda de Valencia 3, Madrid 28012, Spain

Energies 2016, 9(8), 644; https://doi.org/10.3390/en9080644 - 16 Aug 2016

Cited by 5 | Viewed by 8143

Abstract

To make the switching impulse (SI) generator more compact, portable and feasible in field tests, a new approach based on transformer boosting was developed. To address problems such as triggering synchronization and electromagnetic interference involved with the traditional spark gap, an insulated gate [...] Read more.

To make the switching impulse (SI) generator more compact, portable and feasible in field tests, a new approach based on transformer boosting was developed. To address problems such as triggering synchronization and electromagnetic interference involved with the traditional spark gap, an insulated gate bipolar transistor (IGBT) module with drive circuit was employed as the impulse trigger. An optimization design for the component parameters of the primary winding side of the transformer was realized by numerical calculation and error correction. Experiment showed that the waveform parameters of SI and oscillating switching impulse (OSI) voltages generated by the new generator were consistent with the numerical calculation and the error correction. The generator was finally built on a removable high voltage transformer with small size. Thus the volume of the generator is significantly reduced. Experiments showed that the waveform parameters of SI and OSI voltages generated by the new generator were basically consistent with the numerical calculation and the error correction. Full article

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13 pages, 5555 KiB

Open AccessArticle

A Concentrator Photovoltaic System Based on a Combination of Prism-Compound Parabolic Concentrators

by Ngoc Hai Vu

and Seoyong Shin^*

Department of Information and Communication Engineering, Myongji University, San 38-2 Nam-dong, Yongin 449-728, Korea

Energies 2016, 9(8), 645; https://doi.org/10.3390/en9080645 - 16 Aug 2016

Cited by 19 | Viewed by 10238

Abstract

We present a cost-effective concentrating photovoltaic system composed of a prism and a compound parabolic concentrator (P-CPC). In this approach, the primary collector consists of a prism, a solid compound parabolic concentrator (CPC), and a slab waveguide. The prism, which is placed on [...] Read more.

We present a cost-effective concentrating photovoltaic system composed of a prism and a compound parabolic concentrator (P-CPC). In this approach, the primary collector consists of a prism, a solid compound parabolic concentrator (CPC), and a slab waveguide. The prism, which is placed on the input aperture of CPC, directs the incoming sunlight beam to be parallel with the main axes of parabolic rims of CPC. Then, the sunlight is reflected at the parabolic rims and concentrated at the focal point of these parabolas. A slab waveguide is coupled at the output aperture of the CPC to collect focused sunlight beams and to guide them to the solar cell. The optical system was modeled and simulated with commercial ray tracing software (LightTools™). Simulation results show that the optical efficiency of a P-CPC can achieve up to 89%. when the concentration ratio of the P-CPC is fixed at 50. We also determine an optimal geometric structure of P-CPC based on simulation. Because of the simplicity of the P-CPC structure, a lower-cost mass production process is possible. A simulation based on optimal structure of P-CPC was performed and the results also shown that P-CPC has high angular tolerance for input sunlight. The high tolerance of the input angle of sunlight allows P-CPC solar concentrator utilize a single sun tracking system instead of a highly precise dual suntracking system as cost effective solution. Full article

(This article belongs to the Special Issue Solar Photovoltaics Trilemma: Efficiency, Stability and Cost Reduction 2017)

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14 pages, 1840 KiB

Open AccessArticle

Static Formation Temperature Prediction Based on Bottom Hole Temperature

by Changwei Liu¹, Kewen Li^1,*, Youguang Chen², Lin Jia¹ and Dong Ma³

¹ School of Energy Resources, China University of Geosciences, Beijing 100083, China

² Department of Petroleum and Geosystems Engineering, University of Texas at Austin, Austin, TX 78712, USA

³ Petroleum Engineering College, Yangtze University, Wuhan 430100, China

Energies 2016, 9(8), 646; https://doi.org/10.3390/en9080646 - 17 Aug 2016

Cited by 11 | Viewed by 8230

Abstract

Static formation temperature (SFT) is required to determine the thermophysical properties and production parameters in geothermal and oil reservoirs. However, it is not easy to determine SFT by both experimental and physical methods. In this paper, a mathematical approach to predicting SFT, based [...] Read more.

Static formation temperature (SFT) is required to determine the thermophysical properties and production parameters in geothermal and oil reservoirs. However, it is not easy to determine SFT by both experimental and physical methods. In this paper, a mathematical approach to predicting SFT, based on a new model describing the relationship between bottom hole temperature (BHT) and shut-in time, has been proposed. The unknown coefficients of the model were derived from the least squares fit by the particle swarm optimization (PSO) algorithm. Additionally, the ability to predict SFT using a few BHT data points (such as the first three, four, or five points of a data set) was evaluated. The accuracy of the proposed method to predict SFT was confirmed by a deviation percentage less than ±4% and a high regression coefficient R² (>0.98). The proposed method could be used as a practical tool to predict SFT in both geothermal and oil wells. Full article

(This article belongs to the Special Issue Selected Papers from the 5th Annual Conference for the Development and Utilization of Deep Geothermal Energy)

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20 pages, 6414 KiB

Open AccessArticle

Distributed Energy Storage Control for Dynamic Load Impact Mitigation

by Maximilian J. Zangs^†

, Peter B. E. Adams^†, Timur Yunusov

, William Holderbaum^*

and Ben A. Potter

¹ School of Systems Engineering, University of Reading, Whiteknights Campus, Reading RG6 6AY, UK

^† These authors contributed equally to this work.

Energies 2016, 9(8), 647; https://doi.org/10.3390/en9080647 - 17 Aug 2016

Cited by 13 | Viewed by 6038

Abstract

The future uptake of electric vehicles (EV) in low-voltage distribution networks can cause increased voltage violations and thermal overloading of network assets, especially in networks with limited headroom at times of high or peak demand. To address this problem, this paper proposes a [...] Read more.

The future uptake of electric vehicles (EV) in low-voltage distribution networks can cause increased voltage violations and thermal overloading of network assets, especially in networks with limited headroom at times of high or peak demand. To address this problem, this paper proposes a distributed battery energy storage solution, controlled using an additive increase multiplicative decrease (AIMD) algorithm. The improved algorithm (AIMD+) uses local bus voltage measurements and a reference voltage threshold to determine the additive increase parameter and to control the charging, as well as discharging rate of the battery. The used voltage threshold is dependent on the network topology and is calculated using power flow analysis tools, with peak demand equally allocated amongst all loads. Simulations were performed on the IEEE LV European Test feeder and a number of real U.K. suburban power distribution network models, together with European demand data and a realistic electric vehicle charging model. The performance of the standard AIMD algorithm with a fixed voltage threshold and the proposed AIMD+ algorithm with the reference voltage profile are compared. Results show that, compared to the standard AIMD case, the proposed AIMD+ algorithm further improves the network’s voltage profiles, reduces thermal overload occurrences and ensures a more equal battery utilisation. Full article

(This article belongs to the Special Issue Control of Energy Storage)

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24 pages, 10183 KiB

Open AccessArticle

Solar Farm Suitability Using Geographic Information System Fuzzy Sets and Analytic Hierarchy Processes: Case Study of Ulleung Island, Korea

by Jangwon Suh^*

and Jeffrey R. S. Brownson

John & Willie Leone Department of Energy and Mineral Engineering, The Pennsylvania State University, University Park, PA 16802, USA

Energies 2016, 9(8), 648; https://doi.org/10.3390/en9080648 - 17 Aug 2016

Cited by 73 | Viewed by 9615

Abstract

Solar farm suitability in remote areas will involve a multi-criteria evaluation (MCE) process, particularly well suited for the geographic information system (GIS) environment. Photovoltaic (PV) solar farm criteria were evaluated for an island-based case region having complex topographic and regulatory criteria, along with [...] Read more.

Solar farm suitability in remote areas will involve a multi-criteria evaluation (MCE) process, particularly well suited for the geographic information system (GIS) environment. Photovoltaic (PV) solar farm criteria were evaluated for an island-based case region having complex topographic and regulatory criteria, along with high demand for low-carbon local electricity production: Ulleung Island, Korea. Constraint variables that identified areas forbidden to PV farm development were consolidated into a single binary constraint layer (e.g., environmental regulation, ecological protection, future land use). Six factor variables were selected as influential on-site suitability within the geospatial database to seek out increased annual average power performance and reduced potential investment costs, forming new criteria layers for site suitability: solar irradiation, sunshine hours, average temperature in summer, proximity to transmission line, proximity to roads, and slope. Each factor variable was normalized via a fuzzy membership function (FMF) and parameter setting based on the local characteristics and criteria for a fixed axis PV system. Representative weighting of the relative importance for each factor variable was assigned via pairwise comparison completed by experts. A suitability index (SI) with six factor variables was derived using a weighted fuzzy summation method. Sensitivity analysis was conducted to assess four different SI based on the development scenarios (i.e., the combination of factors being considered). From the resulting map, three highly suitable regions were suggested and validated by comparison with satellite images to confirm the candidate sites for solar farm development. The GIS-MCE method proposed can also be applicable widely to other PV solar farm site selection projects with appropriate adaption for local variables. Full article

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19 pages, 6544 KiB

Open AccessArticle

Structure Optimization of Stand-Alone Renewable Power Systems Based on Multi Object Function

by Jae-Hoon Cho¹, Myung-Geun Chun² and Won-Pyo Hong^3,*

¹ Smart Logistics Technology Institute, Hankyong National University, 327 Chungang-ro Anseong-si, Kyonggi-do 17579, Korea

² Department of Electronics Engineering, Chungbuk National University, Chungdae-ro, Seowon-Gu, Cheongju, Chungbuk 28644, Korea

³ Department of Building Services Engineering, Hanbat National University, 125 Dongseodae-ro, Yuseong-Gu, Daejeon 34158, Korea

Energies 2016, 9(8), 649; https://doi.org/10.3390/en9080649 - 17 Aug 2016

Cited by 37 | Viewed by 7958

Abstract

This paper presents a methodology for the size optimization of a stand-alone hybrid PV/wind/diesel/battery system while considering the following factors: total annual cost (TAC), loss of power supply probability (LPSP), and the fuel cost of the diesel generator required by the user. A [...] Read more.

This paper presents a methodology for the size optimization of a stand-alone hybrid PV/wind/diesel/battery system while considering the following factors: total annual cost (TAC), loss of power supply probability (LPSP), and the fuel cost of the diesel generator required by the user. A new optimization algorithm and an object function (including a penalty method) are also proposed; these assist with designing the best structure for a hybrid system satisfying the constraints. In hybrid energy system sources such as photovoltaic (PV), wind, diesel, and energy storage devices are connected as an electrical load supply. Because the power produced by PV and wind turbine sources is dependent on the variation of the resources (sun and wind) and the load demand fluctuates, such a hybrid system must be able to satisfy the load requirements at any time and store the excess energy for use in deficit conditions. Therefore, reliability and cost are the two main criteria when designing a stand-alone hybrid system. Moreover, the operation of a diesel generator is important to achieve greater reliability. In this paper, TAC, LPSP, and the fuel cost of the diesel generator are considered as the objective variables and a hybrid teaching–learning-based optimization algorithm is proposed and used to choose the best structure of a stand-alone hybrid PV/wind/diesel/battery system. Simulation results from MATLAB support the effectiveness of the proposed method and confirm that it is more efficient than conventional methods. Full article

(This article belongs to the Special Issue Next-Generation Low-Carbon Power and Energy Systems)

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18 pages, 5142 KiB

Open AccessArticle

A Price-Based Demand Response Scheme for Discrete Manufacturing in Smart Grids

by Zhe Luo, Seung-Ho Hong^* and Jong-Beom Kim

Department of Electronic Systems Engineering, Hanyang University, 1271 Sa 3-dong, Sangnok-gu, Ansan-Si, Gyeonggi-do 426-791, Korea

Energies 2016, 9(8), 650; https://doi.org/10.3390/en9080650 - 17 Aug 2016

Cited by 28 | Viewed by 6906

Abstract

Demand response (DR) is a key technique in smart grid (SG) technologies for reducing energy costs and maintaining the stability of electrical grids. Since manufacturing is one of the major consumers of electrical energy, implementing DR in factory energy management systems (FEMSs) provides [...] Read more.

Demand response (DR) is a key technique in smart grid (SG) technologies for reducing energy costs and maintaining the stability of electrical grids. Since manufacturing is one of the major consumers of electrical energy, implementing DR in factory energy management systems (FEMSs) provides an effective way to manage energy in manufacturing processes. Although previous studies have investigated DR applications in process manufacturing, they were not conducted for discrete manufacturing. In this study, the state-task network (STN) model is implemented to represent a discrete manufacturing system. On this basis, a DR scheme with a specific DR algorithm is applied to a typical discrete manufacturing—automobile manufacturing—and operational scenarios are established for the stamping process of the automobile production line. The DR scheme determines the optimal operating points for the stamping process using mixed integer linear programming (MILP). The results show that parts of the electricity demand can be shifted from peak to off-peak periods, reducing a significant overall energy costs without degrading production processes. Full article

(This article belongs to the Special Issue Smart Microgrids: Developing the Intelligent Power Grid of Tomorrow)

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15 pages, 3984 KiB

Open AccessArticle

A Coordinated Control for Photovoltaic Generators and Energy Storages in Low-Voltage AC/DC Hybrid Microgrids under Islanded Mode

by Yao Liu¹

, Xiaochao Hou^2,*, Xiaofeng Wang¹, Chao Lin¹ and Josep M. Guerrero³

¹ Zhuhai Power Supply Bureau of Guangdong Power Grid Corporation, Zhuhai 519000, China

² School of Information Science and Engineering, Central South University, Changsha 410083, China

³ Department of Energy Technology, Aalborg University, Aalborg East DK-9220, Denmark

Energies 2016, 9(8), 651; https://doi.org/10.3390/en9080651 - 17 Aug 2016

Cited by 20 | Viewed by 6802

Abstract

The increasing penetration of renewable generators can be a significant challenge due to the fluctuation of their power generation. Energy storage (ES) units are one solution to improve power supply quality and guarantee system stability. In this paper, a hybrid microgrid is built [...] Read more.

The increasing penetration of renewable generators can be a significant challenge due to the fluctuation of their power generation. Energy storage (ES) units are one solution to improve power supply quality and guarantee system stability. In this paper, a hybrid microgrid is built based on photovoltaic (PV) generator and ES; and coordinated control is proposed and developed to achieve power management in a decentralized manner. This control scheme contains three different droop strategies according to characteristics of PV and ES. First, the modified droop control is proposed for PV, which can take full utilization of renewable energy and avoid regulating output active power frequently. Second, to maintain the direct current (DC) bus voltage stability, a novel droop control incorporating a constant power band is presented for DC-side ES. Third, a cascade droop control is designed for alternating current (AC)-side ES. Thus, the ES lifetime is prolonged. Moreover, interlinking converters (ICs) provide a bridge between AC/DC buses in a hybrid microgrid. The power control of IC is enabled when the AC- or DC-side suffer from active power demand shortage. In particular, if the AC microgrid does not satisfy the reactive power demand, IC then acts as a static synchronous compensator (STATCOM). The effectiveness of the proposed strategies is verified by simulations. Full article

(This article belongs to the Special Issue Decentralized Management of Energy Streams in Smart Grids)

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11 pages, 4637 KiB

Open AccessArticle

Heat Transfer and Energy Performance of a PVA Wall Tile Containing Macro-Encapsulated PCM

by Pin-Feng Liu^1,†, Yi-Pin Lin^2,†, Chun-Ta Tzeng^1,† and Chi-Ming Lai^3,*

¹ Department of Architecture, National Cheng Kung University, Tainan 701, Taiwan

² Department of Creative Design, National Yunlin University of Science and Technolog, Yunlin 64002, Taiwan

³ Department of Civil Engineering, National Cheng Kung University, Tainan 701, Taiwan

^† These authors contributed equally to this work.

Energies 2016, 9(8), 652; https://doi.org/10.3390/en9080652 - 18 Aug 2016

Cited by 18 | Viewed by 5622

Abstract

This study integrated building material engineering, building construction practices, and heat transfer mechanisms to develop a polyvinyl acetate (PVA) based wall tile, containing macro-encapsulated phase change material (macro-encapsulated PCM, macroPCM) and PVA. The heat transfer characteristics and energy performances of the proposed prototype [...] Read more.

This study integrated building material engineering, building construction practices, and heat transfer mechanisms to develop a polyvinyl acetate (PVA) based wall tile, containing macro-encapsulated phase change material (macro-encapsulated PCM, macroPCM) and PVA. The heat transfer characteristics and energy performances of the proposed prototype were investigated experimentally. The results indicated that the PVA-based macroPCM wall tile is suitable for use in exterior walls to enhance the thermal performance. The tile shows a lower heat indoor heat flux than other tested similar building materials and increases the time lag of peak load, effectively shifting the summer peak demand. Full article

(This article belongs to the Special Issue PCM Applications in Building Energy)

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15 pages, 4709 KiB

Open AccessArticle

Proposing Wavelet-Based Low-Pass Filter and Input Filter to Improve Transient Response of Grid-Connected Photovoltaic Systems

by Bijan Rahmani and Weixing Li^*

Department of Electrical Engineering, Harbin Institute of Technology, Harbin 150001, China

Energies 2016, 9(8), 653; https://doi.org/10.3390/en9080653 - 18 Aug 2016

Cited by 1 | Viewed by 6469

Abstract

Available photovoltaic (PV) systems show a prolonged transient response, when integrated into the power grid via active filters. On one hand, the conventional low-pass filter, employed within the integrated PV system, works with a large delay, particularly in the presence of system’s low-order [...] Read more.

Available photovoltaic (PV) systems show a prolonged transient response, when integrated into the power grid via active filters. On one hand, the conventional low-pass filter, employed within the integrated PV system, works with a large delay, particularly in the presence of system’s low-order harmonics. On the other hand, the switching of the DC (direct current)–DC converters within PV units also prolongs the transient response of an integrated system, injecting harmonics and distortion through the PV-end current. This paper initially develops a wavelet-based low-pass filter to improve the transient response of the interconnected PV systems to grid lines. Further, a damped input filter is proposed within the PV system to address the raised converter’s switching issue. Finally, Matlab/Simulink simulations validate the effectiveness of the proposed wavelet-based low-pass filter and damped input filter within an integrated PV system. Full article

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20 pages, 538 KiB

Open AccessArticle

An Algorithmic Game Approach for Demand Side Management in Smart Grid with Distributed Renewable Power Generation and Storage

by Ren-Shiou Liu

Department of Industrial and Information Management, National Cheng Kung University, No. 1, University Road, Tainan City 701, Taiwan

Energies 2016, 9(8), 654; https://doi.org/10.3390/en9080654 - 18 Aug 2016

Cited by 10 | Viewed by 5842

Abstract

In this paper, the problem of minimizing electricity cost and the peak system load in smart grids with distributed renewable energy resources is studied. Unlike prior research works that either assume all of the jobs are interruptible or power-shiftable, this paper focuses on [...] Read more.

In this paper, the problem of minimizing electricity cost and the peak system load in smart grids with distributed renewable energy resources is studied. Unlike prior research works that either assume all of the jobs are interruptible or power-shiftable, this paper focuses on more challenging scenarios in which jobs are non-interruptible and non-power-shiftable. In addition, as more and more newly-built homes have rooftop solar arrays, it is assumed that all users are equipped with a solar-plus-battery system in this paper. Thus, power can be drawn from the battery as needed to reduce the cost of electricity or to lower the overall system load. With a quadratic load-dependent cost function, this paper first shows that the electricity cost minimization problem in such a setting is NP-hard and presents a distributed demand-side management algorithm, called DDSM, to solve this. Experimental results show that the proposed DDSM algorithm is effective, scalable and converges to a Nash equilibrium in finite rounds. Full article

(This article belongs to the Collection Smart Grid)

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19 pages, 7657 KiB

Open AccessArticle

Research on the Combustion Characteristics of a Free-Piston Gasoline Engine Linear Generator during the Stable Generating Process

by Yuxi Miao¹, Zhengxing Zuo¹, Huihua Feng^1,*, Chendong Guo¹, Yu Song¹, Boru Jia^1,2 and Yuyao Guo¹

¹ School of Mechanical and Vehicle Engineering, Beijing Institute of Technology, Zhongguancun South Street No. 5, Beijing 100081, China

² Sir Joseph Swan Centre for Energy Research, Newcastle University, Newcastle upon Tyne NE1 7RU, UK

Energies 2016, 9(8), 655; https://doi.org/10.3390/en9080655 - 18 Aug 2016

Cited by 44 | Viewed by 8354

Abstract

The free-piston gasoline engine linear generator (FPGLG) is a new kind of power plant consisting of free-piston gasoline engines and a linear generator. Due to the elimination of the crankshaft mechanism, the piston motion process and the combustion heat release process affect each [...] Read more.

The free-piston gasoline engine linear generator (FPGLG) is a new kind of power plant consisting of free-piston gasoline engines and a linear generator. Due to the elimination of the crankshaft mechanism, the piston motion process and the combustion heat release process affect each other significantly. In this paper, the combustion characteristics during the stable generating process of a FPGLG were presented using a numerical iteration method, which coupled a zero-dimensional piston dynamic model and a three-dimensional scavenging model with the combustion process simulation. The results indicated that, compared to the conventional engine (CE), the heat release process of the FPGLG lasted longer with a lower peak heat release rate. The indicated thermal efficiency of the engine was lower because less heat was released around the piston top dead centre (TDC). Very minimal difference was observed on the ignition delay duration between the FPGLG and the CE, while the post-combustion period of the FPGLG was significantly longer than that of the CE. Meanwhile, the FPGLG was found to operate more moderately due to lower peak in-cylinder gas pressure and a lower pressure rising rate. The potential advantage of the FPGLG in lower NO_x emission was also proven with the simulation results presented in this paper. Full article

(This article belongs to the Special Issue Combustion and Propulsion)

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11 pages, 2545 KiB

Open AccessArticle

Study on Reaction Characteristics of Chemical-Looping Combustion between Maize Stalk and High Index Facet Iron Oxide

by Wu Qin^1,*, Changfeng Lin¹, Jianye Wang¹, Xianbin Xiao¹, Changqing Dong¹ and Li Wei^2,*

¹ National Engineering Laboratory for Biomass Power Generation Equipment, School of Renewable Energy Engineering, North China Electric Power University, Beijing 102206, China

² State Key Laboratory of Urban Water Resource and Environment, Harbin Institute of Technology, Harbin 150090, China

Energies 2016, 9(8), 656; https://doi.org/10.3390/en9080656 - 18 Aug 2016

Cited by 4 | Viewed by 5287

Abstract

In this work, experiments were performed to investigate the activity and regeneration ability of iron-based oxygen carrier with high index facet (104) during chemical looping combustion (CLC), suggesting that morphological control of the oxygen carrier is very rewarding. Fe₂O₃(104) [...] Read more.

In this work, experiments were performed to investigate the activity and regeneration ability of iron-based oxygen carrier with high index facet (104) during chemical looping combustion (CLC), suggesting that morphological control of the oxygen carrier is very rewarding. Fe₂O₃(104) supported on Al₂O₃ was synthesized by a morphology controlled method to undertake maize stalk CLC experiments. Compared with the referenced Fe₂O₃/Al₂O₃ prepared by the impregnation method, Fe₂O₃(104)/Al₂O₃ presents better reactivity, showing higher fuel conversion rate and CO₂ concentration in gaseous products. Further, structural characterizations, including X-ray diffraction (XRD), scanning electron microscopy (SEM) (LEO-1450) and Brunauer-Emmett-Teller (BET) analysis, and multi-cycles CLC reactions were performed to verify the good regeneration and stability of the Fe₂O₃(104)/Al₂O₃. The findings indicate that the Fe₂O₃(104)/Al₂O₃ is efficient when used for CLC of maize stalk. Full article

(This article belongs to the Special Issue Combustion and Propulsion)

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15 pages, 354 KiB

Open AccessArticle

Electromagnetohydrodynamic Effects on Steam Bubble Formation in Vertical Heated Upward Flow

by Mojtaba Mirzaee¹, Payam Hooshmand², Hamed Ahmadi³, Hassan Kavoosi Balotaki⁴, HamidReza KhakRah⁵

and Mohammad Yaghoub Abdollahzadeh Jamalabadi^6,*

¹ Young Researchers and Elite Club, Omidiyeh Branch, Islamic Azad University, Omidiyeh 6373193719, Iran

² Department of Mechanical Engineering, Sanandaj Branch, Islamic Azad University, Sanandaj 6616935391, Iran

³ Department of Energy Engineering, Faculty of Environment and Energy, Science and Research Branch, Islamic Azad University, Tehran 1477893855, Iran

⁴ Department of Mechanical Engineering, Izeh Branch, Islamic Azad University, Izeh 6391997699, Iran

⁵ Department of Mechanical Engineering, Shiraz Branch, Islamic Azad University, Shiraz 7473171987, Iran

⁶ Department of Mechanical, Robotics and Energy Engineering, Dongguk University-Seoul, 30 Pildong-ro 1gil, Jung-gu, Seoul 04620, Korea

Energies 2016, 9(8), 657; https://doi.org/10.3390/en9080657 - 18 Aug 2016

Cited by 5 | Viewed by 4438

Abstract

In this paper, the modeling of a steady state two phase flow heated through a vertical upward flow under electro-magneto-hydro-dynamic forces is presented. The thermal non-equilibrium, non-homogeneous, two-phase flow model consisting of mass, momentum and energy conservation in each phase has been adjusted [...] Read more.

In this paper, the modeling of a steady state two phase flow heated through a vertical upward flow under electro-magneto-hydro-dynamic forces is presented. The thermal non-equilibrium, non-homogeneous, two-phase flow model consisting of mass, momentum and energy conservation in each phase has been adjusted for subcooled inlet conditions close to saturation. The P-1 approximation, viscous dissipation and Joule heating are included in the energy equations. It was seen that the Lorentz force can decrease and postpone the bubble generation, as well as affect the slip velocity, flow forces, viscous dissipation and Joule heating. Furthermore, two correlations for the slip velocity under magnetohydrodynamic (MHD) forces are presented. As shown, skin friction and Joule heating increase with the magnetic field strength. Full article

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15 pages, 2790 KiB

Open AccessArticle

DMFC Performance of Polymer Electrolyte Membranes Prepared from a Graft-Copolymer Consisting of a Polysulfone Main Chain and Styrene Sulfonic Acid Side Chains

by Nobutaka Endo¹, Yoshiaki Ogawa¹, Kohei Ukai¹, Yuriko Kakihana² and Mitsuru Higa^1,*

¹ Graduate School of Science and Technology for Innovation, Yamaguchi University, 2-16-1 Tokiwadai, Ube City, Yamaguchi 755-8611, Japan

² Center for Membrane and Film Technology, Department of Chemical Science and Engineering, Kobe University, 1-1 Rokkodaicho, Nada-ku, Kobe 657-8501, Japan

Energies 2016, 9(8), 658; https://doi.org/10.3390/en9080658 - 19 Aug 2016

Cited by 6 | Viewed by 6724

Abstract

Polymer electrolyte membranes (PEMs) for direct methanol fuel cell (DMFC) applications were prepared from a graft-copolymer (PSF-g-PSSA) consisting of a polysulfone (PSF) main chain and poly(styrene sulfonic acid) (PSSA) side chains with various average distances between side chains (Lav) [...] Read more.

Polymer electrolyte membranes (PEMs) for direct methanol fuel cell (DMFC) applications were prepared from a graft-copolymer (PSF-g-PSSA) consisting of a polysulfone (PSF) main chain and poly(styrene sulfonic acid) (PSSA) side chains with various average distances between side chains (Lav) and side chain lengths (Lsc). The polymers were synthesized by grafting ethyl p-styrenesulfonate (EtSS) on macro-initiators of chloromethylated polysulfone with different contents of chloromethyl (CM) groups, and by changing EtSS content in the copolymers by using atom transfer radical polymerization (ATRP). The DMFC performance tests using membrane electrode assemblis (MEAs) with the three types of the PEMs revealed that: a PSF-g-PSSA PEM (SF-6) prepared from a graft copolymer with short average distances between side chains (Lav) and medium Lsc had higher DMFC performance than PEMs with long Lav and long Lsc or with short Lav and short Lsc. SF-6 had about two times higher PD_max (68.4 mW/cm²) than Nafion^® 112 at 30 wt % of methanol concentration. Furthermore, it had 58.2 mW/cm² of PD_max at 50 wt % of methanol concentration because of it has the highest proton selectivity during DMFC operation of all the PSF-g-PSSA PEMs and Nafion^® 112. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells 2016)

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18 pages, 4556 KiB

Open AccessArticle

Effect on Particulate and Gas Emissions by Combusting Biodiesel Blend Fuels Made from Different Plant Oil Feedstocks in a Liquid Fuel Burner

by Norwazan Abdul Rahim^1,2,*, Mohammad Nazri Mohd Jaafar², Syazwana Sapee² and Hazir Farouk Elraheem³

¹ Department of Mechanical Engineering, Faculty of Engineering, Universiti Pertahanan Nasional Malaysia, Kem Sg. Besi, 57000 Kuala Lumpur, Malaysia

² Institute for Vehicle System and Engineering, Faculty of Mechanical Engineering, Universiti Teknologi Malaysia, UTM Skudai, 81310 Johor Bahru, Malaysia

³ School of Mechanical Engineering, Sudan University of Science and Technology, P.O. Box 407, Khartoum, Sudan

Energies 2016, 9(8), 659; https://doi.org/10.3390/en9080659 - 19 Aug 2016

Cited by 18 | Viewed by 5872

Abstract

This paper focuses on the combustion performance of various blends of biodiesel fuels and diesel fuel from lean to rich mixtures. The biodiesel blend fuel combustion experiments were carried out using a liquid fuel burner and biodiesel fuel made from various plant oil [...] Read more.

This paper focuses on the combustion performance of various blends of biodiesel fuels and diesel fuel from lean to rich mixtures. The biodiesel blend fuel combustion experiments were carried out using a liquid fuel burner and biodiesel fuel made from various plant oil feedstocks, including jatropha, palm and coconut oils. The results show that jatropha oil methyl ester blend 25 (JOME B25) and coconut oil methyl ester blend 25 (COME B25) blended at 25% by volume in diesel fuel produced lower carbon monoxide (CO) and unburned hydrocarbon (UHC) emissions due to more complete combustion. Overall, JOME B25 had the highest CO emission reduction, at about 42.25%, followed by COME B25 at 26.44% emission reduction relative to pure diesel fuel. By contrast, the palm oil methyl ester blend 25 (POME B25) showed a 48.44% increase in these emissions. The results showed that the nitrogen oxides (NO_x) emissions were slightly higher for all biodiesel blend fuels compared with pure diesel fuel combustion. In case of sulphur dioxide (SO₂) and UHC emissions, all biodiesel blends fuels have significantly reduced emissions. In the case of SO₂ emission, the POME B25, JOME B25 and COME B25 emissions were reduced 14.62%, 14.45% and 21.39%, respectively, relative to SO₂ emission from combusting pure diesel fuel. UHC emissions of POME B25, JOME B25 and COME B25 showed 51%, 71% and 70% reductions, respectively, compared to diesel fuel. The conclusion from the results is that all the biodiesel blend fuels are suitable and can be recommended for use in liquid fuel burners in order to get better and ‘greener’ environmental outcomes. Full article

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24 pages, 2110 KiB

Open AccessArticle

The Hidden Burden of Food Waste: The Double Energy Waste in Italy

by Matteo Vittuari^*

, Fabio De Menna

and Marco Pagani

Department of Agricultural and Food Sciences, University of Bologna, Viale Fanin 50, 40124 Bologna, Italy

Energies 2016, 9(8), 660; https://doi.org/10.3390/en9080660 - 19 Aug 2016

Cited by 33 | Viewed by 8756

Abstract

The energy intensity of modern food systems represents a major issue in a scenario of decreasing oil resources and increasing population. Beside the use of renewable energy, an increased efficiency in food systems could contribute to reduce fossil fuels dependence. In this sense, [...] Read more.

The energy intensity of modern food systems represents a major issue in a scenario of decreasing oil resources and increasing population. Beside the use of renewable energy, an increased efficiency in food systems could contribute to reduce fossil fuels dependence. In this sense, food losses and waste (FLW) have crucial consequences on the energy balance. Based on the concept of “embodied energy”, food wastage can be framed as a double waste of energy, both in terms of non-consumed food energy and the inputs used for production. Secondary data regarding direct and indirect energy inputs and FLW have been collected for the Italian food chain to estimate the embodied energy of food waste. Since in 2011 the production and distribution of food implied the use of 822 PJ and 18 Mt of food was discarded, 67 PJ of food energy and 100 PJ of embodied energy were wasted. These figures are equivalent to 12.2% of the total nutritional energy output and to 1.3% of the final energy use in Italy, respectively. The concept of double energy waste sheds new light on the intertwined relationship between energy and food security, suggesting that appropriate food waste reduction policies could result in a higher food production level and relevant energy savings. Full article

(This article belongs to the Special Issue Waste Energy Harvesting)

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21 pages, 4038 KiB

Open AccessArticle

Energy Management of an Off-Grid Hybrid Power Plant with Multiple Energy Storage Systems

by Laura Tribioli^1,*

, Raffaello Cozzolino¹

, Luca Evangelisti¹ and Gino Bella²

¹ Department of Engineering, Niccolò Cusano University, via Don Carlo Gnocchi 3, 00166 Rome, Italy

² Department of Engineering, University of Rome Tor Vergata, via Orazio Raimondo 18, 00173 Rome, Italy

Energies 2016, 9(8), 661; https://doi.org/10.3390/en9080661 - 19 Aug 2016

Cited by 35 | Viewed by 7135

Abstract

In this paper, an off-grid hybrid power plant with multiple storage systems for an artificial island is designed and two possible strategies for the management of the stored energy are proposed. Renewable power sources (wind/solar technologies) are used as primary power suppliers. A [...] Read more.

In this paper, an off-grid hybrid power plant with multiple storage systems for an artificial island is designed and two possible strategies for the management of the stored energy are proposed. Renewable power sources (wind/solar technologies) are used as primary power suppliers. A lead-acid battery pack (BAT) and a reversible polymer electrolyte fuel cell are employed to fulfill the power demand and to absorb extra power. The reversible fuel cell allows reducing costs and occupied space and the fuel cell can be fed by the pure hydrogen produced by means of its reversible operation as an electrolyzer. A diesel engine is employed as backup system. While HOMER Pro^® has been employed for a full-factorial-based optimization of the sizes of the renewable sources and the BAT, Matlab/Simulink^® has been later used for simulating the plant operation and compare two possible power management control strategies. For the reversible fuel cell sizing, a sensitivity analysis has been carried out varying stack and hydrogen tank sizes. The final choice for plant configuration and power management control strategy has been made on the basis of a comparative analysis of the results, aimed at minimizing fossil fuel consumption and CO₂ emissions, battery aging rate and at maximizing the power plant overall efficiency. The obtained results demonstrate the possibility of realizing a renewable power plant, able to match the needs of electrical power in a remote area, by achieving a good integration of different energy sources and facing the intermittent nature of renewable power sources, with very low use of fossil fuels. Full article

(This article belongs to the Special Issue 16th CIRIAF National Congress – Sustainable Development, Environment and Human Health Protection)

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14 pages, 702 KiB

Open AccessArticle

Potential of Reversible Solid Oxide Cells as Electricity Storage System

by Paolo Di Giorgio^† and Umberto Desideri^*,†

¹ Department of Energy, Systems, Territory and Constructions Engineering, University of Pisa, Largo Lucio Lazzarino, Pisa 56122, Italy

^† These authors contributed equally to this work.

Energies 2016, 9(8), 662; https://doi.org/10.3390/en9080662 - 19 Aug 2016

Cited by 53 | Viewed by 7575

Abstract

Electrical energy storage (EES) systems allow shifting the time of electric power generation from that of consumption, and they are expected to play a major role in future electric grids where the share of intermittent renewable energy systems (RES), and especially solar and [...] Read more.

Electrical energy storage (EES) systems allow shifting the time of electric power generation from that of consumption, and they are expected to play a major role in future electric grids where the share of intermittent renewable energy systems (RES), and especially solar and wind power plants, is planned to increase. No commercially available technology complies with all the required specifications for an efficient and reliable EES system. Reversible solid oxide cells (ReSOC) working in both fuel cell and electrolysis modes could be a cost effective and highly efficient EES, but are not yet ready for the market. In fact, using the system in fuel cell mode produces high temperature heat that can be recovered during electrolysis, when a heat source is necessary. Before ReSOCs can be used as EES systems, many problems have to be solved. This paper presents a new ReSOC concept, where the thermal energy produced during fuel cell mode is stored as sensible or latent heat, respectively, in a high density and high specific heat material and in a phase change material (PCM) and used during electrolysis operation. The study of two different storage concepts is performed using a lumped parameters ReSOC stack model coupled with a suitable balance of plant. The optimal roundtrip efficiency calculated for both of the configurations studied is not far from 70% and results from a trade-off between the stack roundtrip efficiency and the energy consumed by the auxiliary power systems. Full article

(This article belongs to the Special Issue Solid Oxide Fuel Cells)

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15 pages, 4756 KiB

Open AccessArticle

Thermoeconomic Modeling and Parametric Study of a Photovoltaic-Assisted 1 MW_e Combined Cooling, Heating, and Power System

by Alexandros Arsalis^1,2,*

, Andreas N. Alexandrou^1,2 and George E. Georghiou^2,3

¹ Department of Mechanical and Manufacturing Engineering, University of Cyprus, Nicosia 1678, Cyprus

² FOSS Research Centre for Sustainable Energy, University of Cyprus, Nicosia 1678, Cyprus

³ Department of Electrical and Computer Engineering, University of Cyprus, Nicosia 1678, Cyprus

Energies 2016, 9(8), 663; https://doi.org/10.3390/en9080663 (registering DOI) - 20 Aug 2016

Cited by 15 | Viewed by 5414 | Correction

Abstract

In this study a small-scale, completely autonomous combined cooling, heating, and power (CCHP) system is coupled to a photovoltaic (PV) subsystem, to investigate the possibility of reducing fuel consumption. The CCHP system generates electrical energy with the use of a simple gas turbine [...] Read more.

In this study a small-scale, completely autonomous combined cooling, heating, and power (CCHP) system is coupled to a photovoltaic (PV) subsystem, to investigate the possibility of reducing fuel consumption. The CCHP system generates electrical energy with the use of a simple gas turbine cycle, with a rated nominal power output of 1 MW_e. The nominal power output of the PV subsystem is examined in a parametric study, ranging from 0 to 600 kW_e, to investigate which configuration results in a minimum lifecycle cost (LCC) for a system lifetime of 20 years of service. The load profile considered is applied for a complex of households in Nicosia, Cyprus. The solar data for the PV subsystem are taken on an hourly basis for a whole year. The results suggest that apart from economic benefits, the proposed system also results in high efficiency and reduced CO₂ emissions. The parametric study shows that the optimum PV capacity is 300 kW_e. The minimum lifecycle cost for the PV-assisted CCHP system is found to be 3.509 million €, as compared to 3.577 million € for a system without a PV subsystem. The total cost for the PV subsystem is 547,445 €, while the total cost for operating the system (fuel) is 731,814 € (compared to 952,201 € for a CCHP system without PVs). Overall, the proposed system generates a total electrical energy output of 52,433 MWh (during its whole lifetime), which translates to a unit cost of electricity of 0.067 €/kWh. Full article

(This article belongs to the Special Issue Simulation of Polygeneration Systems)

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Review

Jump to: Research

18 pages, 2266 KiB

Open AccessReview

Artificial Neural Network Application for Partial Discharge Recognition: Survey and Future Directions

by Abdullahi Abubakar Mas’ud^1,*

, Ricardo Albarracín²

, Jorge Alfredo Ardila-Rey³

, Firdaus Muhammad-Sukki⁴

, Hazlee Azil Illias⁵

, Nurul Aini Bani⁶ and Abu Bakar Munir^7,8

¹ Department of Electrical and Electronics Engineering, Jubail Industrial College, Jubail 10099, Saudi Arabia

² Department of Electrical, Electronics and Automation Engineering and Applied Physics, Universidad Politécnica de Madrid, Ronda de Valencia 3, Madrid 28012, Spain

³ Department of Electrical Engineering, Federico Santa María Technical University, Santiago de Chile 8940000, Chile

⁴ School of Engineering, Faculty of Design and Technology, Robert Gordon University, Aberdeen AB10 7GJ, UK

⁵ Department of Electrical Engineering, Faculty of Engineering, University of Malaya, Kuala Lumpur 50603, Malaysia

⁶ UTM Razak School of Engineering and Advanced Technology, Universiti Teknologi Malaysia, Kuala Lumpur 54100, Malaysia

⁷ Faculty of Law, University of Malaya, Kuala Lumpur 50603, Malaysia

⁸ University of Malaya Malaysian Centre of Regulatory Studies (UMCoRS), University of Malaya, Jalan Pantai Baru, Kuala Lumpur 59990, Malaysia

Energies 2016, 9(8), 574; https://doi.org/10.3390/en9080574 - 25 Jul 2016

Cited by 66 | Viewed by 8937

Abstract

In order to investigate how artificial neural networks (ANNs) have been applied for partial discharge (PD) pattern recognition, this paper reviews recent progress made on ANN development for PD classification by a literature survey. Contributions from several authors have been presented and discussed. [...] Read more.

In order to investigate how artificial neural networks (ANNs) have been applied for partial discharge (PD) pattern recognition, this paper reviews recent progress made on ANN development for PD classification by a literature survey. Contributions from several authors have been presented and discussed. High recognition rate has been recorded for several PD faults, but there are still many factors that hinder correct recognition of PD by the ANN, such as high-amplitude noise or wide spectral content typical from industrial environments, trial and error approaches in determining an optimum ANN, multiple PD sources acting simultaneously, lack of comprehensive and up to date databank of PD faults, and the appropriate selection of the characteristics that allow a correct recognition of the type of source which are currently being addressed by researchers. Several suggestions for improvement are proposed by the authors include: (1) determining the optimum weights in training the ANN; (2) using PD data captured over long stressing period in training the ANN; (3) ANN recognizing different PD degradation levels; (4) using the same resolution sizes of the PD patterns when training and testing the ANN with different PD dataset; (5) understanding the characteristics of multiple concurrent PD faults and effectively recognizing them; and (6) developing techniques in order to shorten the training time for the ANN as applied for PD recognition Finally, this paper critically assesses the suitability of ANNs for both online and offline PD detections outlining the advantages to the practitioners in the field. It is possible for the ANNs to determine the stage of degradation of the PD, thereby giving an indication of the seriousness of the fault. Full article

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34 pages, 11269 KiB

Open AccessEditor’s ChoiceReview

A Review of Dangerous Dust in Fusion Reactors: from Its Creation to Its Resuspension in Case of LOCA and LOVA

by Andrea Malizia^*

, Luigi Antonio Poggi, Jean-François Ciparisse, Riccardo Rossi

, Carlo Bellecci and Pasquale Gaudio

Department of Industrial Engineering, Associazione EUROFUSION-ENEA, University of Rome Tor Vergata, Via del Politecnico 1, 00133 Rome, Italy

Energies 2016, 9(8), 578; https://doi.org/10.3390/en9080578 - 25 Jul 2016

Cited by 43 | Viewed by 9789

Abstract

The choice of materials for the future nuclear fusion reactors is a crucial issue. In the fusion reactors, the combination of very high temperatures, high radiation levels, intense production of transmuting elements and high thermomechanical loads requires very high-performance materials. Erosion of PFCs [...] Read more.

The choice of materials for the future nuclear fusion reactors is a crucial issue. In the fusion reactors, the combination of very high temperatures, high radiation levels, intense production of transmuting elements and high thermomechanical loads requires very high-performance materials. Erosion of PFCs (Plasma Facing Components) determines their lifetime and generates a source of impurities (i.e., in-vessel tritium and dust inventories), which cool down and dilute the plasma. The resuspension of dust could be a consequences of LOss of Coolant Accidents (LOCA) and LOss of Vacuum Accidents (LOVA) and it can be dangerous because of dust radioactivity, toxicity, and capable of causing an explosion. These characteristics can jeopardize the plant safety and pose a serious threat to the operators. The purpose of this work is to determine the experimental and numerical steeps to develop a numerical model to predict the dust resuspension consequences in case of accidents through a comparison between the experimental results taken from campaigns carried out with STARDUST-U and the numerical simulation developed with CFD codes. The authors in this work will analyze the candidate materials for the future nuclear plants and the consequences of the resuspension of its dust in case of accidents through the experience with STARDUST-U. Full article

(This article belongs to the Special Issue Fusion Power)

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19 pages, 4698 KiB

Open AccessReview

Green Material Prospects for Passive Evaporative Cooling Systems: Geopolymers

by Zeynab Emdadi¹, Nilofar Asim^1,*, Mohd Ambar Yarmo², Roslinda Shamsudin³, Masita Mohammad¹ and Kamaruzaman Sopian¹

¹ Solar Energy Research Institute, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

² Department of Chemistry, Faculty of Science and Technology, Universiti Kebangsan Malaysia, 43600 Bangi, Selangor, Malaysia

³ School of Applied Physics, Faculty of Sciences and Technology, Universiti Kebangsaan Malaysia, 43600 Bangi, Selangor, Malaysia

Energies 2016, 9(8), 586; https://doi.org/10.3390/en9080586 - 27 Jul 2016

Cited by 19 | Viewed by 10436

Abstract

Passive cooling techniques have been used mostly in countries with hot and arid climates such as Iran, Egypt, and India. However, the use of this important technology has not been seriously considered until a time of energy crisis, and consequently, environmental crisis scenarios, [...] Read more.

Passive cooling techniques have been used mostly in countries with hot and arid climates such as Iran, Egypt, and India. However, the use of this important technology has not been seriously considered until a time of energy crisis, and consequently, environmental crisis scenarios, emerge. Scholars have renewed their interest in investigating passive cooling technology, particularly the aspects of new materials, thermal comfort, energy efficiency, new designs, climate, and environmental considerations. This review paper highlights the opportunities to use green materials, such as geopolymers, as evaporative cooling materials with different types of industrial and agricultural waste products as components. Novel ideas for passive cooling design using ancient and nature-inspired concepts are also presented to promote green technology for future applications. Full article

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39 pages, 3576 KiB

Open AccessReview

Recent Progress on the Key Materials and Components for Proton Exchange Membrane Fuel Cells in Vehicle Applications

by Cheng Wang^1,5,*, Shubo Wang¹, Linfa Peng², Junliang Zhang³, Zhigang Shao⁴, Jun Huang⁵, Chunwen Sun⁶, Minggao Ouyang⁵ and Xiangming He^1,5,*

¹ Institute of Nuclear and New Energy Technology, Tsinghua University, Beijing 100084, China

² State Key Laboratory of Mechanical System and Vibration, Shanghai Jiao Tong University, Shanghai 200240, China

³ School of Mechanical Engineering, Shanghai Jiao Tong University, Shanghai 200240, China

⁴ Fuel Cell System and Engineering Laboratory, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, Liaoning, China

⁵ State Key Laboratory of Automotive Safety and Energy, Tsinghua University, Beijing 100084, China

⁶ Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, Beijing 100083, China

Energies 2016, 9(8), 603; https://doi.org/10.3390/en9080603 - 29 Jul 2016

Cited by 89 | Viewed by 14249

Abstract

Fuel cells are the most clean and efficient power source for vehicles. In particular, proton exchange membrane fuel cells (PEMFCs) are the most promising candidate for automobile applications due to their rapid start-up and low-temperature operation. Through extensive global research efforts in the [...] Read more.

Fuel cells are the most clean and efficient power source for vehicles. In particular, proton exchange membrane fuel cells (PEMFCs) are the most promising candidate for automobile applications due to their rapid start-up and low-temperature operation. Through extensive global research efforts in the latest decade, the performance of PEMFCs, including energy efficiency, volumetric and mass power density, and low temperature startup ability, have achieved significant breakthroughs. In 2014, fuel cell powered vehicles were introduced into the market by several prominent vehicle companies. However, the low durability and high cost of PEMFC systems are still the main obstacles for large-scale industrialization of this technology. The key materials and components used in PEMFCs greatly affect their durability and cost. In this review, the technical progress of key materials and components for PEMFCs has been summarized and critically discussed, including topics such as the membrane, catalyst layer, gas diffusion layer, and bipolar plate. The development of high-durability processing technologies is also introduced. Finally, this review is concluded with personal perspectives on the future research directions of this area. Full article

(This article belongs to the Special Issue Polymer Electrolyte Membrane Fuel Cells 2016)

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27 pages, 1119 KiB

Open AccessReview

A Review of Classification Problems and Algorithms in Renewable Energy Applications

by María Pérez-Ortiz^1,†, Silvia Jiménez-Fernández^2,†

, Pedro A. Gutiérrez^3,†, Enrique Alexandre^2,†, César Hervás-Martínez^3,† and Sancho Salcedo-Sanz^2,*

¹ Department of Quantitative Methods, Universidad Loyola Andalucía, 14004 Córdoba, Spain

² Department of Signal Processing and Communications, Universidad de Alcalá, 28805 Alcalá de Henares, Spain

³ Department of Computer Science and Numerical Analysis, Universidad de Córdoba, 14071 Córdoba, Spain

^† These authors contributed equally to this work.

Energies 2016, 9(8), 607; https://doi.org/10.3390/en9080607 - 2 Aug 2016

Cited by 115 | Viewed by 9396

Abstract

Classification problems and their corresponding solving approaches constitute one of the fields of machine learning. The application of classification schemes in Renewable Energy (RE) has gained significant attention in the last few years, contributing to the deployment, management and optimization of RE systems. [...] Read more.

Classification problems and their corresponding solving approaches constitute one of the fields of machine learning. The application of classification schemes in Renewable Energy (RE) has gained significant attention in the last few years, contributing to the deployment, management and optimization of RE systems. The main objective of this paper is to review the most important classification algorithms applied to RE problems, including both classical and novel algorithms. The paper also provides a comprehensive literature review and discussion on different classification techniques in specific RE problems, including wind speed/power prediction, fault diagnosis in RE systems, power quality disturbance classification and other applications in alternative RE systems. In this way, the paper describes classification techniques and metrics applied to RE problems, thus being useful both for researchers dealing with this kind of problem and for practitioners of the field. Full article

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32 pages, 6930 KiB

Open AccessEditor’s ChoiceReview

Capacitor Current Feedback-Based Active Resonance Damping Strategies for Digitally-Controlled Inductive-Capacitive-Inductive-Filtered Grid-Connected Inverters

by Iman Lorzadeh¹, Hossein Askarian Abyaneh^1,*, Mehdi Savaghebi²

, Alireza Bakhshai³ and Josep M. Guerrero²

¹ Center of Excellence in Electrical Power Engineering, Electrical Engineering Department, Amirkabir University of Technology, Tehran 15875-4413, Iran

² Department of Energy Technology, Aalborg University, Aalborg East DK-9220, Denmark

³ Department of Electrical and Computer Engineering, Queens University, Kingston, ON K7L 3N6, Canada

Energies 2016, 9(8), 642; https://doi.org/10.3390/en9080642 - 17 Aug 2016

Cited by 33 | Viewed by 11272

Abstract

Inductive-capacitive-inductive (LCL)-type line filters are widely used in grid-connected voltage source inverters (VSIs), since they can provide substantially improved attenuation of switching harmonics in currents injected into the grid with lower cost, weight and power losses than their L-type counterparts. However, the inclusion [...] Read more.

Inductive-capacitive-inductive (LCL)-type line filters are widely used in grid-connected voltage source inverters (VSIs), since they can provide substantially improved attenuation of switching harmonics in currents injected into the grid with lower cost, weight and power losses than their L-type counterparts. However, the inclusion of third order LCL network complicates the current control design regarding the system stability issues because of an inherent resonance peak which appears in the open-loop transfer function of the inverter control system near the control stability boundary. To avoid passive (resistive) resonance damping solutions, due to their additional power losses, active damping (AD) techniques are often applied with proper control algorithms in order to damp the LCL filter resonance and stabilize the system. Among these techniques, the capacitor current feedback (CCF) AD has attracted considerable attention due to its effective damping performance and simple implementation. This paper thus presents a state-of-the-art review of resonance and stability characteristics of CCF-based AD approaches for a digitally-controlled LCL filter-based grid-connected inverter taking into account the effect of computation and pulse width modulation (PWM) delays along with a detailed analysis on proper design and implementation. Full article

(This article belongs to the Special Issue Microgrids 2016)

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