Energies

31 pages, 2338 KiB

Open AccessArticle

Simulation of Malfunctions in Home Appliances’ Power Consumption

by Alexios Papaioannou, Asimina Dimara, Christoforos Papaioannou, Ioannis Papaioannou, Stelios Krinidis, Christos-Nikolaos Anagnostopoulos, Christos Korkas, Elias Kosmatopoulos, Dimosthenis Ioannidis and Dimitrios Tzovaras

Energies 2024, 17(17), 4529; https://doi.org/10.3390/en17174529 - 9 Sep 2024

Abstract

Predicting errors in home appliances is crucial for maintaining the reliability and efficiency of smart homes. However, there is a significant lack of such data on appliance malfunctions that can be used in developing effective anomaly detection models. This research paper presents a [...] Read more.

Predicting errors in home appliances is crucial for maintaining the reliability and efficiency of smart homes. However, there is a significant lack of such data on appliance malfunctions that can be used in developing effective anomaly detection models. This research paper presents a novel approach for simulating errors of heterogeneous home appliance power consumption patterns. The proposed model takes normal consumption patterns as input and employs advanced algorithms to produce labeled anomalies, categorizing them based on the severity of malfunctions. One of the main objectives of this research involves developing models that can accurately reproduce anomaly power consumption patterns, highlighting anomalies related to major, minor, and specific malfunctions. The resulting dataset may serve as a valuable resource for training algorithms specifically tailored to detect and diagnose these errors in real-world scenarios. The outcomes of this research contribute significantly to the field of anomaly detection in smart home environments. The simulated datasets facilitate the development of predictive maintenance strategies, allowing for early detection and mitigation of appliance malfunctions. This proactive approach not only improves the reliability and lifespan of home appliances but also enhances energy efficiency, thereby reducing operational costs and environmental impact. Full article

(This article belongs to the Special Issue Advanced Energy Systems in Energy Resilient, Zero/Positive Energy Buildings, Communities and Districts)

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27 pages, 27010 KiB

Open AccessArticle

Numerical Investigation of Wake Characteristics for Scaled 20 kW Wind Turbine Models with Various Size Factors

by Salim Abdullah Bazher, Juyeol Park, Jungkeun Oh and Daewon Seo

Energies 2024, 17(17), 4528; https://doi.org/10.3390/en17174528 - 9 Sep 2024

Abstract

Wind energy is essential for sustainable energy development, providing a clean and reliable energy source through the wind turbine. However, the vortices and turbulence generated as wind passes through turbines reduce wind speed and increase turbulence, leading to significant power losses for downstream [...] Read more.

Wind energy is essential for sustainable energy development, providing a clean and reliable energy source through the wind turbine. However, the vortices and turbulence generated as wind passes through turbines reduce wind speed and increase turbulence, leading to significant power losses for downstream turbines in wind farms. This study investigates wake characteristics in wind turbines by examining the effects of different scale ratios on wake dynamics, using both experimental and numerical approaches, utilizing scaled-down models of the Aeolos H-20 kW turbine at scales of 1:33, 1:50, and 1:67. The experimental component involved wind tunnel tests in an open-circuit tunnel with adjustable wind speeds and controlled turbulence intensity. Additionally, Computational Fluid Dynamics (CFD) simulations were conducted using STAR-CCM+ (Version 15.06.02) to numerically analyze the wake characteristics. Prior to the simulation, a convergence test was performed by varying grid density and y+ values to establish optimized simulation settings essential for accurately capturing wake dynamics. The results were validated against experimental data, reinforcing the reliability of the simulations. Despite minor inconsistencies in areas affected by tower and nacelle interference, the overall results strongly support the methodology’s effectiveness. The discrepancies between the experimental results and CFD simulations underscore the limitations of the rigid body assumption, which does not fully account for the deformation observed in the experiment. Full article

(This article belongs to the Special Issue Wind Turbines and Wind Farms Performance Analysis through Numerical and Experimental Methods)

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11 pages, 557 KiB

Open AccessFeature PaperArticle

Potential of Wake Scaling Techniques for Vertical-Axis Wind Turbine Wake Prediction

by Dara Vahidi and Fernando Porté-Agel

Energies 2024, 17(17), 4527; https://doi.org/10.3390/en17174527 - 9 Sep 2024

Abstract

Analytical wake models are widely used to predict wind turbine wakes. While these models are well-established for horizontal-axis wind turbines (HAWTs), the analytical wake models for vertical-axis wind turbines (VAWTs) remain under-explored in the wind energy community. In this study, the accuracy of [...] Read more.

Analytical wake models are widely used to predict wind turbine wakes. While these models are well-established for horizontal-axis wind turbines (HAWTs), the analytical wake models for vertical-axis wind turbines (VAWTs) remain under-explored in the wind energy community. In this study, the accuracy of two wake scaling techniques is evaluated to predict the change in the normalized maximum wake velocity deficit behind VAWTs by re-scaling the maximum wake velocity deficit behind an actuator disk with the same thrust coefficient. The wake scaling is defined in terms of equivalent diameter, considering the geometrical properties of the wake-generating object. Two different equivalent diameters are compared, namely the momentum diameter and hydraulic diameter. Different approaches are used to calculate the change in the normalized wake velocity deficit behind a disk with the same thrust coefficient as the VAWT. The streamwise distance is scaled with the equivalent diameter to predict the normalized maximum wake velocity deficit behind the desired VAWT. The performance of the proposed framework is assessed using large-eddy simulation data of VAWTs operating in a turbulent boundary layer with varying operating conditions and aspect ratios. For all of the cases, the momentum diameter scaling provides reasonable predictions of the VAWT normalized maximum wake velocity deficit. Full article

(This article belongs to the Section A3: Wind, Wave and Tidal Energy)

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38 pages, 7157 KiB

Open AccessArticle

A Study Regarding the Relationship between Carbon Emissions, Energy Consumption, and Economic Development in the Context of the Energy Growth Nexus

by Laurențiu-Stelian Mihai, Laura Vasilescu, Cătălina Sitnikov, Anca Băndoi, Leonardo-Geo Mănescu and Lucian Mandache

Energies 2024, 17(17), 4526; https://doi.org/10.3390/en17174526 - 9 Sep 2024

Abstract

As the EU strives to achieve its climate goals, it is becoming increasingly crucial to understand the complex relationships between economic activity, energy consumption, and carbon emissions. In this context, our paper aims to investigate the correlation between carbon emissions, energy consumption, and [...] Read more.

As the EU strives to achieve its climate goals, it is becoming increasingly crucial to understand the complex relationships between economic activity, energy consumption, and carbon emissions. In this context, our paper aims to investigate the correlation between carbon emissions, energy consumption, and economic development. To fulfill our aim, we have used Eurostat and OECD data for the EU-27 member states for a period of 13 years (2010–2022), using a linear regression as the main analysis method. Our results have shown that there is a strong correlation between demand-based and production-based CO₂ emissions as well as between production-based CO₂ emissions and final energy consumption, while at the same time, our findings have shown that there is no direct correlation between energy consumption and economic development, aligning our study with the neutrality hypothesis of the energy growth nexus. This paper expands the ongoing discussion on sustainable development and climate change mitigation by conducting a thorough analysis of the EU-27 countries over a span of thirteen years. The results emphasize the need for integrated strategies that address both production and consumption emissions, emphasize the vital role of energy efficiency, and raise questions about the effectiveness of increasing energy consumption to enhance economic productivity or CO₂ efficiency. Full article

(This article belongs to the Topic Energy Economics and Sustainable Development)

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32 pages, 12297 KiB

Open AccessArticle

A Comparative Study of the Hydrogen Auto-Ignition Process in Oxygen–Nitrogen and Oxygen–Water Vapor Oxidizer: Numerical Investigations in Mixture Fraction Space and 3D Forced Homogeneous Isotropic Turbulent Flow Field

by Lena Caban and Artur Tyliszczak

Energies 2024, 17(17), 4525; https://doi.org/10.3390/en17174525 - 9 Sep 2024

Abstract

In this paper, we analyze the auto-ignition process of hydrogen in a hot oxidizer stream composed of oxygen–nitrogen and oxygen–water vapor with nitrogen/water vapor mass fractions in a range of 0.1–0.9. The temperature of the oxidizer varies from 1100 K to 1500 K [...] Read more.

In this paper, we analyze the auto-ignition process of hydrogen in a hot oxidizer stream composed of oxygen–nitrogen and oxygen–water vapor with nitrogen/water vapor mass fractions in a range of 0.1–0.9. The temperature of the oxidizer varies from 1100 K to 1500 K and the temperature of hydrogen is assumed to be 300 K. The research is performed in 1D mixture fraction space and in a forced homogeneous isotropic turbulent (HIT) flow field. In the latter case, the Large Eddy Simulation (LES) method combined with the Eulerian Stochastic Field (ESF) combustion model is applied. The results obtained in mixture fraction space aim to determine the most reactive mixture fraction, maximum flame temperature, and dependence on the scalar dissipation rate. Among others, we found that the ignition in

H_{2}

-

O_{2}

-

H_{2} O

mixtures occurs later than in

H_{2}

-

O_{2}

-

N_{2}

mixtures, especially at low oxidizer temperatures. On the other hand, for a high oxidizer temperature, the ignitability of

H_{2}

-

O_{2}

-

H_{2} O

mixtures is extended, i.e., the ignition occurs for a larger content of

H_{2} O

and takes place faster. The 3D LES-ESF results show that the ignition time is virtually independent of initial conditions, e.g., randomness of an initial flow field and turbulence intensity. The latter parameter, however, strongly affects the flame evolution. It is shown that the presence of water vapor decreases ignitability and makes flames more prone to extinction. Full article

(This article belongs to the Special Issue Towards Climate Neutral Thermochemical Energy Conversion)

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20 pages, 4209 KiB

Open AccessArticle

How Not to Reduce Carbon Dioxide Emissions: An Unbalanced Focus on Energy Efficiency in Germany’s Building Rehabilitation Policies

by Ray Galvin

Energies 2024, 17(17), 4524; https://doi.org/10.3390/en17174524 - 9 Sep 2024

Abstract

Germany needs to reduce CO₂ emissions from space heating in its old buildings to net zero by 2045 to fulfil its climate goals. However, direct CO₂ reduction measures in existing buildings receive relatively little subsidy support from the federal government’s German [...] Read more.

Germany needs to reduce CO₂ emissions from space heating in its old buildings to net zero by 2045 to fulfil its climate goals. However, direct CO₂ reduction measures in existing buildings receive relatively little subsidy support from the federal government’s German Development Bank, compared to generous subsidies for energy efficiency measures. This interdisciplinary paper evaluates this phenomenon by comparing costs and CO₂ abatement effects of ever higher energy efficiency measures, alongside the costs of direct CO₂ reduction through heat pumps and onsite photovoltaics. It uses a set of carefully selected reports on the costs and benefits of renovation to a range of energy efficiency standards in three common types of multi-apartment buildings in Germany, updating these for 2024 construction, energy, and finance costs. The cost of the CO₂ saved is extremely high with energy efficiency measures and absurdly high with the highest energy efficiency standards, up to 20 times the cost of CO₂ abatement through other means, such as offsite renewables. This reduces markedly with onsite CO₂ reduction measures. This paper sets this analysis in the context of asking what social, cultural, and discursive factors extol energy efficiency so highly that policy tends to thwart its own stated goal of deeply reducing CO₂ emissions. Full article

(This article belongs to the Special Issue Energy Transition and Environmental Sustainability: 3rd Edition)

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22 pages, 5569 KiB

Open AccessReview

Review on Short-Circuit Protection Methods for SiC MOSFETs

by Gang Lyu, Hamid Ali, Hongrui Tan, Lyuzhang Peng and Xiaofeng Ding

Energies 2024, 17(17), 4523; https://doi.org/10.3390/en17174523 - 9 Sep 2024

Abstract

SiC MOSFETs have been a game-changer in the domain of power electronics, thanks to their exceptional electrical traits. They are endowed with a high breakdown voltage, reduced on-resistance, and superior thermal conductivity, which make them supremely suitable for high-power and resilient applications across [...] Read more.

SiC MOSFETs have been a game-changer in the domain of power electronics, thanks to their exceptional electrical traits. They are endowed with a high breakdown voltage, reduced on-resistance, and superior thermal conductivity, which make them supremely suitable for high-power and resilient applications across aviation, automotive, and renewable energy sectors. Despite their intrinsic advantages, SiC MOSFETs also necessitate advanced safeguarding mechanisms to counteract the vulnerability to short-circuit conditions due to their lower short-circuit robustness. This review paper offers an in-depth analysis of the array of short-circuit protection (SCP) methods applied to SiC MOSFETs. This paper scrutinizes techniques such as desaturation detection, di/dt detection, gate charge characteristics monitoring, two-dimensional monitoring, Rogowski coil-based detection, and two-stage turn-off strategies. The paper meticulously explores the operational principles, merits, and limitations of each method, with an emphasis on their adaptability to various fault types, including hard switching faults and load-induced faults. This review acts as a thorough compendium, guiding the choice of pertinent SCP strategies, ensuring the secure and efficient functioning of SiC MOSFETs in demanding applications. Full article

(This article belongs to the Special Issue Power Semiconductor Devices: Optimization, Characterization and Applications)

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19 pages, 6346 KiB

Open AccessArticle

A Novel Single-Stage Boost Single-Phase Inverter and Its Composite Control Strategy to Suppress Low-Frequency Input Ripples

by Yong Wei, Zhenying Jiang, Tao Lv, Xiaohan Tong, Benxu Jiang and Kun Qian

Energies 2024, 17(17), 4522; https://doi.org/10.3390/en17174522 - 9 Sep 2024

Abstract

Low-frequency pulsating ripples exist on the input side of a single-phase inverter, which bring some adverse effects and harm to the inverter and photovoltaic power generation system. In order to suppress the low-frequency pulsating ripple and reduce the filter circuit parameters, a novel [...] Read more.

Low-frequency pulsating ripples exist on the input side of a single-phase inverter, which bring some adverse effects and harm to the inverter and photovoltaic power generation system. In order to suppress the low-frequency pulsating ripple and reduce the filter circuit parameters, a novel single-stage boost single-phase inverter is proposed, which can suppress low-frequency ripple. And a three-closed-loop compound control strategy that can suppress input low-frequency ripples under the limitation of an energy storage inductor current and buffer capacitor voltage is proposed. The circuit topology, control strategy, key circuit parameters design, system modeling, and simulation of the inverters are deeply analyzed and studied. Simulation and experimental results show that the inverter has a good ability to suppress input low-frequency ripples. Full article

(This article belongs to the Section F: Electrical Engineering)

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20 pages, 2302 KiB

Open AccessArticle

Technical–Economic Analysis of Renewable Hydrogen Production from Solar Photovoltaic and Hydro Synergy in a Pilot Plant in Brazil

by Ana Beatriz Barros Souza Riedel, Vitor Feitosa Riedel, Hélio Nunes de Souza Filho, Ennio Peres da Silva, Renato Marques Cabral, Leandro de Brito Silva and Alexandre de Castro Pereira

Energies 2024, 17(17), 4521; https://doi.org/10.3390/en17174521 - 9 Sep 2024

Abstract

Renewable hydrogen obtained from renewable energy sources, especially when produced through water electrolysis, is gaining attention as a promising energy vector to deal with the challenges of climate change and the intermittent nature of renewable energy sources. In this context, this work analyzes [...] Read more.

Renewable hydrogen obtained from renewable energy sources, especially when produced through water electrolysis, is gaining attention as a promising energy vector to deal with the challenges of climate change and the intermittent nature of renewable energy sources. In this context, this work analyzes a pilot plant that uses this technology, installed in the Itumbiara Hydropower Plant located between the states of Goiás and Minas Gerais, Brazil, from technical and economic perspectives. The plant utilizes an alkaline electrolyzer synergistically powered by solar photovoltaic and hydro sources. Cost data for 2019, when the equipment was purchased, and 2020–2023, when the plant began continuous operation, are considered. The economic analysis includes annualized capital, maintenance, and variable costs, which determines the levelized cost of hydrogen (LCOH). The results obtained for the pilot plant’s LCOH were USD 13.00 per kilogram of H₂, with an efficiency loss of 2.65% for the two-year period. Sensitivity analysis identified the capacity factor (CF) as the main determinant of the LCOH. Even though the analysis specifically applies to the Itumbiara Hydropower Plant, the CF can be extrapolated to larger plants as it directly influences hydrogen production regardless of plant size or capacity. Full article

(This article belongs to the Section B: Energy and Environment)

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27 pages, 3505 KiB

Open AccessArticle

A Novel Direct-Expansion Radiant Floor System Utilizing Water (R-718) for Cooling and Heating

by Fadi Alsouda, Nick S. Bennett, Suvash C. Saha and Mohammad S. Islam

Energies 2024, 17(17), 4520; https://doi.org/10.3390/en17174520 - 9 Sep 2024

Abstract

While forced-air convective systems remain the predominant method for heating and cooling worldwide, radiant cooling and heating systems are emerging as a more efficient alternative. Current radiant cooling systems primarily rely on hydronic chilled water systems. This study introduces direct-expansion radiant cooling as [...] Read more.

While forced-air convective systems remain the predominant method for heating and cooling worldwide, radiant cooling and heating systems are emerging as a more efficient alternative. Current radiant cooling systems primarily rely on hydronic chilled water systems. This study introduces direct-expansion radiant cooling as a novel technique that could enhance the efficiency of radiant cooling and reduce its environmental impact. Water (R-718) has been tested as a refrigerant due to its favorable thermodynamic properties and environmental advantages; however, to the author’s knowledge, it has yet to be tested in direct-expansion radiant cooling. This research investigated several refrigerants, including water (R-718), ammonia (R-717), R-410a, R-32, R-134a, and R-1234yf, for this application. The findings indicate that water demonstrates efficiency comparable to other non-natural refrigerants, making it a promising candidate, given its favorable thermodynamic properties and substantial environmental benefits. Despite challenges such as a high compression ratio necessitating multi-stage compression, a high compressor discharge temperature exceeding 300 °C and requiring specialized blade materials, and a high suction volume flow rate, direct-expansion radiant cooling operates within a different temperature range. Consequently, the compressor discharge temperature can be reduced to 176 °C, and the compression ratio can be lowered to approximately 3.5, making water a more viable refrigerant option for this application. Full article

(This article belongs to the Section J: Thermal Management)

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15 pages, 6140 KiB

Open AccessArticle

DAB-Based Bidirectional Wireless Power Transfer System with LCC-S Compensation Network under Grid-Connected Application

by Guocun Li, Zhouchi Cai, Chen Feng, Zeyu Sun and Xuewei Pan

Energies 2024, 17(17), 4519; https://doi.org/10.3390/en17174519 - 9 Sep 2024

Abstract

To realize two-way power transfer without physical connections under a grid-connected application, bidirectional wireless power transfer (BDWPT) is introduced. This paper proposes an LCC-S compensated BDWPT system based on dual-active-bridge (DAB) topology with the minimum component counts. LCC-S is designed to [...] Read more.

To realize two-way power transfer without physical connections under a grid-connected application, bidirectional wireless power transfer (BDWPT) is introduced. This paper proposes an LCC-S compensated BDWPT system based on dual-active-bridge (DAB) topology with the minimum component counts. LCC-S is designed to be a constant voltage (CV) network. To obtain the power transmission characteristics of the system, a mathematical model based on the fundamental harmonic approximation (FHA) method is established, and the result shows that the direction and amount of transfer power can be controlled by changing the magnitude of output voltages of either/both side of H-bridges. The reactive power of the system can be controlled to be zero when the output voltages of two H-bridges are in the same phase. Compared with DAB-based BDWPT systems with constant current (CC) compensation networks, the proposed structure has better transfer power regulation capability and easier control of the direction of power flow. A 1.1 kW experimental prototype is built in the laboratory to verify the characteristics of the proposed system. The results indicate that the power transfer characteristics of the proposed BDWPT system match its mathematical derivation results based on the FHA model. Full article

(This article belongs to the Special Issue Progress and Challenges in Grid-Connected Inverters and Converters)

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32 pages, 954 KiB

Open AccessArticle

LightGBM-, SHAP-, and Correlation-Matrix-Heatmap-Based Approaches for Analyzing Household Energy Data: Towards Electricity Self-Sufficient Houses

by Nitin Kumar Singh and Masaaki Nagahara

Energies 2024, 17(17), 4518; https://doi.org/10.3390/en17174518 - 9 Sep 2024

Abstract

The rapidly growing global energy demand, environmental concerns, and the urgent need to reduce carbon footprints have made sustainable household energy consumption a critical priority. This study aims to analyze household energy data to predict the electricity self-sufficiency rate of households and extract [...] Read more.

The rapidly growing global energy demand, environmental concerns, and the urgent need to reduce carbon footprints have made sustainable household energy consumption a critical priority. This study aims to analyze household energy data to predict the electricity self-sufficiency rate of households and extract meaningful insights that can enhance it. For this purpose, we use LightGBM (Light Gradient Boosting Machine)-, SHAP (SHapley Additive exPlanations)-, and correlation-heatmap-based approaches to analyze 12 months of energy and questionnaire survey data collected from over 200 smart houses in Kitakyushu, Japan. First, we use LightGBM to predict the ESSR of households and identify the key features that impact the prediction model. By using LightGBM, we demonstrated that the key features are the housing type, average monthly electricity bill, presence of floor heating system, average monthly gas bill, electricity tariff plan, electrical capacity, number of TVs, cooking equipment used, number of washing and drying machines, and the frequency of viewing home energy management systems (HEMSs). Furthermore, we adopted the LightGBM classifier with

ℓ^{1}

regularization to extract the most significant features and established a statistical correlation between these features and the electricity self-sufficiency rate. This LightGBM-based model can also predict the electricity self-sufficiency rate of households that did not participate in the questionnaire survey. The LightGBM-based model offers a global view of feature importance but lacks detailed explanations for individual predictions. For this purpose, we used SHAP analysis to identify the impact-wise order of key features that influence the electricity self-sufficiency rate (ESSR) and evaluated the contribution of each feature to the model’s predictions. A heatmap is also used to analyze the correlation among household variables and the ESSR. To evaluate the performance of the classification model, we used a confusion matrix showing a good F1 score (Weighted Avg) of 0.90. The findings discussed in this article offer valuable insights for energy policymakers to achieve the objective of developing energy-self-sufficient houses. Full article

(This article belongs to the Special Issue New and Future Progress for Low-Carbon Energy Policy)

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17 pages, 5377 KiB

Open AccessArticle

The Impact of Fractures on Shale Oil and Gas Enrichment and Mobility: A Case Study of the Qingshankou Formation in the Gulong Depression of the Songliao Basin, NE China

by Xuefeng Bai, Junhui Li, Wei Liu, Jijun Li, Xiuli Fu, Yangxin Su, Qiang Zheng, Shuangfang Lu, Xu Zeng, Hang You and Yingchao Xu

Energies 2024, 17(17), 4517; https://doi.org/10.3390/en17174517 - 9 Sep 2024

Abstract

To study the impact of faults on the enrichment and mobility of shale oil in the Gulong area, representative rock samples were selected in this paper. Based on geochemical data and chemical kinetics methods, coupled with shale oil enrichment and mobility analysis techniques, [...] Read more.

To study the impact of faults on the enrichment and mobility of shale oil in the Gulong area, representative rock samples were selected in this paper. Based on geochemical data and chemical kinetics methods, coupled with shale oil enrichment and mobility analysis techniques, the shale oil generation quantity and in situ oil content were evaluated from the perspectives of shale oil generation and micro migration, and the mobility of shale oil was revealed. At the same time, the hydrocarbon expulsion efficiency (HEE) of shale was qualitatively and quantitatively characterized, combined with the development of faults. The research results indicate that the study area mainly develops organic-rich felsic (ORF)/organic-containing felsic (OCF) shale, their proportion in both wells exceeds 65%, and the resource amount is the largest in this type of lithofacies. The development of a fault controls the enrichment of shale oil, and the in situ oil content and oil saturation index (OSI) of the shale in well Y58, which is close to the fault, are significantly worse than those in well S2. Well Y58 has 9.52 mg/g and 424.83 mg/g TOC respectively, while well S2 has 11.34 mg/g and 488.73 mg/g TOC respectively. The fault enhanced the migration of shale oil, increasing the efficiency of oil expulsion. As a result, the components with weak polarity or small molecules, such as saturated hydrocarbons and low carbon number n-alkanes, are prone to migration, reducing the mobility of shale oil. Full article

(This article belongs to the Special Issue Geological Characteristics, Evaluation Methods and Exploration Prospects of Tight Oil and Gas Resources: 2nd Edition)

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30 pages, 5273 KiB

Open AccessReview

Alcohols as Biofuel for a Diesel Engine with Blend Mode—A Review

by Arkadiusz Jamrozik and Wojciech Tutak

Energies 2024, 17(17), 4516; https://doi.org/10.3390/en17174516 - 9 Sep 2024

Abstract

In the era of decarbonization driven by environmental concerns and stimulated by legislative measures such as Fit for 55, the industry and transportation sectors are increasingly replacing petroleum-based fuels with those derived from renewable sources. For many years, the share of these fuels [...] Read more.

In the era of decarbonization driven by environmental concerns and stimulated by legislative measures such as Fit for 55, the industry and transportation sectors are increasingly replacing petroleum-based fuels with those derived from renewable sources. For many years, the share of these fuels in blends used to power compression ignition engines has been growing. The primary advantage of this fuel technology is the reduction of GHG emissions while maintaining comparable engine performance. However, these fuel blends also have drawbacks, including limited ability to form stable mixtures or the requirement for chemical stabilizers. The stability of these mixtures varies depending on the type of alcohol used, which limits the applicability of such fuels. This study focuses on evaluating the impact of eight types of alcohol fuels, including short-chain (methanol, ethanol, propanol) and long-chain alcohols (butanol, pentanol, hexanol, heptanol, and octanol), on the most critical operational parameters of an industrial engine and exhaust emissions. The engines being compared operated at a constant speed and under a constant load, either maximum or close to maximum. The study also evaluated the effect of alcohol content in the mixture on combustion process parameters such as peak cylinder pressure and heat release, which are the basis for parameterizing the engine’s combustion process. Determining ignition delay and combustion duration is fundamental for optimizing the engine’s thermal cycle. As the research results show, both the type of alcohol and its concentration in the mixture influence these parameters. Another parameter important from a usability perspective is engine stability, which was also considered. Engine performance evaluation also includes assessing emissions, particularly the impact of alcohol content on NO_x and soot emissions. Based on the analysis, it can be concluded that adding alcohol fuel to diesel in a CI engine increases ignition delay (up to 57%), p_max (by approximately 15–20%), HRR_max (by approximately 80%), and PPR_max (by approximately 70%). Most studies indicate a reduction in combustion duration with increasing alcohol content (by up to 50%). For simple alcohols, an increase in thermal efficiency (by approximately 15%) was observed, whereas for complex alcohols, a decrease (by approximately 10%) was noted. The addition of alcohol to diesel slightly worsens the stability of the CI engine. Most studies pointed to the positive impact of adding alcohol fuel to diesel on NOx emissions from the compression ignition engine, with the most significant reductions reaching approximately 50%. Increasing the alcohol fuel content in the diesel blend significantly reduced soot emissions from the CI engine (by up to approximately 90%). Full article

(This article belongs to the Special Issue Renewable Fuels for Internal Combustion Engines: 2nd Edition)

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17 pages, 6239 KiB

Open AccessArticle

Position Servo Control of Electromotive Valve Driven by Centralized Winding LATM Using a Kalman Filter Based Load Observer

by Yi Yang, Xin Cheng and Rougang Zhou

Energies 2024, 17(17), 4515; https://doi.org/10.3390/en17174515 - 9 Sep 2024

Abstract

The exhaust gas recirculation (EGR) valve plays an important role in improving engine fuel economy and reducing emissions. In order to improve the positioning accuracy and robustness of the EGR valve under uncertain dynamics and external disturbances, this paper proposes a positioning servo [...] Read more.

The exhaust gas recirculation (EGR) valve plays an important role in improving engine fuel economy and reducing emissions. In order to improve the positioning accuracy and robustness of the EGR valve under uncertain dynamics and external disturbances, this paper proposes a positioning servo system design for an electromotive (EM) EGR valve based on the Kalman filter. Taking a novel valve driven by a central winding limited angle torque motor (LATM) as the object, we have fully considered the influence of the motor rotor position and load current, as well as the magnetic field saturation and cogging effect, improved the existing LTAM model, and derived accurate torque expression. The parameter uncertainty of the above internal model and the external stochastic disturbance were unified as “total disturbance”, and a Kalman filter-based observer was designed for disturbance estimations and real-time feed-forward compensation. Furthermore, using non-contact magnetic angle measurements to obtain accurate valve position information, a position control model with real-time response and high accuracy was established. Numerous simulated and experimental data show that in the presence of ± 25% plant model parameter fluctuations and random shock-type disturbances, the servo system scheme proposed in this paper achieves a maximum position deviation of 0.3 mm, a repeatability of positioning accuracy after disturbances of 0.01 mm, and a disturbance recovery time of not more than 250 ms. In addition, the above performance is insensitive to the duration of the disturbance, which demonstrates the strong robustness, high accuracy, and excellent dynamic response capability of the proposed design. Full article

(This article belongs to the Section F1: Electrical Power System)

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41 pages, 20389 KiB

Open AccessReview

Technology for Green Hydrogen Production: Desk Analysis

by Bożena Łosiewicz

Energies 2024, 17(17), 4514; https://doi.org/10.3390/en17174514 - 9 Sep 2024

Abstract

The use of green hydrogen as a high-energy fuel of the future may be an opportunity to balance the unstable energy system, which still relies on renewable energy sources. This work is a comprehensive review of recent advancements in green hydrogen production. This [...] Read more.

The use of green hydrogen as a high-energy fuel of the future may be an opportunity to balance the unstable energy system, which still relies on renewable energy sources. This work is a comprehensive review of recent advancements in green hydrogen production. This review outlines the current energy consumption trends. It presents the tasks and challenges of the hydrogen economy towards green hydrogen, including production, purification, transportation, storage, and conversion into electricity. This work presents the main types of water electrolyzers: alkaline electrolyzers, proton exchange membrane electrolyzers, solid oxide electrolyzers, and anion exchange membrane electrolyzers. Despite the higher production costs of green hydrogen compared to grey hydrogen, this review suggests that as renewable energy technologies become cheaper and more efficient, the cost of green hydrogen is expected to decrease. The review highlights the need for cost-effective and efficient electrode materials for large-scale applications. It concludes by comparing the operating parameters and cost considerations of the different electrolyzer technologies. It sets targets for 2050 to improve the efficiency, durability, and scalability of electrolyzers. The review underscores the importance of ongoing research and development to address the limitations of current electrolyzer technology and to make green hydrogen production more competitive with fossil fuels. Full article

(This article belongs to the Section A5: Hydrogen Energy)

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23 pages, 3079 KiB

Open AccessArticle

European Green Deal: Substantiation of the Rational Configuration of the Bioenergy Production System from Organic Waste

by Inna Tryhuba, Anatoliy Tryhuba, Taras Hutsol, Szymon Szufa, Szymon Glowacki, Oleh Andrushkiv, Roman Padyuka, Oleksandr Faichuk and Nataliia Slavina

Energies 2024, 17(17), 4513; https://doi.org/10.3390/en17174513 - 9 Sep 2024

Abstract

A review of the current state of the theory and practice of bioenergy production from waste allowed us to identify the scientific and applied problem of substantiating the rational configuration of a modular anaerobic bioenergy system, taking into account the volume of organic [...] Read more.

A review of the current state of the theory and practice of bioenergy production from waste allowed us to identify the scientific and applied problem of substantiating the rational configuration of a modular anaerobic bioenergy system, taking into account the volume of organic waste generated in settlements. To solve this problem, this paper develops an approach and an algorithm for matching the configuration of a modular anaerobic bioenergy production system with the amount of organic waste generated in residential areas. Unlike the existing tools, this takes into account the peculiarities of residential areas, which is the basis for accurate forecasting of organic waste generation and, accordingly, determining the configuration of the bioenergy production system. In addition, for each of the scenarios, the anaerobic digestion process is modeled, which allows us to determine the functional indicators that underlie the determination of a rational configuration in terms of cost and environmental performance. Based on the use of the developed tools for the production conditions of the Golosko residential area, Lviv (Ukraine), possible scenarios for the installation of modular anaerobic bioenergy production systems are substantiated. It was found that the greatest annual benefits are obtained from the processing of mixed food and yard waste. The payback period of investments in modular anaerobic bioenergy production systems for given conditions of a residential area largely depends on their configuration and ranges from 3.3 to 8.4 years, which differ from each other by 2.5 times. This indicates that the developed toolkit is of practical value, as it allows the coordination of the rational configuration of modular anaerobic bioenergy production systems with real production conditions. In the future, it is recommended to use the proposed decision support system to model the use of biomass as an energy resource in residential areas, which ensures the determination of the rational configuration of a modular anaerobic bioenergy production system for given conditions. Full article

(This article belongs to the Special Issue Recent Advances in Biomass Energy Torrefaction, Pyrolysis and Gasification Technologies)

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14 pages, 2577 KiB

Open AccessArticle

The Time-Varying Characteristics of Relative Permeability in Oil Reservoirs with Gas Injection

by Hengjie Liao, Xinzhe Liu, Xianke He, Yuansheng Li, Zhehao Jiang, Kaifen Li and Keliu Wu

Energies 2024, 17(17), 4512; https://doi.org/10.3390/en17174512 - 9 Sep 2024

Abstract

Relative permeability is a critical parameter in reservoir numerical simulation and production prediction, intimately associated with reservoir architecture and fluid property. During gas injection development, substantial alterations in reservoir properties and fluid phase behavior induce dynamic changes in relative permeability. Clearly characterizing the [...] Read more.

Relative permeability is a critical parameter in reservoir numerical simulation and production prediction, intimately associated with reservoir architecture and fluid property. During gas injection development, substantial alterations in reservoir properties and fluid phase behavior induce dynamic changes in relative permeability. Clearly characterizing the time-varying features of relative permeability is very useful for an understanding of how gas injection influences fluid mobility within the reservoir and enhances recovery rates. In this paper, core displacement experiments are firstly conducted to obtain the characteristics of the relative permeability of oil and gas under various development stages and displacement conditions, further delineating the comprehensive shifts in reservoir properties at different gas injection stages. Subsequently, a novel reservoir numerical simulation method is proposed that considers the spatial and temporal segmentation of relative permeability curves in the reservoir simulation. Finally, a practical application is presented to clarify the effects of injection and production parameters on the development performance of gas flooding oil reservoirs. The results show the following: (i) Significant time-varying characteristics of relative permeability occur throughout gas injection development, in the early stages of gas injection, where most of the reservoir is at the gas injection front, and a rightward shift in relative oil and gas permeability indicates that gas injection promotes oil mobility. Conversely, in the later stages of gas injection, as the reservoir reaches the trailing edge of gas injection, the change trend in relative oil and gas permeability reverses, shifting leftward, thereby exacerbating the gas breakout phenomena. (ii) Increasing the rate of gas injection causes relative oil and gas permeability to move leftward, effectively enhancing the gas volume sweep coefficient and microscopic oil displacement efficiency at lower injection speeds while reducing development performance at higher injection speeds. (iii) An increase in gas injection pressure causes relative oil and gas permeability to shift rightward, and although it reduces residual oil saturation and enhances microscopic oil displacement efficiency, it also intensifies gas breakout phenomena and lowers the gas volume sweep coefficient. This paper provides theoretical guidance and technical support for the design of gas injection strategies, optimization of injection and production parameters, and production forecasting. Full article

(This article belongs to the Special Issue Oil and Gas Reservoirs: Phase Behavior, Seepage Mechanism, Productivity Prediction, and Novel Modelling Methods)

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29 pages, 3364 KiB

Open AccessArticle

Breaking the CO₂ Gridlock: Can Renewables Lead the Way for the OECD?

by Wang Jie and Rabnawaz Khan

Energies 2024, 17(17), 4511; https://doi.org/10.3390/en17174511 - 9 Sep 2024

Abstract

The use of low-carbon energy in power grids is essential for minimizing negative effects on the environment. Energy consumption causes environmental damage to the OECD’s economy. This study aims to investigate the effect of energy consumption, population, and GDP on CO₂ emissions [...] Read more.

The use of low-carbon energy in power grids is essential for minimizing negative effects on the environment. Energy consumption causes environmental damage to the OECD’s economy. This study aims to investigate the effect of energy consumption, population, and GDP on CO₂ emissions using panel data from 17 OECD countries over the period 2000–2023. We use regression approaches, such as partial least squares and principal components, to study the effects of GDP, urban and total population, oil and nuclear use, renewable energy, and industrialization on CO₂ emissions. The regression process in this study reduces the data to a two-dimensional representation using a stochastic model and estimation techniques. The findings of this empirical investigation indicate that the United States, Canada, France, Germany, Italy, Korea, Mexico, and the United Kingdom exhibit higher levels of primary energy consumption in comparison to value-added sectors, renewable–geothermal energy, and nuclear energy. We determined the effects of CO₂ emissions, GDP, and energy consumption by considering these as the most significant elements. This has made it possible to reduce CO₂ emissions by focusing one’s attention and energy on the development of novel technologies, the use of renewable energy sources, and the execution of strategic plans. Attracting increasing attention are technological shifts that deliver enormous quantities of clean energy to combat climate change. Findings from this study can help environmentalists and policymakers better understand the role of structural change and energy consumption processes in the globalization process. Full article

(This article belongs to the Special Issue Dual Control of Carbon Emissions and High-Quality Economic Development)

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25 pages, 3148 KiB

Open AccessReview

A Review of Flow Field and Heat Transfer Characteristics of Jet Impingement from Special-Shaped Holes

by Liang Xu, Naiyuan Hu, Hongwei Lin, Lei Xi, Yunlong Li and Jianmin Gao

Energies 2024, 17(17), 4510; https://doi.org/10.3390/en17174510 - 9 Sep 2024

Abstract

The jet impingement cooling technique is regarded as one of the most effective enhanced heat transfer techniques with a single-phase medium. However, in order to facilitate manufacturing, impingement with a large number of smooth circular hole jets is used in engineering. With the [...] Read more.

The jet impingement cooling technique is regarded as one of the most effective enhanced heat transfer techniques with a single-phase medium. However, in order to facilitate manufacturing, impingement with a large number of smooth circular hole jets is used in engineering. With the increasing maturity of additive technology, some new special-shaped holes (SSHs) may be used to further improve the cooling efficiency of jet impingement. Secondly, the heat transfer coefficient of the whole jet varies greatly on the impact target surface. The experiments with a large number of single smooth circular hole jets show that the heat transfer coefficient of the impact target surface will form a bell distribution—that is, the Nusselt number has a maximum value near the stagnation region, and then rapidly decreases exponentially in the radial direction away from the stagnation region. The overall surface temperature distribution is very uneven, and the target surface will form an array of cold spots, resulting in a high level of thermal stress, which will greatly weaken the structural strength and life of the equipment. Establishing how to ensure the uniformity of jet impingement cooling has become a new problem to be solved. In order to achieve uniform cooling, special-shaped holes that generate a swirling flow may be a solution. This paper presents a summary of the effects of holes with different geometrical features on the flow field and heat transfer characteristics of jet impingement cooling. In addition, the effect of jet impingement cooling with SSHs in different array methods is compared. The current challenges of jet impingement cooling technology with SSHs are discussed, as well as the prospects for possible future advances. Full article

(This article belongs to the Collection Advances in Heat Transfer Enhancement)

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18 pages, 4187 KiB

Open AccessArticle

Utilizing Connection of Multiple Peltier Cells to Enhance the Coefficient of Performance

by Jan Rimbala, Jan Kyncl, Jan Koller and Ghaeth Fandi

Energies 2024, 17(17), 4509; https://doi.org/10.3390/en17174509 - 9 Sep 2024

Abstract

Peltier cells are commonly used in low-power cooling applications, such as automotive refrigerators and electronics temperature regulation systems. These applications are typically low-energy in nature. There is currently a growing emphasis on energy conservation and waste heat utilization in the energy industry. This [...] Read more.

Peltier cells are commonly used in low-power cooling applications, such as automotive refrigerators and electronics temperature regulation systems. These applications are typically low-energy in nature. There is currently a growing emphasis on energy conservation and waste heat utilization in the energy industry. This paper explores the possibility of improving the heating or cooling coefficient of performance (COP) of Peltier cells through intelligent serial and parallel connections. The purpose of this work is to raise the question of whether it would be possible to reconsider the concept of harnessing the “energy” potential of Peltier cells. The utilized model is in line with the current state of the art, and the case study is based on parameters measured on a commercially available Peltier cell. The resulting COP, when considering current materials, remains inferior to the COP of compressor-based heat pumps. For low-power devices, it can represent a technically and economically comparable solution. Full article

(This article belongs to the Section F: Electrical Engineering)

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30 pages, 17253 KiB

Open AccessArticle

The Influence of Switching Frequency on Control in Voltage Source Inverters

by Zbigniew Rymarski

Energies 2024, 17(17), 4508; https://doi.org/10.3390/en17174508 - 8 Sep 2024

Abstract

This paper aims to show how the switching frequency influences the properties of the digitally controlled voltage source inverter (VSI). The measurements of the Bode plots of the inverter are shown and discussed to present the existing signal delays and power conversion efficiency, [...] Read more.

This paper aims to show how the switching frequency influences the properties of the digitally controlled voltage source inverter (VSI). The measurements of the Bode plots of the inverter are shown and discussed to present the existing signal delays and power conversion efficiency, depending on the switching/sampling frequency. Two types of controllers are presented, Single-Input–Single-Output (SISO) and Multi-Input–Single-Output (MISO), and adequate prediction units (the Smith Predictor for SISO—Coefficient Diagram Method and the full-state Luenberger Observer for MISO—Passivity Based Control) were used to compensate for the delays. It will be shown by comparing the THD of the VSI output voltage that prediction is useful with low VSI switching frequency (about 10 kHz) but is not important for the middle switching frequencies (about 25 kHz) or the high switching frequency (>50 kHz). This paper shows that increasing the switching frequency simplifies digital control without reasonably decreasing efficiency. The theoretical considerations, the Matlab/Simulink 2021b simulations, the final experimental laboratory verification are presented. Full article

(This article belongs to the Special Issue State-of-the-Art Research in Advanced Power Electronic Conversion Systems)

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16 pages, 2919 KiB

Open AccessArticle

Efficiency Optimization of LCL-Resonant Wireless Power Transfer Systems via Bidirectional Electromagnetic–Thermal Coupling Field Dynamics

by Yao Yuan, Yuan La, Sicheng Shen, Yihui Zhao, Jianchao Li and Fanghui Yin

Energies 2024, 17(17), 4507; https://doi.org/10.3390/en17174507 - 8 Sep 2024

Abstract

This paper delved into the thermal dynamics and stability of Wireless Power Transfer (WPT) systems, with a focus on the temperature effects on the coil structure. Using the Finite Element Method (FEM), this study investigated both unidirectional and bidirectional coupling field simulations, assessing [...] Read more.

This paper delved into the thermal dynamics and stability of Wireless Power Transfer (WPT) systems, with a focus on the temperature effects on the coil structure. Using the Finite Element Method (FEM), this study investigated both unidirectional and bidirectional coupling field simulations, assessing their impacts on the transmission efficiency of LCL-resonant WPT systems. The boundary conditions and processes of the electromagnetic–thermal coupling field related to coil loss were analyzed, as well as the dynamic thermal balance in the bidirectional coupling field model. It was found that there is a significant temperature variation across the coil, with the highest temperatures at the central position and the lowest at the edges. This temperature rise notably changed the electrical parameters of the system, leading to variations in its operating state and a reduction in transmission efficiency. A constant coil voltage control strategy was more effective in mitigating the temperature rise compared to a constant coil current strategy, providing valuable insight for enhancing the efficiency and stability of WPT systems. Full article

(This article belongs to the Section F1: Electrical Power System)

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26 pages, 1161 KiB

Open AccessReview

Additives Improving the Efficiency of Biogas Production as an Alternative Energy Source—A Review

by Agnieszka A. Pilarska, Krzysztof Pilarski, Tomasz Kulupa, Adrianna Kubiak, Agnieszka Wolna-Maruwka, Alicja Niewiadomska and Jacek Dach

Energies 2024, 17(17), 4506; https://doi.org/10.3390/en17174506 - 8 Sep 2024

Abstract

Additives for anaerobic digestion (AD) can play a significant role in optimizing the process by increasing biogas production, stabilizing the system, and improving digestate quality. The role of additives largely boils down to, among others, enhancing direct interspecies electron transfer (DIET) between microbial [...] Read more.

Additives for anaerobic digestion (AD) can play a significant role in optimizing the process by increasing biogas production, stabilizing the system, and improving digestate quality. The role of additives largely boils down to, among others, enhancing direct interspecies electron transfer (DIET) between microbial communities, resulting in improved syntrophic interactions, adsorption of toxic substances that may inhibit microbial activity, improving microbial activity, and increasing process stability and accelerating the decomposition of complex organic materials, thereby increasing the rate of hydrolysis. Through the aforementioned action, additives can significantly affect AD performance. The function of these materials varies, from enhancing microbial activity to maintaining optimal conditions and protecting the system from inhibitors. The choice of additives should be carefully tailored to the specific needs and conditions of the digester to maximize benefits and ensure sustainability. In light of these considerations, this paper characterizes the most commonly used additives and their combinations based on a comprehensive review of recent scientific publications, including a report on the results of conducted studies. The publication features chapters that describe carbon-based conductive materials, metal oxide nanomaterials, trace metal, and biological additives, including enzymes and microorganisms. It concludes with the chapters summarising reports on various additives and discussing their functional properties, as well as advantages and disadvantages. The presented review is a substantive and concise analysis of the latest knowledge on additives for the AD process. The application of additives in AD is characterized by great potential; hence, the subject matter is very current and future-oriented. Full article

(This article belongs to the Special Issue State-of-the-Art Research in Advanced Materials for Energy Storage Applications)

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25 pages, 19232 KiB

Open AccessArticle

Electric Vehicle Charging Load Demand Forecasting in Different Functional Areas of Cities with Weighted Measurement Fusion UKF Algorithm

by Minan Tang, Xi Guo, Jiandong Qiu, Jinping Li and Bo An

Energies 2024, 17(17), 4505; https://doi.org/10.3390/en17174505 - 8 Sep 2024

Abstract

The forecasting of charging demand for electric vehicles (EVs) plays a vital role in maintaining grid stability and optimizing energy distribution. Therefore, an innovative method for the prediction of EV charging load demand is proposed in this study to address the downside of [...] Read more.

The forecasting of charging demand for electric vehicles (EVs) plays a vital role in maintaining grid stability and optimizing energy distribution. Therefore, an innovative method for the prediction of EV charging load demand is proposed in this study to address the downside of the existing techniques in capturing the spatial–temporal heterogeneity of electric vehicle (EV) charging loads and predicting the charging demand of electric vehicles. Additionally, an innovative method of electric vehicle charging load demand forecasting is proposed, which is based on the weighted measurement fusion unscented Kalman filter (UKF) algorithm, to improve the accuracy and efficiency of forecasting. First, the data collected from OpenStreetMap and Amap are used to analyze the distribution of urban point-of-interest (POI), to accurately classify the functional areas of the city, and to determine the distribution of the urban road network, laying a foundation for modeling. Second, the travel chain theory was applied to thoroughly analyze the travel characteristics of EV users. The Improved Floyd (IFloyd) algorithm is used to determine the optimal route. Also, a Monte Carlo simulation is performed to estimate the charging load for electric vehicle users in a specific region. Then, a weighted measurement fusion UKF (WMF–UKF) state estimator is introduced to enhance the accuracy of prediction, which effectively integrates multi-source data and enables a more detailed prediction of the spatial–temporal distribution of load demand. Finally, the proposed method is validated comparatively against traffic survey data and the existing methods by conducting a simulation experiment in an urban area. The results show that the method proposed in this paper is applicable to predict the peak hours more accurately compared to the reference method, with the accuracy of first peak prediction improved by 53.53% and that of second peak prediction improved by 23.23%. The results not only demonstrate the high performance of the WMF–UKF prediction model in forecasting peak periods but also underscore its potential in supporting grid operations and management, which provides a new solution to improving the accuracy of EV load demand forecasting. Full article

(This article belongs to the Section G: Energy and Buildings)

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16 pages, 3024 KiB

Open AccessArticle

A CHEMCAD Software Design Approach for Non-Conventional Biodiesel Production Using Methyl Acetate as Feedstock

by Letitia Petrescu, Oana Beudean, Stefan Cristian Galusnyak and Calin-Cristian Cormos

Energies 2024, 17(17), 4504; https://doi.org/10.3390/en17174504 - 8 Sep 2024

Abstract

Biodiesel is a sustainable and renewable fuel generated from renewable resources, including vegetable oil or animal fats. It is thought to be a non-toxic fuel that degrades gradually and causes no harm to the environment. In the present study, a non-conventional supercritical method [...] Read more.

Biodiesel is a sustainable and renewable fuel generated from renewable resources, including vegetable oil or animal fats. It is thought to be a non-toxic fuel that degrades gradually and causes no harm to the environment. In the present study, a non-conventional supercritical method for industrial biodiesel production is investigated. The non-conventional method refers to a single-step interesterification reaction between triglycerides and methyl acetate resulting in methyl esters of fatty acids and triacetin as a secondary product. Process flowsheet modeling, using CHEMCAD chemical engineering software, was used as an investigation tool. The production capacity was set to 25,000 kg/h biodiesel. Methyl acetate requested in the biodiesel production is produced from methanol esterification with acetic acid using an intensified reactive distillation unit. Methanol, in turn, is obtained using synthetic gas derived from biomass as a raw material, the process representing a new method at the industrial level to solve problems related to the energy that is required, storage and disposal of residual materials, and pollution through the release of pollutants into the air. The methanol synthesis process is similar to the one based on natural gas, consisting of three main steps, namely: (i) synthesis gas production, followed by (ii) methanol production, and (iii) methanol purification. Acetic acid is an essential chemical product, generated in the proposed approach by a sustainable method with low energy consumption and low air emissions, more exactly methanol carbonylation. All the processes previously mentioned: (i) biodiesel production, (ii) methyl acetate production, (iii) acetic acid production, and (iv) methanol production were modeled and simulated, leading to the desired biodiesel productivity (e.g., 25,000 kg/h) with the obtained purity being higher than 99%. Relevant discussions regarding the design assumptions used, the simulation and validation results, as well as other technical issues (i.e., electricity and thermal energy consumption) for the system being simulated, are provided, leading to the conclusion that the proposed route is well suited for the desired application and can deliver significant results. The simulation outcomes have provided confidence in the feasibility and effectiveness of the chosen process design, making it a viable option for further development and implementation. Full article

(This article belongs to the Special Issue Recent Advances in Biofuels Production and Usage: Challenges and Solutions)

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24 pages, 8539 KiB

Open AccessArticle

A Nonlinear Wind Turbine Wake Expansion Model Considering Atmospheric Stability and Ground Effects

by Xingxing Han, Tongguang Wang, Xiandong Ma, Chang Xu, Shifeng Fu, Jinmeng Zhang, Feifei Xue and Zhe Cheng

Energies 2024, 17(17), 4503; https://doi.org/10.3390/en17174503 - 8 Sep 2024

Abstract

This study investigates the influence of atmospheric stability and ground effects on wind turbine wake recovery, challenging the conventional linear relationship between turbulence intensity and wake expansion coefficient. Through comprehensive field measurements and numerical simulations, we demonstrate that the linear wake expansion assumption [...] Read more.

This study investigates the influence of atmospheric stability and ground effects on wind turbine wake recovery, challenging the conventional linear relationship between turbulence intensity and wake expansion coefficient. Through comprehensive field measurements and numerical simulations, we demonstrate that the linear wake expansion assumption is invalid at far-wake locations under high turbulence conditions, primarily due to ground effects. We propose a novel nonlinear wake expansion model that incorporates both atmospheric stability and ground effects by introducing a logarithmic relationship between the wake expansion coefficient and turbulence intensity. Validation results reveal the superior prediction accuracy of the proposed model compared to typical engineering wake models, with root mean square errors of wake wind speed predictions ranging from 0.04 to 0.063. The proposed model offers significant potential for optimizing wind farm layouts and enhancing overall wind energy production efficiency. Full article

(This article belongs to the Special Issue Advances in Wind Turbines)

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28 pages, 759 KiB

Open AccessReview

New Zero-Carbon Wooden Building Concepts: A Review of Selected Criteria

by Agnieszka Starzyk, Kinga Rybak-Niedziółka, Aleksandra Nowysz, Janusz Marchwiński, Alicja Kozarzewska, Joanna Koszewska, Anna Piętocha, Polina Vietrova, Przemysław Łacek, Mikołaj Donderewicz, Karol Langie, Katarzyna Walasek, Karol Zawada, Ivanna Voronkova, Barbara Francke and Anna Podlasek

Energies 2024, 17(17), 4502; https://doi.org/10.3390/en17174502 - 8 Sep 2024

Abstract

A Carbon Footprint (CF) is defined as the total emissions of greenhouse gases, primarily carbon dioxide, methane, and nitrous oxide, and is a specific type of Environmental Footprint that measures human impact on the environment. Carbon dioxide emissions are a major contributor to [...] Read more.

A Carbon Footprint (CF) is defined as the total emissions of greenhouse gases, primarily carbon dioxide, methane, and nitrous oxide, and is a specific type of Environmental Footprint that measures human impact on the environment. Carbon dioxide emissions are a major contributor to anthropogenic greenhouse gases driving climate change. Wood, as a renewable and ecological material, has relatively low carbon emissions. The study aimed to review and analyze the criteria influencing the feasibility of constructing modern zero-carbon wooden buildings. The review was conducted in two phases: (i) a literature review and (ii) an assessment of existing buildings. The preliminary research led to (i) narrowing the focus to the years 2020–2024 and (ii) identifying key criteria for analysis: sustainable material sourcing, carbon sequestration, energy efficiency, life cycle assessment (LCA), and innovative construction practices. The study’s findings indicate that all these criteria play a vital role in the design and construction of new zero-carbon wooden buildings. They highlight the significant potential of wood as a renewable material in achieving zero-carbon buildings (ZCBs), positioning it as a compelling alternative to traditional construction materials. However, the research also underscores that despite wood’s numerous potential benefits, its implementation in ZCBs faces several challenges, including social, regulatory, and financial barriers. Full article

(This article belongs to the Special Issue Solutions towards Zero Carbon Buildings)

22 pages, 1057 KiB

Open AccessReview

Impact of Artificial Intelligence on the Planning and Operation of Distributed Energy Systems in Smart Grids

by Paul Arévalo and Francisco Jurado

Energies 2024, 17(17), 4501; https://doi.org/10.3390/en17174501 - 8 Sep 2024

Abstract

This review paper thoroughly explores the impact of artificial intelligence on the planning and operation of distributed energy systems in smart grids. With the rapid advancement of artificial intelligence techniques such as machine learning, optimization, and cognitive computing, new opportunities are emerging to [...] Read more.

This review paper thoroughly explores the impact of artificial intelligence on the planning and operation of distributed energy systems in smart grids. With the rapid advancement of artificial intelligence techniques such as machine learning, optimization, and cognitive computing, new opportunities are emerging to enhance the efficiency and reliability of electrical grids. From demand and generation prediction to energy flow optimization and load management, artificial intelligence is playing a pivotal role in the transformation of energy infrastructure. This paper delves deeply into the latest advancements in specific artificial intelligence applications within the context of distributed energy systems, including the coordination of distributed energy resources, the integration of intermittent renewable energies, and the enhancement of demand response. Furthermore, it discusses the technical, economic, and regulatory challenges associated with the implementation of artificial intelligence-based solutions, as well as the ethical considerations related to automation and autonomous decision-making in the energy sector. This comprehensive analysis provides a detailed insight into how artificial intelligence is reshaping the planning and operation of smart grids and highlights future research and development areas that are crucial for achieving a more efficient, sustainable, and resilient electrical system. Full article

(This article belongs to the Special Issue Planning and Operation of Distributed Energy Resources in Smart Grids II)

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20 pages, 834 KiB

Open AccessArticle

Towards Energy Equity: Understanding and Addressing Multifaceted Energy Inequality

by Lina Volodzkiene and Dalia Streimikiene

Energies 2024, 17(17), 4500; https://doi.org/10.3390/en17174500 - 8 Sep 2024

Abstract

Given the pressing necessity to mitigate the consequences of climate change, it is of the utmost importance to establish a carbon-neutral society. Nevertheless, sustainability is significantly impeded by energy inequality. It is the term used to describe the unequal distribution, access, and utilization [...] Read more.

Given the pressing necessity to mitigate the consequences of climate change, it is of the utmost importance to establish a carbon-neutral society. Nevertheless, sustainability is significantly impeded by energy inequality. It is the term used to describe the unequal distribution, access, and utilization of energy resources among demographic groups, which has been further exacerbated by the pandemic and geopolitical tensions. This research aims to conceptualize and quantify energy inequality in Lithuania and compare it with EU data in order to bolster the ambitious objective of a climate-neutral Europe by 2050. This article elucidates the intricacy of energy inequality by utilizing a Lithuanian population survey and a literature review, which are supplemented by an EU macroeconomic analysis. The findings underline the necessity of locally tailored solutions and underscore the significant disparities in energy access between Lithuanian regions and demographic groups. Targeted policy measures are necessary to overcome economic, technological, and socio-political obstacles that impede progress toward a climate-neutral society. The necessity of a multidimensional approach and global cooperation is underscored by a comparative analysis of EU statistics, which reveals variable progress in addressing energy inequality. Theis research is a pertinent contribution to the discourse on sustainability and social justice, and it offers policy-makers, practitioners, and stakeholders guidance for a more inclusive and sustainable energy future. Full article

(This article belongs to the Special Issue New and Future Progress for Low-Carbon Energy Policy)

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