Next Issue
Previous Issue

E-Mail Alert

Add your e-mail address to receive forthcoming issues of this journal:

Journal Browser

Journal Browser

Table of Contents

Energies, Volume 12, Issue 6 (March-2 2019)

  • Issues are regarded as officially published after their release is announced to the table of contents alert mailing list.
  • You may sign up for e-mail alerts to receive table of contents of newly released issues.
  • PDF is the official format for papers published in both, html and pdf forms. To view the papers in pdf format, click on the "PDF Full-text" link, and use the free Adobe Readerexternal link to open them.
Cover Story (view full-size image) Tidal stream turbines operate in some of the most energetic seas, and consequently must withstand [...] Read more.
View options order results:
result details:
Displaying articles 1-222
Export citation of selected articles as:
Open AccessArticle Software Architectures for Smart Grid System—A Bibliographical Survey
Energies 2019, 12(6), 1183; https://doi.org/10.3390/en12061183
Received: 3 January 2019 / Revised: 25 February 2019 / Accepted: 6 March 2019 / Published: 26 March 2019
Viewed by 401 | PDF Full-text (969 KB) | HTML Full-text | XML Full-text
Abstract
Smart grid software interconnects multiple Engineering disciplines (power systems, communication, software and hardware technology, instrumentation, big data, etc.). The software architecture is an evolving concept in smart grid systems, in which system architecture development is a challenging process. The architecture has to realize [...] Read more.
Smart grid software interconnects multiple Engineering disciplines (power systems, communication, software and hardware technology, instrumentation, big data, etc.). The software architecture is an evolving concept in smart grid systems, in which system architecture development is a challenging process. The architecture has to realize the complex legacy power grid systems and cope with current Information and Communication Technologies (ICT). The distributed generation in a smart grid environment expects the software architecture to be distributed and to enable local control. Smart grid architecture should also be modular, flexible, and adaptable to technology upgrades. In this paper, the authors have made a comprehensive review of architectures for smart grids. An in depth analysis of layered and agent-based architectures based on the National Institute of Standards and Technology (NIST) conceptual model is presented. Also presented is a set of smart grid Reference Architectures dealing with cross domain technology. Full article
Figures

Figure 1

Open AccessArticle A Horizon Optimization Control Framework for the Coordinated Operation of Multiple Distributed Energy Resources in Low Voltage Distribution Networks
Energies 2019, 12(6), 1182; https://doi.org/10.3390/en12061182
Received: 27 February 2019 / Revised: 19 March 2019 / Accepted: 21 March 2019 / Published: 26 March 2019
Viewed by 534 | PDF Full-text (2608 KB) | HTML Full-text | XML Full-text
Abstract
In recent years, the installation of residential Distributed Energy Resources (DER) that produce (mainly rooftop photovoltaics usually bundled with battery system) or consume (electric heat pumps, controllable loads, electric vehicles) electric power is continuously increasing in Low Voltage (LV) distribution networks. Several technical [...] Read more.
In recent years, the installation of residential Distributed Energy Resources (DER) that produce (mainly rooftop photovoltaics usually bundled with battery system) or consume (electric heat pumps, controllable loads, electric vehicles) electric power is continuously increasing in Low Voltage (LV) distribution networks. Several technical challenges may arise through the massive integration of DER, which have to be addressed by the distribution grid operator. However, DER can provide certain degree of flexibility to the operation of distribution grids, which is generally performed with temporal shifting of energy to be consumed or injected. This work advances a horizon optimization control framework which aims to efficiently schedule the LV network’s operation in day-ahead scale coordinating multiple DER. The main objectives of the proposed control is to ensure secure LV grid operation in the sense of admissible voltage bounds and rated loading conditions for the secondary transformer. The proposed methodology leans on a multi-period three-phase Optimal Power Flow (OPF) addressed as a nonlinear optimization problem. The resulting horizon control scheme is validated within an LV distribution network through multiple case scenarios with high microgeneration and electric vehicle integration providing admissible voltage limits and avoiding unnecessary active power curtailments. Full article
(This article belongs to the Special Issue Distributed Energy Resources Management 2018)
Figures

Figure 1

Open AccessArticle Improvement in Energy Performance of Building Envelope Incorporating Electrochromic Windows (ECWs)
Energies 2019, 12(6), 1181; https://doi.org/10.3390/en12061181
Received: 7 March 2019 / Revised: 22 March 2019 / Accepted: 23 March 2019 / Published: 26 March 2019
Viewed by 326 | PDF Full-text (7634 KB) | HTML Full-text | XML Full-text
Abstract
The present study sets out to review the thermal and optical properties of electrochromic windows (ECWs) through an analysis of the improvement in the energy performance of a building resulting from their application. The performance analysis was based on the change in the [...] Read more.
The present study sets out to review the thermal and optical properties of electrochromic windows (ECWs) through an analysis of the improvement in the energy performance of a building resulting from their application. The performance analysis was based on the change in the room temperature according to the solar transmittance and the orientation of the ECWs, the energy consumptions of the building’s heating/cooling systems, and that of the building’s lighting according to the visible light transmittance (VLT). To achieve this, the Quick Energy Simulation Tool (eQUEST), a building energy interpretation program, was used. The solar heat gain coefficient (SHGC) of the ECWs was found to be significantly reduced. This had the effect of lowering the room temperature in summer, such that the effect on the summer cooling energy consumption was also remarkable. However, with a reduction in the VLT, the lighting energy consumption increased. The net result of the changes in the heating/cooling and lighting energy consumptions was a reduction of about 11,207 kWh/yr (8.89%). The ECWs were found to realize a greater reduction in a building’s energy consumption than was possible with windows glazed with low-E coated glass. Full article
Figures

Figure 1

Open AccessArticle Improving Simultaneous Cooling and Power Load-Following Capability for MGT-CCP Using Coordinated Predictive Controls
Energies 2019, 12(6), 1180; https://doi.org/10.3390/en12061180
Received: 23 January 2019 / Revised: 21 March 2019 / Accepted: 22 March 2019 / Published: 26 March 2019
Viewed by 270 | PDF Full-text (6945 KB) | HTML Full-text | XML Full-text
Abstract
The distributed energy system is an energy supply method built around the end users, which can achieve energy sustainability and reduce emissions compared to traditional centralized energy systems. The micro gas turbine (MGT)-based combined cooling and power (CCP) system has received renewed attention [...] Read more.
The distributed energy system is an energy supply method built around the end users, which can achieve energy sustainability and reduce emissions compared to traditional centralized energy systems. The micro gas turbine (MGT)-based combined cooling and power (CCP) system has received renewed attention as an important distributed energy system technology due to its substantial energy savings and reduced emission levels. The task of the MGT-CCP system is to quickly adapt to changes in various renewable energy sources to maintain the balance in energy supply and demand in a distributed energy system. Therefore, it is imperative to improve the load tracking capability of the MGT-CCP system with advanced control technologies toward achieving this goal. However, the difficulty of controlling the MGT-CCP system is that the MGT responds very fast while CCP responds very slowly. To this end, the dynamic characteristics and nonlinear distribution of the MGT and CCP processes are analyzed, and a coordinated predictive control strategy is proposed by utilizing the generalized predictive control for the MGT system and the Hammerstein generalized predictive control for the CCP system. The coordinated predictive control of generalized predictive control and Hammerstein generalized predictive control was implemented in an 80 kW MGT-CCP simulator to verify the effectiveness of the proposed method. The simulation results show that compared with PID and MPC, the proposed control method not only can greatly improve simultaneous cooling and power load-following capability, but also has the best control effect when accessing with renewable energy. Full article
Figures

Figure 1

Open AccessArticle Representative Sampling Implementation in Online VFA/TIC Monitoring for Anaerobic Digestion
Energies 2019, 12(6), 1179; https://doi.org/10.3390/en12061179
Received: 25 February 2019 / Revised: 20 March 2019 / Accepted: 22 March 2019 / Published: 26 March 2019
Viewed by 288 | PDF Full-text (10496 KB) | HTML Full-text | XML Full-text
Abstract
This paper describes an automatic sampling system for anaerobic reactors that allows taking representative samples following the guidelines of Gy’s (1998) theory of sampling. Due to the high heterogeneity degree in a digester the sampling errors are larger than the analysis error, making [...] Read more.
This paper describes an automatic sampling system for anaerobic reactors that allows taking representative samples following the guidelines of Gy’s (1998) theory of sampling. Due to the high heterogeneity degree in a digester the sampling errors are larger than the analysis error, making representative sampling a prerequisite for successful process control. In our system, samples are automatically processed, generating a higher density of data and avoiding human error by sample manipulation. The combination of a representative sampling system with a commercial automate titration unit generates a robust online monitoring system for biogas plants. The system was successfully implemented in an operating biogas plant to control a feeding-on-demand biogas system. Full article
Figures

Figure 1

Open AccessArticle Does Reduction of Material and Energy Consumption Affect to Innovation Efficiency? The Case of Manufacturing Industry in South Korea
Energies 2019, 12(6), 1178; https://doi.org/10.3390/en12061178
Received: 1 January 2019 / Revised: 17 March 2019 / Accepted: 23 March 2019 / Published: 26 March 2019
Viewed by 263 | PDF Full-text (1220 KB) | HTML Full-text | XML Full-text
Abstract
“Reduction of material and energy consumption” (RMEC) exists as a major objective of innovation and it is proved to affect positively to innovation performance from previous literature. Though innovation should be measured in efficiency rather than performance itself, however, the relationship between material [...] Read more.
“Reduction of material and energy consumption” (RMEC) exists as a major objective of innovation and it is proved to affect positively to innovation performance from previous literature. Though innovation should be measured in efficiency rather than performance itself, however, the relationship between material and energy reduction on innovation efficiency is still unanswered. In this paper, we analyzed the effect of RMEC on innovation efficiency considering both innovation inputs and outputs. We utilized data of 388 manufacturing enterprises in Korea, and performed data envelopment analysis (DEA) and tobit regression analysis. According to the result, firms show difference by industry type in terms of innovation efficiency and RMEC. Moreover, the effect of RMEC on innovation efficiency turned out to be negative. The result indicates a possibility that input used for innovation might overweigh the output yielded when firms pursue innovation for the RMEC. Full article
Figures

Figure 1

Open AccessFeature PaperArticle Estimating On-Road Vehicle Fuel Economy in Africa: A Case Study Based on an Urban Transport Survey in Nairobi, Kenya
Energies 2019, 12(6), 1177; https://doi.org/10.3390/en12061177
Received: 16 February 2019 / Revised: 14 March 2019 / Accepted: 15 March 2019 / Published: 26 March 2019
Viewed by 655 | PDF Full-text (4853 KB) | HTML Full-text | XML Full-text
Abstract
In African cities like Nairobi, policies to improve vehicle fuel economy help to reduce greenhouse gas emissions and improve air quality, but lack of data is a major challenge. We present a methodology for estimating fuel economy in such cities. Vehicle characteristics and [...] Read more.
In African cities like Nairobi, policies to improve vehicle fuel economy help to reduce greenhouse gas emissions and improve air quality, but lack of data is a major challenge. We present a methodology for estimating fuel economy in such cities. Vehicle characteristics and activity data, for both the formal fleet (private cars, motorcycles, light and heavy trucks) and informal fleet—minibuses (matatus), three-wheelers (tuktuks), goods vehicles (AskforTransport) and two-wheelers (bodabodas)—were collected and used to estimate fuel economy. Using two empirical models, general linear modelling (GLM) and artificial neural network (ANN), the relationships between vehicle characteristics for this fleet and fuel economy were analyzed for the first time. Fuel economy for bodabodas (4.6 ± 0.4 L/100 km), tuktuks (8.7 ± 4.6 L/100 km), passenger cars (22.8 ± 3.0 L/100 km), and matatus (33.1 ± 2.5 L/100 km) was found to be 2–3 times worse than in the countries these vehicles are imported from. The GLM provided the better estimate of predicted fuel economy based on vehicle characteristics. The analysis of survey data covering a large informal urban fleet helps meet the challenge of a lack of availability of vehicle data for emissions inventories. This may be useful to policy makers as emissions inventories underpin policy development to reduce emissions. Full article
(This article belongs to the Section Sustainable Energy)
Figures

Figure 1

Open AccessArticle Guidelines and Cost-Benefit Analysis of the Structural Health Monitoring Implementation in Offshore Wind Turbine Support Structures
Energies 2019, 12(6), 1176; https://doi.org/10.3390/en12061176
Received: 14 February 2019 / Revised: 15 March 2019 / Accepted: 18 March 2019 / Published: 26 March 2019
Viewed by 304 | PDF Full-text (2249 KB) | HTML Full-text | XML Full-text
Abstract
This paper investigates how the implementation of Structural Health Monitoring Systems (SHMS) in the support structure (SS) of offshore wind turbines (OWT) affects capital expenditure (CAPEX) and operational expenditure (OPEX) of offshore wind farms (WF). In order to determine the added value of [...] Read more.
This paper investigates how the implementation of Structural Health Monitoring Systems (SHMS) in the support structure (SS) of offshore wind turbines (OWT) affects capital expenditure (CAPEX) and operational expenditure (OPEX) of offshore wind farms (WF). In order to determine the added value of Structural Health Monitoring (SHM), the balance between the reduction in OPEX and the increase in CAPEX is evaluated. In this paper, guidelines for SHM implementation in offshore WF are developed and applied to a baseline scenario. The application of these guidelines consist of a review of present regulations in the United Kingdom and Germany, the development of SHM strategy, where the first stage of the Statistical Pattern Recognition (SPR) paradigm is explored, failure modes that can be monitored are identified, and SHM technologies and sensor distributions within the turbines are described for a baseline scenario. Furthermore, an inspection strategy where the different structural inspections to be carried out above and below water is also developed, together with an inspection plan for the lifetime of the structures, for the aforementioned baseline scenario. Once the guidelines have been followed and the SHM and inspection strategies developed, a cost-benefit analysis is performed on the baseline case (10% instrumented assets) and three other scenarios with 20%, 30% and 50% of instrumented assets. Finally, a sensitivity analysis is conducted to evaluate the effects of SHM hardware cost and the time spent in completing the inspections on OPEX and CAPEX of the WF. The results show that SHM hardware cost increases CAPEX significantly, however this increase is much lower than the reduction in OPEX caused by SHM. The results also show that an increase in the percentage of instrumented assets will reduce OPEX and this reduction is considerably higher than the cost of SHM implementation. Full article
Figures

Figure 1

Open AccessArticle Exergy Analysis and Optimization of a Combined Heat and Power Geothermal Plant
Energies 2019, 12(6), 1175; https://doi.org/10.3390/en12061175
Received: 22 February 2019 / Revised: 22 March 2019 / Accepted: 24 March 2019 / Published: 26 March 2019
Viewed by 351 | PDF Full-text (4934 KB) | HTML Full-text | XML Full-text
Abstract
This paper presents the optimization of parallel distribution between electricity and heat production for a geothermal plant. The geothermal fluid is split into two streams, one used for an Organic Rankine Cycle (ORC) system, and the other for a District Heating Network (DHN). [...] Read more.
This paper presents the optimization of parallel distribution between electricity and heat production for a geothermal plant. The geothermal fluid is split into two streams, one used for an Organic Rankine Cycle (ORC) system, and the other for a District Heating Network (DHN). The superstructure to be used for the optimization problem includes the ORC components and the DHN topology constituted by a definite consumer and optional consumers. A Mixed Integer Non-Linear Programming (MINLP) optimization problem is formulated and solved using the GAMS software. This paper is focused on exergetic aspect. The main lines for formulation of the problem are reminded, yet the exergetic model is fully described. Exergy analysis is performed for two optimal solutions (economic and exergetic objective functions). Results for both optimizations are first compared. The analysis of exergetic efficiency of the ORC and the DHN may suggest that exergetic optimization privileges the system with the highest efficiency: the ORC. The DHN configuration is then the smallest as possible. Finally, a sensitive analysis is performed for the exergetic optimization. This analysis reveals our previous conclusion is not necessarily true. Taller configuration can exist even if ORC efficiency is higher than DHN efficiency. These results highlight the relevance of using an optimization approach for a Combined Heat and Power (CHP) plant. Full article
Figures

Figure 1

Open AccessArticle Evaluating the Effectiveness of New and Old Kinetic Energy Conversion from an Electric Power Economics Perspective: Evidence on the Shandong Province of China
Energies 2019, 12(6), 1174; https://doi.org/10.3390/en12061174
Received: 7 March 2019 / Revised: 19 March 2019 / Accepted: 24 March 2019 / Published: 26 March 2019
Viewed by 286 | PDF Full-text (1014 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes a hybrid model for evaluating the effectiveness of new and old kinetic energy conversion (NOKEC), China’s major strategic move aiming to transform the mode of economic growth and improvie the quality of economic development. Considering the goals of NOKEC and [...] Read more.
This paper proposes a hybrid model for evaluating the effectiveness of new and old kinetic energy conversion (NOKEC), China’s major strategic move aiming to transform the mode of economic growth and improvie the quality of economic development. Considering the goals of NOKEC and the supporting roles of power industry to NOKEC, this paper constructs an index system for NOKEC effectiveness evaluation from an electric power economics perspective, involving three dimensions and 17 secondary indicators. Furthermore, a hybrid evaluation model based on DEMATEL-ANP and DQ-GRA techniques is developed to accomplish the evaluation of Shandong’s NOKEC effectiveness. The results show that Shandong’s NOKEC effectiveness increased from 2015–2017, indicating that Shandong’s NOKEC policies have achieved remarkable results. According to the evaluation results, this paper puts forward the indicators that should be paid close attention to and the following work priorities in Shandong’s future NOKEC process, which has certain practical value for the promotion of Shandong’s NOKEC. In addition, the evaluation model proposed in this paper considers the interrelationships between indicators and overcomes the shortcomings of traditional GRA, showing good applicability to similar effectiveness evaluation issues. Finally, the limitations and universality of the model are discussed and the improvement direction is put forward. Full article
Figures

Figure 1

Open AccessArticle Optimal Placement of UHF Sensors for Accurate Localization of Partial Discharge Source in GIS
Energies 2019, 12(6), 1173; https://doi.org/10.3390/en12061173
Received: 12 February 2019 / Revised: 20 March 2019 / Accepted: 21 March 2019 / Published: 26 March 2019
Viewed by 248 | PDF Full-text (5031 KB) | HTML Full-text | XML Full-text
Abstract
This paper proposes an optimal placement model of ultra-high frequency (UHF) sensors for accurate location of partial discharge (PD) in gas-insulated switchgear (GIS). The model is based on 0-1 program in consideration of the attenuation influence on the propagation of electromagnetic (EM) waves [...] Read more.
This paper proposes an optimal placement model of ultra-high frequency (UHF) sensors for accurate location of partial discharge (PD) in gas-insulated switchgear (GIS). The model is based on 0-1 program in consideration of the attenuation influence on the propagation of electromagnetic (EM) waves generated by PD in GIS. the optimal placement plan improves the economy, observability, and accuracy of PD locating. After synchronously acquiring the time of the initial EM waves reaching each UHF sensor, PD occurring time can be obtained. Then, initial locating results can be acquired by using the Euclidean distance measuring method and the extended time difference of arriving (TDOA) location method. With the information of all UHF sensors and the inherent topological structure of GIS, the locating accuracy can be further improved. The method is verified by experiment, showing that the method can avoid the influence of false information and obtain higher locating accuracy by revising initial locating results. Full article
(This article belongs to the Special Issue Optimization Methods Applied to Power Systems Ⅱ)
Figures

Figure 1

Open AccessArticle Research of the Fundamental Wave of Wound-Rotor Brushless Doubly-Fed Machine
Energies 2019, 12(6), 1172; https://doi.org/10.3390/en12061172
Received: 22 January 2019 / Revised: 17 March 2019 / Accepted: 21 March 2019 / Published: 26 March 2019
Viewed by 243 | PDF Full-text (4836 KB) | HTML Full-text | XML Full-text
Abstract
The brushless doubly-fed machine (BDFM) is a special type of machine with two sets of stator windings and one set of rotor winding. The magnetic field of the BDFM is considered to be complex with no regularity. To study the principles of magnetic [...] Read more.
The brushless doubly-fed machine (BDFM) is a special type of machine with two sets of stator windings and one set of rotor winding. The magnetic field of the BDFM is considered to be complex with no regularity. To study the principles of magnetic fields for the BDFM, a general expression of the fundamental wave is deduced, which shows that the fundamental wave can be regarded as a standing wave when it is observed from rotor reference; also, some discussions about the characteristics of the fundamental wave are presented in the paper. Next, a model of wound-rotor BDFM prototype is established, and the enveloping line and the relations between rotor position and its electrical angle of the magnetic field are figured out in the paper. Finally, after detecting the induced electromotive force (EMF) of measurement coils embedded in the corresponding prototype machine, the validity of the proposed conclusions is verified. Full article
(This article belongs to the Special Issue Electrical Engineering for Sustainable and Renewable Energy)
Figures

Figure 1

Open AccessArticle Water Condensation in Traction Battery Systems
Energies 2019, 12(6), 1171; https://doi.org/10.3390/en12061171
Received: 1 March 2019 / Revised: 21 March 2019 / Accepted: 22 March 2019 / Published: 26 March 2019
Viewed by 280 | PDF Full-text (5558 KB) | HTML Full-text | XML Full-text
Abstract
Lithium-ion traction battery systems of hybrid and electric vehicles must have a high level of durability and reliability like all other components and systems of a vehicle. Battery systems get heated while in the application. To ensure the desired life span and performance, [...] Read more.
Lithium-ion traction battery systems of hybrid and electric vehicles must have a high level of durability and reliability like all other components and systems of a vehicle. Battery systems get heated while in the application. To ensure the desired life span and performance, most systems are equipped with a cooling system. The changing environmental condition in daily use may cause water condensation in the housing of the battery system. In this study, three system designs were investigated, to compare different solutions to deal with pressure differences and condensation: (1) a sealed battery system, (2) an open system and (3) a battery system equipped with a pressure compensation element (PCE). These three designs were tested under two conditions: (a) in normal operation and (b) in a maximum humidity scenario. The amount of the condensation in the housing was determined through a change in relative humidity of air inside the housing. Through PCE and available spacing of the housing, moisture entered into the housing during the cooling process. While applying the test scenarios, the gradient-based drift of the moisture into the housing contributed maximum towards the condensation. Condensation occurred on the internal surface for all the three design variants. Full article
(This article belongs to the Section Electric Vehicles)
Figures

Figure 1

Open AccessArticle Thermal Stress and Cyclic Stress Analysis of a Vertical Water-Cooled Wall at a Utility Boiler under Flexible Operation
Energies 2019, 12(6), 1170; https://doi.org/10.3390/en12061170
Received: 11 January 2019 / Revised: 21 March 2019 / Accepted: 22 March 2019 / Published: 26 March 2019
Viewed by 230 | PDF Full-text (9485 KB) | HTML Full-text | XML Full-text
Abstract
Supercritical once-through utility boilers are increasingly common in flexible operations in China. In this study, the tube temperature changes at a vertical water-cooled wall are analyzed during a fluctuating flexible operation. There are considerable differences in the temperatures of the parallel tubes at [...] Read more.
Supercritical once-through utility boilers are increasingly common in flexible operations in China. In this study, the tube temperature changes at a vertical water-cooled wall are analyzed during a fluctuating flexible operation. There are considerable differences in the temperatures of the parallel tubes at the minimum load, and the resulting thermal stress distributions at a front water-cooled wall are established using structural calculation software ANSYS 17.1, USA. A wide thermal stress distribution occurs among the parallel tubes, and the local cyclic stress amplitudes under flexible operation are higher than those under cold, warm, hot, or load-following operations. Because of the water wall expansion structure at the furnace, the higher tube temperature areas suffer from compressive stress, while the lower tube temperature areas suffer from tensile stress. During flexible operation, combustion uniformity and a two-phase flow distribution can improve the safety of vertical water-cooled wall operation. The minimum load of the utility boiler should be set as a limitation, and the tube temperature is an important parameter affecting the thermal and cyclic stresses. Full article
(This article belongs to the Section Electrical Power and Energy System)
Figures

Figure 1

Open AccessArticle A Comprehensive VSM Control Strategy Designed for Unbalanced Grids
Energies 2019, 12(6), 1169; https://doi.org/10.3390/en12061169
Received: 7 March 2019 / Revised: 16 March 2019 / Accepted: 18 March 2019 / Published: 26 March 2019
Viewed by 244 | PDF Full-text (6968 KB) | HTML Full-text | XML Full-text
Abstract
A virtual synchronous machine (VSM) is a converter which, compared to other types of converters, has more friendly interactions with the power grid because it is able to simulate the external characteristics of a synchronous machine, which can provide virtual inertia and damping. [...] Read more.
A virtual synchronous machine (VSM) is a converter which, compared to other types of converters, has more friendly interactions with the power grid because it is able to simulate the external characteristics of a synchronous machine, which can provide virtual inertia and damping. When the grid voltage is unbalanced, there will be negative sequence current and power oscillations. There will also be double-frequency ripples on the DC bus, which affect the normal operation of the DC power source or load. In order to solve these problems, a comprehensive control strategy is proposed in this paper. The principle of a VSM operated as a current source converter, also called VISMA, is used in the design. A complex coefficient filter is applied to separate the positive and negative sequence components of the grid voltage. By analyzing the reasons of power oscillations under unbalanced voltage, the electrical simulation part of the VSM is improved to achieve several objectives: to suppress negative sequence current and DC voltage ripples. Additionally, the rated voltage in the reactive control part is adaptively adjusted to stabilize the system. The validity of the proposed control strategy is verified by simulation and experiment. Full article
(This article belongs to the Special Issue Control in Power Electronics)
Figures

Figure 1

Open AccessArticle Application of Silicon Oxide on High Efficiency Monocrystalline Silicon PERC Solar Cells
Energies 2019, 12(6), 1168; https://doi.org/10.3390/en12061168
Received: 31 December 2018 / Revised: 17 March 2019 / Accepted: 21 March 2019 / Published: 26 March 2019
Viewed by 247 | PDF Full-text (3844 KB) | HTML Full-text | XML Full-text
Abstract
In the photovoltaic industry, an antireflection coating consisting of three SiNx layers with different refractive indexes is generally adopted to reduce the reflectance and raise the efficiency of monocrystalline silicon PERC (passivated emitter and rear cell) solar cells. However, for SiNx [...] Read more.
In the photovoltaic industry, an antireflection coating consisting of three SiNx layers with different refractive indexes is generally adopted to reduce the reflectance and raise the efficiency of monocrystalline silicon PERC (passivated emitter and rear cell) solar cells. However, for SiNx, a refractive index as low as about 1.40 cannot be achieved, which is the optimal value for the third layer of a triple-layer antireflection coating. Therefore, in this report the third layer is replaced by SiOx, which possesses a more appropriate refractive index of 1.46, it and can be easily integrated into the SiNx deposition process with the plasma-enhanced chemical vapor deposition (PECVD) method. Through simulation and analysis with SunSolve, three different thicknesses were selected to construct the SiOx third layer. The replacement of 15 nm SiNx with 30 nm SiOx as the third layer of antireflection coating can bring about an efficiency gain of 0.15%, which originates from the reflectance reduction and spectral response enhancement below about 550 nm wavelength. However, because the EVA encapsulation material of the solar module absorbs light in short wavelengths, the spectral response advantage of solar cells with 30 nm SiOx is partially covered up, resulting in a slightly lower cell-to-module (CTM) ratio and an output power gain of only 0.9 W for solar module. Full article
Figures

Graphical abstract

Open AccessArticle Impedance Estimation with an Enhanced Particle Swarm Optimization for Low-Voltage Distribution Networks
Energies 2019, 12(6), 1167; https://doi.org/10.3390/en12061167
Received: 14 February 2019 / Revised: 18 March 2019 / Accepted: 21 March 2019 / Published: 26 March 2019
Viewed by 264 | PDF Full-text (2952 KB) | HTML Full-text | XML Full-text
Abstract
Many researchers in recent years have studied voltage deviation issues in distribution networks. Characterizing the impedance between consuming nodes in a network is the key to controlling the network voltage. Existing impedance estimation methods are faced with three challenges: time synchronized measurement, a [...] Read more.
Many researchers in recent years have studied voltage deviation issues in distribution networks. Characterizing the impedance between consuming nodes in a network is the key to controlling the network voltage. Existing impedance estimation methods are faced with three challenges: time synchronized measurement, a generalization of the network model, and convergence of the optimization for objective functions. This paper extends an existing impedance estimation algorithm by introducing an enhanced particle swarm optimization (PSO). To overcome this method’s local optimum problem, we propose adaptive inertia weights. Also, our proposed method is based on a new general model for a low voltage distribution network with non-synchronized measurements. In the case study, the improved impedance estimation algorithm realizes better accuracy than the existing method. Full article
(This article belongs to the Special Issue Machine Learning and Optimization with Applications of Power System)
Figures

Figure 1

Open AccessReview A Brief Review of Anaerobic Digestion of Algae for Bioenergy
Energies 2019, 12(6), 1166; https://doi.org/10.3390/en12061166
Received: 7 March 2019 / Revised: 21 March 2019 / Accepted: 23 March 2019 / Published: 26 March 2019
Cited by 1 | Viewed by 325 | PDF Full-text (976 KB) | HTML Full-text | XML Full-text
Abstract
The potential of algal biomass as a source of liquid and gaseous biofuels has been the subject of considerable research over the past few decades, with researchers strongly agreeing that algae have the potential of becoming a viable aquatic energy crop with a [...] Read more.
The potential of algal biomass as a source of liquid and gaseous biofuels has been the subject of considerable research over the past few decades, with researchers strongly agreeing that algae have the potential of becoming a viable aquatic energy crop with a higher energy potential compared to that from either terrestrial biomass or municipal solid waste. However, neither microalgae nor seaweed are currently cultivated solely for energy purposes due to the high costs of harvesting, concentrating and drying. Anaerobic digestion of algal biomass could theoretically reduce costs associated with drying wet biomass before processing, but practical yields of biogas from digestion of many algae are substantially below the theoretical maximum. New processing methods are needed to reduce costs and increase the net energy balance. This review examines the biochemical and structural properties of seaweeds and of microalgal biomass that has been produced as part of the treatment of wastewater, and discusses some of the significant hurdles and recent initiatives for producing biogas from their anaerobic digestion. Full article
(This article belongs to the Special Issue Production and Utilization of Biogas)
Figures

Figure 1

Open AccessArticle A Class-E Amplifier for a Loosely Coupled Inductive Power Transfer System with Multiple Receivers
Energies 2019, 12(6), 1165; https://doi.org/10.3390/en12061165
Received: 1 March 2019 / Revised: 19 March 2019 / Accepted: 20 March 2019 / Published: 26 March 2019
Viewed by 287 | PDF Full-text (1124 KB) | HTML Full-text | XML Full-text
Abstract
We present a method for optimizing the electronic power system for a new type of photobioreactor or photoreactor in general. In the case of photobioreactors, photosynthetic active microorganisms or cells are grown. A novel concept for the illumination of photobioreactors was necessary, as [...] Read more.
We present a method for optimizing the electronic power system for a new type of photobioreactor or photoreactor in general. In the case of photobioreactors, photosynthetic active microorganisms or cells are grown. A novel concept for the illumination of photobioreactors was necessary, as the external illumination of those reactors leads to a limited penetration depth of light. Due to the limited penetration depth, no standard reactors can be use for cultivation, but custom made reactors with very small volume to surface ratio have to be used. This still prevents the technology from a large scale industrial impact. The solution we propose in this paper is an internal illumination via Wireless Light Emitters. This increases the manageable culture volume of photosynthetic active microorganisms or cells. The illumination system is based on floating light emitters, which are powered wirelessly by near field resonant inductive coupling. The floating light emitters are able to illuminate a photobioreactor more homogeneously than external illumination systems do. We designed a class-E amplifier and field coils to produce an intermediate frequency electromagnetic field inside the reactor. An appropriate magnetic flux density was found to be approx. B = 1 mT and the driving frequency is f = 176 kHz. We conducted experiments with a laboratory size photoreactor. The cultivation volume was 30 L containing up to 3000 WLEs. The maximum electric power input was more than 300 W and we calculated an efficiency of up to 76%. Full article
(This article belongs to the Section Energy Storage and Application)
Figures

Figure 1

Open AccessArticle Data-Driven Decentralized Algorithm for Wind Farm Control with Population-Games Assistance
Energies 2019, 12(6), 1164; https://doi.org/10.3390/en12061164
Received: 5 February 2019 / Revised: 15 March 2019 / Accepted: 21 March 2019 / Published: 26 March 2019
Viewed by 319 | PDF Full-text (2572 KB) | HTML Full-text | XML Full-text
Abstract
In wind farms, the interaction between turbines that operate close by experience some problems in terms of their power generation. Wakes caused by upstream turbines are mainly responsible of these interactions, and the phenomena involved in this case is complex especially when the [...] Read more.
In wind farms, the interaction between turbines that operate close by experience some problems in terms of their power generation. Wakes caused by upstream turbines are mainly responsible of these interactions, and the phenomena involved in this case is complex especially when the number of turbines is high. In order to deal with these issues, there is a need to develop control strategies that maximize the energy captured from a wind farm. In this work, an algorithm that uses multiple estimated gradients based on measurements that are classified by using a simple distributed population-games-based algorithm is proposed. The update in the decision variables is computed by making a superposition of the estimated gradients together with the classification of the measurements. In order to maximize the energy captured and maintain the individual power generation, several constraints are considered in the proposed algorithm. Basically, the proposed control scheme reduces the communications needed, which increases the reliability of the wind farm operation. The control scheme is validated in simulation in a benchmark corresponding to the Horns Rev wind farm. Full article
(This article belongs to the Special Issue Control Schemes for Wind Electricity Systems)
Figures

Figure 1

Open AccessArticle A Novel Approach to Stabilize Foam Using Fluorinated Surfactants
Energies 2019, 12(6), 1163; https://doi.org/10.3390/en12061163
Received: 9 February 2019 / Revised: 12 March 2019 / Accepted: 22 March 2019 / Published: 26 March 2019
Viewed by 315 | PDF Full-text (2216 KB) | HTML Full-text | XML Full-text
Abstract
Selection of surfactants for enhanced oil recovery and other upstream applications is a challenging task. For enhanced oil recovery applications, a surfactant should be thermally stable, compatible with reservoir brine, and have lower adsorption on reservoir rock, have high foamability and foam stability, [...] Read more.
Selection of surfactants for enhanced oil recovery and other upstream applications is a challenging task. For enhanced oil recovery applications, a surfactant should be thermally stable, compatible with reservoir brine, and have lower adsorption on reservoir rock, have high foamability and foam stability, and should be economically viable. Foam improves the oil recovery by increasing the viscosity of the displacing fluid and by reducing the capillary forces due to a reduction in interfacial tension. In this work, foamability and foam stability of two different surfactants were evaluated using a dynamic foam analyzer. These surfactants were fluorinated zwitterionic, and hydrocarbon zwitterionic surfactants. The effect of various parameters such as surfactant type and structure, temperature, salinity, and type of injected gas was investigated on foamability and foam stability. The foamability was assessed using the volume of foam produced by injecting a constant volume of gas and foam stability was determined by half-life time. The maximum foam generation was obtained using hydrocarbon zwitterionic surfactant. However, the foam generated using fluorinated zwitterionic surfactant was more stable. A mixture of zwitterionic fluorinated and hydrocarbon fluorinated surfactant showed better foam generation and foam stability. The foam generated using CO2 has less stability compared to the foam generated using air injection. Presence of salts increases the foam stability and foam generation. At high temperature, the foamability of the surfactants increased. However, the foam stability was reduced at high temperature for all type of surfactants. This study helps in optimizing the surfactant formulations consisting of a fluorinated and hydrocarbon zwitterionic surfactant for foam injections. Full article
(This article belongs to the Special Issue CO2 EOR and CO2 Storage in Oil Reservoirs)
Figures

Figure 1

Open AccessArticle Research on the Operation Control Strategy of a Low-Voltage Direct Current Microgrid Based on a Disturbance Observer and Neural Network Adaptive Control Algorithm
Energies 2019, 12(6), 1162; https://doi.org/10.3390/en12061162
Received: 26 February 2019 / Revised: 23 March 2019 / Accepted: 25 March 2019 / Published: 25 March 2019
Viewed by 286 | PDF Full-text (6886 KB) | HTML Full-text | XML Full-text
Abstract
Low-voltage direct current (DC) microgrid based on distributed generation (DG), the problems of load mutation affecting the DC bus under island mode, and the security problems that may arise when the DC microgrid is switched from island mode to grid-connected mode are considered. [...] Read more.
Low-voltage direct current (DC) microgrid based on distributed generation (DG), the problems of load mutation affecting the DC bus under island mode, and the security problems that may arise when the DC microgrid is switched from island mode to grid-connected mode are considered. Firstly, a DC bus control algorithm based on disturbance observer (DOB) was proposed to suppress the impact of system load mutation on DC bus in island mode. Then, in a grid-connected mode, a pre-synchronization control algorithm based on a neural network adaptive control was proposed, and the droop controller was improved to ensure better control accuracy. Through this pre-synchronization control, the microgrid inverters output voltage could quickly track the power grid’s voltage and achieve an accurate grid-connected operation. The effectiveness of the algorithms was verified by simulation. Full article
Figures

Figure 1

Open AccessArticle Hybrid Adsorption-Compression Systems for Air Conditioning in Efficient Buildings: Design through Validated Dynamic Models
Energies 2019, 12(6), 1161; https://doi.org/10.3390/en12061161
Received: 5 March 2019 / Revised: 19 March 2019 / Accepted: 21 March 2019 / Published: 25 March 2019
Viewed by 342 | PDF Full-text (7467 KB) | HTML Full-text | XML Full-text
Abstract
Hybrid sorption-compression systems are gaining interest for heating/cooling/ refrigeration purposes in different applications, since they allow exploiting the benefits of both technologies and a better utilization of renewable sources. However, design of such components is still difficult, due to the intrinsic complexity of [...] Read more.
Hybrid sorption-compression systems are gaining interest for heating/cooling/ refrigeration purposes in different applications, since they allow exploiting the benefits of both technologies and a better utilization of renewable sources. However, design of such components is still difficult, due to the intrinsic complexity of the systems and the lack of reliable models. In particular, the combination of adsorption-compression cascade unit has not been widely explored yet and there are no simulations or sizing tools reported in the literature. In this context, the present paper describes a model of a hybrid adsorption-compression system, realised in Modelica language using the commercial software Dymola. The models of the main components of the sorption and vapour compression unit are described in details and their validation presented. In addition, the integrated model is used for proving the feasibility of the system under dynamic realistic conditions and an example of the technical sizing that the model is able to accomplish is given. Full article
(This article belongs to the Section Energy Storage and Application)
Figures

Figure 1

Open AccessFeature PaperArticle A Power Exchange Strategy for Multiple Areas with Hydro Power and Flexible Loads
Energies 2019, 12(6), 1160; https://doi.org/10.3390/en12061160
Received: 22 January 2019 / Revised: 5 March 2019 / Accepted: 22 March 2019 / Published: 25 March 2019
Viewed by 283 | PDF Full-text (2596 KB) | HTML Full-text | XML Full-text
Abstract
Areas with hydro power may purchase extra power from the outside power market during dry seasons, which will cause a deviation between the actual and expected power purchase amount due to the inaccurate judgment of the market situation. Because of the uncertainty of [...] Read more.
Areas with hydro power may purchase extra power from the outside power market during dry seasons, which will cause a deviation between the actual and expected power purchase amount due to the inaccurate judgment of the market situation. Because of the uncertainty of price fluctuations, the risk of purchasing power in the real-time market to eliminate this deviation is very high. This paper proposes an innovative trade mode, where the power exchange strategy between multiple areas is adopted through forming an alliance, i.e., one area can use the controllable elements within others, and constructing a monthly and post day-ahead two phase optimization model. The objective function of the monthly stochastic robust optimization considers the power purchase cost to determine the controllable elements dispatch dates for every area in the alliance. Thus, areas can make reasonable dispatch schedules for controllable elements to avoid the resource waste that means more controllable elements are prepared before post day-ahead optimization but less are used after post day-ahead optimization. While the post day-ahead optimization model determines the internal controllable elements dispatch and power exchange amount after the day-ahead market clearing process, users’ satisfaction and dispatch schedule changes for energy storage device are also considered. In order to solve the proposed two phase model, the dual principle and linearization methods are used to convert them into mixed-integer linear programming problems that can be effectively solved by the Cplex solver. The study case verifies the power deviation cost decreases with the power exchange strategy and the important role of energy storage devices. Full article
(This article belongs to the Section Smart Grids and Microgrids)
Figures

Figure 1

Open AccessArticle Modeling the Performance of a Zinc/Bromine Flow Battery
Energies 2019, 12(6), 1159; https://doi.org/10.3390/en12061159
Received: 8 February 2019 / Revised: 11 March 2019 / Accepted: 21 March 2019 / Published: 25 March 2019
Viewed by 269 | PDF Full-text (6015 KB) | HTML Full-text | XML Full-text
Abstract
The zinc/bromine (Zn/Br2) flow battery is an attractive rechargeable system for grid-scale energy storage because of its inherent chemical simplicity, high degree of electrochemical reversibility at the electrodes, good energy density, and abundant low-cost materials. It is important to develop a [...] Read more.
The zinc/bromine (Zn/Br2) flow battery is an attractive rechargeable system for grid-scale energy storage because of its inherent chemical simplicity, high degree of electrochemical reversibility at the electrodes, good energy density, and abundant low-cost materials. It is important to develop a mathematical model to calculate the current distributions in a Zn/Br2 flow cell in order to predict such quantities as current, voltage, and energy efficiencies under various charge and discharge conditions. This information can be used to design both of bench and production scale cells and to select the operating conditions for optimum performance. This paper reports a modeling methodology to predict the performance of a Zn/Br2 flow battery. The charge and discharge behaviors of a single cell is calculated based on a simple modeling approach by considering Ohm’s law and charge conservation on the electrodes based on the simplified polarization characteristics of the electrodes. An 8-cell stack performance is predicted based on an equivalent circuit model composed of the single cells and the resistances of the inlet and outlet streams of the positive and negative electrolytes. The model is validated by comparing the modeling results with the experimental measurements. Full article
(This article belongs to the Special Issue Grid-Scale Energy Storage Management)
Figures

Figure 1

Open AccessArticle An Improved Droop Control Method for Voltage-Source Inverter Parallel Systems Considering Line Impedance Differences
Energies 2019, 12(6), 1158; https://doi.org/10.3390/en12061158
Received: 19 February 2019 / Revised: 13 March 2019 / Accepted: 21 March 2019 / Published: 25 March 2019
Viewed by 270 | PDF Full-text (3982 KB) | HTML Full-text | XML Full-text
Abstract
In this paper, the effect of the line impedance difference between various inverters on power sharing with the traditional droop control method is fully analyzed. It reveals that the line impedance difference causes a significant reactive power error. An improved droop control method [...] Read more.
In this paper, the effect of the line impedance difference between various inverters on power sharing with the traditional droop control method is fully analyzed. It reveals that the line impedance difference causes a significant reactive power error. An improved droop control method to eliminate the reactive power errors caused by the line impedance errors is proposed. In the proposed method, a voltage compensation determined by the actual reactive power error between the local inverter and the average one is added into the local voltage reference based on the CAN communication. Even when the communication is interrupted, the controller will operate with the last value of the average power, which still outperforms the traditional method. The effectiveness of the proposed control method is verified by simulation and experimental results, which show the proposed method possesses the better power sharing performance and dynamic response. Full article
Figures

Figure 1

Open AccessArticle Improvements of the Starting Performance of A Novel Brushless Doubly-fed Motor Based on the Composite Coils
Energies 2019, 12(6), 1157; https://doi.org/10.3390/en12061157
Received: 18 February 2019 / Revised: 15 March 2019 / Accepted: 21 March 2019 / Published: 25 March 2019
Viewed by 287 | PDF Full-text (5284 KB) | HTML Full-text | XML Full-text
Abstract
Brushless doubly-fed motor (BDFM) has well applicable potentials in the speed control driving field due to its excellent speed regulation performance. However, the poor starting performance becomes a shortage that still limits the development and application of wound BDFM. To solve the problem, [...] Read more.
Brushless doubly-fed motor (BDFM) has well applicable potentials in the speed control driving field due to its excellent speed regulation performance. However, the poor starting performance becomes a shortage that still limits the development and application of wound BDFM. To solve the problem, this paper presents a novel BDFM adopted rotor winding based on the principle of the composite coil. Both the principle of the composite coil and the designed example of the rotor winding are analyzed in detail in this content, and the stator winding designed by the change-pole method is described. The performance of the prototype was tested by simulation and experiments, both results reveal that this method can effectively improve the starting performance of BDFM, the system is simplified, and the stability of it is prompted. Full article
Figures

Figure 1

Open AccessArticle MPC with Constant Switching Frequency for Inverter-Based Distributed Generations in Microgrid Using Gradient Descent
Energies 2019, 12(6), 1156; https://doi.org/10.3390/en12061156
Received: 13 February 2019 / Revised: 21 March 2019 / Accepted: 22 March 2019 / Published: 25 March 2019
Viewed by 262 | PDF Full-text (5473 KB) | HTML Full-text | XML Full-text
Abstract
Variable switching frequency in the finite control set model predictive control (FCS-MPC) method causes a negative impact on the converter efficiency and the design of the output filters. Several studies have addressed the problem, but they are either complicated or require heavy computation. [...] Read more.
Variable switching frequency in the finite control set model predictive control (FCS-MPC) method causes a negative impact on the converter efficiency and the design of the output filters. Several studies have addressed the problem, but they are either complicated or require heavy computation. This study proposes a new model predictive control (MPC) method with constant switching frequency, which is simple to implement and needs only a small computation time. The proposed MPC method is based on the gradient descent (GD) method to find the optimal voltage vector. Since the cost function of the MPC method is represented in the strongly convex function, the optimal voltage vector could be found quickly by using the GD method, which reduces the computation time of the MPC method. The design of the proposed MPC method based on GD (GD-MPC) is shown in this study. The feasibility of the proposed GD-MPC is evaluated in the real-time simulation using OPAL-RT technologies. The performance of the proposed method in the case of single inverter operation or parallel inverter operation is shown. A comparison study on the proposed GD-MPC and the MPC with the concept of the virtual state vector (VSV-MPC) is presented to demonstrate the effectiveness of the proposed predictive control. Real-time simulation results show that the proposed GD-MPC method performs better with a low total harmonic distortion (THD) value of output current and short computation time, compared to the VSV-MPC method. Full article
(This article belongs to the Special Issue Control in Power Electronics)
Figures

Figure 1

Open AccessArticle Comparison of Bioethanol Preparation from Triticale Straw Using the Ionic Liquid and Sulfate Methods
Energies 2019, 12(6), 1155; https://doi.org/10.3390/en12061155
Received: 26 January 2019 / Revised: 17 March 2019 / Accepted: 19 March 2019 / Published: 25 March 2019
Viewed by 286 | PDF Full-text (1802 KB) | HTML Full-text | XML Full-text
Abstract
Triticale straw constitutes a potential raw material for biofuel production found in Poland in considerable quantities. Thus far, production of bioethanol has been based on food raw materials such as cereal seeds, sugar beets or potatoes, and the biofuel production methods developed for [...] Read more.
Triticale straw constitutes a potential raw material for biofuel production found in Poland in considerable quantities. Thus far, production of bioethanol has been based on food raw materials such as cereal seeds, sugar beets or potatoes, and the biofuel production methods developed for these lignocellulose raw materials can threaten the environment and are inefficient. Therefore, this study aimed to compare of methods for pretreatment of triticale straw using 1-ethyl-3-methylimidazolium acetate and the sulfate method in the aspect of ethanol production intended for fuel. Based on the conducted experiments it has been determined that the use of 1-ethyl-3-methylimidazolium acetate for the pretreatment of triticale straw resulted in an increase of reducing sugars after enzymatic hydrolysis and ethyl alcohol after alcoholic fermentation. Furthermore, the study compared the efficiency of enzymatic hydrolysis of triticale straw without pretreatment, after processing with ionic liquid, recycled ionic liquid and using sulfate method, allowing a comparison of these methods. The more favorable method of lignocellulose material purification was the use of ionic liquid, due to the lower amount of toxic byproducts formed during the process, and the efficiency test results of bioethanol production using pretreatment with ionic liquid and sulfate method were similar. Ionic liquid recycling after pretreatment of rye straw using lyophilization allowed us to reuse this solvent to purify rye straw, yet the efficiency of this method remained at a low level. As a result of the conducted study it was determined that the use of ionic liquid-1-ethyl-3-methylimidazolium acetate enhanced the yield of bioethanol from triticale straw from 1.60 g/dm3 after processing without pre-treatment to 10.64 g/dm3 after pre-treatment. Full article
(This article belongs to the Special Issue Advanced Technologies of Lignocellulosic Biomass Conversion)
Figures

Figure 1

Open AccessArticle Quantitative and Qualitative Assessment of Job Role Localization in the Oil and Gas Industry: Global Experiences and National Differences
Energies 2019, 12(6), 1154; https://doi.org/10.3390/en12061154
Received: 20 January 2019 / Revised: 18 February 2019 / Accepted: 6 March 2019 / Published: 25 March 2019
Viewed by 236 | PDF Full-text (1226 KB) | HTML Full-text | XML Full-text | Supplementary Files
Abstract
Job role localization is the replacement of expatriates by competent host country nationals. This study investigates the viability of localizing job roles in the oil and gas industry in two stages. The first stage addresses the global level using a survey about local [...] Read more.
Job role localization is the replacement of expatriates by competent host country nationals. This study investigates the viability of localizing job roles in the oil and gas industry in two stages. The first stage addresses the global level using a survey about local content issues. The second stage focuses on the national level using interviews to investigate how national factors can affect job role localization in Ghana, one of Africa’s oil and gas producing nations. The findings show that different stakeholders often share opinions about local content issues. At the national level there are many national context specific factors that affect job role localization including legislations, culture, attitudes and experience within the labour market. This study finds that localization is becoming increasingly prevalent worldwide. Oil and gas companies must adapt their localization strategies to the national context where they are operating. Full article
Figures

Figure 1

Energies EISSN 1996-1073 Published by MDPI AG, Basel, Switzerland RSS E-Mail Table of Contents Alert
Back to Top