Energies

32 pages, 4439 KiB

Open AccessArticle

Developing an Optimized Energy-Efficient Sustainable Building Design Model in an Arid and Semi-Arid Region: A Genetic Algorithm Approach

by Ahmad Walid Ayoobi and Mehmet Inceoğlu

Energies 2024, 17(23), 6095; https://doi.org/10.3390/en17236095 (registering DOI) - 3 Dec 2024

Abstract

The building sector is a major contributor to resource consumption, energy use, and greenhouse gas emissions. Sustainable architecture offers a solution, leveraging Building Energy Modeling (BEM) for early-stage design optimization. This study explores the use of genetic algorithms for optimizing sustainable design strategies [...] Read more.

The building sector is a major contributor to resource consumption, energy use, and greenhouse gas emissions. Sustainable architecture offers a solution, leveraging Building Energy Modeling (BEM) for early-stage design optimization. This study explores the use of genetic algorithms for optimizing sustainable design strategies holistically. A comprehensive analysis and optimization model was developed using genetic algorithms to individually optimize various sustainable strategies. The optimized strategies were then applied to a pre-existing building in Kabul City, a region facing significant environmental challenges. To enhance accuracy, this study integrated energy simulations with Computational Fluid Dynamics (CFD). This research combines genetic algorithms with energy simulation and CFD analysis to optimize building design for a specific climate. Furthermore, it validates the optimized strategies through a real-world case study building. Optimizing the Window-to-Wall Ratio (WWR) and shading devices based on solar exposure significantly improved the building’s energy performance. South (S)-facing single windows and specific combinations of opposing and adjacent windows emerged as optimal configurations. The strategic optimization of building component materials led to substantial energy savings: a 58.6% reduction in window energy loss, 78.3% in wall loss, and 69.5% in roof loss. Additionally, the optimized pre-existing building achieved a 48.1% reduction in cooling demand, a 97.5% reduction in heating demand, and an overall energy reduction of 84.4%. Improved natural ventilation and controlled solar gain led to a 72.2% reduction in peak-month CO₂ emissions. While this study focused on applicable passive design strategies, the integration of advanced technologies like Phase Change Materials (PCMs), kinetic shading devices, and renewable energy systems can further improve building performance and contribute to achieving net-zero buildings. Full article

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

31 pages, 1136 KiB

Open AccessReview

A Comprehensive Review of Biogeochemical Modeling of Underground Hydrogen Storage: A Step Forward in Achieving a Multi-Scale Approach

by Nicolò Santi Vasile

Energies 2024, 17(23), 6094; https://doi.org/10.3390/en17236094 (registering DOI) - 3 Dec 2024

Abstract

This paper presents an in-depth investigation of the biogeochemical modeling approaches applied to underground hydrogen storage. It delves into the intricate dynamics of hydrogen in the subsurface, focusing on small (pore-lab scale) and reservoir-scale models, highlighting the importance of capturing microbial, geochemical, and [...] Read more.

This paper presents an in-depth investigation of the biogeochemical modeling approaches applied to underground hydrogen storage. It delves into the intricate dynamics of hydrogen in the subsurface, focusing on small (pore-lab scale) and reservoir-scale models, highlighting the importance of capturing microbial, geochemical, and fluid flow dynamic interactions in porous media to simulate storage performance accurately. Small-scale models offer detailed insights into localized phenomena, such as microbial hydrogen consumption and mineral reactions, and can be verified and calibrated against laboratory data. Conversely, large-scale models are essential to assess the feasibility of a project and forecast the storage performance, but cannot be proven by real data yet. This work addresses the challenge of transitioning from fine-scale to reservoir models, integrating spatial heterogeneity and long-term dynamics while retaining biogeochemical complexity. Through the use of several simulation tools, like PHREEQC, Comsol, DuMuX, Eclipse, CMG-GEM, and others, this study explores how modeling approaches are evolving to incorporate multiphysics processes and biochemical feedback loops, which are essential for predicting hydrogen retention, flow, and potential risks. The findings highlight the strengths and limitations of current modeling techniques and suggest a workflow for exploiting at best existing modeling capabilities and developing reservoir models to support hydrogen storage appraisal and management. Full article

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

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10 pages, 875 KiB

Open AccessArticle

The Conversion of Ethanol to Syngas by Partial Oxidation in a Non-Premixed Moving Bed Reactor

by Sergei Dorofeenko, Dmitry Podlesniy, Eugene Polianczyk, Marina Salganskaya, Maxim Tsvetkov, Leonid Yanovsky and Andrey Zaichenko

Energies 2024, 17(23), 6093; https://doi.org/10.3390/en17236093 (registering DOI) - 3 Dec 2024

Abstract

An experimental investigation into the conversion of ethanol to syngas by partial oxidation in a non-premixed counterflow moving bed filtration combustion reactor was carried out. Regimes of conversion depending on the mass flow rates of fuel and air (separate feeding), as well as [...] Read more.

An experimental investigation into the conversion of ethanol to syngas by partial oxidation in a non-premixed counterflow moving bed filtration combustion reactor was carried out. Regimes of conversion depending on the mass flow rates of fuel and air (separate feeding), as well as a granular solid heat carrier, were studied. Depending on the mass flow rate of the heat carrier, two combustion modes were realized—reaction trailing and intermediate—with different temperature patterns in the gas preheating, combustion, and cooling zones along the reactor. The product gas composition is far from the predictions of the equilibrium model; it contains substation fractions of methane and ethylene. Combustion temperature and conversion are limited by the relatively high level of heat loss from the laboratory-scale reactor. The effect of the heat loss can be reduced by enhancing the absolute flow rate of the reactants. Full article

(This article belongs to the Section I2: Energy and Combustion Science)

15 pages, 5762 KiB

Open AccessArticle

Experimental Study on the Alternate Oil Displacement Mechanism of CO₂ and Modified Water in Low-Permeability Oil Layers

by Shupei Zhao, Meilong Fu, Jun Chen, Zhaoxing Li, Jiayi Lin, Shuo Zhang and Pengju Wang

Energies 2024, 17(23), 6092; https://doi.org/10.3390/en17236092 (registering DOI) - 3 Dec 2024

Abstract

Alternating carbon dioxide and water flooding can not only seal greenhouse gases, but also combine the advantages of water flooding and carbon dioxide flooding, and can well control mobility and stabilize the displacement front, thereby greatly improving the macro-replacing efficiency. In order to [...] Read more.

Alternating carbon dioxide and water flooding can not only seal greenhouse gases, but also combine the advantages of water flooding and carbon dioxide flooding, and can well control mobility and stabilize the displacement front, thereby greatly improving the macro-replacing efficiency. In order to further improve the development effect of water–carbon dioxide alternating flooding, this paper, based on sufficient collection of the literature, research, and analysis, pre-uses modified water instead of water, and deeply explores and studies the impact of modified water–carbon dioxide alternating flooding on the improvement of development effect and the mechanism of enhancing oil recovery in low-permeability reservoirs. The main work completed is as follows: (1) A comparative experiment of multiple groups of sand-filled tubes with different displacement media, modified water concentrations, and injection plug sizes was conducted under the conditions of simulating reservoir formation temperature of 70 °C and formation pressure of 18 MPa, and the optimal scheme and injection parameters of alternating modified water and carbon dioxide flooding were rationally selected. The results show that the alternating flooding of modified water and carbon dioxide in low-permeability reservoirs can significantly improve the development effect. The optimal injection parameters are a formulation concentration of 0.3% and an injection method of alternating a 0.1 PV slug injection of carbon dioxide and modified water. (2) Using Berea cores instead of sand-fill tubes, a comparative experiment of alternating oil displacement using carbon dioxide and modified water was carried out under the same experimental conditions. Nuclear magnetic resonance measurements were performed on five of the cores to analyze the microscopic oil displacement mechanisms of different displacement media. The results show the following: nuclear magnetic resonance testing shows that carbon dioxide displacement can greatly improve the oil recovery efficiency in tiny pores (about 47.43%); alternating injection can further improve the oil recovery efficiency in tiny pores (about 70.6%); and modified water can improve the oil recovery efficiency in larger pores (about 56.47%). Full article

(This article belongs to the Section H: Geo-Energy)

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47 pages, 7868 KiB

Open AccessArticle

Analysis of the Selected Design Changes in a Wheel Hub Motor Electromagnetic Circuit on Motor Operating Parameters While Car Driving

by Piotr Dukalski and Roman Krok

Energies 2024, 17(23), 6091; https://doi.org/10.3390/en17236091 (registering DOI) - 3 Dec 2024

Abstract

The drive system of an electric car must meet road requirements related to overcoming obstacles and driving dynamics depending on the class and purpose of the vehicle. The driving dynamics of modern cars as well as size and weight limitations mean that wheel [...] Read more.

The drive system of an electric car must meet road requirements related to overcoming obstacles and driving dynamics depending on the class and purpose of the vehicle. The driving dynamics of modern cars as well as size and weight limitations mean that wheel hub motors operate with relatively high current density and high power supply frequency, which may generate significant power losses in the windings and permanent magnets and increase their operating temperature. Designers of this type of motor often face the need to minimize the motor’s weight, as it constitutes the unsprung mass of the vehicle. Another limitation for motor designers is the motor dimensions, which are limited by the dimensions of the rim, the arrangement of suspension elements and the braking system. The article presents two directions in the design of wheel hub motors. The first one involves minimizing the length of the stator magnetic core, which allows for shortening of the axial dimension and mass of the motor but involves increasing the thermal load and the need for deeper de-excitation. The second one involves increasing the number of pairs of magnetic poles, which reduces the mass, increases the internal diameter of the motor and shortens the construction of the fronts, but is associated with an increase in the motor operating frequency and increased power losses. Additionally, increasing the number of pairs of magnetic poles is often associated with reducing the number of slots per pole and the phase for technological reasons, which in turn leads to a greater share of spatial harmonics of the magnetomotive force in the air gap and may lead to the generation of higher power losses and higher operating temperatures of permanent magnets. The analysis is based on a simulation of the motor operation, modeled on the basis of laboratory tests of the prototype, while the car is driving in various driving cycles. Full article

(This article belongs to the Special Issue Energy, Electrical and Power Engineering: 3rd Edition)

25 pages, 8620 KiB

Open AccessArticle

Revealing the NO Formation Kinetics for NH₃/CH₄ Blends Under Dual-Flame and Premixed Swirl Flame Configurations

by Siqi Wang, Cheng Tung Chong, Soroush Sheykhbaglou, Jo-Han Ng, Bo Tian and Agustin Valera-Medina

Energies 2024, 17(23), 6090; https://doi.org/10.3390/en17236090 (registering DOI) - 3 Dec 2024

Abstract

Ammonia stands out as a promising zero-carbon fuel and an efficient hydrogen carrier, offering great promise for industrial applications in gas turbines and boilers. However, different combustion modes significantly influence the flame structure and combustion characteristics of ammonia. In this study, two distinct [...] Read more.

Ammonia stands out as a promising zero-carbon fuel and an efficient hydrogen carrier, offering great promise for industrial applications in gas turbines and boilers. However, different combustion modes significantly influence the flame structure and combustion characteristics of ammonia. In this study, two distinct fuel injection strategies were employed in a model combustor: ammonia and methane, under fully premixed and dual-flame combustion modes. Numerical simulations were performed to analyze the flame structure, velocity fields, and temperature distribution, complemented by planar flow field, flame OH* chemiluminescence, and NO emission measurements. Findings reveal that with an increasing NH₃ ratio, the flame front becomes more elongated with more pronounced temperature fluctuations at the swirler exit. Particularly, at 50% NH₃, a significant reduction in flame temperature is observed, notably at a height of 30 mm from the burner. For dual flames, the reaction NH₂ + O ↔ HNO + H was less significant compared to its effect in premixed flames, whereas the H + O₂ ↔ O + OH reaction demonstrated the highest sensitivity coefficient. An increase in the NH₃ ratio correspondingly led to a reduction in NO consumption reaction rates, heightening the sensitivity coefficient for NO inhibition, and providing critical insights into ammonia combustion optimization. Full article

(This article belongs to the Special Issue New Research in Advanced Combustion Technologies for Low-Carbon Emissions)

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16 pages, 1998 KiB

Open AccessArticle

Modelling of Biomass Gasification Through Quasi-Equilibrium Process Simulation and Artificial Neural Networks

by Vera Marcantonio, Marcello De Falco, Luisa Di Paola and Mauro Capocelli

Energies 2024, 17(23), 6089; https://doi.org/10.3390/en17236089 (registering DOI) - 3 Dec 2024

Abstract

In the past two decades, advancements in thermochemical technologies have improved biomass gasification for distributed power generation, enhancing efficiency, scalability, and emission control. This study aims to optimize syngas production from biomass gasification by comparing two computational models: a quasi-equilibrium thermodynamic model implemented [...] Read more.

In the past two decades, advancements in thermochemical technologies have improved biomass gasification for distributed power generation, enhancing efficiency, scalability, and emission control. This study aims to optimize syngas production from biomass gasification by comparing two computational models: a quasi-equilibrium thermodynamic model implemented in Aspen Plus and an artificial neural network (ANN) model. Operating at 850 °C with varying steam-to-biomass (S/B) ratios, both models were validated against experimental data. Results show that hydrogen concentration in syngas increased from 19.96% to 43.28% as the S/B ratio rose from 0.25 to 0.5, while carbon monoxide concentration decreased from 24.6% to 19.1%, consistent with the water–gas shift reaction. The ANN model provided rapid predictions, showing a mean absolute error of 3% for hydrogen and 2% for carbon monoxide compared to experimental data, though it lacks thermodynamic constraints. Conversely, the Aspen Plus model ensures mass and energy balance compliance, achieving a cold gas efficiency of 95% at an S/B ratio of 0.5. A Multivariate Statistical Analysis (MVA) further clarified correlations between input and output variables, validating model reliability. This combined modelling approach reduces experimental costs, enhances gasification process control and offers practical insights for improving syngas yield and composition. Full article

(This article belongs to the Special Issue Going Carbon Neutral and Carbon Negative through Thermochemical Conversion of Biomass)

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11 pages, 5956 KiB

Open AccessArticle

A Study on Wind Collection Effect of Vertical Axis Windmills

by Tadashi Hosoe and Kazuto Yukita

Energies 2024, 17(23), 6088; https://doi.org/10.3390/en17236088 (registering DOI) - 3 Dec 2024

Abstract

In recent years, global warming caused by greenhouse gasses such as carbon dioxide has become a concern. This has resulted in increased focus on environmentally friendly power systems. Consequently, renewable energy power generation methods, such as wind and solar power generation, have attracted [...] Read more.

In recent years, global warming caused by greenhouse gasses such as carbon dioxide has become a concern. This has resulted in increased focus on environmentally friendly power systems. Consequently, renewable energy power generation methods, such as wind and solar power generation, have attracted attention. Wind power generation is expected to significantly increase in the future. However, in many inland areas in Japan, the average wind speed remains 6 m/s or less. In this study, we proposed the introduction of winglets and wind collectors (used in aircraft wings) into straight-wing vertical-axis wind turbines to improve their power generation efficiency. Field tests were conducted to confirm the effectiveness of the proposed method. Using winglets and wind collectors, the wind turbine rotation speed was increased at low wind speeds, which facilitated the generation of power. Moreover, it was confirmed that a wind turbine equipped with the proposed winglets and wind collectors could capture wind without its dispersal as it passed through the turbine. Full article

(This article belongs to the Special Issue Vertical Axis Wind Turbines: Current Technologies and Future Trends)

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25 pages, 1106 KiB

Open AccessArticle

Hyper-FDB-INFO Algorithm for Optimal Placement and Sizing of FACTS Devices in Wind Power-Integrated Optimal Power Flow Problem

by Bekir Emre Altun, Enes Kaymaz, Mustafa Dursun and Ugur Guvenc

Energies 2024, 17(23), 6087; https://doi.org/10.3390/en17236087 (registering DOI) - 3 Dec 2024

Abstract

In this study, firstly, the balance between the exploration and exploitation capabilities of the weighted mean of vectors (INFO) algorithm was developed using the fitness–distance balance (FDB) method. Then, the FDB-INFO algorithm was developed with a hyper-heuristic method to create the beginning optimal [...] Read more.

In this study, firstly, the balance between the exploration and exploitation capabilities of the weighted mean of vectors (INFO) algorithm was developed using the fitness–distance balance (FDB) method. Then, the FDB-INFO algorithm was developed with a hyper-heuristic method to create the beginning optimal population by using Linear Population Reduction Success History-based Adaptive Differential Evolution (LSHADE) and a novel Hyper-FDB-INFO algorithm was presented. Finally, the developed Hyper-FDB-INFO algorithm was applied to solve the optimal placement and sizing of FACTS devices for the optimal power flow (OPF) problem incorporating wind energy sources. Moreover, determining the placement and sizing of FACTS devices is an additional problem to minimize the total cost of generation and reducing the power losses of the power system. The experimental results showed that the Hyper-FDB-INFO algorithm is a more effective solver than the SHADE-SF, INFO, FDB-INFO and Hyper-INFO algorithms for wind power and FACTS devices integrating the OPF problem. Full article

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

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37 pages, 7462 KiB

Open AccessArticle

A Study on Electric Vehicle Footprint in South Africa

by Oluwafemi Emmanuel Oni and Omowunmi Mary Longe

Energies 2024, 17(23), 6086; https://doi.org/10.3390/en17236086 (registering DOI) - 3 Dec 2024

Abstract

There has been a progressive global increase in the usage of electric vehicles in this dispensation. This is mostly due to the need to decarbonise the transport sector and mitigate the concerns of climate change and depleting oil reserves of which South Africa [...] Read more.

There has been a progressive global increase in the usage of electric vehicles in this dispensation. This is mostly due to the need to decarbonise the transport sector and mitigate the concerns of climate change and depleting oil reserves of which South Africa is not an exception. In fact, South Africa is the country with the highest CO₂ emissions in Africa and can reduce its carbon footprint by embracing green mobility. Compared to the internal combustion engine (ICE) market, the electric vehicle (EV) market in South Africa is still in its early stages, with limited local production and usage since its introduction to the country’s automotive sector in 2013. Therefore, in this study, the usage of EVs in South Africa, along with adoption rates and challenges were carried out to make a stronger case that would offer a better pathway for increased EV adoption in the country. It has been discovered that the slow adoption rate of EVs is due to factors such as EV procurement, ownership costs, vehicle parts, safety issues, battery technology, tax and import duties, load shedding, and availability of charging stations. This paper also provides insights into government policies, funding, and other efforts that can support EV adoption in the country through the analyses of primary and secondary data. The proposed strategies include the introduction of tax rebates on imported EVs, local production of EVs and their vehicle parts, retrofitting ICE vehicles to EVs, and science-informed strategies to transition from ICE to electric vehicles. Furthermore, more renewable energy grid integration and renewable energy-powered EV charging stations would also provide support for the energy required to power EVs even during load shedding. Preliminary findings from the survey also suggest that the local production of EV components and government-sponsored training programmes on various EV skills are crucial for increasing the adoption rate of EVs in the country. Full article

(This article belongs to the Special Issue Energy, Electrical and Power Engineering: 3rd Edition)

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18 pages, 1837 KiB

Open AccessArticle

Gasification of Chlorella vulgaris for Syngas Production and Energy Generation Through Gas Turbine

by Lucrezia Scopel and Vera Marcantonio

Energies 2024, 17(23), 6085; https://doi.org/10.3390/en17236085 (registering DOI) - 3 Dec 2024

Abstract

The increasing need for sustainable energy sources has driven research toward innovative solutions, including biomass gasification for syngas production, with applications in the chemical industry and energy generation. This study explores the application of Chlorella vulgaris in the gasification process to produce syngas [...] Read more.

The increasing need for sustainable energy sources has driven research toward innovative solutions, including biomass gasification for syngas production, with applications in the chemical industry and energy generation. This study explores the application of Chlorella vulgaris in the gasification process to produce syngas intended for gas turbine operation. Using Aspen Plus V11 (academic version) simulations, the study evaluates optimal process conditions and syngas yields, focusing on operational parameters such as the S/B ratio and gasifier temperature. Results show that a higher S/B ratio increases H₂ and CO₂ concentrations while reducing CO and CH₄, with final syngas composition in dry conditions reaching 0.42 CO, 0.52 H₂, and 0.036 H₂O. Contaminants like H₂S and HCl were effectively reduced below critical thresholds, with H₂S levels under 20 ppm and HCl under 1 ppm to meet GT requirements. The system achieved a cold gas efficiency of 55% and an overall turbine cycle efficiency of 25%, with CO₂ emissions of 0.198 kg per kWh produced. In conclusion, the gasification of C. vulgaris offers a promising and sustainable solution for syngas production and energy generation, with reduced environmental impacts. However, economic feasibility and certain technical challenges will require further advancements to fully realize this technology’s potential. Full article

(This article belongs to the Special Issue New Trends in Biofuels and Bioenergy for Sustainable Development II)

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52 pages, 1083 KiB

Open AccessReview

A Review of Renewable Energy Technologies in Municipal Wastewater Treatment Plants (WWTPs)

by Derick Lima, Li Li and Gregory Appleby

Energies 2024, 17(23), 6084; https://doi.org/10.3390/en17236084 (registering DOI) - 3 Dec 2024

Abstract

The global trend towards sustainable development has included the implementation of renewable energy recovery technologies in municipal wastewater treatment plants (WWTPs). WWTPs are energy-intensive consumers with high operational costs and often are dependent from the electricity supplied by the main grid. In this [...] Read more.

The global trend towards sustainable development has included the implementation of renewable energy recovery technologies in municipal wastewater treatment plants (WWTPs). WWTPs are energy-intensive consumers with high operational costs and often are dependent from the electricity supplied by the main grid. In this context, the integration of renewable energy recovery technologies into WWTPs emerges as an environment-friendly strategy that enhances energy efficiency, sustainability and reduces energy operating costs. Renewable energy recovery technologies, such as anaerobic digestion, microbial fuel cells, and sludge gasification, can offer multiple benefits for a WWTP. Anaerobic digestion is the most widely adopted technology due to its efficiency in treating sewage sludge and its ability to generate biogas—a valuable renewable energy source. The use of biogas can offset the energy demands of the wastewater treatment process, potentially leading to energy self-sufficiency for the WWTP and a reduction in reliance from the electricity supply from the main grid. Similarly, microbial fuel cells harness the electrochemical activity of bacteria to produce electricity directly from wastewater, presenting a promising alternative for low-energy processes for sustainable power generation. Gasification of sewage sludge is a promising technology for managing municipal sewage sludge, offering key advantages, especially by generating a renewable energy production (sludge is converted into syngas), which further decreases the sludge volume and operating costs with sludge management, helps to eliminate odour associated with sewage sludge, and effectively destroys the pathogens. Adoption of renewable energy sources in WWTPs can be a great alternative to overcome issues of high operating costs and high dependency of electricity from the main grid, but their successful integration requires addressing challenges such as technological maturity, economic feasibility, and regulatory frameworks. This study aims to comprehensively explore the significance of different renewable energy technologies in municipal WWTPs, including site-specific and non-site-specific sources, evaluating their impact on sustainability, energy efficiency, and overall operational effectiveness. This review also highlights some studies in which different strategies were adopted to generate extra revenue and/or reduce operating costs. Through a comprehensive review of current practices and emerging technologies, this study underscores the transformative potential of these innovations in advancing low-emission wastewater management. Full article

(This article belongs to the Special Issue Advances in Wastewater Treatment 2024)

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13 pages, 5312 KiB

Open AccessArticle

The Observation of Performance Trends by Numerical Simulation with Different Parameters in a Nonlinear Reversible Solid Oxide Cell System

by Jai-Houng Leu, Ay Su, Shun-Chi Kuo and Kuang-Chung Chen

Energies 2024, 17(23), 6083; https://doi.org/10.3390/en17236083 (registering DOI) - 3 Dec 2024

Abstract

The reversible solid oxide cell model is established by COMSOL Multiphysics^® (version 5.4) software under multi-physics coupling. According to the governing equation, the simulations were conducted based on the same parameters for many control groups numerically. At the same time, a comparison [...] Read more.

The reversible solid oxide cell model is established by COMSOL Multiphysics^® (version 5.4) software under multi-physics coupling. According to the governing equation, the simulations were conducted based on the same parameters for many control groups numerically. At the same time, a comparison of these results was involved. For the air electrode in SOFC mode, the performance of the fuel cell will increase with the increase in the porosity. For the fuel electrode in SOFC mode, the increase is much greater than the impact of the porosity. The design parameters compared in this simulation are used to simulate and analyze and predict fuel cell performance under different conditions. The design parameters related to the electrode microstructure are defined in this model as: porosity (electrode porosity), pore size (electrode internal average pore size), and permeability (electrode internal permeability). Full article

(This article belongs to the Special Issue Modeling and Simulation of Solid Oxide Cells)

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18 pages, 3464 KiB

Open AccessReview

Advancements and Future Prospects in the Hydraulic Fracturing of Geothermal Reservoirs

by Kun Shan, Qinqin Zou, Chongshuai Li and Ziwang Yu

Energies 2024, 17(23), 6082; https://doi.org/10.3390/en17236082 (registering DOI) - 3 Dec 2024

Abstract

Reservoir reconstruction is a critical challenge in many significant underground energy projects, such as enhanced geothermal systems, oil shale extraction, and shale gas development. Effectively reconstructing geothermal reservoirs can significantly enhance the exploitation and production capacity of geothermal resources. However, this process requires [...] Read more.

Reservoir reconstruction is a critical challenge in many significant underground energy projects, such as enhanced geothermal systems, oil shale extraction, and shale gas development. Effectively reconstructing geothermal reservoirs can significantly enhance the exploitation and production capacity of geothermal resources. However, this process requires stringent technical standards and varies with different geological conditions across regions, necessitating tailored reconstruction strategies. This review offers a comprehensive examination of hydraulic fracturing within geothermal reservoirs, covering the geological and physical characteristics inherent to these systems, the effects of injection methods and thermal stimulation on hydraulic fracturing processes, and the assessment and optimization of transformation effects, as well as environmental implications and risk management considerations. We explore the influence of various injection modes on hydraulic fracturing dynamics. Moreover, we compare the differences between hydraulic fracture propagation with and without thermal effects. Additionally, we summarize optimization strategies for reservoir reconstruction. Finally, we discuss several challenges and potential future directions for development, offering insights into possible advancements. This review is of substantial significance for both research and commercial applications related to hydraulic fracturing in geothermal reservoirs. Full article

(This article belongs to the Special Issue Advances in the Development of Geoenergy: 2nd Edition)

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16 pages, 13187 KiB

Open AccessArticle

NMR-Based Investigation of Pore–Fracture Structure Heterogeneity in Deep Coals of Different Macrolithotypes in the Daning-Jixian Block, Ordos Basin

by Wei Zhang, Zheng Zhang, Liheng Bian, Rui Shi, Hewei Zhang and Jian Shen

Energies 2024, 17(23), 6081; https://doi.org/10.3390/en17236081 (registering DOI) - 3 Dec 2024

Abstract

Deep coalbed methane (CBM) demonstrates significant production potential, and a fervent exploration and development boom is currently underway in China. The permeability of coal reservoirs is heavily influenced by pore–fracture structure heterogeneity. Some researches have been conducted on deep coals’ pore–fracture structure; however, [...] Read more.

Deep coalbed methane (CBM) demonstrates significant production potential, and a fervent exploration and development boom is currently underway in China. The permeability of coal reservoirs is heavily influenced by pore–fracture structure heterogeneity. Some researches have been conducted on deep coals’ pore–fracture structure; however, these studies mostly consider coal as a homogeneous material, neglecting the heterogeneity of the macrolithotypes within the coal. In this study, 33 deep coals with burial depths of more than 2000 m were obtained from the Daning-Jixian block of the Ordos Basin, covering all macrolithotypes: bright coal (BC), semi-bright coal (SBC), semi-dull coal (SDC), and dull coal (DC). These samples were subjected to three sets of NMR tests in dry, fully saturated, and irreducible water conditions, with the pore–fracture structure characteristics being analyzed. The results demonstrate that the sampled deep coals’ pore–fracture structure is highly heterogeneous, with transitional pores being dominant, followed by mesopores, “macropores and fractures”, and micropores. The NMR T_2C ranges from 0.61 to 2.44 ms, with an average of 1.19 ms; a higher T_2C value indicates more developed micropores. The ranges for producible water porosity (φ_pr) and producible water saturation (S_pr) are 0.31–7.24% (avg. 2.42%) and 6.97–71.47% (avg. 31.06%), respectively. Both of them exhibit a high positive correlation with the total volumes of “macropores and fractures” and mesopores. Compared to SDC and DC, the BC and SBC, especially the former, overall contain more “macropores and fractures” and mesopores, fewer transitional pores and micropores, and higher φ_pr and S_pr. These findings suggest that regions with abundant BC and SBC should be prioritized during deep CBM exploration and production due to the inherently superior permeability and gas extraction potential of BC and SBC, and these coals are likely to require less intensive stimulation to achieve higher recovery rates and could provide more sustainable gas production over time. Full article

(This article belongs to the Special Issue Exploration and Development of Unconventional Oil and Gas Resources: Latest Advances and Prospects: 2nd Edition)

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20 pages, 7581 KiB

Open AccessArticle

Kinematics Analysis and Oil Film Lubrication Characteristics in the Piston–Cylinder Interface of a Bent-Axis-Type Piston Motor

by Jinlin Yu and Xiaozhou Hu

Energies 2024, 17(23), 6080; https://doi.org/10.3390/en17236080 (registering DOI) - 3 Dec 2024

Abstract

Hydraulic piston motors are characterized by their excellent starting performance, high transmission torque, good sealing performance, compact design, and lightweight. These attributes make them highly applicable in fields such as construction machinery and marine applications. With the advancement of hydraulic transmission technology, higher [...] Read more.

Hydraulic piston motors are characterized by their excellent starting performance, high transmission torque, good sealing performance, compact design, and lightweight. These attributes make them highly applicable in fields such as construction machinery and marine applications. With the advancement of hydraulic transmission technology, higher performance requirements have been set for hydraulic motors. While extensive research has been conducted on hydraulic pumps, studies focusing on the performance of hydraulic motors remain relatively limited. Therefore, this paper is novel in that, based on the motion and force conditions of the piston, it differs from previous research on swashplate-type machinery by considering the complex structure of the bent-axis motor; it employs a micro finite element method to analyze the oil film characteristics at the piston–cylinder interface in a bent-axis piston motor, the structural changes in the piston assembly in the bent-axis motor are comprehensively considered, and a fluid–structure coupling model for the piston–cylinder interface is established. The leakage and viscous friction power loss equations for the piston–cylinder interface are derived. Simulation analyses are conducted using MATLAB R2016a to reveal the variation patterns of leakage and viscous friction power loss under different operating conditions and structural parameters, providing valuable insights for the operation analysis, energy loss evaluation, structural design optimization, and engineering applications of bent-axis piston motors. Full article

(This article belongs to the Section H: Geo-Energy)

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21 pages, 3083 KiB

Open AccessArticle

Control Strategy for Power Fluctuation Smoothing at Distribution Network Substations Considering Multiple Types of Adjustment Resources

by Shaobo Yang, Xuekai Hu, Liang Meng, Shiwei Xue, Hao Zhou, Fengming Shi and Siyang Liao

Energies 2024, 17(23), 6079; https://doi.org/10.3390/en17236079 (registering DOI) - 3 Dec 2024

Abstract

With the proposal of the dual carbon target, the distributed photovoltaic (PV) industry has rapidly developed in recent years. However, the randomness and volatility of photovoltaic energy can be transmitted to the main grid through distribution network substations, posing challenges to the stable [...] Read more.

With the proposal of the dual carbon target, the distributed photovoltaic (PV) industry has rapidly developed in recent years. However, the randomness and volatility of photovoltaic energy can be transmitted to the main grid through distribution network substations, posing challenges to the stable operation of the power system. Therefore, this paper considers tapping into the regulation potential of feeder loads on the distribution network side, as well as distributed energy storage and distributed PV resources, to enhance the grid’s control methods. A power fluctuation smoothing control strategy for substations in distribution networks, accounting for multiple types of regulation resources, is proposed. In the day-ahead stage, traditional voltage regulation devices such as the OLTC (on-load tap changer) and CB (circuit breaker) are pre-dispatched based on source–load forecasts, optimizing the fluctuation range of substation power and the number of device operations. This provides optimal substation power values for day-to-day optimization. During the intraday phase, fast regulation devices such as PV (photovoltaic), SVC (static var compensator), and energy storage systems are coordinated, and an optimization model is established with the goal of reducing power curtailment while closely tracking substation trends. This model quickly calculates the active power regulation and device operations of various adjustable resources, improving the economic efficiency of the distribution network system while achieving power fluctuation smoothing at the substation level. Finally, the feasibility and effectiveness of the power fluctuation smoothing control model are verified through simulations on an improved standard distribution system. Full article

(This article belongs to the Special Issue Advances in Power Distribution Systems)

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17 pages, 4860 KiB

Open AccessArticle

Comparative Analysis of the Carbon Footprint Value Resulting from the Selected Mode of Transport, Based on the Example of Transporting Neodymium Magnets

by Rafał Baron, Daniel Kowol, Piotr Matusiak, Paweł Friebe and Marcin Lutyński

Energies 2024, 17(23), 6078; https://doi.org/10.3390/en17236078 (registering DOI) - 3 Dec 2024

Abstract

The article presents a sensitivity analysis of the carbon footprint for different modes of transporting neodymium magnets over a selected route, in the context of their environmental impact and sustainable development. Neodymium magnets, widely used in modern technologies such as wind turbines, are [...] Read more.

The article presents a sensitivity analysis of the carbon footprint for different modes of transporting neodymium magnets over a selected route, in the context of their environmental impact and sustainable development. Neodymium magnets, widely used in modern technologies such as wind turbines, are essential for renewable energy sources, making the selection of environmentally optimal transportation crucial. The calculations included road, rail, inland waterway, and air transport, using available emission calculators, which allowed for an analysis using averaged emission indicators for each mode of transport. Additionally, a comparative analysis was conducted with the SimaPro program to verify the consistency and accuracy of the results. The findings indicated that rail transport, with access to low-emission infrastructure and a reduced carbon footprint per unit of mass, is the most efficient option for CO₂ emissions reduction, whereas air transport, despite its speed, generates the highest emissions per ton of cargo, making it the least environmentally friendly alternative. A t-test analysis was also conducted to statistically validate the results for each transportation option. Full article

(This article belongs to the Special Issue Green, Low-Carbon and Sustainable Development)

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16 pages, 9719 KiB

Open AccessArticle

Optimal Variable Frequency Soft Switching for Interleaved Grid Tied Inverters in Electric Vehicle Charging Applications

by Youssef A. Fahmy, Matthew Jahnes and Matthias Preindl

Energies 2024, 17(23), 6077; https://doi.org/10.3390/en17236077 (registering DOI) - 3 Dec 2024

Abstract

Synchronized variable frequency soft-switching is analyzed and implemented in a 3-phase bidirectional grid-tied inverter. The common-mode connected topology and control allow for independent analysis of a single phase leg before six are combined into two interleaved, 3-phase inverters. Effective operation is enabled by [...] Read more.

Synchronized variable frequency soft-switching is analyzed and implemented in a 3-phase bidirectional grid-tied inverter. The common-mode connected topology and control allow for independent analysis of a single phase leg before six are combined into two interleaved, 3-phase inverters. Effective operation is enabled by discretizing the variable switching frequencies before synchronizing them with a control signal. The resulting inverter can operate at any power factor at power levels up to 50 kVA while maintaining zero-voltage switching (ZVS) throughout the grid cycle. Formal conditions for soft-switching and methods for achieving ZVS while maintaining global synchronization are presented. These conditions are then verified in a simulation. Finally, results for different power factors with and without interleaving are demonstrated in a prototype that achieves >98.1% efficiency when converting all real power. Full article

(This article belongs to the Special Issue Novel Applications of Power Converters for Energy Storage and Grid Integration)

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