Publications

Hydrogen gas is a promising clean-energy vector that can alleviate the current imbalance between energy supply and demand diversify the energy portfolio and underpin the sustainable development of oil and gas resources. This study pinpoints the factors that govern hydrogen quantification by pulsed-neutron logging. Monte Carlo simulations were performed to map the spatial distribution of capture γ-rays in formations saturated with either water or hydrogen and to systematically assess the effects of pore-fluid composition hydrogen density gas saturation lithology and borehole-fluid type. The results show that the counts of capture γ-rays are litter in hydrogen-bearing formations. For lowto moderate-porosity rocks the dynamic response window for hydrogensaturated pores is approximately 10% wider than that for methane-saturated pores. Increasing hydrogen density or decreasing gas saturation raises the capture-γ ratio while narrowing the dynamic range. Changes in borehole fluid substantially affect the capture-γ ratio yet have only a minor impact on the dynamic range. Lithology imposes an additional control: serpentinite enriched in structural water generates markedly higher capture-γ ratios that may complicate the quantitative evaluation of hydrogen.

Long-term reliability and accuracy of pressure valves are critical for hydrogen infrastructure and applications particularly in hydrogen-powered vehicles exposed to extreme weather conditions like cold winters and hot summers. This study evaluates such valves using the Endurance Test specified in European Commission Regulation (EU) No 406/2010 fulfilling Regulation (EC) No 79/2009 requirements for hydrogen vehicle type approval. A long short-term memory (LSTM) network accelerates valve development and validation by simulating endurance tests. The LSTM model with three inputs and one output predicts valve outlet pressure responses using experimental data collected at 25 ◦C 85 ◦C and − 40 ◦C simulating a 20-year lifecycle of 75000 cycles. At 25 ◦C the model achieves optimal performance with 40000 training cycles and an R2 of 0.969 with R2 values exceeding 0.960 across all temperatures. This efficient robust approach accelerates testing enabling realtime diagnostics and advancing hydrogen technologies for a sustainable future.

Biohydrogen is known for its clean fuel properties with zero emissions. It serves as a reliable alternative to fossil fuel. This paper analyses the status of bio-hydrogen production in Malaysia and the on-going efforts on its advancement. Critical discussions were put forward on biohydrogen production from thermochemical and biological technologies governing associated technological issues and development. Moreover a comprehensive and vital overview has been made on Malaysian and global polices with road maps for the development of biohydrogen and its application in different sectors. This review article provides a framework for researchers on bio-hydrogen production technologies investors and the government to align policies for the biohydrogen based economy. Current biohydrogen energy outlook for production installation units and storage capacity are the key points to be highlighted from global and Malaysia’s perspectives. This critical and comprehensive review provides a strategic route for the researcher to research towards sustainable technology. Current policies related to hydrogen as fuel infrastructure in Malaysia and commercialization are highlighted. Malaysia is also gearing towards clean and decarbonization planning.

The Research Priorities Workshop (RPW) brought together experts from academia industry and government to identify and prioritise future research directions with regard to hydrogen safety. Over two days participants engaged in presentations and discussions covering key areas such as transportation and storage ignition phenomena cryogenic hydrogen risk assessment methodologies and others. A critical component of the workshop was the prioritisation exercise during which attendees voted on the most urgent and impactful areas for future research. This document summarises the workshop’s activities including the prioritisation results which will serve as input to guide global hydrogen safety research efforts. The combined rankings from industry and non-industry stakeholders highlighted Quantitative Risk Assessment (QRA) and Reliability Data as the top priority followed closely by Mitigation Sensors and Hazard Prevention and Phenomena Understanding and Modelling. Regulations Codes and Standards followed immediately with a particularly high ranking from the industry representatives. These priorities reflect a strong collective focus on those topics to ensure hydrogen’s safe and scalable adoption. The insights and recommendations gathered during the RPW are important for shaping the strategic research priorities necessary to support the safe commercialisation of hydrogen technologies.

Biodiesel production through transesterification results in a large quantity of crude glycerol as a byproduct the utilization of which is technically and economically challenging. Because of the ability to efficiently process wet feedstocks supercritical water gasification (SCWG) is utilized in this study to convert crude glycerol into hydrogen-rich syngas. A significant challenge addressed through this study is the decomposition routes of different heterogeneous components of crude glycerol during SCWG. Pure glycerol methanol and oleic acid were investigated for SCWG as the model compounds of crude glycerol. SCWG of model compounds at temperature pressure feedstock concentration and reaction time of 500 ◦C 23–25 MPa 10 wt% and 1 h respectively revealed methanol to exhibit the highest H2 yield of 7.7 mmol/g followed by pure glycerol (4.4 mmol/g) and oleic acid (1.1 mmol/g). The effects of feedstock concentration from 30 wt% to 10 wt% increased H2 yield from all model compounds. Response surface methodology (RSM) was used to develop a response curve to visualize the interactive behavior and develop model equations for the prediction of H2 -rich gas yields as a function of the composition of model compounds in the crude glycerol mixture. Predictive models showed a good agreement with experimental results demonstrating high accuracy and robustness of the model. These findings demonstrated a strong potential of crude glycerol for SCWG to generate H2 -rich syngas.

This study performed a technical–economic analysis for ship-based ammonia transportation to investigate the feasibility of international ammonia transportation. Ammonia is considered to be a vital hydrogen carrier so the international trade in ammonia by ship will considerably increase in the future. This study proposed three scenarios for transporting ammonia from the USA Saudi Arabia and Australia to South Korea and employed an 84000 m3 class ammonia carrier. Not only traditional very low sulfur fuel oil (VLSFO)/marine diesel oil (MDO) but also LNG and ammonia fuels were considered as propulsion and power generation fuels in the carrier. A life-cycle cost (LCC) model consisting of capital expenditure (CAPEX) and operational expenditure (OPEX) was employed for the cost estimation. The results showed that the transportation costs depend on the distance. The unit transportation cost from the USA to South Korea was approximately three times higher than that of Australia to South Korea. Ammonia fuel yielded the highest costs among the fuels investigated (VLSFO/MGO LNG and ammonia). When using ammonia fuel the unit transportation cost was approximately twice that when using VLSFO/MDO. The fuel costs occupied the largest portion of the LCC. The unit transportation costs from Australia to South Korea were 23.6 USD/ton-NH3 for the LVSFO/MDO fuel case 31.6 USD/ton-NH3 for the LNG fuel case and 42.9 USD/ton-NH3 for the ammonia fuel case. This study also conducted a sensitivity analysis to investigate the influence of assumptions including assumed parameters.

The study of the electrochemical catalyst conversion of renewable electricity and carbon oxides into chemical fuels attracts a great deal of attention by different researchers. The main role of this process is in mitigating the worldwide energy crisis through a closed technological carbon cycle where chemical fuels such as hydrogen are stored and reconverted to electricity via electrochemical reaction processes in fuel cells. The scientific community focuses its efforts on the development of high-performance polymeric membranes together with nanomaterials with high catalytic activity and stability in order to reduce the platinum group metal applied as a cathode to build stacks of proton exchange membrane fuel cells (PEMFCs) to work at low and moderate temperatures. The design of new conductive membranes and nanoparticles (NPs) whose morphology directly affects their catalytic properties is of utmost importance. Nanoparticle morphologies like cubes octahedrons icosahedrons bipyramids plates and polyhedrons among others are widely studied for catalysis applications. The recent progress around the high catalytic activity has focused on the stabilizing agents and their potential impact on nanomaterial synthesis to induce changes in the morphology of NPs.

Green hydrogen could contribute to climate change mitigation but its greenhouse gas footprint varies with electricity source and allocation choices. Using life-cycle assessment we conclude that if electricity comes from additional renewable capacity green hydrogen outperforms fossil-based hydrogen. In the short run alternative uses of renewable electricity likely achieve greater emission reductions.

Proliferation of co-located petrol-hydrogen fueling stations is an effective solution for widespread deployment of hydrogen as a transportation fuel. Such combined fueling stations largely rely on existing infrastructure hence represent a low-cost option for setting up hydrogen fueling facilities. However optimizing the layout of dual petrol-hydrogen fueling stations and their rational site selection is critical for ensuring the efficient use of re sources. This paper investigates the site selection of combined hydrogen and petrol fueling stations at the ter minus of China’s "West-to-East Hydrogen Pipeline" project. A weighting model based on EWM-CRITIC-Game Theory is developed and the weight coefficients derived from game theory are used to perform the compre hensive ranking of potential sites. The combined evaluation results yield an overall ranking of A9 > A4 > A8 > A26 > A20 > A21 > A11. The effectiveness of this novel method is verified by comparing the results with those obtained from Copeland Borda Average and geometric mean methods. Considering the actual distance con straints the final site ranking is A9 > A4 > A8 > A20 > A21 > A11 > A14. This location offers optimal con ditions for infrastructure integration and hydrogen fueling service coverage. The reliability analysis indicates that the proposed game theory-based method delivers strong performance across various scenarios underscoring its reliability and versatility in consistently delivering accurate results.

Photocatalysis offers an attractive strategy to upgrade H2O to renewable fuel H2. However current photocatalytic hydrogen production technology often relies on additional sacrificial agents and noble metal cocatalysts and there are limited photocatalysts possessing overall water splitting performance on their own. Here we successfully construct an efficient catalytic system to realize overall water splitting where hole-rich nickel phosphides (Ni2P) with polymeric carbon-oxygen semiconductor (PCOS) is the site for oxygen generation and electron-rich Ni2P with nickel sulfide (NiS) serves as the other site for producing H2. The electron-hole rich Ni2P based photocatalyst exhibits fast kinetics and a low thermodynamic energy barrier for overall water splitting with stoichiometric 2:1 hydrogen to oxygen ratio (150.7 μmol h−1 H2 and 70.2 μmol h−1 O2 produced per 100 mg photocatalyst) in a neutral solution. Density functional theory calculations show that the co-loading in Ni2P and its hybridization with PCOS or NiS can effectively regulate the electronic structures of the surface active sites alter the reaction pathway reduce the reaction energy barrier boost the overall water splitting activity. In comparison with reported literatures such photocatalyst represents the excellent performance among all reported transition-metal oxides and/or transition-metal sulfides and is even superior to noble metal catalyst.

A form of long-term hydrogen storage with high volume efficiency is hydrogen absorption into the host lattice of a metal or an alloy. Unlike high-pressure hydrogen storage this form of storage is characterised by a low operating pressure. By employing metal hydride (MH) materials in a low-pressure refuelling station it is possible to significantly increase the safety of hydrogen storage and at the same time to facilitate the refuelling of external devices that use MH storage tanks without the necessity of using a compressor. In this article a methodology for the identification of the mathematical correlations among the hydrogen pressure in the storage tank the hydrogen concentration in the alloy and the volumetric flow rate of hydrogen is described. This methodology may be used to identify the kinetics of the process and to create simplified simulations of the hydrogen release from an absorption-based storage tank by applying a finite difference method. The mathematical correlations are based on measurements of hydrogen desorption during which hydrogen was released from the storage tank at stabilised pressure levels. The resulting mathematical description facilitates the identification of the approximate hydrogen pressure depending on its flow rate for a particular MH storage tank while respecting the complexity of its internal structure heat transfer and the hydrogen’s passage through a porous powder MH material. The identified mathematical dependence applies to the certified MNTZV-159 storage tank at pressures ranging from 7 to 29.82 bar with hydrogen concentrations ranging from 0.223 to 1.342% an input temperature of 59.5 ◦C and a cooling water flow rate of 4.36 L·min−1 . This methodology for the identification of a correlation between the flow rate pressure and hydrogen concentration applies to this particular type of storage tank and it depends not only on the alloy used and the quantity of this alloy but also on the internal structure of the heat exchanger.

A key factor in reducing the cost of green hydrogen production projects using water electrolysis systems is to minimize the degradation of the electrolyzer stacks as this impacts the lifetime of the stacks and therefore the frequency of their replacement. To create a better understanding of the economics of stack degradation we present a linear optimization approach minimizing the costs of a green hydrogen supply chain including an electrolyzer with degradation modeling. By calculating the levelized cost of hydrogen depending on a variable degradation threshold the cost optimal time for stack replacement can be identified. We further study how this optimal time of replacement is affected by sensitivities such as the degradation scale the load-dependency of both degradation and energy demand and the costs of the electrolyzer. The variation of the identified major sensitivity degradation scale results in a difference of up to 9 years regarding the cost optimal time for stack replacement respectively lifetime of the stacks. Therefore a better understanding of the degradation impact is imperative for project cost reductions which in turn would support a proceeding hydrogen market ramp-up.

Green hydrogen is a cornerstone in the global quest for a carbon-neutral future offering transformative potential for decarbonizing transportation. This study investigates its role by assessing the feasibility of a large-scale hydrogen refueling station in Germany focusing on integrating renewable energy sources. A hydrogen demand model with a 10-min time resolution to refuel 30 trucks and 20 vans (1019 kg/day) is combined with a techno-economic optimization model to evaluate a hybrid energy system utilizing wind solar and grid electricity. Scenario-based analysis reveals that Levelized Cost of Hydrogen ranges from 13.92 to 18.12 €/kg primarily influenced by electricity costs. Excess electricity sales can reduce this cost to 13.34–16.92 €/kg. On-site wind energy reduces storage and grid reliance achieving the lowest hydrogen cost. Unlike prior studies this work combines temporally resolved hydrogen demand profiles with comprehensive techno-economic modeling offering unprecedented insights into decentralized green hydrogen systems for heavy-duty transport. By bridging critical gaps in the scalability and economic feasibility of Power-to-Hydrogen systems it provides viable strategies for advancing green hydrogen infrastructure.

This prospective life cycle assessment (LCA) compares the environmental impacts of alkaline electrolyser (AE) and proton exchange membrane (PEM) electrolyser systems for green hydrogen production with a special focus on the stack components. The study evaluates both baseline and near-future advanced designs considering cradle-to-gate life cycle from material production to operation. The electricity source followed by the stacks are identified as major contributors to environmental impacts. No clear winner emerges between AE and PEM in relation to environmental impacts. The advanced designs show a reduced impact in most categories compared to baseline designs which can mainly be attributed to the increased current density. Advanced green hydrogen production technologies outperform grey and blue hydrogen production technologies in all impact categories except for minerals and metals resource use due to rare earth metals in the stacks. Next to increasing current density decreasing minimal load requirements. improving sustainable mining practices (including waste treatment) and low carbon intensity steel production routes can enhance the environmental performance of electrolyser systems aiding the transition to sustainable hydrogen production.

Underground Hydrogen Storage (UHS) has gathered interest over the past decade as an efficient means of storing energy. Although a significant number of research and demonstration projects have sought to understand the associated technical challenges it is yet to be achieved on commercial scales. We highlight case studies from town gas and blended hydrogen storage focusing on leakage pathways and hydrogen reactivity. Experience from helium storage serves as an analogue for the containment security of hydrogen as the two gases share physiochemical similarities including small molecular size and high diffusivity. Natural gas storage case studies are also investigated to highlight well integrity and safety challenges. Technical parameters identified as having adverse effects on storage containment security efficiency and hydrogen reactivity were then used to develop high-level and site-specific screening criteria. Thirty-two depleted offshore hydrocarbon reservoirs in the UK Continental Shelf (UKCS) are identified as potential storage formations based on the application of our high-level criteria. The screened fields reflect large hydrogen energy capacities low cushion gas requirements and proximity to offshore wind farms thereby highlighting the widespread geographic availability and potential for efficient UHS in the UKCS. Following the initial screening we propose that analysis of existing helium concentrations and investigation of local tectonic settings are key site-specific criteria for identifying containment security of depleted fields for stored hydrogen.

Adopting machine learning (ML) in hydrogen systems is a promising approach that enhances the efficiency reliability and sustainability of hydrogen power systems and revolutionizes the hydrogen energy sector to optimize energy usage/management and promote sustainability. This study explores hydrogen energy systems including production storage and applications while establishing a connection between machine learning solutions and the challenges these systems face. The paper provides an in-depth review of the literature examining not only ML techniques but also optimization algorithms evaluation methods explainability techniques and emerging technologies. By addressing these aspects we highlight the key factors of new technologies and their potential benefits across the three stages of the hydrogen value chain. We also present the advantages and limitations of applying ML models in this field offering recommendations for their optimal use. This comprehensive and precise work serves as the most current and complete examination of ML applications within the hydrogen value chain providing a solid foundation for future research across all stages of the hydrogen industry.

The utilization of “green” hydrogen in transportation areas gives rise to production- and supply infrastructure-related challenges; therefore its wider application in automotive transport would lead to higher demand with cost reduction and a faster expansion of the hydrogen refuelling network. This study presents energy and environmental performance indicators analyses of a Nissan Qashqai J10 engine during the Worldwide Harmonised Light Vehicles Test Cycle (WLTC) replacing conventional fossil gasoline with dual-fuel (D-F) gasoline and hydrogen. Numerical modelling was conducted using AVL Cruise™ (Version R2022.2) software utilizing the torque fuel consumption and environmental performance data of the HR16DE engine obtained through experimental testing across a wide range of loads and speeds on an engine test bench. The experimental investigation was carried out in two stages: using pure gasoline (G100); injecting a hydrogen additive into the intake air constituting 5% of the gasoline mass (G95H5). Following similar stages numerical modelling was conducted using the vehicle’s technical specifications to calculate engine load and speed throughout the WLTC range. Instant fuel consumption and pollutant emissions (CO CH NOx) were determined for various driving modes using experimental data maps. CO2 emissions were calculated considering fuel composition and consumption. By integrating the instant values the total and specific fuel consumption and emissions were calculated. As a result this study identified the effect of a 5% hydrogen additive in improving engine energy efficiency reducing incomplete combustion products and lowering greenhouse gas (CO2) emissions under various driving modes. Finally the results were compared with the requirements of EU standards.

Explosions of combustible gases under ambient turbulence exhibit complex flame propagation and overpressure evolution characteristics posing challenges to explosion safety assessments. In this study explosion behaviors of hydrogen-doped natural gas under various wind speeds were investigated using a small-scale experimental system. The results show that when the wind speed does not exceed 2 m/s ambient turbulence promotes flame acceleration and overpressure enhancement with the maximum overpressure increased by 20.7% compared to the no-wind condition. However when the wind speed exceeds 2 m/s turbulence suppresses flame propagation leading to a reduction in maximum overpressure by up to 50.5%. Under early-stage turbulent disturbances the flame front exhibits instability from the ignition stage resulting in a continuous transition from laminar to turbulent combustion without a distinct critical instability radius. Furthermore a modified overpressure prediction model is proposed by incorporating a flame wrinkling factor into the Thomas model and adopting a dimensionless distance treatment from the TNO multi-energy model. The proposed model achieves a root mean square error of 0.140 kPa under various wind speed conditions demonstrating good predictive accuracy.

This paper presents a novel literature survey on leveraging electrolysis for grid frequency stabilization in power systems with high penetration of renewable energy sources (RESs) uniquely integrating global research findings with specific insights into the Polish energy context—a region facing acute grid challenges due to rapid RES growth and infrastructure limitations. The intermittent nature of wind and solar power exacerbates frequency fluctuations necessitating dynamic demand-side management solutions like hydrogen production via electrolysis. By synthesizing over 30 studies the survey reveals key results: electrolysis systems particularly PEM and alkaline electrolyzers can reduce frequency deviations by up to 50% through fast frequency response (FFR) and primary reserve provision as demonstrated in simulations and real-world pilots (e.g. in France and the Netherlands); however economic viability requires enhanced compensation schemes with current models showing unprofitability without subsidies. Technological advancements such as transistor-based rectifiers improve efficiency under partial loads while integration with RES farms mitigates overproduction issues as evidenced by Polish cases where 44 GWh of solar energy was curtailed in March 2024. The survey contributes actionable insights for policymakers and engineers including recommendations for deploying electrolyzers to enhance grid resilience support hydrogen-based transportation and facilitate Poland’s target of 50.1% RESs by 2030 thereby advancing the green energy transition amid rising instability risks like blackouts in RES-heavy systems.

Methanol steam reforming (MSR) represents a highly promising pathway for sustainable hydrogen production due to its favorable hydrogen-to-carbon ratio and relatively low operating temperatures. The performance of the MSR process is strongly dependent on the selection and rational design of catalysts which govern methanol conversion hydrogen selectivity and the suppression of undesired side reactions such as carbon monoxide formation. Moreover advancements in reactor configuration and thermal management strategies play a vital role in minimizing heat loss and enhancing heat and mass transfer efficiency. Effective carbon monoxide removal technologies are indispensable for obtaining high-purity hydrogen particularly for applications sensitive to CO contamination. This review systematically summarizes recent progress in catalyst development reactor design and gas purification technologies for MSR. In addition the key technical challenges and potential future directions of the MSR process are critically discussed. The insights provided herein are expected to contribute to the development of more efficient stable and scalable MSR-based hydrogen production systems.

Given the rising interest in hydrogen economy alternative feedstocks are explored for their potential use for hydrogen production such as H2S a notable byproduct from oil and gas operations. This study presents a computational investigation on the thermodynamics kinetics and mechanisms of non-catalytic H2S-steam reforming (H2SSR) as a pathway for H2S-to-H2 benchmarked to H2S thermal decomposition (H2SPyrol) (as a limiting case without water). The mechanism integrates key elementary steps form different reaction pathways including H2S partial oxidation H2O reduction and H2S thermal decomposition. Results from the model are validated using available experimental data for H2SPyrol and H2SSR. Homogeneous gas-phase reactions are modelled at different H2O:H2S ratios reaction temperatures pressure and times. Thermodynamically the H2SSR reaction is unfavorable due to the presence of water and its role in increasing the reaction complexity and endothermicity; however kinetically water contributes to increasing the hydrogen yield at least 9 times that from H2SPyrol achieving 99.23 % H2S conversion at 1473 K with an excess H2O:H2S feed ratio of 200:1. The contribution of water during the H2SSR reaction is interpreted using reaction path and rate of production analyses demonstrating its role in producing an abundant pool of OH and H radicals. These radicals catalyze the cleavage of H2S-SH bonds accelerating hydrogen production at an optimal reaction time of 0.07–0.105 s. This study paves the path for future kinetic and catalytic research to optimize the technical viability of H2SSR as a promising H2S-to-H2 conversion pathway for sour wastewater reutilization.

The hydrogen economy stands at the forefront of the global energy transition and additive manufacturing (AM) is increasingly recognized as a critical enabler of this transformation. AM offers unique capabilities for improving the performance and durability of hydrogen energy components through rapid prototyping topology optimization functional integration of cooling channels and the fabrication of intricate hierarchical structured pores with precisely controlled connectivity. These features facilitate efficient heat and mass transfer thereby improving hydrogen production storage and utilization efficiency. Furthermore AM’s multi-material and functionally graded printing capability holds promise for producing components with tailored properties to mitigate hydrogen embrittlement significantly extending operational lifespan. Collectively these advances suggest that AM could lower manufacturing costs for hydrogen-related systems while improving performance and reliability. However the current literature provides limited evidence on the integrated techno-economic advantages of AM in hydrogen applications posing a significant barrier to large-scale industrial adoption. At present the technological readiness level (TRL) of AM-based hydrogen components is estimated to be 4–5 reflecting laboratory-scale progress but underscoring the need for further development validation and industrial-scale demonstration before commercialization can be realized.

The present research work investigates the performance of two large-scale energy storage technologies: hydro-pumped storage (HPS) and green hydrogen production within a hybrid renewable energy system (HRES) developed for Kefalonia Island Greece. Given the island’s seasonal water and electricity shortages driven by summer demand and limited infrastructure the goal is to identify which storage option better supports local autonomy. Two scenarios differing only in storage method were simulated using identical wind input and desalination setup. Performance was evaluated based on climate and demand data focusing on water and electricity needs. Both scenarios achieved 99.9 % potable water coverage. The HPS system exhibited notably higher energy efficiency (67 %) compared to hydrogen (33 %) and produced slightly more desalinated water reaching 18157791 m3 versus 17986544 m3 respectively. Electricity demand coverage reached 77.8 % with HPS and 76.0 % with hydrogen while irrigation demand was met by 80.2 % and 79.4 % respectively. Seasonal storage analysis revealed pronounced summer depletion in both cases due to high demand and low wind availability with HPS recovering faster and maintaining higher storage levels owing to lower energy losses. The comparison underscores the need for storage strategies adapted to island-specific water and energy dynamics. HPS is more efficient for short-to-medium-term needs while green hydrogen offers potential for long-duration storage and deeper decarbonization.

The carbon-neutral and carbon-negative energy utilization technologies have long been people pursued to realize the strategic objective of carbon neutrality. Herein we propose a cation-exchange membrane (CEM) direct formate-CO2 fuel cell that possesses the capability of simultaneously generating electricity and producing hydrogen as well as continuously transforming carbon dioxide into pure sodium bicarbonate. Using the CO2- derived formate fuel the roof-of-concept CEM direct formate-CO2 fuel cell exhibits a peak power density of 38 mW cm− 2 at 80 ◦C without the assistance of additional electrolyte. The fairly stable constant-current discharge curve along with the detected hydrogen and pure sodium bicarbonate prove the conceptual feasibility of this electricity‑hydrogen-bicarbonate co-production device. By adding alkaline electrolyte to the anode we achieved a higher peak power density of 63 mW cm− 2 at the corresponding hydrogen production rate of 0.57 mL min− 1 cm− 2 . More interestingly the concentrations of pure NaHCO3 solution can be controlled by adjusting the cathode water flow rate and fuel cell discharge current density. This work presents a theoretically feasible avenue for coupling hydrogen production and CO2 utilization.

This study conducts a thorough review of fuel cell technology including types economy applications and V2G scheme. Fuel cells have been considered for diverse applications namely electric vehicles specialty vehicles such as warehouse forklifts public transportation including buses trains and ferries. Other applications include grid-related stationary and portable applications. Among available five types of fuel cells PEMFC is presently the optimal choice for electric vehicle usage due to its low operating temperature and durability. Meanwhile high temperature fuel cells such as MCFC and SOFC currently remain the best choice for utility and grid related applications. The economy of fuel cells has been continuously improving and has been illustrated to only grow into a potential main source of sustainable energy soon. With the transportation sector as fuel cell electric ve hicles evolve V2G technology is beneficial towards energy efficiency and fuel cell economy. There is evidence for V2G using FCEV being more advantageous in comparison to conventional BEVs. The costs of the five types of fuel cell vary from US$1784 to US$4500 per kW capacity. The findings are beneficial for researchers and industry professionals who wish to gain comprehensive understanding of fuel cells for adoption and development of the emerging low-emission energy solutions.

Hydrogen-powered unmanned aerial vehicles (UAVs) offer significant advantages such as environmental sustainability and extended endurance demonstrating broad application prospects. However the hydrogen fuel cells face prominent thermal management challenges during flight operations. This study established a numerical model of the fuel cell thermal management system (TMS) for a hydrogen-powered UAV. Computational fluid dynamics (CFD) simulations were subsequently performed to investigate the impact of various design parameters on cooling performance. First the cooling performance of different fan density configurations was investigated. It was found that dispersed fan placement ensures substantial airflow through the peripheral flow channels significantly enhancing temperature uniformity. Specifically the nine-fan configuration achieves an 18.5% reduction in the temperature difference compared to the four-fan layout. Additionally inlets were integrated with the fan-based cooling system. While increased external airflow lowers the minimum fuel cell temperature its impact on high-temperature zones remains limited with a temperature difference increase of more than 19% compared to configurations without inlets. Furthermore the middle inlet exhibits minimal vortex interference delivering superior thermal performance. This configuration reduces the maximum temperature and average temperature by 9.1% and 22.2% compared to the back configuration.

We develop a bidding strategy for a hybrid power plant combining co-located wind turbines and an electrolyzer constructing a price-quantity bidding curve for the day-ahead electricity market while optimally scheduling hydrogen production. Without risk management single imbalance pricing leads to an all-or-nothing trading strategy which we term “betting”. To address this we propose a data-driven pragmatic approach that leverages contextual information to train linear decision policies for both power bidding and hydrogen scheduling. By introducing explicit risk constraints to limit imbalances we move from the all-or-nothing approach to a “trading” strategy where the plant diversifies its power trading decisions. We evaluate the model under three scenarios: when the plant is either conditionally allowed always allowed or not allowed to buy power from the grid which impacts the green certification of the hydrogen produced. Comparing our data-driven strategy with an oracle model that has perfect foresight we show that the risk-constrained data-driven approach delivers satisfactory performance.

This study presents a hybrid power system comprising a fuel cell (FC) and a lithium-ion battery (LIB) for liquid hydrogen (LH2) carriers which is expected to increase globally due to the production cost gap of green hydrogen between renewable-rich and renewable-poor countries. The LH2 carrier has a key challenge in handling the inevitably considerable boil-off hydrogen (BOH). As a target ship of a 50000 m3 LH2 carrier with a boil-off rate (BOR) of 0.4% per day this study employs an optimization tool to determine the economic power dispatch between the FC and LIB aimed at minimizing the lifetime cost of the ship. The BOH is used as fuel for FC during the voyage. Moreover when the ship is under cargo loading and unloading operations at the port the considerable surplus BOH is utilized to generate electricity and then sold to the shore grid (StG). The results indicate that 45.2% of the BOH can be utilized as fuel for the FC and the StG system can effectively reduce the total lifetime cost by 32.0%. Further the paper presents the outcomes of a sensitivity analysis conducted on critical parameters. This study provides new insights into the BOH issue of LH2 carriers and helps to increase the international green hydrogen market.

Recent studies on additive manufacturing (AM) have indicated the necessity of understanding the hydrogen embrittlement (HE) of high-strength steels fabricated by AM due to the different microstructure obtained compared to their conventionally processed counterparts. This study investigated the influence of post-AM tempering (at 205 ◦C 315 ◦C and 425 ◦C) on the HE resistance of AM-fabricated AISI 4340 steel a representative ultrahigh-strength medium-carbon low-alloy steel. The present results show that tempering effectively reduced the HE sensitivity of the steel. When tested in air tempering at a low temperature of 205 ◦C slightly increased both the yield strength (YS) and ultimate tensile strength (UTS) accompanied by a reduction in elongation (EL). This behaviour is attributed to the precipitation of carbides. In contrast higher tempering temperatures of 315 ◦C and 425 ◦C resulted in a progressive decrease in both YS and UTS as anticipated. However when tested in a hydrogen-rich environment although the HE dramatically reduced the ductility and YS could not even be determined for the samples tempered at 205 ◦C and 315 ◦C the tempered samples retained higher UTS and EL compared to the as-AM-fabricated samples because of the increased HE resistance by tempering. Microstructural examination indicated that tempering at 205 ◦C and 315 ◦C retained the bainitic microstructure while promoting the formation of fine carbide precipitates which softened the bainitic ferrite matrix enhancing the hydrogen trapping capacity. Tempering at 425 ◦C promoted recovery of the AM-fabricated steel reducing dislocation density producing a lower subsurface hydrogen concentration and higher hydrogen diffusivity which led to an enhanced HE resistance. As a result testing of the samples tempered at 425 ◦C in hydrogen resulted in a high YS (~1200 MPa) and only a ~5 % reduction in UTS and a 64 % reduction in EL compared with the untempered samples of which the reductions were 31 % in UTS and 79 % in EL. Furthermore this study underscores the critical role of the trap character in governing the HE behaviour offering a pathway toward optimised heat treatment strategies for improved HE resistance of additively manufactured high-strength steels.

A compact hydrogen supply system for thermally integrating metal hydride (MH) tanks with a proton exchange membrane fuel cell (PEMFC) for a hydrogen-powered electric-assist bicycle (H-bike) is proposed. The system recovers the exhaust heat generated by the PEMFC to sustain hydrogen desorption and improve the system’s energy efficiency. The results demonstrate that the split-tank strategy decreases thermal and pressure gradients and enhances heat transfer and hydrogen release. The honeycomb tank configuration further improves hydrogen desorption by promoting uniform airflow distribution around each tank thereby improving exhaust heat utilization from the PEMFC. It employs a layer-adjustable configuration facilitating the flexible adaptation of MH cartridge quantities to meet hydrogen demand and prevailing road conditions in urban areas. Under a PEMFC power output of 215 W the system maintains a stable hydrogen flow rate for over 30 min with a heat recovery efficiency of 22.62 %. Furthermore increasing the number of MH cartridge layers significantly improves the thermal utilization of the system achieving a utilization efficiency of 39.90 % with two layers. These findings confirm the feasibility and scalability of the proposed system for H-bike highlighting its potential as a decentralized hydrogen supply solution for lightweight mobility and urban transportation applications.

Hydrogen plasma offers an emerging route for carbon-free iron oxide reduction but typical inert gas dilution limits industrial applicability. This study explores pure hydrogen and hydrogen–carbon dioxide plasma for in-flight hematite reduction in atmospheric elongated arc discharge. Pure hydrogen yields the lowest power consumption but reduced plasma stability and limited conversion. CO2 addition enhances stability increasing gas temperature from approximately 1900 K (pure H2 ) to 2900 K at 50% CO2 driven by exothermic H2 oxidation. Particle rapidly reach gas temperature (>2000 K within 5 ms). The highest metallization degree (≈37%) achieved at 30% CO2 corresponds to an optimal reductant gas composition balancing hydrogen carbon monoxide and atomic hydrogen availability. Higher dilution (50% CO2 ) significantly decreased the reductant gas availability lowering the degree of reduction despite higher temperatures. These insights demonstrate that controlled CO2 co-feeding and regeneration optimize plasma stability temperature and reductant gas chemistry presenting a promising approach towards scalable and energy-efficient hydrogen plasma smelting reduction for sustainable metallurgy with a CO2 closed loop.

Improving the efficiency and range of hydrogen-powered electric vehicles (HPEVs) is essential for their global adoption especially in developing countries with limited resources. This study systematically evaluates regenerative braking and suspension systems in HPEVs and proposes a deployment-focused framework tailored to the needs of developing nations. A comprehensive search was performed across multiple databases to identify relevant studies. The selected studies are screened assessed for quality and analyzed based on predefined criteria. The data is synthesized and interpreted to identify patterns gaps and conclusions. The findings show that regeneration systems such as regenerative braking and regenerative suspension are the most effective energy recovery systems in most electric and hydrogen-powered vehicles. Although the regenerative braking system (RBS) offers higher energy efficiency gains that enhance cost-effectiveness despite its high initial investment the regenerative suspension system (RSS) involves increased complexity. Still it offers comparatively efficient energy recovery particularly in developing countries with patchy road infrastructure. The gaps highlighted in this review will aid researchers and vehicle manufacturers in designing optimizing developing and commercializing HPEVs for deployment in developing countries.

By turning a waste stream into a clean energy source green hydrogen generation from wastewater provides a dual solution to energy and environmental problems. This study presents a thorough bibliometric analysis of research trends in the field of green hydrogen generation from wastewater between 2010 and 2024. A total of 221 publications were extracted from Scopus database and VOSviewer (1.6.20) was used as a visualization tool to identify influential authors institutions collaborations and thematic focus areas. The analysis revealed a significant increase in research output with a peak of 122 publications in 2024 with a total of 705 citations. China had the most contributions with 60 publications followed by India (30) and South Korea (26) indicating substantial regional involvement in Asia. Keyword co-occurrence and coauthorship network mapping revealed 779 distinct keywords grouped around key themes like electrolysis hydrogen evolution reactions and wastewater treatment. Significantly this work was supported by contributions from 115 publication venues with the International Journal of Hydrogen Energy emerging as the most active and cited source (40 articles 539 citations). The multidisciplinary aspect of the area was highlighted by keyword co-occurrence analysis which identified recurring themes including electrolysis wastewater treatment and hydrogen evolution processes. Interestingly the most-cited study garnered 131 citations and discussed the availability of unconventional water sources for electrolysis. Although there is growing interest in the field it is still in its initial phases indicating a need for additional research particularly in developing countries. This work offers a basic overview for researchers and policymakers who are focused on promoting the sustainable generation of green hydrogen from wastewater.

Photocatalytic membrane reactors (PMRs) which combine photocatalysis with membrane separation represent a pivotal technology for sustainable water treatment and resource recovery. Although extensive research has documented various configurations of photocatalytic-membrane hybrid processes and their potential in water treatment applications a comprehensive analysis of the interrelationships among reactor architectures intrinsic physicochemical mechanisms and overall process efficiency remains inadequately explored. This knowledge gap hinders the rational design of highly efficient and stable reactor systems—a shortcoming that this review seeks to remedy. Here we critically examine the connections between reactor configurations design principles and cutting-edge applications to outline future research directions. We analyze the evolution of reactor architectures relevantreaction kinetics and key operational parameters that inform rational design linking these fundamentals to recent advances in solar-driven hydrogen production CO2 conversion and industrial scaling. Our analysis reveals a significant disconnect between the mechanistic understanding of reactor operation and the system-level performance required for innovative applications. This gap between theory and practice is particularly evident in efforts to translate laboratory success into robust and economically feasible industrial-scale operations. We believe that PMRs willrealize theirtransformative potential in sustainable energy and environmental applications in future.

The main component of the hydrogen production system is the electrolyzer (EL) which is used to convert electrical energy and water into hydrogen and oxygen. The power converter supplies the EL and the controller is used to ensure the global stability and safety of the overall system. This review aims to investigate and analyze each one of these components: Proton Exchange Membrane Electrolyzer (PEM EL) electrical modeling DC/DC power converters and control approaches. To achieve this desired result a review of the literature survey and an investigation of the PEM EL electrical modeling of the empirical and semi-empirical including the static and dynamic models are carried out. In addition other sub-models used to predict the temperature gas flow rates (H2 and O2 ) hydrogen pressure and energy efficiency for PEM EL are covered. DC/DC power converters suitable for PEM EL are discussed in terms of efficiency current ripple voltage ratio and their ability to operate in the case of power switch failure. This review involves analysis and investigation of PEM EL control strategies and approaches previously used to achieve control objectives robustness and reliability in studying the DC/DC converter-PEM electrolyzer system. The paper also highlights the online parameter identification of the PEM electrolyzer model and adaptive control issues. Finally a discussion of the results is developed to emphasize the strengths weaknesses and imperfections of the literature on this subject as well as proposing ideas and challenges for future work.

Solid oxide fuel cells (SOFC) have not received enough attention as a power source in the transportation sector. However with the development of the technology its advantages over other types of fuel cells such as fuel flexibility and high energy efficiency have made SOFC an interesting option. The present study aims at simulation and experimentally validation of the performance of a hydrogen-powered SOFC in an automotive application. A 6 kW SOFC stack is tested and its model is integrated into a series hybrid electric vehicle model. A fuzzy controller is designed to regulate the charging current between the battery and the SOFC in the vehicle model. Experimental tests are also conducted in a few cases on the SOFC based on the simulation results. The performance of the real SOFC stack is then analysed under dynamic loads to see how the desired current is provided in practice. The results demonstrate a good performance of the SOFC stack under variable load conditions.

This article proposes a novel open-circuit switch fault diagnosis method (FDM) for a three-level interleaved buck converter (TLIBC) in a hydrogen production system based on the water electrolysis process. The control algorithm is suitably modified to ensure the same hydrogen production despite the fault. The TLIBC enables the interfacing of the power source (i.e. low-carbon energy sources) and electrolyzer while driving the hydrogen production of the system in terms of current or voltage. On one hand the TLIBC can guarantee a continuity of operation in case of power switch failures because of its interleaved architecture. On the other hand the appearance of a power switch failure may lead to a loss of performance. Therefore it is crucial to accurately locate the failure in the TLIBC and implement a fault-tolerant control strategy for performance purposes. The proposed FDM relies on the comparison of the shape of the input current and the pulse width modulation (PWM) gate signal of each power switch. Finally an experimental test bench of the hydrogen production system is designed and realized to evaluate the performance of the developed FDM and fault-tolerant control strategy for TLIBC during post-fault operation. It is implemented with a real-time control based on a MicroLabBox dSPACE (dSPACE Paderborn Germany) platform combined with a TI C2000 microcontroller. The obtained simulation and experimental results demonstrate that the proposed FDM can detect open-circuit switch failures in one switching period and reconfigure the control law accordingly to ensure the same current is delivered before the failure.

In the search of low-carbon hydrogen production routes this study evaluates four biomass gasification processes: conventional steam gasification (CSG) sorption-enhanced gasification (SEG) and their solar-assisted variants (SSG and SSEG). The comparison focuses on three key aspects: hydrogen production overall energy efficiency (to H2 and power) and carbon capture potential (generation of a pure CO2 process stream for storage or utilization). For a realistic comparison a pseudo-equilibrium model of a double-bed gasifier was developed based on experimental correlations of char conversion under conventional and SEG conditions. The solar processes were designed for stable year-round operation considering seasonal weather variations by appropriately dimensioning the heliostat field and the thermal and chemical energy storage systems whose inventory dynamics were modelled. Both the gasifier and central solar tower models were rigorously validated with published data enhancing the reliability of the results. Solar-assisted configurations significantly outperform non-solar ones in hydrogen production with SSEG yielding 128 kg H2/ton biomassdaf compared to 90–95 kg for non-solar options. SEG demonstrates superior carbon capture potential (76 %) while solar-assisted systems achieve higher energy efficiency (67–73 % vs. 60–63 % for non-solar). These results underscore the potential of solar-assisted gasification for sustainable hydrogen production offering enhanced yields improved efficiency and substantial carbon capture capabilities. Future work will involve economic and environmental analysis to determine the best overall configuration.

Hydrogen is a sustainable clean source of energy and a viable alternative to carbon-based fossil fuels. To support the transport sector’s transition from fossil fuels to hydrogen a hydrogen refuelling station network is being developed to refuel hydrogen-powered vehicles. However hydrogen’s inherent properties present a significant safety challenge and there have been several hydrogen incidents noted with severe impacts to people and assets reported from operational hydrogen refuelling stations worldwide. This paper presents the outcome of an analysis of hydrogen incidents that occurred at hydrogen refuelling stations. For this purpose the HIAD 2.1 and H2tool.org databases were used for the collection of hydrogen incidents. Forty-five incidents were reviewed and analysed to determine the frequent equipment failures in the hydrogen refuelling stations and the underlying causes. This study adopted a mixed research approach for the analysis of the incidents in the hydrogen refuelling stations. The analysis reveals that storage tank failures accounted for 40% of total reported incidents hydrogen dispenser failures accounted for 33% compressors accounted for 11% valves accounted for 9% and pipeline failures accounted for 7%. To enable the safe operation of hydrogen refuelling stations hazards must be understood effective barriers implemented and learning from past incidents incorporated into safety protocols to prevent future incidents.

This paper investigates technological pathways for the conversion of coal-fired power plants toward sustainable energy sources using an integrated multi-criteria decisionmaking approach that combines Proknow-C AHP and PROMETHEE. Eight alternatives were identified: full conversion to natural gas full conversion to biomass coal and natural gas hybridization coal and biomass hybridization electricity and hydrogen cogeneration coal and solar energy hybridization post-combustion carbon capture systems and decommissioning with subsequent reuse. The analysis combined bibliographic data (26 scientific articles and 13 patents) with surveys from 14 energy experts using Total Decision version 1.2.1041.0 and Visual PROMETHEE version 1.1.0.0 software tools. Based on six criteria (environmental structural technical technological economic and social) the most viable option was full conversion to natural gas (ϕ = +0.0368) followed by coal and natural gas hybridization (ϕ = +0.0257) and coal and solar hybridization (ϕ = +0.0124). These alternatives emerged as the most balanced in terms of emissions reduction infrastructure reuse and cost efficiency. In contrast decommissioning (ϕ = −0.0578) and carbon capture systems (ϕ = −0.0196) were less favorable. This study proposes a structured framework for strategic energy planning that supports a just energy transition and contributes to the United Nations Sustainable Development Goals (SDGs) 7 and 13 highlighting the need for public policies that enhance the competitiveness and scalability of sustainable alternatives.

The ongoing energy transition and decarbonization efforts have prompted the development of Hybrid Renewable Energy Systems (HRES) capable of integrating multiple generation and storage technologies to enhance energy autonomy. Among the available options hydrogen has emerged as a versatile energy carrier yet most studies have focused either on stationary applications or on mobility seldom addressing their integration withing a single framework. In particular the potential of Metal Hydride (MH) tanks remains largely underexplored in the context of sector coupling where the same storage unit can simultaneously sustain household demand and provide in-house refueling for lightduty fuel-cell vehicles. This study presents the design and analysis of a residential-scale HRES that combines photovoltaic generation a PEM electrolyzer a lithium-ion battery and MH storage intended for direct integration with a fuel-cell electric microcar. A fully dynamic numerical model was developed to evaluate system interactions and quantify the conditions under which low-pressure MH tanks can be effectively integrated into HRES with particular attention to thermal management and seasonal variability. Two simulation campaigns were carried out to provide both component-level and system-level insights. The first focused on thermal management during hydrogen absorption in the MH tank comparing passive and active cooling strategies. Forced convection reduced absorption time by 44% compared to natural convection while avoiding the additional energy demand associated with thermostatic baths. The second campaign assessed seasonal operation: even under winter irradiance conditions the system ensured continuous household supply and enabled full recharge of two MH tanks every six days in line with the hydrogen requirements of the light vehicle daily commuting profile. Battery support further reduced grid reliance achieving a Grid Dependency Factor as low as 28.8% and enhancing system autonomy during cold periods.

Global demand for clean energy carriers like hydrogen (H2) is rising under carbon-reduction policies. While domestic H2 projects are progressing international trade presents significant opportunities for countries with abundant renewables or advanced production capabilities. Yet establishing H2 as a viable global commodity requires overcoming supply chain challenges in flexibility efficiency and cost. This review examines hydrogen supply chain network design (HSCND) studies and highlights key research gaps in export-oriented systems. Current work often focuses on transport technologies but lacks integrated analyses combining technical economic and policy dimensions. Notable gaps include limited research on retrofitting infrastructure for H2 derivatives underexplored roles of ports as export hubs and insufficient evaluation of regulatory frameworks and financial risks. This review proposes a methodological approach to guide HSCND for export supporting data collection and strategic planning. Future research should integrate technical geopolitical and social factors into models backed by methodological innovation and empirical evidence.

Developing cleaner processes via newer technologies will accelerate advancement toward more sustainable energy systems. Hydrogen is an energy carrier and an intermediate molecule in chemical processes. This research investigates an innovative hydrogen production process utilizing a non-thermal Cold Atmospheric Pressure Plasma-based Reformer (CAPR). Exploring environmentally friendly and economically viable pathways for hydrogen production is crucial for addressing climate change and reducing the carbon footprint of industrial processes. The study investigates the conversion of natural gas to hydrogen at ambient temperature and pressure highlighting the ability of plasma-based technology to operate without direct CO2 emissions.<br/>Initially through experimental studies natural gas was passed through the CAPR where the plasma's energetic discharges initiate the reforming process. Subsequently the produced hydrogen along with other light hydrocarbons enters the separation system for producing purified hydrogen. The research focuses on techno-economic analyses and sensitivity assessments to determine the levelized cost of producing hydrogen via a nanosecond plasma-based refining plant and benchmark technologies. Sensitivity analyses identify two primary factors that significantly affect the levelized cost of hydrogen production in a plasma-based reforming system.<br/>The research suggests that instead of producing carbon dioxide and capturing the emitted CO2 utilize processes that do not emit direct CO2. CAPR shows potential for cost competitiveness with conventional hydrogen production methods including steam methane reforming (SMR) and electrolysis. The findings underscore the need for further research to optimize the system's performance and cost-effectiveness positioning CAPR as a potentially transformative technology for the chemical process industry.

Solid oxide electrolysis cells (SOECs) have emerged as a promising technology for efficient energy storage and CO2 utilization via H2O–CO2 co-electrolysis. While most previous studies focused on planar or tubular configurations this work investigated a novel flat tubular SOEC design using a comprehensive 3D multi-physics model developed in COMSOL Multiphysics 5.6. This model integrates charge transfer gas flow heat transfer chemical/electrochemical reactions and structural mechanics to analyze operational behavior and thermo-mechanical stress under different voltages and pressures. Simulation results indicate that increasing operating voltage leads to significant temperature and current density inhomogeneity. Furthermore elevated pressure improves electrochemical performance possibly due to increased reactant concentrations and reduced mass transfer limitations; however it also increases temperature gradients and the maximum first principal stress. These findings underscore that the design and optimization of flat tubular SOECs in H2O–CO2 co-electrolysis should take the trade-off between performance and durability into consideration.

Hydrogen production from natural gas or biogas at different purity levels has emerged as an important technology with continuous development and improvement in order to stand for sustainable and clean energy. Regarding biogas which can be obtained from multiple sources hydrogen production through the steam reforming of methane is one of the most important methods for its energy use. In that sense the role of catalysts to make the process more efficient is crucial normally contributing to a higher hydrogen yield under milder reaction conditions in the final product. The aim of this review is to cover the main points related to these catalysts as every aspect counts and has an influence on the use of these catalysts during this specific process (from the feedstocks used for biogas production or the biodigestion process to the purification of the hydrogen produced). Thus a thorough review of hydrogen production through biogas steam reforming was carried out with a special emphasis on the influence of different variables on its catalytic performance. Also the most common catalysts used in this process as well as the main deactivation mechanisms and their possible solutions are included supported by the most recent studies about these subjects.

The transition to sustainable and smart urban energy systems requires combustion technologies that combine high efficiency with near-zero emissions. Moderate or intense low-oxygen dilution (MILD) combustion has emerged as a promising solution offering volumetric heat release reduced peak temperatures and strong NOX suppression ideal for integrating green hydrogen carriers such as ammonia and ammonia–hydrogen blends into stationary energy systems. While MILD combustion is well-studied for hydrocarbons its application to carbon-free fuels presents challenges including high ignition temperatures low reactivity and potential NOX formation. This review examines the behavior of ammonia-based fuels under MILD conditions mapping combustion regimes across reactor types and operating parameters. To address ignition and stability issues the review also explores plasma-assisted MILD combustion (PAMC). Non-equilibrium plasma (NEP) discharges promote radical generation reduce ignition delay times and enhance flame stability under lean highly diluted conditions. Recent experimental and numerical studies demonstrate that plasma activation can reduce ignition delay times by up to an order of magnitude lower flame lift-off heights by over 30 % in certain configurations and enhance OH radical concentrations and heat release intensity. The extent of these improvements depends on factors such as plasma energy input fuel type and dilution level. This review synthesizes key findings identifies technical gaps and highlights the potential of MILD and PAMC as clean flexible and scalable solutions for low-emission stationary energy generation in smart city environments.

With the rapid development of alternative fuel vehicles (AFVs) and renewable energy sources the increasing coordination between electric vehicles (EVs) and hydrogen vehicles (HVs) in urban coupled powertransportation networks (CPTNs) fosters optimized energy scheduling and enhanced system performance. This study proposes a two-level Stackelberg-Nash game framework for AFV-integrated microgrids in a CPTN to enhance the economic efficiency of microgrid. This framework employs a Stackelberg game model to define the leader-follower relationship between the microgrid operator and the vehicle-to-grid (V2G) aggregator. Nash equilibrium games are established to capture competitive interactions among charging stations (CSs) and among hydrogen refueling stations (HRSs). Furthermore an optimal scheduling model is proposed to minimize microgrid operation costs considering the spatiotemporal dynamics and user preferences of EVs and HVs supported by the proposed dynamic choice model. A game-theoretic pricing and incentive mechanism promotes AFV participation in V2G services enhancing the profitability of CSs and HRSs. Afterward a momentum-enhanced Stackelberg-Nash equilibrium algorithm is developed to address the bi-level optimization problem. Finally numerical simulations validate the effectiveness of the proposed method in improving economic efficiency and reducing operation costs. The proposed approach offers an effective solution for integrating large-scale AFV fleets into sustainable urban energy and transportation systems.

In recent years there has been an increasingly larger fraction of intermittent energy sources. In the northern parts of Europe the main source of intermittent power is wind power. This source of power is low inertia inconsistent and will always fluctuate with different magnitudes leaving a need for balancing. One source of balancing is to have the widespread non-zero inertia combined heat and power stations work as back-up sources. One way to boost the capability of these power sources is by adding an oxyfuel internal hydrogen combustor. To study the effects of this the steam generator was tested in four different positions within the power plant to test different possibilities with different levels of retrofits. The first was in the high- and lowpressure crossover the second was a reheat at a higher pressure the third was a superheat of the admission steam and finally the fourth was a superheat using the overload valves. The final results showed that the configurations of crossover reheat and superheat of admission steam were the best in terms of retrofit while the reheat at higher pressure was deemed the best in terms of backup capacity reaching a gain in power of 9.5 MW at a fuel efficiency of 30.93 %. The highest fuel efficiencies were shown by the latter two amounting to 45.19 % and 51.58 % in district heating mode respectively. There is great potential to be made from these power plants due to the possibility of increased capacity all across Sweden.

This study presents the conceptual design and evaluation of an HRS for light-duty FCEVs. The proposed system integrates wind turbines a water electrolyzer three-stage hydrogen compressor heat recovery and storage a two-stage Organic Rankine Cycle (TS-ORC) hydrogen storage tanks a Vapor Compression Refrigeration Cycle (VCRC) and a hydrogen dispenser. Waste heat from the hydrogen compression process is harnessed to power the TS-ORC where the first stage drives the VCRC and the second stage generates additional electricity. A comprehensive assessment of the system confirmed the system's compliance with the principles of thermodynamics. The results indicate an overall system efficiency of 25.4% and the wind turbines alone achieve 46.21% efficiency. The overall exergy destruction rate of the system is computed to be 2120 kW and the main exergy destruction occurs in wind turbines and water electrolyzer. The first and second stages of the ORC exhibit efficiencies of 14.45% and 6.05% respectively while the VCRC yields a Coefficient of Performance (COP) of 1.24. The specific energy consumption for electrolytic hydrogen production compression and pre-cooling are calculated as 58.83 1.99 and 0.29 kWh/kg respectively. The hydrogen dispenser fills an onboard hydrogen storage tank with a 4 kg capacity at 700 bar in 5.5 min.

The rapid development of fuel cell electric vehicles (FCEVs) has highlighted the critical importance of optimizing energy management strategies to improve vehicle performance energy efficiency durability and reduce hydrogen consumption and operational costs. However existing approaches often face limitations in real-time applicability adaptability to varying driving conditions and computational efficiency. This paper aims to provide a comprehensive review of the current state of FCEV energy management strategies systematically classifying methods and evaluating their technical principles advantages and practical limitations. Key techniques including optimization-based methods (dynamic programming model predictive control) and machine learning-based approaches (reinforcement learning deep neural networks) are analyzed and compared in terms of energy distribution efficiency computational demand system complexity and real-time performance. The review also addresses emerging technologies such as artificial intelligence vehicle-to-everything (V2X) communication and multi-energy collaborative control. The outcomes highlight the main bottlenecks in current strategies their engineering applicability and potential for improvement. This study provides theoretical guidance and practical reference for the design implementation and advancement of intelligent and adaptive energy management systems in FCEVs contributing to the broader goal of efficient and low-carbon vehicle operation.