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Volume 19
Issue 11
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Energies, Volume 19, Issue 11 (June-1 2026) – 245 articles

Cover Story (view full-size image): High-sensitivity detection of DC partial discharge in HVDC equipment is challenging due to electrical noise and lack of a phase reference. While photon counting offers exceptional noise immunity, its use has been confined to AC. In this study, we develop a photon-counting platform to classify DC PD from three typical gas–solid defects. Successive inter-pulse time intervals were mapped into 2D heatmaps to visualize temporal characteristics. A Random Forest classifier, integrated with SHAP for feature reduction, achieved accuracies of 97.50% (positive polarity) and 99.17% (negative polarity). The model adaptively prioritized angular over radial features under space-charge-suppressed conditions. These results demonstrate a robust, less experience-dependent framework for identifying insulation defects in DC systems using time-domain photon counting. View this paper
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21 pages, 2399 KB  
Article
Research on Framework for and Strategies of Green Energy Consumption Based on Unsupervised Machine Learning
by Jun Lyu, Yu Shu and Shuo Wang
Energies 2026, 19(11), 2733; https://doi.org/10.3390/en19112733 - 5 Jun 2026
Viewed by 370
Abstract
Documentary videos on green energy consumption are widely distributed via platforms such as YouTube, yet the verbal framing strategies embedded in their subtitle transcripts remain systematically understudied. This study applies the Analysis of Topic Model Networks (ATMN)—an unsupervised machine learning approach combining LDA [...] Read more.
Documentary videos on green energy consumption are widely distributed via platforms such as YouTube, yet the verbal framing strategies embedded in their subtitle transcripts remain systematically understudied. This study applies the Analysis of Topic Model Networks (ATMN)—an unsupervised machine learning approach combining LDA topic modeling, semantic network analysis, and hierarchical clustering—to subtitle transcripts extracted from 60 YouTube green energy consumption documentaries. Three distinct framing communities are identified: (1) the Technological Supply Frame, which foregrounds zero-carbon resources, renewable generation, smart grid systems, and AI-enabled energy management as the technical foundation of decarbonization; (2) the Socioeconomic Transition Frame, the most thematically expansive, which positions the energy transition simultaneously as an economic opportunity, a behavioral imperative, and a systemic industrial transformation spanning green investment, end-use substitution, industrial decarbonization, and green mobility; and (3) the Ecological Governance Frame, which integrates ecological co-benefits with international climate commitments to construct the transition as a globally mandated planetary responsibility. Together, these frames reveal a richer and more multi-dimensional verbal framing landscape than previously documented in the green energy communication literature, extending beyond techno-optimism or environmentalism to encompass financial, governance, and behavioral dimensions within a single integrated corpus. The identified framing strategies offer actionable guidance for policymakers, energy enterprises, and media producers seeking to accelerate green energy consumption transition through targeted, evidence-based video communication. Full article
(This article belongs to the Special Issue Managing the Low-Carbon Energy Transformation: Strategies and Prospects for 2050)
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18 pages, 4743 KB  
Article
Low-Energy Pretreatment of Organic Waste Using a Vortex Layer Reactor: Effects on Biogas Production, Carbon Conversion, and Process Optimization
by Marcin Niemiec, Marcin Suder, Małgorzata Okręglicka, Monika Komorowska, Yurii Syromiatnykov, Jakub Sikora and Karolina Jakóbik
Energies 2026, 19(11), 2732; https://doi.org/10.3390/en19112732 - 5 Jun 2026
Viewed by 399
Abstract
The sustainable management of agri-food waste is a key challenge in the context of the circular economy and energy transition. Anaerobic digestion is an effective method for converting organic waste into renewable energy; however, its efficiency is often limited by substrate properties, such [...] Read more.
The sustainable management of agri-food waste is a key challenge in the context of the circular economy and energy transition. Anaerobic digestion is an effective method for converting organic waste into renewable energy; however, its efficiency is often limited by substrate properties, such as high lignin content, low biodegradability, and unfavorable C: N ratios. This study evaluates a low-energy pretreatment method based on a Vortex Layer Reactor (VLR, equivalent to the AVS-100 system) applied to slaughterhouse waste, swine manure, and spent mushroom substrate. The analysis included biogas yield, methane production, carbon conversion, process kinetics, and net energy efficiency. The results showed that pretreatment effectiveness depends on substrate type. No improvement was observed in slaughterhouse waste, with net energy efficiency decreasing by approximately 9%. In contrast, biogas yield increased by 14% for swine manure and 18% for spent mushroom substrate, with a maximum net energy gain of 17.6%. The process required only 2.16–3.6 kWh·Mg−1 (about 9 kWh·Mg−1 TS), significantly less than conventional methods. The findings indicate that pretreatment should be applied selectively, depending on substrate characteristics. This study supports decision-making in biogas plant management by integrating technological efficiency with energy and operational criteria. Full article
(This article belongs to the Special Issue New Challenges of Anaerobic Digestion for Bioproducts and Bioenergy Production)
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23 pages, 11818 KB  
Article
Predicted Thermoacoustic Flame Response at Megawatt Scale in a Near-Stoichiometric Atmospheric Industrial Furnace
by Jesse Hofsteenge and Jim Kok
Energies 2026, 19(11), 2731; https://doi.org/10.3390/en19112731 - 5 Jun 2026
Viewed by 303
Abstract
While gas-turbine combustors have received much research attention, the forced response of large atmospheric industrial flames is much less studied. To improve the understanding of thermoacoustic instabilities in industrial combustion systems, the forced response of a large natural-gas fired test furnace is computed [...] Read more.
While gas-turbine combustors have received much research attention, the forced response of large atmospheric industrial flames is much less studied. To improve the understanding of thermoacoustic instabilities in industrial combustion systems, the forced response of a large natural-gas fired test furnace is computed using Scale-Adaptive Simulations (SASs) with a Flamelet Generated Manifold model. Two test burner configurations are compared. One produces a partially premixed flame (case P) and the other a non-premixed flame. Furthermore, the non-premixed configuration is simulated at both a slightly rich (case N) and a slightly lean set point (case NL). The flame is forced by perturbing the airflow using a superposition of sine waves at four discrete frequencies. That way, the gain and phase of the Flame Transfer Function (FTF) are determined in three simulations for a total of 12 discrete frequencies between 10 and 230 Hz. The results show very different behaviour of the partially premixed and non-premixed configurations. Case P is simulated to be a compact flame, with a maximum FTF gain of one around 70–80 Hz and a quasi-steady limit of 0.7. Case N and NL are characterised by slightly lifted flames acting as low-pass filters that quickly drop off towards higher frequencies. While the phase shift in case P is linearly dependent on frequency and can be related to its flame length, the non-premixed cases have a sharp initial phase shift that levels off with increasing frequency as the gain reduces to zero. Importantly, a non-zero phase shift at 0 Hz is observed for case NL. The nature of the combustion dynamics is further explored by a Proper Orthogonal Decomposition (POD) analysis. The FTFs are applied to predict the thermoacoustic stability using an Acoustic Network Model (ANM). This model is able to reproduce the stability of the cases observed in experiments. The results presented in this study provide insight on the effect of mixing and stoichiometry on the stability of large industrial furnaces. Full article
(This article belongs to the Special Issue Applied Computational Fluid Dynamics in Energy Systems)
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36 pages, 5059 KB  
Article
Forecast-Driven Virtual Power Plant Dispatch for Hybrid Renewable Energy Systems: Reducing Grid Dependency Using LSTM Models
by Omaira Jajbhay, Mohamed F. Khan and Andrew G. Swanson
Energies 2026, 19(11), 2730; https://doi.org/10.3390/en19112730 - 5 Jun 2026
Viewed by 471
Abstract
This study presents a forecast-driven Advanced Forecasting Model (AFM) and Virtual Power Plant (VPP) framework for a hybrid renewable energy system comprising utility-scale solar PV, wind generation, and a Battery Energy Storage System. Long Short-Term Memory neural networks provide real-time short-term forecasts to [...] Read more.
This study presents a forecast-driven Advanced Forecasting Model (AFM) and Virtual Power Plant (VPP) framework for a hybrid renewable energy system comprising utility-scale solar PV, wind generation, and a Battery Energy Storage System. Long Short-Term Memory neural networks provide real-time short-term forecasts to dynamically schedule power flows based on battery state-of-charge, grid import limits, and system constraints. Solar irradiance forecasting achieved MAE = 10.674 W/m2, RMSE = 16.348 W/m2, and MAPE = 14.18%, while wind speed forecasting achieved MAE = 0.880 m/s, RMSE = 1.115 m/s, and MAPE = 22.01%. Two dispatch scenarios were evaluated over a 72 h window: a reactive baseline and the proposed AFM/VPP strategy. The AFM reduced total grid imports by 57.48% (1466.34 MWh to 623.47 MWh), increased renewable utilization, and minimized curtailment. Financial analysis indicates an accelerated break-even (Year 6 vs. Year 9), a higher net present value, and cumulative 20-year profits exceeding R26.01 billion despite marginally higher capital expenditure. Emissions analysis shows annual CO2 reductions from 123,680 t to 61,841 t, yielding 1.236 million tons of avoided emissions over 20 years. These results confirm that forecast-driven dispatch enhances operational efficiency, economic performance, and environmental sustainability, establishing a scalable approach for VPP operation in renewable-rich energy systems. Full article
(This article belongs to the Special Issue AI-Driven Sustainable Power Grids: Enhancing Cybersecurity, Operation, and Control of Conventional, Modern, and Renewable-Based Energy Systems—2nd Edition)
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19 pages, 2157 KB  
Article
FTimeDD: A Time–Frequency Collaborative Model for Multi-Energy Load Forecasting
by Zi Lin, Ziyi Wang, Tengyue Guo and Min Xia
Energies 2026, 19(11), 2729; https://doi.org/10.3390/en19112729 - 5 Jun 2026
Viewed by 339
Abstract
With the global energy transition, Integrated Energy Systems (IESs) improve efficiency by coordinating multiple energy sources, including electricity, cooling, and heating. Accurate load forecasting is essential for reliable energy system operation. However, multi-energy loads show complex coupling, non-stationarity, and long-term dependencies. These characteristics [...] Read more.
With the global energy transition, Integrated Energy Systems (IESs) improve efficiency by coordinating multiple energy sources, including electricity, cooling, and heating. Accurate load forecasting is essential for reliable energy system operation. However, multi-energy loads show complex coupling, non-stationarity, and long-term dependencies. These characteristics pose significant challenges to forecasting tasks. Existing methods have improved short-term forecasting accuracy, but still struggle to jointly capture long-term trends and local fluctuations. To address these issues, this paper proposes FTimeDD, a time–frequency collaborative model for multi-energy load forecasting in IESs. It adopts a dual-path decoupling architecture. The time-domain path separates trend and fluctuation components, while the frequency-domain path extracts dominant periodic features. The two paths are then fused to predict electricity, cooling, and heating loads. Experiments on the ASU Integrated Energy System dataset show that FTimeDD performs well across different forecasting horizons. Compared with the strongest baseline for each metric and horizon, FTimeDD reduces MAE, RMSE, and MAPE by 3.85%, 2.48%, and 1.91% on average, respectively. The method improves forecasting accuracy under the adopted experimental setting while maintaining a compact model scale and low computational cost. Full article
(This article belongs to the Special Issue Artificial Intelligence for Energy Forecasting)
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16 pages, 7107 KB  
Article
Influence of Ionomer Overcoating on the Interfacial Properties and Performance of Gas Diffusion Electrode-Based Proton Exchange Membrane Fuel Cells
by Ayon Karmakar, Mrittunjoy Sarker, Zabihollah Najafianashrafi, Joy Marie Mora, Nitul Kakati and Po-Ya Abel Chuang
Energies 2026, 19(11), 2728; https://doi.org/10.3390/en19112728 - 5 Jun 2026
Cited by 1 | Viewed by 405
Abstract
Membrane electrode assemblies (MEA) based on gas diffusion electrodes (GDEs) usually suffer from greater ohmic losses and proton transport resistances owing to poor contact at the membrane–catalyst layer (CL) interface. This affects the overall performance of the proton-exchange-membrane fuel cells (PEMFCs). To address [...] Read more.
Membrane electrode assemblies (MEA) based on gas diffusion electrodes (GDEs) usually suffer from greater ohmic losses and proton transport resistances owing to poor contact at the membrane–catalyst layer (CL) interface. This affects the overall performance of the proton-exchange-membrane fuel cells (PEMFCs). To address this, it is essential to strengthen the interface between the membrane and CL, especially at the cathode side. In this context, the present work is focused on engineering the membrane–CL interface by applying an optimized Nafion ionomer overcoat on top of a Mayer-rod-coated cathode-GDE, within an asymmetric MEA architecture. The role of the Nafion overcoat in improving the membrane–CL interface is inferred from morphological observations and in situ electrochemical characterizations. The electrochemical evaluation indicates the critical role of the ionomer overcoat on GDE, followed by the hot pressing during MEA fabrication, in improving the PEMFC performance. Furthermore, the surface characteristics of the overcoated GDEs have been characterized by profilometry and scanning electron microscopy. The findings suggest progressive smoothening of the CL surface with increasing ionomer overcoat concentration till 10 wt.% and further increase leads to crack generation. The polarization behavior of the overcoated (0–20 wt.%) GDE-MEAs identifies 10 wt.% as the best-performing sample among the discrete cases examined, corresponding to an ~4.8 μm ionomer overlayer (0.86 mg cm−2). This configuration exhibits the lowest ohmic resistance and improved proton and mass transport behavior, suggesting enhanced interfacial interaction based on HFR/EIS trends. In addition, the study of relative humidity (RH) transitions (100% RH → 40% RH) and polarization curves indicate superior performance of the 10 wt.%-overcoated GDE-MEA compared to the catalyst-coated membrane (CCM) type MEA under fully humidified conditions. This study manifests that interfacial engineering is highly effective in fabricating a high-performance GDE-based MEA for PEMFCs. Full article
(This article belongs to the Special Issue Research and Development of Key Materials and Devices for Fuel Cells)
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25 pages, 307 KB  
Article
Industrial Structure, Green Finance, and Energy Resilience Enhancement in China
by Qiuyao Fu
Energies 2026, 19(11), 2727; https://doi.org/10.3390/en19112727 - 5 Jun 2026
Viewed by 305
Abstract
Against the backdrop of global energy transition and multiple uncertainties, enhancing energy resilience has become a core priority for China’s pursuit of secure and sustainable development. Using Chinese provincial panel data from 2011 to 2019, this study applies a two-way fixed effects model, [...] Read more.
Against the backdrop of global energy transition and multiple uncertainties, enhancing energy resilience has become a core priority for China’s pursuit of secure and sustainable development. Using Chinese provincial panel data from 2011 to 2019, this study applies a two-way fixed effects model, mediation effect tests, and interaction term analysis to empirically investigate the relationship between industrial structure, green finance, and energy resilience. The main findings are as follows. First, the increases in gross regional product (GRP) and the added value of the secondary and tertiary sectors significantly enhance energy resilience. Second, heterogeneity analysis indicates that in regions with a high level of green finance, both GRP and the secondary sector’s added value exhibit stronger positive effects on energy resilience, whereas in regions with lower levels of green finance, the tertiary sector’s added value contributes more significantly to energy resilience improvement. In areas with high coal dependency, the secondary sector’s added value shows a significantly positive effect on energy resilience. Increases in industrial and construction industry added value significantly enhance energy resilience, suggesting that the expansion of the secondary industry contributes positively to the stability and resilience of the energy system. Third, the mechanism analysis shows that green finance contributes to energy resilience partly through the optimization of the energy consumption structure. Specifically, by effectively curbing coal consumption and, to a lesser extent, fuel oil production, green finance reduces the structural dependence of the economy on high-carbon energy. By contrast, channels such as electricity generation yield weaker and less robust evidence. These findings suggest that energy resilience is fundamentally shaped by the interplay of industrial structure, financial intermediation, and energy structure adjustment. Therefore, policy should shift from single instruments to integrated governance, synergizing industrial policy, green finance, and energy optimization to bolster energy resilience. Full article
(This article belongs to the Section A: Sustainable Energy)
21 pages, 2198 KB  
Article
Potential Use of Methane Gas from Municipal Waste Storage Facilities: A Case Study of the Karaganda Region
by Ravil Mussin, Denis Akhmatnurov, Nail Zamaliyev, Yelena Tseshkovskaya, Natalya Tsoy, Alexandr Zakharov, Vadim Tseshkovskiy, Nikita Ganyukov, Krzysztof Skrzypkowski, Krzysztof Zagórski and Anna Zagórska
Energies 2026, 19(11), 2726; https://doi.org/10.3390/en19112726 - 5 Jun 2026
Cited by 1 | Viewed by 309
Abstract
This article presents an environmental assessment of emissions from a solid waste landfill in the Karaganda Region of the Republic of Kazakhstan in order to study the dynamics of methane release and determine its energy potential. The study is based on an analysis [...] Read more.
This article presents an environmental assessment of emissions from a solid waste landfill in the Karaganda Region of the Republic of Kazakhstan in order to study the dynamics of methane release and determine its energy potential. The study is based on an analysis of a 13-hectare facility that has been operating since 2015 in a reclaimed quarry with an average annual accumulation volume of up to 4000 tons. The methodology includes a detailed analysis of the morphological composition of waste (57% of the organic fraction) and consideration of regional climatic parameters for modeling the phase-specific formation of biogas, according to the approved national methodology. It has been established that, by 2030, the volume of methane will be 81.7–92.6 tons/year. Based on the data obtained, a set of environmental protection measures is proposed, including the installation of special pipes for degassing and the introduction of automated monitoring based on stationary sensors. The results confirm the technical feasibility of using landfill gas as an alternative energy resource and can serve as a scientific and methodological basis for designing environmentally safe landfills in a sharply continental climate and intensive industrial infrastructure. Full article
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29 pages, 23367 KB  
Article
Numerical Simulation of Heat Transfer in Saline Soil Energy Pile Groups
by Weidong Lyu, Zirui Wang, Xudong Zhao and Jinwei Qiu
Energies 2026, 19(11), 2725; https://doi.org/10.3390/en19112725 - 5 Jun 2026
Viewed by 406
Abstract
To reduce adverse environmental impacts and boost renewable energy utilization, energy pile technology bridges traditional energy systems and building structures, offering an innovative route for urban low-carbonization. Currently, research on energy piles is confined to conventional non-saline soil, with insufficient exploration of their [...] Read more.
To reduce adverse environmental impacts and boost renewable energy utilization, energy pile technology bridges traditional energy systems and building structures, offering an innovative route for urban low-carbonization. Currently, research on energy piles is confined to conventional non-saline soil, with insufficient exploration of their heat transfer performance in saline soil. Thus, this paper studies the latter based on prior non-saline soil research. The heat transfer performance of pile groups is analyzed in COMSOL Multiphysics by varying the pile diameters, spacing, configurations, and numbers. The findings show that the central pile undergoes the most significant thermal interference, with its water temperature on the 30th day being 1.26 °C higher than that of a single pile. A pile spacing equal to four times the diameter greatly reduces thermal interference, and a spacing of six times the diameter renders the accumulated heat effect insignificant. Additionally, a plum-shaped pile arrangement reduces energy pile group interference effectively, with higher heat transfer capacity than the traditional square arrangement. Increasing pile diameter only benefits heat transfer greatly in the first 10 days, as thermal interference offsets the advantage of expanded heat transfer area from larger diameters. Full article
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25 pages, 8796 KB  
Article
Integrated Geology–Engineering Evaluation and Strategy Optimization for Tight Oil Development in Complex Fault Blocks: A Case Study of the G5 Block, Nanpu Sag
by Zhongliang Yu, Tongfeng Cao, Yang Sun, Hong Liu, Jian Cui, Rong Fan, Yajuan Ju, Qian Cheng, Hengbao Li and Junyi Xia
Energies 2026, 19(11), 2724; https://doi.org/10.3390/en19112724 - 5 Jun 2026
Viewed by 374
Abstract
To address core challenges involving severe reservoir heterogeneity, complex fracture systems, and rapid energy depletion encountered in the development of tight oil reservoirs in the G5 block of the Nanpu Sag, this study performs a systematic analysis of geological characteristics and optimizes an [...] Read more.
To address core challenges involving severe reservoir heterogeneity, complex fracture systems, and rapid energy depletion encountered in the development of tight oil reservoirs in the G5 block of the Nanpu Sag, this study performs a systematic analysis of geological characteristics and optimizes an integrated geology–engineering development strategy. Through the integration of 3D seismic and well-logging data, the “sandwich-style” superposition architecture of sand bodies in the Es34 sub-member is quantitatively characterized. It reveals that productivity is co-controlled by high-quality main channel sand bodies (permeability: 0.5–1 mD) and high-density fracture zones (linear density: 3.2 fractures·m−1) along structural ridges. Consequently, a comprehensive technical system is established, incorporating trajectory optimization for high-angle wells, differential stimulated reservoir volume (SRV) fracturing based on the Reservoir Quality Index (RQI), and CO2 huff-n-puff for energy supplementation. Field applications demonstrate that optimized well placement increased the drilling encounter rate of high-quality reservoirs from 42% to 78%, while CO2 huff-n-puff technology successfully restored the formation pressure coefficient from 0.65 to 0.82. The implementation of this integrated approach extended the stable production period of typical wells to 18 months, significantly mitigating production decline and increasing the ultimate recovery factor of the block to 14.5%, which provides a favorable recovery level for a complex fault-block tight oil reservoir compared with the generally low primary-recovery performance reported for analogous tight oil systems in rift-basin settings. This study confirms that the coupling zone of fracture systems along structural ridges and high-quality sand bodies represents the optimal target for economic development. The proposed geology–engineering synergy model provides a transferable technical paradigm for the efficient development of similar complex fault-block tight oil reservoirs. Full article
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16 pages, 1413 KB  
Article
Electric Shock Simulation and Risk Assessment in Low-Voltage Distribution Networks Under Unknown Topology: A Two-Stage Approach Based on Smart Meter Data
by Zhe Li, Shoukang Luo, Xiaojia Sun, Yang Li, Yubo Zhang, Chakhung Yeung and Yuxuan Ding
Energies 2026, 19(11), 2723; https://doi.org/10.3390/en19112723 - 5 Jun 2026
Viewed by 321
Abstract
Low-voltage distribution networks are critical for supplying power to end-users, and electric shock safety is a key concern; however, the frequent incompleteness of topology information in practical operations makes it challenging to accurately assess electric shock risks. This paper proposes a two-stage approach [...] Read more.
Low-voltage distribution networks are critical for supplying power to end-users, and electric shock safety is a key concern; however, the frequent incompleteness of topology information in practical operations makes it challenging to accurately assess electric shock risks. This paper proposes a two-stage approach for electric shock simulation and risk assessment in low-voltage distribution networks with completely unknown topology and absent phase-angle measurements, addressing the critical challenge of unavailable, incomplete, or outdated topology information using only conventional smart meter data. It innovatively investigates shock risks under TT, TN-C, and TN-S grounding systems without prior topology knowledge or synchronized phasors. The proposed methodology combines a phase-angle-agnostic data-driven stage and a model-driven stage: the data-driven stage uses an iterative algorithm for topology label matrix estimation and weighted Laplacian matrix reconstruction with hierarchical clustering to identify network structure and line parameters, requiring only active power, reactive power, voltage magnitude, and current magnitude. The model-driven stage adopts modified nodal analysis with the finite-difference time-domain (MNA-FDTD) method to evaluate transient leakage voltage distribution under single-phase-to-ground faults, thereby assessing electric shock risks in line with international safety standards. Key contributions include a practical phase-free topology identification framework, comparative risk analysis of three grounding systems, and an integrated data-model approach for real-world low-observability networks. Simulation results show accurate topology/parameter identification with a relative Frobenius-norm error of only 1.8% even without phase data. TN-S provides the highest safety complying with IEC standards, followed by TN-C and TT under specific conditions, offering a practical solution for utilities lacking detailed topology records. Full article
(This article belongs to the Section A1: Smart Grids and Microgrids)
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14 pages, 8318 KB  
Article
Enhanced Liquid–Solid Triboelectric Nanogenerator with Multi-Tube Nesting Structure for Efficient Wave Energy Harvesting
by Denghui Li, Peng Zhang, Peng Luo, Jiamei Su, Wenhao Li, Shishi Li and Qianxi Zhang
Energies 2026, 19(11), 2722; https://doi.org/10.3390/en19112722 - 5 Jun 2026
Viewed by 1224
Abstract
Real-time monitoring of marine ecosystems is crucial for global climate change research. In extreme marine environments such as the westerly regions in the Arctic and Antarctic, monitoring buoys and platforms often suffer from severe challenges, including insufficient energy supply, limited battery life, and [...] Read more.
Real-time monitoring of marine ecosystems is crucial for global climate change research. In extreme marine environments such as the westerly regions in the Arctic and Antarctic, monitoring buoys and platforms often suffer from severe challenges, including insufficient energy supply, limited battery life, and difficult maintenance. Triboelectric nanogenerators (TENGs) offer a promising strategy for self-powered marine sensing. However, conventional tubular liquid–solid triboelectric nanogenerators (LS-TENGs) suffer from low efficiency of interfacial charge transfer due to limited contact area and excessive internal resistance, which restricts their output. In this study, a multi-tube nested liquid–solid triboelectric nanogenerator (MLS-TENG) is proposed, and the suitable filling ratio is determined through comparative experiments on structural parameters. This design significantly increases the effective contact area, reduces internal resistance, and improves synergistic charge transfer at multiple interfaces. Experimental results demonstrate that the MLS-TENG exhibits substantially improved electrical output compared with the corresponding single-tube structures. When integrated with a power management module, the capacitor charging efficiency is improved by approximately 120 times. In real sea trials, an array composed of MLS-TENG units successfully drives a self-powered sensing system, achieving stable 4G transmission of environmental parameters. This work provides a scalable structural optimization strategy for constructing high-performance blue energy-harvesting self-powered nodes for the marine Internet of Things. Full article
(This article belongs to the Section D3: Nanoenergy)
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24 pages, 8327 KB  
Review
Low-Carbon Technologies in Reconstructing Ukraine’s Energy Sector: The Role of Green Hydrogen
by Manuela Tvaronavičienė and Wadim Strielkowski
Energies 2026, 19(11), 2721; https://doi.org/10.3390/en19112721 - 5 Jun 2026
Viewed by 547
Abstract
This paper assesses the role of green hydrogen and green ammonia in the low-carbon reconstruction of Ukraine’s energy sector. The country, severely affected by war, has more than 70% of its energy infrastructure damaged or destroyed, which calls for novel solutions for not [...] Read more.
This paper assesses the role of green hydrogen and green ammonia in the low-carbon reconstruction of Ukraine’s energy sector. The country, severely affected by war, has more than 70% of its energy infrastructure damaged or destroyed, which calls for novel solutions for not only reconstructing but also rethinking Ukraine’s energy sector shaped by the Soviet-era planning. In this context, decentralized and renewable energy solutions appear to be one of the best options to achieve this goal. This study combines four novel and mutually reinforcing methods: a Scopus-based literature review of highly cited green hydrogen publications, natural language processing (NLP) and bibliometric network analysis of Ukraine-related hydrogen research, a SWOT assessment, and a geospatial hydrogen production cost model (GEOH2). The novelty of this research lies in this integrated Ukraine-specific framework, which links research trends, wartime reconstruction constraints, hub-level policy choices, and financing risk-sensitive cost modeling. Therefore, the quantitative part of GEOH2 estimates the levelized cost of green hydrogen, while ammonia is treated as a downstream screening-level conversion and export pathway rather than as a full plant-level ammonia model. Our results show that Ukrainian green hydrogen research is concentrated on renewable-energy strategy, wind and solar electrolysis, water and desalination constraints, gas grid blending, underground storage, ammonia derivatives, and decentralized energy systems. The GEOH2 results indicate that southern Ukraine has strong physical potential for competitive green hydrogen production under de-risked financing, while war risk financing can make even resource-rich areas economically unattractive. Odesa and Dnipro emerge as important export-oriented and industrial hubs, whereas Zakarpattia remains strategically relevant as a safer western corridor linked to European markets. Our findings demonstrate that Ukraine’s hydrogen and ammonia development needs to follow a phased pathway: domestic renewable build-out and grid repair, pilot electrolysis projects and screening-level ammonia conversion pathways, targeted de-risking and insurance mechanisms, and only then broader export corridor development. This pathway can support decarbonization, energy security, industrial modernization, and Ukraine’s long-term integration into European clean energy value chains. Full article
(This article belongs to the Section B: Energy and Environment)
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19 pages, 1572 KB  
Article
Minimal Photovoltaic Solar Cooker for a Catalytic Effect on Energy Poverty
by Antonio Lecuona-Neumann, José-Ignacio Nogueira-Goriba and Jean Boubour
Energies 2026, 19(11), 2720; https://doi.org/10.3390/en19112720 - 4 Jun 2026
Viewed by 623
Abstract
One to four million annual premature deaths are associated with household air pollution. This indoor pollution is mainly generated by traditional biomass cookstoves. Thus, solar cooking can significantly reduce this toll. Its proliferation would also mitigate deforestation pressures. Additionally, for developing countries, it [...] Read more.
One to four million annual premature deaths are associated with household air pollution. This indoor pollution is mainly generated by traditional biomass cookstoves. Thus, solar cooking can significantly reduce this toll. Its proliferation would also mitigate deforestation pressures. Additionally, for developing countries, it would alleviate the fuel collection workload, mainly borne by women responsible for fuel collection. Electric cooking provides a clean and controllable alternative to thermal cookers for indoor food preparation, sterilization and heating. This study presents a minimal, off-grid photovoltaic solar cooker that operates without batteries and power electronics. Such a cooker constitutes a low-cost and high-reliability solution for electrically decentralized locations. The system encompassing the cooker is conceived as an accessible entry point for household-level photovoltaic (PV) adoption. So, it offers the potential to catalyze the uptake of clean-energy technologies and to support sustainable development. The proposed design dissipates PV power into heat using commercial positive temperature coefficient (PTC) resistors operating near their Curie temperature. A simplified theoretical model is formulated to easily estimate the thermal power and heat-transfer conductances required for achieving cooking temperatures. An instrumented prototype allows for characterizing the transient temperature evolution during controlled heating and cooling experiments in the laboratory, facilitating development in an initial step avoiding the PV panel. The results demonstrate that the minimal PV configuration is technically feasible, robust, and compatible with low-resource settings. This encourages its adoption in communities experiencing energy poverty. Full article
(This article belongs to the Collection Featured Papers in Solar Energy and Photovoltaic Systems Section)
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27 pages, 5655 KB  
Article
Energy Supply Resilience and Industrial Continuity Under a Strait of Hormuz Blockade
by Feng An, Shuai Ren, Xuyang Liu and Jingwen Cui
Energies 2026, 19(11), 2719; https://doi.org/10.3390/en19112719 - 4 Jun 2026
Cited by 2 | Viewed by 820
Abstract
A blockade or severe disruption in the Strait of Hormuz would test energy supply resilience by reducing crude oil and LNG availability and by raising routing, freight, insurance, port-handling, warehousing, and transport-support costs. This paper develops a short-run multi-regional input–output stress test to [...] Read more.
A blockade or severe disruption in the Strait of Hormuz would test energy supply resilience by reducing crude oil and LNG availability and by raising routing, freight, insurance, port-handling, warehousing, and transport-support costs. This paper develops a short-run multi-regional input–output stress test to assess where such an energy-route shock enters the production system, how reserves and inventories reduce pass-through, which cross-border links carry residual costs, and where final demand absorbs them. Using the OECD ICIO 2025 edition for 2022, we map the shock to oil and gas extraction, refining, utilities, transport, and transport-support sectors, with an additional premium for major Gulf energy exporters. We propagate the shock for seven input–output rounds under inventory damping. First-round exposure and later-round burden do not coincide, as energy-intensive materials, aviation services, chemicals, minerals, metals, electronics, and machinery face higher downstream costs through material and logistics purchases. With 30% inventory absorption, the upstream energy shock needed for downstream manufacturing to reach a 10% added-cost threshold rises from 73.6% to 85.3%. The results support targeted reserve release, coordinated rerouting, port-logistics priority, inventory management around high-value links, and continuity protection for vulnerable sectors. Full article
(This article belongs to the Special Issue Energy Policies and Sustainable Development)
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26 pages, 8310 KB  
Article
Monitoring and Simulation of Curing-Induced Residual Strain in Epoxy Core of Ultra-High-Voltage Bushing
by Yu Zhang, Rui Liu, Yun Feng, Wenlong Liao, Zhou Mu, Yueping Yang, Zhenyu Wang, Lei Yan and Hongyu Nie
Energies 2026, 19(11), 2718; https://doi.org/10.3390/en19112718 - 4 Jun 2026
Viewed by 324
Abstract
The UHV dry-type bushing plays a critical role in power transmission by enabling electrical connection, electrical insulation, and mechanical support, making it a core component for ensuring the safe and stable operation of UHV direct current (DC) transmission projects. Epoxy resin, serving as [...] Read more.
The UHV dry-type bushing plays a critical role in power transmission by enabling electrical connection, electrical insulation, and mechanical support, making it a core component for ensuring the safe and stable operation of UHV direct current (DC) transmission projects. Epoxy resin, serving as the fundamental insulating material for the bushing core, undergoes significant residual strain during high-temperature curing due to chemical shrinkage and thermal strain, which directly affects the molding quality and service reliability of the component. This paper investigates the curing process of a large-thickness epoxy material, which is on the same scale as a UHV bushing. An in situ monitoring system combining fiber Bragg grating (FBG) sensors and thermocouples, together with COMSOL Multiphysics simulations, is employed to systematically study the evolution of the temperature field and residual strain throughout the entire curing process, considering the demolding effect. The results show that during the curing stage, the internal temperature distribution is non-uniform, with a maximum temperature difference of 65 °C between the center and the edge. The residual strain is dominated by chemical shrinkage (accounting for 73.25%) and exhibits a pronounced radial gradient. Mold constraint and demolding cause abrupt changes in the strain. The developed thermo-chemo-mechanical coupled model shows good agreement between simulations and experimental measurements. Thermal cycling relaxes the residual stress, achieving a reduction of 3.89–5.77%. This study provides support for process optimization and defect prevention in large-scale epoxy insulation components. Full article
(This article belongs to the Special Issue Simulation and Analysis of Electrical Power Systems—2nd Edition)
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15 pages, 5945 KB  
Perspective
Toward Energy-Efficient and Circular Wind Power Systems: Closing the Material Loops of Wind Turbine Blades
by Jie Yang, Yiye Lu, Junze Gong, Mingxin Xu, Jiale Wu, Lele Dong, Haocheng Xu, Qing Lu, Wei Li and Qiang Lu
Energies 2026, 19(11), 2717; https://doi.org/10.3390/en19112717 - 4 Jun 2026
Viewed by 454
Abstract
This perspective focuses on the field of solid waste recovery and resource utilization for end-of-life (EoL) wind turbine blades. Wind energy plays a central role in the global transition toward low-carbon energy systems owing to its technological maturity, scalability, and widespread resource availability. [...] Read more.
This perspective focuses on the field of solid waste recovery and resource utilization for end-of-life (EoL) wind turbine blades. Wind energy plays a central role in the global transition toward low-carbon energy systems owing to its technological maturity, scalability, and widespread resource availability. As global installed wind power capacity exceeded 1000 GW in 2024, improving the life-cycle energy efficiency and resource productivity of wind energy systems has become increasingly important. In this context, wind turbine blades (WTBs), the most material-intensive components with high embodied energy, are approaching large-scale end-of-life replacement, with global EoL blade waste projected to reach 2–4 million tons by 2030. Although blades may reach the end of their structural service life, they contain substantial quantities of reinforcing fibers and polymeric matrices that embody significant material and manufacturing energy. Integrating blade recycling into the wind energy value chain represents a critical opportunity to reduce dependence on energy-intensive virgin materials and lower life-cycle energy consumption and associated carbon emissions. However, the realization of energy-efficient circular utilization remains constrained by several challenges, including inefficient heat and mass transfer during blade depolymerization, limited valorization of resin-derived products, and performance degradation of recovered fibers. This perspective examines the material characteristics of blades from a life-cycle energy utilization standpoint, assesses existing recycling pathways, and identifies key technological and system-level bottlenecks. Emphasis is placed on process intensification, product upgrading, and design-for-circularity strategies to support the long-term sustainability of wind power systems. Full article
(This article belongs to the Section B: Energy and Environment)
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21 pages, 3337 KB  
Article
Assessment of the Renewable Energy Recovery Potential from Municipal Solid Waste: A Polish Case Study
by Emilia den Boer, Kamil Banaszkiewicz, Iwona Pasiecznik, Jan den Boer, Hongzhi Ma, Elias Hakalehto and Łukasz Kowalczyk
Energies 2026, 19(11), 2716; https://doi.org/10.3390/en19112716 - 4 Jun 2026
Viewed by 407
Abstract
This study investigates whether the optimal utilization of the biomass potential contained in municipal solid waste (MSW) can support the implementation of circular economy (CE) principles and contribute to climate policy objectives, particularly the reduction in greenhouse gas (GHG) emissions in the waste [...] Read more.
This study investigates whether the optimal utilization of the biomass potential contained in municipal solid waste (MSW) can support the implementation of circular economy (CE) principles and contribute to climate policy objectives, particularly the reduction in greenhouse gas (GHG) emissions in the waste management sector. The analysis evaluates whether waste-to-energy recovery can support the objectives of the European Green Deal, including a 55% reduction in GHG emissions by 2035 and the achievement of climate neutrality by 2050. The assessment was conducted for two MSW streams generated in a Polish municipality: separately collected biowaste and residual MSW remaining after meeting European reuse and recycling targets. The study summarizes the results of detailed experimental investigations of the physicochemical and fuel properties of these waste streams. Proven and commercially available energy recovery technologies, including anaerobic digestion (AD) of biowaste and incineration of residual waste, were analyzed. GHG emissions were assessed using a life cycle assessment (LCA) approach, taking into account both direct emissions and avoided emissions resulting from the substitution of conventional energy and fertilizer production. The experimental results revealed significant variability in the biodegradability and energy potential of individual biowaste fractions, with the highest biogas yields observed for kitchen waste. Residual waste exhibited a considerable calorific value and a significant share of renewable energy due to its biomass content. The results indicate that the share of renewable energy in electricity generated from waste is expected to increase from 46.1% in 2025 to 49.9% in 2040. In relation to the total electricity demand of the analyzed city, energy recovered from waste accounts for 1.8 ± 0.3% in 2025 and 1.3 ± 0.2% in 2040. Scenario-based modeling demonstrated that the target system, maximizing energy recovery from both biowaste and residual waste, achieves a consistently negative GHG emission balance throughout the analyzed period (2025–2040), ranging from −72 ± 15 kg CO2-eq/ton in 2025, through the most favorable value of −81 ± 17 kg CO2-eq/ton in 2035, to −57 ± 12 kg CO2-eq/ton in 2040, expressed per ton of total managed biowaste and residual waste. Full article
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37 pages, 15961 KB  
Review
Optimal Planning of Electric–Hydrogen Coupled Integrated Energy System: A Comprehensive Review
by Hongbo Ren, Lili Miao, Qiong Wu, Xinyu Liu and Weisheng Zhou
Energies 2026, 19(11), 2715; https://doi.org/10.3390/en19112715 - 4 Jun 2026
Cited by 2 | Viewed by 448
Abstract
Against the backdrop of climate change, the volatility of energy supply and demand in integrated energy systems (IESs) has intensified, resulting in heightened scheduling challenges. Electric–hydrogen coupling has emerged as a pivotal approach to fostering multi-energy complementarity while enhancing the flexibility and stability [...] Read more.
Against the backdrop of climate change, the volatility of energy supply and demand in integrated energy systems (IESs) has intensified, resulting in heightened scheduling challenges. Electric–hydrogen coupling has emerged as a pivotal approach to fostering multi-energy complementarity while enhancing the flexibility and stability of IES. Rational planning of an electric–hydrogen coupled integrated energy system (EH-IES) can further strengthen energy interconnection and mutual support. First, the architecture and diverse coupling modes of the EH-IES are outlined based on key technologies and coupling mechanisms. Accurate modeling serves as the “cornerstone” of planning, with electric power and hydrogen energy equipment acting as the foundational “carriers” and electric–hydrogen coupling devices as the critical “link.” By examining application scenarios across the transportation, building, and industrial sectors, the study analyzes EH-IES planning scenarios, objectives, and modeling methodologies. Sector-specific planning primarily focuses on equipment configuration and layout, evaluated from economic and/or environmental perspectives. Finally, future research directions for EH-IES planning are proposed, addressing multiple uncertainties, energy demand dynamics, and market mechanisms. These insights aim to provide a reference for subsequent studies. Full article
(This article belongs to the Special Issue Sustainable Energy Systems: Progress, Challenges and Prospects)
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22 pages, 11024 KB  
Article
Time–Frequency Domain Signal Analysis for Knock Detection in Hydrogen-Fueled Engines
by Brijesh Kinkhabwala, Uwe Wagner and Thomas Koch
Energies 2026, 19(11), 2714; https://doi.org/10.3390/en19112714 - 4 Jun 2026
Viewed by 517
Abstract
Hydrogen is a promising carbon-neutral fuel for future internal combustion engines due to its wide flammability range, high flame speed, and absence of carbon-based emissions. However, its high reactivity significantly increases susceptibility to abnormal combustion phenomena such as knock and pre-ignition, which can [...] Read more.
Hydrogen is a promising carbon-neutral fuel for future internal combustion engines due to its wide flammability range, high flame speed, and absence of carbon-based emissions. However, its high reactivity significantly increases susceptibility to abnormal combustion phenomena such as knock and pre-ignition, which can compromise engine efficiency, durability, and operational stability. Accurate detection and characterization of knock in hydrogen-fueled spark-ignition engines remain challenging due to the highly transient, broadband, and cycle-dependent nature of abnormal combustion-induced pressure oscillations. Conventional knock indicators based solely on time-domain pressure oscillations or fixed-band frequency analysis are limited in their ability to capture transient resonance behavior and cyclic variability. This study presents an integrated frequency- and time–frequency-domain methodology for knock detection using high-resolution in-cylinder pressure data acquired from a single-cylinder research engine operating under hydrogen port fuel injection (PFI). A discrete Fast Fourier Transform (DFFT) approach applied at stationary points of dynamically windowed pressure signals enables accurate identification of dominant resonance modes while minimizing spectral leakage. A Gaussian-based adaptive windowing strategy is introduced to capture combustion-driven cyclic variations more effectively. Short-Time Fourier Transform (STFT) and sum-based spectral analysis further provide detailed time–frequency localization of transient knock events. The proposed methodology demonstrates a clear separation between normal combustion and knock conditions, enabling reliable cycle-by-cycle identification of abnormal combustion events under varying operating conditions. The experimentally observed resonance frequencies are validated against theoretical predictions using Draper’s acoustic resonance equation, supporting the physical interpretation of knock-induced pressure oscillations. The results demonstrate that the proposed adaptive spectral methodology significantly improves knock detection accuracy compared to conventional indicators and provides a robust framework for advanced knock diagnostics, engine calibration, and combustion control in hydrogen-fueled engines. Full article
(This article belongs to the Special Issue Advanced Combustion Technologies: Challenges and Solutions for a Low-Carbon Future)
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19 pages, 5741 KB  
Article
Lifecycle Carbon Reduction Potential and Economic Valuation of Pumped Storage in a Multi-Energy Complementary System
by Jiangjiang Wu, Junrui Chai, Yuan Qin and Shun Yang
Energies 2026, 19(11), 2713; https://doi.org/10.3390/en19112713 - 4 Jun 2026
Viewed by 419
Abstract
Under international climate governance frameworks, including the Paris Agreement, the global decarbonization process has accelerated, imposing more stringent requirements on power system flexibility and low-carbon operation. Against this backdrop, pumped storage power stations, characterized by high flexibility and rapid response capability, serve as [...] Read more.
Under international climate governance frameworks, including the Paris Agreement, the global decarbonization process has accelerated, imposing more stringent requirements on power system flexibility and low-carbon operation. Against this backdrop, pumped storage power stations, characterized by high flexibility and rapid response capability, serve as large-scale energy storage solutions that can replace thermal power for peak shaving, thereby enhancing renewable energy integration and delivering significant carbon reduction benefits in multi-energy complementary systems. A carbon reduction calculation model is developed within the framework of the Chinese Certified Emission Reduction (CCER) trading mechanism to quantify the annual contributions of pumped storage to carbon reduction. Using a Fractional-Order Gray Model (FGM) optimized via Particle Swarm Optimization (PSO), future carbon market prices are forecasted, facilitating a robust economic evaluation. The findings reveal that, over its lifecycle, pumped storage could achieve a total carbon reduction of approximately 23.27 million tons of CO2, yielding approximately 7.981 billion CNY in carbon reduction value, with an initial 7-year CCER inclusion period contributing 254.0787 million CNY in carbon credits. It provides critical economic and policy insights, supporting the design of advanced power systems that position pumped storage as a central regulatory asset in carbon reduction strategies. Full article
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31 pages, 28564 KB  
Article
Representation of Tidal Turbine Support Structures in a Regional-Scale 3D Hydrodynamic Model and Their Effects on Wake Prediction
by Raymond Lam, Nairn Spence, Tian Tan, Chris Old and Brian Sellar
Energies 2026, 19(11), 2712; https://doi.org/10.3390/en19112712 - 4 Jun 2026
Viewed by 426
Abstract
Tidal turbine wake predictions in regional-scale hydrodynamic models typically account for rotor thrust but neglect the drag of support structures. This study introduces a method for representing turbine support structures as permeable drag volumes within TELEMAC-3D and evaluates their influence on wake characteristics. [...] Read more.
Tidal turbine wake predictions in regional-scale hydrodynamic models typically account for rotor thrust but neglect the drag of support structures. This study introduces a method for representing turbine support structures as permeable drag volumes within TELEMAC-3D and evaluates their influence on wake characteristics. The method is demonstrated for the 1 MW DeepGen-IV turbine deployed at the Fall of Warness test site at the European Marine Energy Centre, Scotland. The tripod foundation, tower, and nacelle are each implemented as momentum source terms alongside an actuator disc rotor in a regional-scale model with mesh resolution down to 1.5 m with 24 sigma layers and output at 60 s intervals (1 s at instrument locations), validated against seabed-mounted ADCP measurements. Including the support structures improves the agreement with measured wake profiles by 6–18% in root-mean-square error at 3.7 rotor diameters downstream and extends the hub-height 5% velocity deficit distance by an average of three rotor diameters (~54 m), with substantial variability across tidal conditions. The tripod and tower drag also extend the velocity deficit into the lower water column, a feature absent from the rotor-only formulation, with potential relevance to near-bed processes such as bed shear stress and sediment transport which are not examined in the present study. The implementation is in principle extendable to other support concepts and multi-device studies, and the results indicate that support structure drag should be considered in regional wake models where wake persistence and downstream interactions are important. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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30 pages, 2570 KB  
Article
Adaptive-Confidence-Window-Modulated Predictive Control for Induction Motor Drives: Real-Time HIL Validation on DS1202
by Belgacem Said Khaldi, Naas Charrak, Abdellah Kouzou, Jose Rodriguez and Mohamed Abdelrahem
Energies 2026, 19(11), 2711; https://doi.org/10.3390/en19112711 - 4 Jun 2026
Viewed by 396
Abstract
This paper proposes an adaptive-confidence-window-modulated model predictive controller (ACW-M2PC) for induction motor drives. The method combines angle-guided local sector selection with a confidence-triggered bounded expansion toward adjacent sectors, so that the online search remains local whenever the local solution is reliable and expands [...] Read more.
This paper proposes an adaptive-confidence-window-modulated model predictive controller (ACW-M2PC) for induction motor drives. The method combines angle-guided local sector selection with a confidence-triggered bounded expansion toward adjacent sectors, so that the online search remains local whenever the local solution is reliable and expands only when necessary. This decision structure reduces unnecessary candidate evaluations while preserving low computational burden and improving the quality of the selected voltage action. The proposed controller was implemented and validated through real-time hardware-in-the-loop experiments on a dSPACE DS1202 platform. Compared with a baseline full-search-modulated model predictive controller (M2PC), ACW-M2PC reduced the average number of evaluated sectors by 79.7% while maintaining zero-overrun real-time execution. At the same time, it improved torque quality, reducing torque ripple peak-to-peak by 70.2% and torque ripple RMS by 62.0%, with a slight reduction in speed integral absolute error. An ablation study further showed that angle-guided local reduction already captures a large part of the computational benefit, whereas the confidence-triggered bounded expansion provides the additional corrective action required when the local solution becomes insufficient. Overall, these results show that ACW-M2PC improves the performance–complexity trade-off while remaining suitable for real-time induction motor drive control. Full article
(This article belongs to the Section F: Electrical Engineering)
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22 pages, 5115 KB  
Article
Hydrogen–Methane Blending in Gas Turbine Combustion Chambers: NOx and CO Emissions, Flame Stabilization, and Thermodynamic Integration with Combined-Cycle Power Plants
by Abay Mukhamediyarovich Dostiyarov, Abat Zhumagaliyev, Alisher Teltay, Ermekkyzy Diana and Maxat Arganatovich Anuarbekov
Energies 2026, 19(11), 2710; https://doi.org/10.3390/en19112710 - 4 Jun 2026
Viewed by 578
Abstract
The global push for low-carbon electricity generation has made hydrogen-enriched natural gas an attractive near-term decarbonization option. This paper combines experimental and thermodynamic analyses of H2–CH4 combustion in gas turbine combustion chambers. Experiments were conducted on a patented two-stage swirl [...] Read more.
The global push for low-carbon electricity generation has made hydrogen-enriched natural gas an attractive near-term decarbonization option. This paper combines experimental and thermodynamic analyses of H2–CH4 combustion in gas turbine combustion chambers. Experiments were conducted on a patented two-stage swirl burner across 240 operating conditions. The effects of hydrogen fraction (γ = 0–40%), swirler vane angle (30°, 45°, 60°), equivalence ratio (φ = 0.17–1.00), and fuel injection strategy were measured against NOx and CO emissions and lean blowout stability. Each 10% increase in hydrogen content raised NOx by 23–24% via the Zel’dovich thermal mechanism, while CO fell by up to 28.5% at φ = 0.3 and 60° due to enhanced OH-radical activity. The minimum recorded NOx was 12.08 ppm (Type 2 injection, 30°, γ = 0%, φ = 0.3). Hydrogen addition improved lean blowout stability by 32–46% per 10% H2. A parallel thermodynamic analysis showed that integrating an organic Rankine cycle (ORC) and supplementary H2–CH4 firing in the heat recovery steam generator cuts specific CO2 emissions by 7.5–10% and raises net efficiency by 0.79–4.0 percentage points. Critical comparison with 28 published studies identified an optimal operating window: γ = 20–30%, φ = 0.5–0.7, 45° vane angle (SW = 0.8). Full article
(This article belongs to the Section A5: Hydrogen Energy)
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25 pages, 490 KB  
Article
Research on the Economic Transmission Mechanism and Dynamic Optimization of Computing Power Networks Based on a Multi-Sectoral Input–Output Model and a Hybrid Algorithm Solution
by Chunxiang Du, Shuangjie Li, Huijuan Wang, Wenhua Shi, Lu Feng, Xinyu Zhang, Xiaojuan Zhang and Nan Jia
Energies 2026, 19(11), 2709; https://doi.org/10.3390/en19112709 - 4 Jun 2026
Viewed by 552
Abstract
In the digital economy era, computing power, as a novel factor of production, serves as a vital engine for driving high-quality economic development. Building upon China’s traditional 42-sector input–output table, this paper incorporates computing power networks as a new sector to construct a [...] Read more.
In the digital economy era, computing power, as a novel factor of production, serves as a vital engine for driving high-quality economic development. Building upon China’s traditional 42-sector input–output table, this paper incorporates computing power networks as a new sector to construct a 43-sector dynamic input–output (IO) model. Based on this framework, a Dynamic Stochastic General Equilibrium (DSGE) analysis framework is constructed to systematically reveal the dynamic transmission mechanism of computing power within industrial linkages and capital accumulation. From an energy perspective, energy consumption is implicitly captured through carbon emissions and energy structure, which together reflect the scale, efficiency, and composition of energy use in computing power networks. The findings show that the optimal computing power allocation follows a temporal evolution pattern from the service sector to the manufacturing sector, with ICT manufacturing’s computing power quota reaching 31% by 2030. An investment inflection point occurs in 2026, aligning with the digital infrastructure cycle of China’s 14th Five-Year Plan. The “Eastern Data, Western Computing” strategy reduces unit carbon emissions from computing power by 41%. Policy simulations demonstrate that R&D tax credits generate a 2.9-fold multiplier effect through industrial linkages, boosting GDP by 2.3%. The integrated IO-DSGE framework developed in this study provides a quantitative tool for the full-cycle management of “construction–application–regulation” in computing power networks. It holds significant theoretical value and practical implications for enhancing resource allocation efficiency and promoting green, climate-friendly development. Full article
(This article belongs to the Special Issue Advancements in Energy Economy and Finance)
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26 pages, 4534 KB  
Article
A Privacy-Preserving Multi-Time-Scale Tie-Line Power Smoothing Method for Multiple Data Centers
by Quanyong Luo, Jiexiao Yu and Xiangwei Feng
Energies 2026, 19(11), 2708; https://doi.org/10.3390/en19112708 - 4 Jun 2026
Viewed by 333
Abstract
As renewable penetration in data-center power supply increases, stochastic renewable output can cause tie-line power fluctuations between data centers (DCs) and the utility grid. This paper proposes a privacy-preserving multi-time-scale tie-line power smoothing method for multiple DCs. A two-stage first-order low-pass filter decomposes [...] Read more.
As renewable penetration in data-center power supply increases, stochastic renewable output can cause tie-line power fluctuations between data centers (DCs) and the utility grid. This paper proposes a privacy-preserving multi-time-scale tie-line power smoothing method for multiple DCs. A two-stage first-order low-pass filter decomposes tie-line fluctuations into high- and low-frequency regulation targets. Server task shifting tracks the high-frequency target, while uninterruptible power supply (UPS) regulation compensates the low-frequency residual under practical energy and power constraints. Second, a federated adaptive proximal policy optimization (Fed-AdaPPO) framework is developed. Proximal policy optimization (PPO) provides stable policy optimization in the continuous action space, and the upper confidence bound (UCB)-guided adaptive exploration improves task-shifting exploration. Critically, only Critic gradients are aggregated across DCs; Actor networks, raw workload data, and user-sensitive information remain local. This design reduces the risk of exposing local state-action mappings. Results show that coordinated server-cluster and UPS regulation reduces the standard deviation of tie-line power by at least 33.4% while maintaining service quality and data privacy. Full article
(This article belongs to the Special Issue Artificial Intelligence and Machine Learning Applications in Smart Energy Systems—2nd Edition)
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20 pages, 9436 KB  
Article
Systematic Characterization and Global Sensitivity Analysis of Structural Responses for a Spar-Type FOWT Across Wind–Wave Misalignment
by Tuanhai Chen, Yufeng Bu, Sen Gong, Wenhua Wang and Xin Li
Energies 2026, 19(11), 2707; https://doi.org/10.3390/en19112707 - 4 Jun 2026
Viewed by 435
Abstract
Wind–wave misalignment is a pervasive environmental phenomenon that significantly affects the structural integrity of floating offshore wind turbines (FOWTs). For a Spar-type FOWT across the full 0°–90° misalignment range, this study systematically conducts dynamic response characterization and parameter sensitivity analysis, quantifying the directional [...] Read more.
Wind–wave misalignment is a pervasive environmental phenomenon that significantly affects the structural integrity of floating offshore wind turbines (FOWTs). For a Spar-type FOWT across the full 0°–90° misalignment range, this study systematically conducts dynamic response characterization and parameter sensitivity analysis, quantifying the directional modulation effects on five critical dynamic indicators, including tower-base Fore-Aft (F-A) and side-to-side (S-S) bending moments, maximum Von Mises stress, and fairlead tensions. Results demonstrate that wind–wave misalignment triggers a significant redistribution of structural energy, where side-to-side bending moments and fairlead tensions exhibit distinct peak characteristics at specific non-collinear headings. Rather than merely evaluating structural responses, this study emphasizes the sensitivity of environmental parameters to reveal a dominance-switching mechanism. As the misalignment angle increases, the governing factors of structural response dynamically shift from wind variables to wave variables. This research provides a rigorous mechanical explanation for complex response evolution and offers a scientific basis for the robust design of floating wind turbines in multi-directional sea states. Full article
(This article belongs to the Special Issue Advanced Control Technology of Integrated Wind and Wave Energy Conversion Systems: 2nd Edition)
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16 pages, 4460 KB  
Article
Nanofluid-Driven Heat Transfer Augmentation for Enhanced Geothermal Extraction in U-Shaped Wells
by Junhui Guo, Jingyi Wang, Shefeng Gu, Jing Li, Zheng Wang and Sijia Wang
Energies 2026, 19(11), 2706; https://doi.org/10.3390/en19112706 - 4 Jun 2026
Viewed by 390
Abstract
U-shaped well geothermal energy exploitation has become a key pathway for sustainable energy development, valued for its clean and stable attributes. However, constrained by the limited heat transfer capacity between the wellbore and traditional circulating water, the thermal extraction efficiency of the circulating [...] Read more.
U-shaped well geothermal energy exploitation has become a key pathway for sustainable energy development, valued for its clean and stable attributes. However, constrained by the limited heat transfer capacity between the wellbore and traditional circulating water, the thermal extraction efficiency of the circulating fluid in the U-shaped well remains difficult to breakthrough, severely hindering the large-scale application. This work conducts a study on the optimization of the thermal conductivity performance of circulating working fluids based on water-phase dispersed nanoparticles, aiming to explore efficient heat transfer methods for the circulating working fluids in geothermal reservoir U-shaped wells. The finite element simulation is employed to analyze the influence of Al2O3 nanoparticle concentration (0–5%) and injection rate (4000–9000 m3/d) on thermal conductivity performance and flow characteristics. The results demonstrate that the Al2O3-H2O nanofluid with a particle size of 10 nm and a concentration of 5% exhibits the optimal heat transfer performance. Under the optimization objective of maximizing net heat output with the pipe-velocity safety constraint satisfied, when the injection rate is 5000 m3/d, the heat extraction efficiency is improved by 21.31% compared with that of pure water. This work may provide theoretical data for efficient geothermal exploitation. Full article
(This article belongs to the Section H2: Geothermal)
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36 pages, 12042 KB  
Article
A Unified Co-Optimization Framework for Hybrid Renewable Systems Incorporating Degradation-Aware Multi-Storage and Demand-Side Management
by Majed A. Alotaibi
Energies 2026, 19(11), 2705; https://doi.org/10.3390/en19112705 - 4 Jun 2026
Viewed by 472
Abstract
The intermittent nature of renewable energy systems and the mismatch between power generation and load demand necessitate the integration of efficient energy storage systems (ESSs). Among large-scale energy storage technologies, pumped hydro-energy storage systems (PHESs) are widely recognized as one of the most [...] Read more.
The intermittent nature of renewable energy systems and the mismatch between power generation and load demand necessitate the integration of efficient energy storage systems (ESSs). Among large-scale energy storage technologies, pumped hydro-energy storage systems (PHESs) are widely recognized as one of the most cost-effective and longest-lifetime storage solutions under favorable geographical conditions. This study proposes and optimizes a hybrid renewable energy system (HRES) for the Wadi Baish region in Saudi Arabia as a real case study, where the significant elevation difference between the nearby mountains and the existing lake provides favorable conditions for PHES implementation. A nested optimization framework is developed to determine the optimal sizing and operation of the HRES components. The external optimization loop employs the non-dominated sorting genetic algorithm II (NSGA-II) to optimize system sizing, while the internal optimization loop uses mixed-integer linear programming (MILP) to optimally dispatch the PHES, battery energy storage system (BESS), and hydrogen energy storage system (HESS). In addition, demand-side management (DSM) is coordinated with the MILP dispatch strategy to improve system performance and reliability. The results show that the optimized system can supply a 10 MW average load with a renewable energy penetration of 98.7%. The proposed configuration achieves a total lifecycle cost of USD 231.37 million and avoids approximately 898.58 kt of CO2 emissions over the project lifetime. PHES operates as the primary bulk energy storage technology due to its high storage capacity and low degradation characteristics. Furthermore, the degradation-aware model predicts battery replacement every 12 years and HESS replacement every 5 years. Compared with rule-based control, the MILP-based dispatch strategy reduces grid dependency by 87%. The coordinated DSM and MILP operation also reduces the levelized cost of energy to USD 0.066/kWh while improving overall system reliability. These findings demonstrate the importance of coordinated energy management and accurate degradation modeling in the optimal design and operation of renewable-based HRES configurations. Full article
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26 pages, 10775 KB  
Review
A Review of Overvoltage Protection Technologies and Protective Devices for Wind Turbines
by Jinru Sun, Zhicheng Peng, Dongxin Liu, Zhuoyan Chen, Yihe Li, Aoyu Wang, Zijia Jiao and Xueling Yao
Energies 2026, 19(11), 2704; https://doi.org/10.3390/en19112704 - 4 Jun 2026
Viewed by 389
Abstract
Wind turbines are persistently threatened by both lightning overvoltage and switching overvoltage due to their ultra-high structure, dense power electronics, and harsh operational environments, which severely endanger the safe and stable operation of the units. This paper systematically reviews the generation mechanism, type [...] Read more.
Wind turbines are persistently threatened by both lightning overvoltage and switching overvoltage due to their ultra-high structure, dense power electronics, and harsh operational environments, which severely endanger the safe and stable operation of the units. This paper systematically reviews the generation mechanism, type characteristics, and hazards of overvoltages in wind turbines. An internal and collaborative overvoltage protection system based on lightning protection zones (LPZs) is described. Focusing on three core protective devices—metal oxide varistors (MOVs), gas discharge tubes (GDTs), and Transient Voltage Suppressors (TVSs)—the research progress in material modification, structural optimisation, and performance evolution laws is explored. Additionally, the development of series-parallel topological collaborative design for multiple devices and active-triggered intelligent protection technologies is analysed. It is highlighted that current wind turbine overvoltage protection still faces bottlenecks in standard applicability, device operating condition adaptability, and system-level collaborative design. Future research should focus on the application of a wide bandgap and nanomaterials, the improvement of test standards tailored for actual operating conditions, and the construction of multi-physics coupling simulation and active intelligent early warning protection systems, so as to provide theoretical and technical support for high-reliability overvoltage protection of large-capacity and offshore wind turbines. Full article
(This article belongs to the Section A3: Wind, Wave and Tidal Energy)
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