Applications & Pathways

As hydrogen fuel cell vehicles gain momentum as crucial zero-emission transportation solutions the urgency to address hydrogen permeability through the polymer liner becomes paramount for ensuring the safety efficiency and longevity of Type IV hydrogen storage tanks. This paper synthesizes existing research findings analyzes the influence of different materials and structures on gas permeability elucidates the dissolution and diffusion mechanisms of hydrogen in plastic liners and discusses their engineering applications. We focus on measurement methods influencing factors and improvement strategies for liner gas permeability. Additionally we explore the prospects of Type IV hydrogen storage tanks in fields such as automotive aerospace and energy storage industries. Through this comprehensive review of liner gas permeability critical insights are provided to guide the development of efficient and safe hydrogen storage and transportation systems. These insights are vital for advancing the widespread application of hydrogen energy technology and fostering sustainable energy development significantly contributing to efforts aimed at enhancing the performance and safety of Type IV hydrogen storage tanks.

The transportation sector is a significant contributor to global carbon emissions thus necessitating a transition toward renewable energy sources (RESs) and electric vehicles (EVs). Among EV technologies fuel-cell EVs (FCEVs) offer distinct advantages in terms of refueling time and operational efficiency thus rendering them a promising solution for sustainable transportation. Nevertheless the integration of FCEVs in rural areas poses challenges due to the limited availability of refueling infrastructure and constraints in energy access. In order to address these challenges this study proposes a multi-objective energy management model for a hydrogen refueling station (HRS) integrated with RESs a battery storage system an electrolyzer (EL) a fuel cell (FC) and a hydrogen tank serving diverse FCEVs in rural areas. The model formulated using mixed-integer linear programming (MILP) optimizes station operations to maximize both cost and load factor performance. Additionally bi-directional trading with the power grid and hydrogen network enhances energy flexibility and grid stability enabling a more resilient and self-sufficient energy system. To the best of the authors’ knowledge this study is the first in the literature to present a multi-objective optimal management approach for grid-interactive renewablesupported HRSs serving hydrogen-powered vehicles in rural areas. The simulation results demonstrate that RES integration improves economic feasibility by reducing costs and increasing financial gains while maximizing the load factor enhances efficiency cost-driven strategies that may impact stability. The impact of the EL on cost is more significant while RES capacity has a relatively smaller effect on cost. However its influence on the load factor is substantial. The optimization of RES-supported hydrogen production has been demonstrated to reduce external dependency thereby enabling surplus trading and increasing financial gains to the tune of USD 587.83. Furthermore the system enhances sustainability by eliminating gasoline consumption and significantly reducing carbon emissions thus supporting the transition to a cleaner and more efficient transportation ecosystem.

Virtual power plants (VPPs) are gaining significance in the energy sector due to their capacity to aggregate distributed energy resources (DERs) and optimize energy trading. However their effectiveness largely depends on accurately modeling the uncertain parameters influencing optimal bidding strategies. This paper proposes a deep learning-based forecasting method to predict these uncertain parameters including solar irradiation temperature wind speed market prices and load demand. A stochastic programming approach is introduced to mitigate forecasting errors and enhance accuracy. Additionally this research assesses the flexibility of VPPs by mapping the flexible regions to determine their operational capabilities in response to market dynamics. The study also incorporates power-to‑hydrogen (P2H) and hydrogen-to-power (H2P) conversion processes to facilitate the integration of hydrogen fuel cell vehicles (HFCVs) into VPPs enhancing both technical and economic aspects. A network-aware VPP connected to generation resources storage facilities demand response programming (DRP) vehicle-to-grid technology (V2G) P2H and H2P is used to evaluate the proposed method. The problem is formulated as a convex model and solved using the GUROBI optimizer. Results indicate that a hydrogen refueling station can increase profits by approximately 49 % compared to the base case of directly selling surplus generation from renewable energy sources (RESs) to the market and profits can further increase to roughly 86 % when other DERs are incorporated alongside the hydrogen refueling station.

Reducing CO2 emissions is an increasingly important goal in general aviation. The dual-fuel hydrogen–kerosene combustion process has proven to be a suitable technology for use in small aircraft. This robust and reliable technology significantly reduces CO2 emissions due to the carbon-free combustion of hydrogen during operation while pure kerosene or sustainable aviation fuel (SAF) can be used in safety-critical situations or in the event of fuel supply issues. Previous studies have demonstrated the potential of this technology in terms of emissions performance and efficiency while also highlighting challenges related to abnormal combustion phenomena such as knocking and pre-ignition which limit the maximum achievable hydrogen energy share. However the causes of such phenomena—especially regarding the role of lubricating oils—have not yet been sufficiently investigated in hydrogen engines making this a crucial area for further development. In this paper investigations at the TU Wien Institute of Powertrain and Automotive Technology concerning the role of different engine oils in influencing pre-ignition tendencies in a hydrogen–kerosene dual-fuel engine are described. A specialized test procedure was developed to account for the unique combustion characteristics of the dual-fuel process along with a detailed purge procedure to minimize oil carryover. Multiple engine oils with varying compositions were tested to evaluate their influence on pre-ignition tendencies with a particular focus on additives containing calcium magnesium and molybdenum known for their roles in detergent and anti-wear properties. Additionally the study addressed the contribution of particles to pre-ignition occurrences. The results indicate that calcium and magnesium exhibit no notable impact on pre-ignition behavior; however the addition of molybdenum results in a pronounced reduction in pre-ignition events which could enable a higher hydrogen energy share and thus decrease CO2 emissions in the context of hydrogen dual-fuel aviation applications.

This study explores a multi-faceted approach to improving the combustion performance and emission characteristics of a single-cylinder four-stroke direct injection (DI) compression ignition engine through the combined effects of butanol enrichment green-synthesized copper oxide (CuO) nanoparticles and hydrogen supplementation. The baseline fuel was a B20 biodiesel blend further enriched with 10 % butanol to enhance oxygen availability and atomization. CuO nanoparticles were synthesized via an eco-friendly aloe vera extractmediated method and dispersed into the fuel to promote oxidation kinetics and stabilize combustion. Experimental results revealed that the B20+But10 %+CuO100 blend achieved the highest brake thermal efficiency (BTE) of 33.6 % at full load alongside notable reductions in carbon monoxide (CO) unburned hydrocarbons (HC) nitrogen oxides (NOx) and smoke opacity compared to neat B20. Reactivity controlled compression ignition (RCCI) trials further demonstrated that hydrogen enrichment at 5 LPM and 10 LPM improved flame propagation Brake thermal efficiency (33.89 % & 35.43 %) and reduced brake-specific fuel consumption of nearly 10 % (0.26 Kg/KWh) & 0.25 Kg/KWh). While excessive hydrogen supply (10 LPM) marginally increased HC emissions (110 PPM) at higher loads due to localized incomplete oxidation overall results confirm significant emission mitigation. The findings highlight that the synergistic integration of butanol oxygenation catalytically active CuO nanoparticles and optimized hydrogen enrichment offers a viable pathway toward cleaner combustion improved energy efficiency and reduced pollutant emissions in biodiesel-fueled CI engines.

This study develops and applies a life cycle assessment (LCA) framework combined with predictive market models to evaluate the environmental impacts of electricity and hydrogen for transport in the EU27+UK from 2020 to 2050. By linking evolving power sector scenarios with hydrogen supply models we assess the wellto-wheels (WTW) performance of battery electric vehicles (BEVs) and fuel cell electric vehicles (FCEVs) under consistent energy assumptions. Results show that electricity decarbonization can reduce GWP by up to 80% by 2050 but increases land use and mineral/metal demand due to renewable infrastructure expansion. The environmental impacts of hydrogen production are strongly influenced by the electricity mix especially in high electrolysis scenarios. WTW analysis indicates that while BEVs consistently achieve lower WTW GWP than FCEVs across all scenarios both drivetrains exhibit notable trade-offs in other impact categories. Scenarios dominated by blue hydrogen although not optimal in terms of GWP present a more balanced environmental profile making them a viable transitional pathway in contexts that prioritize minimizing other environmental impacts.

The thermal management system and the balance-of-plant (BoP) in fuel cell electric vehicles (FCEV) are characterized by a particularly high level of complexity and a number of interfaces. Optimizing the efficiency of the overall vehicle is of special importance to maximize the range and increase the attractiveness of this technology to customers. This paper focuses on the optimization potential of the air supply system in the BoP whereby the charging concepts of the electric supercharger (ESC) and the electrically assisted turbocharger (EAT) as well as the integration of water spray injection (WSI) at the compressor inlet are investigated in the framework of an FCEV complete vehicle co-simulation. As a benchmark for the integration of these optimization measures the complete vehicle co-simulation is designed for a fuel cell electric passenger car of the current generation. Here thermo-hydraulic fluid circuits in the thermal management software KULI are coupled with mathematical-physical models in MATLAB/Simulink. Applying advanced simulation methodologies for the components of fuel cell powertrain and vehicle cabin enables the mapping of the effects of realistic operating conditions on the FCEV characteristics. The EAT offers the advantage over the ESC that due to the arrangement of an exhaust gas turbine a part of the exhaust gas enthalpy flow downstream of the fuel cell stack can be recovered which reduces the electrical compressor drive power. Moreover an additional reduction of this power consumption can be achieved by WSI as the effect of evaporative cooling lowers the initial compression temperature. For analysis and comparison these concepts are again modeled with high degree of detail and integrated into the benchmark overall vehicle simulation. The results indicate considerable reductions in the electric compressor drive power of the EAT compared to the ESC with noteworthy potential for reducing the vehicle’s hydrogen consumption. At an operating point in Worldwide harmonized Light Duty Test Cycle (WLTC) under 35 ◦ C ambient temperature and 25 % relative humidity the electrical compressor drive power shows a reduction potential of −40 % which corresponds to a vehicle-level hydrogen consumption reduction of up to −3 %. In addition the results also highlight the effect of the WSI in both charging concepts whereby its potential to reduce the hydrogen consumption on the overall vehicle level is relatively small. In WLTC at 35 ◦C ambient temperature and 25 % relative humidity the compressor drive power reduction potential for ESC and EAT averages −5 % while the effect on hydrogen consumption is only around −0.25 %.

This paper presents QDQN-ThermoNet a novel Quantum-Driven Dual Deep Q-Network framework for intelligent thermal regulation in next-generation electric vehicles with hybrid energy systems. Our approach introduces a dual-agent architecture where a classical DQN governs solid-state battery thermal management while a quantumenhanced DQN regulates proton exchange membrane fuel cell dynamics both sharing a unified quantumenhanced experience replay buffer to facilitate cross-system information transfer. Hardware-in-the-Loop validation across diverse operational scenarios demonstrates significant performance improvements compared to classical methods including enhanced thermal stability (95.1 % vs. 82.3 %) faster thermal response (2.1 s vs. 4.7 s) reduced overheating events (0.3 vs. 3.2) and superior energy efficiency (22.4 % energy savings). The quantum-enhanced components deliver 38.7 % greater sample efficiency and maintain robust performance under sparse data conditions (33.9 % improvement) while material-adaptive control strategies leveraging MXeneenhanced phase change materials achieve a 50.3 % reduction in peak temperature rise during transients. Component lifetime analysis reveals a 33.2 % extension in battery service life through optimized thermal management. These results establish QDQN-ThermoNet as a significant advancement in AI-driven thermal management for future electric vehicle platforms effectively addressing the complex challenges of coordinating thermal regulation across divergent energy sources with different optimal operating temperatures.

This study investigates numerically combustion attributes and NOx formation of premixed ammonia-hydrogen/air flames within a swirl burner of a gas turbine considering various conditions of hydrogen fraction (HF: 0 % 5 % 30 % 40 % and 50 %) equivalence ratio (φ: 0.85 1.0 and 1.2) and mixture inlet temperature (Tin: 400–600 K). The results illustrate that flame temperature increases with hydrogen addition from 1958 K for pure ammonia to 2253 K at 50 % HF. Raising the inlet temperature from 400 K to 600 K markedly enhances combustion intensity resulting in an increase of the Damköhler number (Da) from 117 to 287. NOx levels rise from ∼1800 ppm (0 % HF) to ∼7500 ppm (50 % HF) and peak at 8243 ppm under lean conditions (φ = 0.85). Individual NO N2O and NO2 emissions also reach maxima at φ = 0.85 with values of 5870 ppm 2364 ppm and 10 ppm respectively decreasing significantly under richer conditions (2547 ppm 1245 ppm and 5 ppm at φ = 1.2). These results contribute to advancing low-carbon fuel technologies and highlight the viability of ammonia-hydrogen co-firing as a pathway toward sustainable gas turbine operation.

This study presents a comprehensive review of the viability of hydrogen as an energy carrier for offshore wind energy compared to existing electricity carrier systems. To enable a state-of-the-art system comparison a review of wind-to-hydrogen energy conversion and transmission systems is conducted alongside wind-to-electricity systems. The review reveals that the wind-to-hydrogen energy conversion and transmission system becomes more cost-effective than the wind-to-electricity conversion and transmission system for offshore wind farms located far from the shore. Electrical transmission systems face increasing technical and economic challenges relative to the hydrogen transmission system when the systems move farther offshore. This study also explores the feasibility of using seawater for hydrogen production to conserve freshwater resources. It was found that while this approach conserves freshwater and can reduce transportation costs it increases overall system costs due to challenges such as membrane fouling in desalination units. Findings indicated that for this approach to be sustainable proper management of these challenges and responsible handling of saline waste are essential. For hydrogen energy transmission this paper further explores the potential of repurposing existing oil and gas pipeline infrastructure instead of constructing new pipelines. Findings indicated that with proper retrofitting the existing natural gas pipelines could provide a cost-effective and environmentally sustainable solution for hydrogen transport in the near future.

This paper explores how the deployment of “High-Performance Heat-Powered Heat Pumps” (HP3 s)—a novel heating technology—could help meet the domestic heating demand in the UK and reduce how much grid-scale energy storage is needed in comparison to a scenario where electrical heat pumps fully supply the heating demand. HP3 systems can produce electricity which can partially alleviate the stress caused by electrical heat pumps. A parametric analysis focusing on two variables the penetration of HP3 systems (H) and the amount of electricity exported (Ɛ) is presented. For every combination of H and Ɛ the electricity system is optimized to minimize the cost of electricity. Three parameters define the electricity system: the generation mix the energy storage mix and the amount of over-generation. The cost of electricity is at its highest when electrical heat pumps supply all demand. This reduces as the penetration of HP3 systems increases due to a reduction in the need for energy storage. When HP3 systems supply 100% of the heating demand the total cost of electricity and the storage capacity needed are 6% and 50% lower respectively compared to a scenario where electrical heat pumps are in 100% of residences.

Ammonia is a highly promising zero-carbon fuel for engines. However it exhibits high ignition energy slow flame propagation and severe pollutant emissions so it is usually burned in combination with highly reactive fuels such as hydrogen. An accurate understanding and modeling of ammonia–hydrogen combustion is of fundamental and practical significance to its application. Deep Neural Networks (DNNs) demonstrate significant potential in autonomously learning the interactions between high-dimensional inputs. This study proposed a deep neural network-based method for optimizing chemical reaction mechanism parameters producing an optimized mechanism file as the final output. The novelty lies in two aspects: first it systematically compares three DNN structures (Multilayer perceptron (MLP) Convolutional Neural Network and Residual Regression Neural Network (ResNet)) with other machine learning models (generalized linear regression (GLR) support vector machine (SVM) random forest (RF)) to identify the most effective structure for mapping combustion-related variables; second it develops a ResNet-based surrogate model for ammonia–hydrogen mechanism optimization. For the test set (20% of the total dataset) the ResNet outperformed all other ML models and empirical correlations achieving a coefficient of determination (R2 ) of 0.9923 and root mean square error (RMSE) of 135. The surrogate model uses the trained ResNet to optimize mechanism parameters based on a Stagni mechanism by mapping the initial conditions to experimental IDT. The results show that the optimized mechanism improves the prediction accuracy on laminar flame speed (LFS) by approximately 36.6% compared to the original mechanism. This method while initially applied to the optimization of an ammonia–hydrogen combustion mechanism can potentially be adapted to optimize mechanisms for other fuels.

The transport sector is the largest source of greenhouse gases in the EU after the energy supply one contributing approximately 27% of total emissions. Although decarbonization pathways for light-duty transport are relatively well established heavy-duty transport shipping and aviation emissions are difficult to eliminate through electrification. In particular the aviation sector is strongly dependent on liquid hydrocarbons making the development of sustainable aviation fuels (SAFs) a critical priority for achieving long-term climate targets. This study evaluates four biomass-to-liquid pathways for producing jet-like SAF from lignocellulosic biomass: (1) triacylglycerides (TAGs) production from syngas fermentation (2) TAGs production from sugar fermentation (3) ethanol production from syngas fermentation and (4) ethanol production from sugar fermentation. These pathways are simulated using Aspen Plus™ and the mass and heat balances obtained are used to assess their technical performance (e.g. carbon utilization energetic fuel efficiency) and techno-economic viability (e.g. production cost capital investment). Pathway (4) demonstrated the highest jet fuel selectivity (63%) and total carbon utilization (32.5%) but at higher power demands. Pathway (1) was self-sufficient in energy due to internal syngas utilization but exhibited lower carbon efficiencies. Cost analysis revealed that microbial oil-based pathways were restrained by higher hydrogen demands and lower product selectivity compared to ethanol-based routes. However with advancements in microbial oil production efficiency and reduced water usage these pathways could become competitive.

The article examines the use of hydrogen fuel as an alternative to traditional diesel fuel for internal combustion engines (ICE) in railway applications. The main objective of the study is to analyze the operational consumption of hydrogen fuel based on the mathematical modeling of the working cycle of the EMD 12-645E3C engine installed on CIE 071 locomotives used in freight and passenger service. The article provides information on the design features of the EMD 12-645E3C engine its technical parameters and the results of bench tests. The indicator parameters of the engine at various controller positions are determined and analyzed and the results of mathematical modeling of its operation on hydrogen fuel are presented. Particular attention is paid to changes in indicator parameters including the maximum combustion pressure and the peak gas temperature in the cylinder as well as comparing the mass consumption of diesel and hydrogen fuel. The study results demonstrate that the use of hydrogen allows the engine to maintain effective power across all operational modes while simultaneously reducing energy costs up to 8%. In this case the pressure and temperature of the gases in the cylinder increased by 3–6% and 5–8%. Recommendations are also provided regarding technical challenges associated with transitioning to hydrogen fuel including the modernization of the combustion chamber fuel system and safety system.

Lift–cruise-type unmanned aerial vehicles (UAVs) powered by hydrogen fuel cells often integrate secondary energy storage devices to improve responsiveness to load fluctuations during different flight phases which necessitates an efficient energy management strategy that optimizes power allocation among multiple power sources. This paper presents an innovative fuel cell DC–DC converter (FDC) design for the hybrid power system of a lift–cruise-type UAV comprising a multi-stack fuel cell system and a battery. The novelty of this work lies in the development of an FDC suitable for a multi-stack fuel cell system through a dual-input single-output converter structure and a control algorithm. To integrate inputs supplied from two hydrogen fuel cell stacks into a single output a controller with a single voltage controller–dual current controller structure was applied and its performance was verified through simulations and experiments. Load balancing was maintained even under input asymmetry and fault-tolerant performance was evaluated by analyzing the FDC output waveform under a simulated single-stack input failure. Furthermore under the assumed flight scenarios the results demonstrate that stable and efficient power supply is achieved through power-supply mode switching and application of a power distribution algorithm.

The gradual exhaustion of fossil fuel reserves along with the adverse effects of their consumption on global climate drives the need for research into alternative energy sources that can meet the growing demand in a sustainable and eco-friendly way. Among these hydrogen stands out as one of the most promising options for the automotive sector being the cleanest available fuel and capable of being produced from renewable resources. This paper reviews the existing literature on compression ignition engines operating in a dualfuel configuration where diesel serves as the ignition source and hydrogen is used to enhance the combustion process. The reviewed studies focus on engine systems with hydrogen injection into the intake manifold. The investigations analyzed the influence of hydrogen energy fraction on combustion characteristics engine performance combustion stability and exhaust emissions in diesel/hydrogen dual-fuel engines operating under full or near-full-load conditions. The paper identifies the main challenges hindering the widespread and commercial application of hydrogen in diesel/hydrogen dual-fuel engines and discusses potential methods to overcome the existing barriers in this area.

Integrated Energy Systems (IESs) which leverage the synergistic coordination of electricity heat and gas networks serve as crucial enablers for a low-carbon transition. Current research predominantly treats energy storage as a subordinate resource in dispatch schemes failing to simultaneously optimise IES economic efficiency and storage operators’ profit maximisation thereby overlooking their potential value as independent market entities. To address these limitations this study establishes an operator-autonomous management framework incorporating electrical thermal and hydrogen storage in IESs. We propose a joint optimal dispatch model for hybrid energy storage systems in low-carbon IES operation. The upper-level model minimises total system operation costs for IES operators while the lower-level model maximises net profits for independent storage operators managing various storage assets. These two levels are interconnected through power price and carbon signals. The effectiveness of the proposed model is verified by setting up multiple scenarios for example analysis.

This study investigates the integration of on-site green hydrogen as a substitute for methane in steam generation in the dairy industry specifically in the production of Parmigiano Reggiano cheese. This represents a novel application of green hydrogen in industrial dairy processing with the potential to reduce greenhouse gas emissions. Hydrogen is assumed to be generated via electrolysis powered by photovoltaic energy. A comprehensive techno-economic assessment was conducted with simulations covering key design variables such as hydrogen fraction in steam production photovoltaic panel orientation and storage pressure. A wide range of scenarios was defined in order to account for variability in system structures and performance and a comprehensive economic assessment was then carried out using a Monte Carlo simulation approach and a sensitivity analysis. Results indicate that in all scenarios the net present value over a 15-year period remains negative when benefits are limited to methane savings. Indeed the high capital expenditure associated with hydrogen systems presents a major barrier. The most favorable cases occur at low hydrogen shares with seasonal storage while full conversion to hydrogen maximizes CO2 abatement but is least economical. With public funding the emissions saved per euro of public support range from 1.58 to 2.14 kg CO2eq/€.

In order to assess the decarbonization potential and overall environmental benefits of new reduction pathways in the ironmaking industry using hydrogen to produce Direct Reduced Iron (DRI) a coupled approach combining process simulation for rigorous technical and energy evaluation of iron ore conversion and Life Cycle Assessment (LCA) for environmental assessment was developed and extended to two alternative renewable heating strategies: (i) electric gas heating and (ii) solar reactor heating. The entire hydrogen-based ironmaking process including conversion in a shaft reactor gas and solid heating gas recycling and electrolysis was therefore simulated. The hydrogen-based reduction of iron ores in the shaft reactor was modeled using a rigorous reactor model describing the reduction of multi-layer iron ore pellets in countercurrent gas–solid moving beds with the particularity of representing the dual influence of particle size and temperature on conversion. The remainder of the process including gas recycling and hydrogen production was simulated using ProSim software. The hydrogen-based green ironmaking scenarios were then compared to MIDREX NG a leading natural gas-based reduction technology. Hydrogen-based scenarios powered by the French electricity mix reduce carbon footprints by 53 % for electric gas heating and 57 % for solar reactor heating potentially reaching 82 % (− 0.79 kgCO2-eq/kgDRI) with low-carbon electricity (hydro nuclear). Compared to MIDREX NG the energy requirements of both hydrogen-based scenarios are primarily determined by the use of electricity for hydrogen production illustrating the importance of hydrogen production for the assessment of future hydrogen-based green ironmaking.

Curvature effects are incorporated into a one-dimensional composition-space formulation of a non-unity Lewis number lean premixed flame with strong heat loss. The results of this new canonical problem successfully compare with direct numerical simulations (DNS) of a lean hydrogen-air flame propagating in a narrow channel with heat conduction through the confining plates. The complex dynamics of the flame front consisting of isolated flame kernels are analyzed through the various terms arising from the projection of the fuel and energy equations onto a moving scalar reference frame attached to the reaction zone. Novelty and significance statement A novel one-dimensional flame model incorporating curvature and differential diffusion effects is introduced to address non-unity Lewis number lean premixed flames with strong heat loss. This canonical flame model arises from the projection of temperature and fuel gradient magnitude onto composition space. The framework is employed to analyze flame front dynamics and identify the reaction zones governing flame kernel propagation and heat release. The composition-space flame structure shows strong agreement between the canonical problem and direct numerical simulations (DNS) of a lean hydrogen-air flame propagating in a narrow channel with heat conduction.

In sustainable energy transitions the utilization of hydrogen is crucial providing flexibility in the operation of net-zero emission renewable-based energy systems. This paper presents a study on the optimal operation of netzero emission multi-energy future microgrids that utilize hydrogen as an alternative fuel instead of natural gas. The electrolyzers’ output is injected into the hydrogen grid to meet demand or converted back to electricity later using generating units owing to the storage capability of pipes called linepack. For this purpose a detailed mathematical model is developed to simulate the main characteristics of grids (e.g. voltage current hydrogen flow and pressure) as well as various components (e.g. renewable systems electrolyzers and hydrogen-fired units). To become more realistic a possibilistic-robust approach is developed to account for the uncertainty arising from the lack of real-world implementation. By representing a case study a test is performed to evaluate the possibility of employing a low-pressure gas grid to meet the demand for hydrogen. After that the effects of electrolyzers are analyzed in the presence and absence of the uncertainty consideration approach. The result indicates that despite hydrogen’s lower energy density compared to natural gas it is still feasible to satisfy the same energy demand level considering the technical characteristics of the grid. The integration of electrolyzers can reduce wind curtailment by 2 % and supplement hydrogen demand by 50 %. A higher level of conservatism in the possibilistic-robust approach leads to an increase in the mean value of the objective function and a reduction in the standard deviation under the realization of uncertain parameters which provides the decisionmakers with a more realistic insight.

Fuel cell electric vehicles (FCEVs) are zero-emission but face cost and power density challenges. To mitigate these limitations a novel 3D-ordered nano-structured self-supporting membrane electrode assembly (MEA) has been developed. This paper investigates the optimal component sizing of the battery and fuel cell in FCEVs equipped with 3D-ordered MEAs integrating the energy management. To explore the trade-offs between component cost operational cost and fuel cell degradation the sizing and energy management problem is formulated into a multi-objective optimisation problem. A Pareto frontier (PF) study is conducted using the decomposed multi-objective evolutionary algorithm (MOEA/D) for a more diverse distribution of feasible solutions. The modular design of fuel cells is derived from a scaled and stressed experiment. After executing MOEA/D across the three aggressive driving cycles power source configurations are selected from the corresponding PFs based on objective trade-offs ensuring robustness of the overall system. The optimisation performance of the MOEA/D is compared with that of the multi-objective Particle Swarm Optimisation. In addition the selected powertrain configurations are evaluated and compared through standard and realworld driving cycles in a simulation environment. This paper also performs a sensitivity analysis to reveal the influence of diverse component unit costs and hydrogen price. The results indicate that the mediumsized configuration consisting of a 63.31 kW fuel cell stack and a 52.15 kWh battery pack delivers the best overall performance. It achieves a 26.71% reduction in component cost and up to 12.76% savings in hydrogen consumption across various driving conditions. These findings provide valuable insights into the design and optimisation of fuel cell systems for FCEVs.

Coastal regions in Cameroon including Douala Kribi Campo Dibamba and Limbe faced persistent electricity challenges driven by grid instability growing demand and dependence on fossil fuels. Solar resource availability was high but intermittent whereas tidal energy was predictable and energy-dense yet underused. This pilot delivers the first Cameroonian assessment of an off-grid tidal/PV/electrolyzer/hydrogen-storage/fuel-cell architecture explicitly co-optimizing electricity service and green hydrogen production and evaluating performance with a tri-metric economic lens (net present cost levelized cost of electricity and the levelized cost of hydrogen). The system was optimized to minimize net present cost (NPC) levelized cost of electricity (LCOE) levelized cost of hydrogen (LCOH) and three tidal-flow scenarios were analyzed to represent hydrokinetic variability. The design served households small businesses fishing activities schools and health facilities with a baseline demand of 389.50 kWh/day; surplus renewable power drove the electrolyzer to produce hydrogen for later reconversion in the fuel cell. Under the first scenario (1.25 m/s average speed) the optimal mix comprised 137 PV modules (600 W each) a 100 kW fuel cell six 40 kW tidal turbines six 10 kW electrolyzers a 19.5 kW converter and 41 hydrogen tanks (40 L each) yielding an NPC of US$ 2.16 million an LCOE of US$ 0.782/kWh and a LCOH of US$ 19.2/kg of hydrogen. The second scenario (1.47 m/s) required only 12 PV modules one electrolyzer and an 11.3 kW converter lowering costs to an NPC of US$ 1.52 million an LCOE of US$ 0.553/ kWh and a LCOH of US$ 15.4/kg of hydrogen. In the third scenario (1.61 m/s) the configuration shifted to 298 PV modules three tidal turbines eight electrolyzers and a 39.6 kW converter resulting in the highest NPC (US$ 2.47 million) and LCOE (US$ 0.901/kWh) with a LCOH of US$ 18.8/kg of hydrogen. The study also contributes a transparent component-wise employment indicator linking installed capacities/energies to jobs; deployment is expected to create about seven local jobs during installation and early operation tidal turbines (3) solar panels (1) electrolyzers (1) hydrogen tanks (1) and fuel cell (1) with additional minor operation and maintenance positions thereafter. Social analysis indicated improved energy access support for local livelihoods and job creation; environmental results confirmed clean operation with limited marine disturbance. A sensitivity study varying capital and replacement-cost multipliers showed robust performance across economic conditions. Taken together these contributions provide a decision-ready blueprint for coastal communities: a first-of-its-kind Cameroonian hybrid that quantifies both electricity and hydrogen costs (including feasible LCOH) and demonstrates socio-economic co-benefits offering a cost-effective pathway to strengthen energy security foster local development and reduce environmental impact.

This study presents an experimental investigation of a direct injection ammonia-fuelled engine using hydrogen pre-chamber jet ignition. All tests have been conducted in an optically accessible combustion chamber that is installed in the head of a single-cylinder engine. The effect of ammonia injection timing on ignition and combustion characteristics was investigated with the timing varied from 165 CAD BTDC to 40 CAD BTDC. The experiments were conducted with a fixed spark timing of 14 CAD BTDC while ammonia injection duration was adjusted to maintain a main chamber global equivalence ratio of 0.6. Two pre-chamber nozzle configurations a single-hole and a multi-hole were tested. The results show that the later NH3 injection timing (40 CAD BTDC) significantly improved combustion with a peak in-cylinder pressure of 80 bar measured compared to a peak in-cylinder pressure of 50 bar with earlier injection (165 CAD BTDC). This study indicates the importance of optimising ammonia injection timing in order to enhance combustion stability and efficiency. The hydrogen pre-chamber jet ignition combined with a late ammonia injection is a promising approach for addressing the combustion challenges of ammonia as a zero-carbon fuel for maritime applications.

Hydrogen-based Local Energy Communities (LECs) play a pivotal role in modern energy systems and form the fundamental building blocks of hydrogen cities. This review provides a comprehensive assessment of how hydrogen-based LECs advance the hydrogen city concept by examining the technological economic environmental regulatory and social dimensions that shape the integration of green hydrogen into local energy networks. The paper explores the structure of hydrogen cities focusing on the role of multiple LECs in alignment with the European Union’s Clean Energy Package (CEP). Furthermore a case study and mathematical model are presented where the hydrogen city is modelled and the impact of Electric Parking Lot (EPL) and Hydrogen Parking Lot (HPL) management on the hydrogen city’s operation cost is evaluated. The results show that optimised EPL and HPL management can reduce overall operational costs by 5.53 % demonstrating the economic advantages of intelligent scheduling strategies in hydrogen cities.

The recent updates to the Single Day-Ahead Coupling (SDAC) framework in the European energy market along with new rules for providing manual frequency restoration reserve (mFRR) products in the Nordic Energy Activation Market (EAM) have introduced a finer Market Time Unit (MTU) resolution. These developments underscore the growing importance of flexible assets such as power-to-hydrogen (PtH) facilities in delivering system flexibility. However to successfully participate in such markets well-designed and accurate bidding strategies are essential. To fulfill this aim this paper proposes a Mixed Integer Linear Programming (MILP) model to determine the optimal bidding strategies for a typical PtH facility accounting for both the technical characteristics of the involved technologies and the specific participation requirements of the mFRR EAM. The study also explores the economic viability of sourcing electricity from nearby wind turbines (WTs) under a Power Purchase Agreement (PPA). The simulation is conducted using a case study of a planned PtH facility at the Port of Hirtshals Denmark. Results demonstrate that participation in the mFRR EAM particularly through the provision of downward regulation can yield significant economic benefits. Moreover involvement in the mFRR market reduces power intake from the nearby WTs as capacity must be reserved for downward services. Finally the findings highlight the necessity of clearly defined business models for such facilities considering both technical and economic aspects.

To address the economic and reliability challenges of high-penetration renewable energy integration in electricity-heat-hydrogen integrated energy systems and support the dualcarbon strategy this paper proposes an optimal dispatch method integrating Information Gap Decision Theory (IGDT) and Fuzzy Chance-Constrained Programming (FCCP). An IES model coupling multiple energy components was constructed to exploit multi-energy complementarity. A stepped carbon trading mechanism was introduced to quantify emission costs. For interval uncertainties in renewable generation IGDT-based robust and opportunistic dispatch models were established; for fuzzy load uncertainties FCCP transformed them into deterministic equivalents forming a dual-layer “IGDT-FCCP” uncertainty handling framework. Simulation using CPLEX demonstrated that the proposed model dynamically adjusts uncertainty tolerance and confidence levels effectively balancing economy robustness and low-carbon performance under complex uncertainties: reducing total costs by 12.7% cutting carbon emissions by 28.1% and lowering renewable curtailment to 1.8%. This study provides an advanced decision-making paradigm for low-carbon resilient IES.

In northern China the long winter heating period is accompanied by severe wind curtailment. To address this issue a joint optimization scheduling strategy of electric vehicles (EVs) and electro–olefin–hydrogen electromagnetic energy supply device (EHED) is proposed to promote deep wind–solar integration. Firstly the feasibility analysis of EVs participating in scheduling is conducted and the operation models of dispatchable EVs and thermal energy storage EHEDs within the scheduling period are established. Secondly a control strategy for the joint optimization scheduling of wind–solar farms EVs EHEDs and power grid is constructed. Then an economic dispatch model for joint optimization of EVs and EHEDs is established to minimize the system operation cost within the scheduling period and the deep wind–solar integration of the joint optimization model is studied by considering EVs under different demand responses. Finally the proposed model is solved by CPLEX solver. The simulation results show that the established joint optimization economic dispatch model of EV-EHEDs can improve the enthusiasm of dispatchable EVs to participate in deep wind–solar integration reduce wind curtailment power and decrease the overall system operation cost.

High-temperature proton exchange membrane fuel cells (HT-PEM FCs) represent a promising avenue for generating carbon dioxide-free electricity through the utilization of hydrogen fuel. These systems present numerous advantages and challenges for mobile applications positioning them as pivotal technologies for the realization of emission-free regional aircraft. Efficient thermal management of such fuel cell-powered systems is crucial for ensuring the safe and durable operation of the aircraft while concurrently optimizing system volume mass and minimizing parasitic energy consumption. This paper presents four distinct heat transfer principles tailored for the FC-system of a conceptual hydrogen-electric regional aircraft exemplified by DLR’s H2ELECTRA. The outlined approaches encompass conductive cooling air cooling liquid cooling phase change cooling and also included is the utilization of liquid hydrogen as a heat sink. Approaches are introduced with schematic cooling architectures followed by a comprehensive evaluation of their feasibility within the proposed drivetrain. Essential criteria pertinent to airborne applications are evaluated to ascertain the efficacy of each thermal management strategy. The following criteria are selected for evaluation: safety ease of integration reliability and life-cycle costs technology readiness and development as well as performance which is comprised of heat transfer weight volume and parasitic power consumption. Of the presented cooling methods two emerged to be functionally suitable for the application in MW-scale aircraft applications at their current state of the art: liquid cooling utilizing water under high pressure or other thermal carrier liquids and phase-change cooling. Air cooling and conductive cooling have a high potential due to their reduced system complexity and mass but additional studies investigating effects at architecture level in large-scale fuel cell stacks are needed to increase performance levels. These potentially suitable heat transfer technologies warrant further investigation to assess their potential for complexity and weight reduction in the aircraft drivetrain.

This report evaluates the role of Hybrid Renewable Energy Systems (HRESs) in supporting South Africa’s energy transition amidst persistent power shortages coal dependency and growing decarbonisation imperatives. Drawing on national policy frameworks including the Integrated Resource Plan (IRP 2019) the Just Energy Transition (JET) strategy and Net Zero 2050 targets this study analyses five major HRES configurations: PV–Battery PV–Diesel–Battery PV–Wind–Battery PV–Hydrogen and Multi-Source EMS. Through technical modelling lifecycle cost estimation and trade-off analysis the report demonstrates how hybrid systems can decentralise energy supply improve grid resilience and align with socio-economic development goals. Geographic application cost-performance metrics and policy alignment are assessed to inform region-specific deployment strategies. Despite enabling technologies and proven field performance the scale-up of HRESs is constrained by financial regulatory and institutional barriers. The report concludes with targeted policy recommendations to support inclusive and regionally adaptive HRES investment in South Africa.

This paper analyzes the potential of hydrogen technologies in transport placing it within the context of global environmental and energy challenges. Its primary purpose is to eval‑ uate the prospects for the implementation of these technologies at international and na‑ tional levels including Poland. This study utilizes a literature review and an analysis of the results of a highly limited exploratory pilot survey measuring public perception of hydrogen technology in transport. It is critical to note that the survey was conducted on a small non‑representative sample and exhibited a strong geographical bias primarily collecting responses from Europe (50 people) and North America (30 people). This study also details hydrogen vehicle types (FCEV HICE) and the essential infrastructure required (HRS). Despite solid technological foundations the development of hydrogen technology heavily relies on non‑technical factors such as infrastructure development support pol‑ icy and social acceptance. Globally the number of vehicles and stations is growing but remains limited with the pace of development correlating with the involvement of coun‑ tries. The pilot survey revealed a generally positive perception of the technology (mainly due to environmental benefits) but highlighted three key barriers: limited availability of refueling infrastructure—51.5% of respondents strongly agreed on this obstacle high pur‑ chase and maintenance costs and insufficient public awareness. Infrastructure subsidies and tax breaks were identified as effective incentives. Hydrogen technology offers a poten‑ tially competitive and sustainable transport solution but it demands significant systemic support intensive investment in large‑scale infrastructure expansion and comprehensive educational activities. Further governmental engagement is crucial. The severe limitations resulting from the pilot nature of the survey should be rigorously taken into account dur‑ ing interpretation.

This paper focuses on assessing different sustainable energy generation and storage systems for residential buildings in Spain identifying the best-performing system according to the end-user requirements. As outlined by the consulted literature the authors have selected two types of hybrid configurations—a Photovoltaic System with Battery Backup (PSBB) and a Photovoltaic System with Hydrogen Hybrid Storage Backup (PSHB)—and a Grid-Based System with Renewable Hydrogen Contribution (GSHC) is proposed. A Fuzzy Analytical Hierarchy Process methodology (FAHP) is employed for evaluating the hybrid power systems from a multi-criteria approach: acquisition operational and environmental. The main requirements for selecting the optimal system are organized under these criteria and evaluated using key performance indicators. This methodology allows the selection of the best option considering objective and subjective system performance indicators. Beyond establishing the ranking a sensitivity analysis was conducted to provide insights into how individual criteria influence the ranking of the hybrid power systems alternatives. The results demonstrate that the selection of hybrid power systems for a residential building is highly dependent on consumer preferences but the PSBB system scores highly in operation and acquisition criteria while the GSHC has good performance in all the criteria.

Algeria’s transition toward sustainable energy requires the exploitation of its abundant solar and wind resources for green hydrogen production. This study assesses the technoeconomic feasibility of an off-grid PV/wind hybrid system integrated with a hydrogen subsystem (electrolyzer fuel cell and hydrogen storage) to supply both electricity and hydrogen to decentralized sites in Algeria. Using HOMER Pro five representative Algerian regions were analyzed accounting for variations in solar irradiation wind speed and groundwater availability. A deferrable water-extraction and treatment load was incorporated to model the water requirements of the electrolyzer. In addition a comprehensive sensitivity analysis was conducted on solar irradiation wind speed and the capital costs of PV panels and wind turbines to capture the effects of renewable resource and investment cost fluctuations. The results indicate significant regional variation with the levelized cost of energy (LCOE) ranging from 0.514 to 0.868 $/kWh the levelized cost of hydrogen (LCOH) between 8.31 and 12.4 $/kg and the net present cost (NPC) between 10.28 M$ and 17.7 M$ demonstrating that all cost metrics are highly sensitive to these variations.

Electric Vehicles (EVs) are rapidly expanding resulting in increased demand on power systems and transportation networks. This study reviews recent advancements in planning EV Charging Stations (EVCSs) focusing on siting sizing grid upgrades and managing uncertainty. Analysis suggests that while many studies optimize either the location or the size of these stations few consider their combined effects resulting in missed opportunities for synergy. A lack of attention to cross-sector integration with hydrogen inadequate treatment of grid reinforcement and fragmented approaches to modeling uncertainties such as EV behavior renewable energy variability and market dynamics is also observed. To address these gaps a synthesis of the interdependencies between siting and sizing is provided along with a review of multi-energy integration opportunities an evaluation of Vehicle-to-Grid technology and smart charging including technical benefits and challenges strategies that link the deployment of EVCS to grid upgrades and a taxonomy of uncertainty sources along with advanced stochastic and data-driven solutions. This review emphasizes the importance of integrated data-informed planning in the development of EV charging infrastructure.

High-temperature (HT) proton exchange membrane (PEM) fuel cells (FC) offer key advantages for sustainable transportation especially in heavy-duty applications due to their improved thermal efficiency and water management. This study introduces an inverse design framework to develop flow field plates integrated with a gas diffusion layer (GDL) enabling scalable electrochemical performance from the unit cell to the plate level. A reduced-order homogenization-based multiphysics model is developed to evaluate designs with approximately 1000× faster computation. Flow channel orientation is optimized using a tensor field method and dehomogenized into manufacturable geometries. Optimized designs validated through high-fidelity 3D simulations show up to 12% higher average current density and 88% lower pressure drop compared to conventional parallel and mesh configurations. To address fabrication challenges solid-to-porous metal additive manufacturing is employed producing monolithic structures that integrate flow channels with a porous metal GDL. Both numerical and physical tests confirm high permeability and improved power output compared to carbon-based GDLs. These findings highlight the effectiveness of combining advanced computational modeling with metal 3D printing to enhance the performance and manufacturability of high-temperature PEMFC supporting their broader adoption in sustainable energy applications.

Ammonia is a cornerstone of modern agriculture supplying the nitrogen essential for crops that nourish nearly half the global population. Yet its production is responsible for ~2 % of global greenhouse gas emissions. To meet climate and food security goals sustainable low-carbon and resilient ammonia production systems are needed. Here we develop a spatially explicit techno-economic model to compare centralized and decentralized ammonia production pathways across the U.S. a major global ammonia producer and consumer spanning the full supply chain from hydrogen production to fertilizer delivery. We integrate high-resolution supply and demand data and apply linear optimization to estimate delivered ammonia costs accounting for geographic mismatches and transportation. Our results show that decentralized ammonia production whether powered by grid electricity or solar energy is substantially more expensive than centralized production from natural gas or coal. Centralized natural gas-based ammonia has a median production cost of 326 USD/tonne NH3 compared to 499 USD/tonne for coal. Decentralized grid-powered systems range from 659 to 1634 USD/tonne and solar-powered systems from 1077 to 2266 USD/tonne. Transportation costs for centralized production range from 7 to 85 USD/tonne with a median of 40 USD/tonne resulting in a delivered cost of 343 USD/tonne. Median delivered costs for decentralized grid- and solar-powered systems are 1069 and 1494 USD/tonne respectively. Decentralized systems require electricity prices below 19 USD/MWh (grid) and 17 USD/MWh (solar) to achieve cost parity well below 2024 U S. averages of 117 USD/MWh. These results highlight the economic challenges facing decentralized ammonia production and the importance of electricity cost reductions tax credits carbon pricing or further technological breakthroughs for broader viability.

Solid oxide fuel cell (SOFC) systems offer high-efficiency conversion of the chemical energy of fuel gases into electrical energy. To meet market and policy targets such systems must be able of operating on an industrial scale and be compatible with environmentally friendly fuels. This study models the scale-up of a 750 W naturalgas-fueled SOFC to a 240 kW system with various gas-path configurations evaluating the impact of blending up to 30 vol% of hydrogen (H2) into the methane feed. Aspen Plus simulations coupled with pressure-loss and carbon-deposition models were used to optimize recirculation ratio and reactant utilization for maximum efficiency. The parallel configuration achieved the highest electrical efficiency of 64.0 % while series-connected and intermediate systems suffered from increased pressure losses. H2 admixture simulations confirm that operation is feasible without loss of efficiency in the small- and large-scale systems due to reduced carbondeposition potential. A techno-economic analysis indicates a 91.7 % cost reduction through scale-up and a 1.6 % cost increase for adjusting the system to H2 admixtures. The economic viability of the large-scale system was evaluated for all tested fuel compositions (0.201–0.204 €/kWh) with payback times under 20 years at market-relevant electricity prices. These results demonstrate the technical and economic feasibility of large-scale H2-adapted SOFC systems for industrial decarbonization.

The application of OH* chemiluminescence diagnostics is becoming increasingly prevalent in the combustion characterization of hydrogen. As the current literature is lacking a systematic study of OH* chemiluminescence in non-premixed turbulent natural gas (NG) and hydrogen (H2 ) flames the present work was designed to address this research gap. Therefore extensive experiments were performed on a semi-industrial burner operating at 50–100 kW in NG/H2–Air/O2 combustion modes which were complemented by comprehensive numerical simulations including 1D laminar counterflow diffusion flamelet calculations and full 3D CFD simulations of the semi-industrial furnace setup. In this way an OH* chemistry model is presented that accurately predicts the global reaction zone characteristics and their difference between CH4 and H2 in air-fired and oxygen-fired flames. The comprehensive numerical approach in conjunction with the subsequent study of different operating conditions yielded novel insights into both combustion modeling and the underlying thermochemical phenomena providing an essential contribution to the transition of the thermal energy sector towards hydrogen as an alternative carbon-free fuel.

This study presents a comparative life cycle and economic assessment of using clean hydrogen as a sustainable alternative to natural gas and propane for corn grain drying. The study compares the environmental performance limited to GWP100 and cost-effectiveness of hydrogen from various renewable sources (hydro wind solar) and plasma pyrolysis of natural gas against conventional fossil fuels under two delivery scenarios: pipeline and trucking. A life cycle assessment is conducted using Open LCA to quantify the carbon intensity of each fuel from cradle to combustion at multiple energy requirements based on four burner efficiencies across each scenario. In parallel economic analysis is conducted by calculating the fuel cost required per ton of dried corn grains at each efficiency across both scenarios. The results indicate that green hydrogen consistently outperforms current fuels in terms of emissions but it is generally more expensive at lower burner efficiencies and in trucking scenarios. However the cost competitiveness of green hydrogen improves significantly at higher efficiency and with pipeline infrastructure development it can become more economical when compared to propane. Hydrogen produced via plasma pyrolysis offers high environmental and economic costs due to its electricity and natural gas requirements. Sensitivity analysis further explores the impact of a 50% reduction in hydrogen production and transportation costs revealing that hydrogen could become a viable option for grain drying in both pipeline and trucking scenarios. This study highlights the long-term potential of hydrogen in reducing carbon emissions and offers insights into the economic feasibility of hydrogen adoption in agricultural drying processes. The findings suggest that strategic investments in hydrogen infrastructure could significantly enhance the sustainability of agricultural practices paving the way for a greener future in food production.

This article discusses the potential of using the double-Wiebe function to model combustion in a compression-ignition engine fueled by diesel fuel or its substitutes such as hydrotreated vegetable oil (HVO) and rapeseed methyl ester (RME) and hydrogen injected into the engine intake manifold. The hydrogen amount ranged from 0 to 35% of the total energy content of the fuels burned. It was found that co-combustion of liquid fuel with hydrogen is characterized by two distinct combustion phases: premixed and diffusion combustion. The premixed phase occurring just after ignition is characterized by a rapid combustion rate which increases with an increase in hydrogen injected. The novelty in this work is the modified formula for a double-Wiebe function and the proposed parameters of this function depending on the amount of hydrogen added for co-combustion with liquid fuel. To model this combustion process the modified double-Wiebe function was proposed which can model two phases with different combustion rates. For this purpose a normalized HRR was calculated and based on this curve coefficients for the double-Wiebe function were proposed. Satisfactory consistency with the experiment was achieved at a level determined by the coefficient of determination (R-squared) of above 0.98. It was concluded that the presented double-Wiebe function can be used to model combustion in 0-D and 1-D models for fuels: RME and HVO with hydrogen addition.

Hybrid Renewable Energy Systems (HRESs) are a practical solution for providing reliable low-carbon electricity to off-grid and remote communities. This review examines the role of energy storage within HRESs by systematically comparing electrochemical mechanical thermal and hydrogen-based technologies in terms of technical performance lifecycle cost operational constraints and environmental impact. We synthesize findings from implemented off-grid projects across multiple countries to evaluate real-world performance metrics including renewable fraction expected energy not supplied (EENS) lifecycle cost and operation & maintenance burdens. Special attention is given to the emerging role of hydrogen as a long-term and cross-sector energy carrier addressing its technical regulatory and financial barriers to widespread deployment. In addition the paper reviews real-world implementations of off-grid HRES in various countries summarizing practical outcomes and lessons for system design and policy. The discussion also includes recent advances in metaheuristic optimization algorithms which have improved planning efficiency system reliability and cost-effectiveness. By combining technological operational and policy perspectives this review identifies current challenges and future directions for developing sustainable resilient and economically viable HRES that can accelerate equitable electrification in remote areas. Finally the review outlines key limitations and future directions calling for more systematic quantitative studies long-term field validation of emerging technologies and the development of intelligent Artificial Intelligence (AI)-driven energy management systems within broader socio-techno-economic frameworks. Overall this work offers concise insights to guide researchers and policymakers in advancing the practical deployment of sustainable and resilient HRES.

The global steel industry emits 1.92 tons of CO2 per ton of output and faces urgent pressure to decarbonize. In Pakistan the sector accounts for 0.29 tons of CO2 per ton of output with limited mitigation frameworks in place. Green hydrogen (GH2)-based steelmaking offers a strategic pathway toward decarbonization. However realizing its potential depends on access to renewable energy. Despite Pakistan’s substantial technical wind potential of 340 GW grid limitations currently restrict wind power to only 4% of national electricity generation. This study explores GH2 production through sector coupling and power wheeling repurposing curtailed wind energy from Sindh to supply Karachi’s steel industry and proposing a phased roadmap for GH enabling fossil fuel substitution industrial resilience and alignment with global carbon-border regulations.

As hydrogen gains prominence in energy systems its adoption as an energy source for fuel cell electric vehicles (FCEVs) necessitates the establishment of hydrogen refueling stations (HRS). These stations contain critical compo-nents including nozzles storage tanks heat exchangers and compressors which must be certified by regulatory agen-cies to ensure safety and public trust. Current certification processes are fragmented and manually intensive creating inefficiencies and limiting transparency across the infrastructure lifecycle. In this paper we propose a blockchain-based solution that creates a secure and auditable network for certifying key HRS components. The system integrates an EVM-compatible blockchain decentralized storage and a modular suite of smart contracts (SCs) that formalize registration bidding accreditation certification and governance. Each contract encodes a distinct actor-driven work-flow enabling traceable and role-specific operations. A Decentralized Application (DApp) interface supports real-time and role-based interaction across the ecosystem. We present and evaluate the SCs and their underlying algorithms us-ing gas usage analysis load testing and security auditing. Load testing across the certification lifecycle shows stable transaction throughput and predictable cost profiles under increasing actor activity. A static security analysis con-firms resilience against common vulnerabilities. Our cost analysis indicates that while the framework is technically deployable on public blockchains the execution costs of certain functions make it more cost-effective for private blockchains or Layer 2 networks. We also compare our framework with existing systems to highlight its novelty and technical advantages. Our SCs DApp interface and load testing scripts are publicly available on GitHub.

Hydrogen-based fuels are potential candidates to help international shipping achieve net-zero greenhouse gas (GHG) emissions by around 2050. This paper quantifies the environmental impacts of liquid hydrogen liquid ammonia and methanol used in a Post-Panamax container ship from 2020 to 2050. It considers cargo capacity changes electricity decarbonization and hydrogen production transitions under two International Energy Agency scenarios: the Stated Policies Scenario (STEPS) and the Net Zero Emissions by 2050 Scenario (NZE). Results show that compared to the existing HFO ship hydrogen-based propulsion systems can decrease cargo weight capacity by 0.3 % to 25 %. In the NZE scenario hydrogen-based fuels can reduce GHG emissions per tonne-nautical mile by 48 %–65 % compared to heavy fuel oil by 2050. Even with fully renewable hydrogenbased fuels 18 %–31 % of GHG emissions would still remain. Using hydrogen-based fuels in internal combustion engines requires attention to minimize environmental trade-offs.

In 2023 global carbon dioxide emissions reached 40 billion tonnes 60 % more than in 1990 intensifying climate concerns. This study explores hydrogen-natural gas blending as a transitional strategy for decarbonization across several regions and energy sectors – residential commercial industrial and agricultural. A multi-regional analysis framework evaluates integration of 20 % by volume low-carbon hydrogen blending into natural gas systems by identifying hydrogen producers importers and exporters based on production and import costs. Applied to Canada 528 scenarios (2026–2050) assess inter-regional hydrogen trade within Canadian provinces. The lowest-cost scenario involves Alberta exporting hydrogen produced through autothermal reforming with 91 % carbon capture and storage and British Columbia producing its own. The grid electrolysis scenario achieves the highest GHG reductions with a 4.5 % GHG mitigation in Canada with full energy system representation. These findings provide insights for policymakers and stakeholders in advancing hydrogen infrastructure and decarbonization strategies.

Fluidized bed systems play a crucial role in industrial processes such as combustion and gasification. In the Iron Power Cycle fluidized bed systems are essential for enabling the reduction of combusted iron back to iron making them a critical component in the regeneration step of the cycle. This study investigates the impact of operating gas velocity on conversion by performing reduction experiments at three distinct fluidization numbers (us/umf): 16 (bubbling regime) 55 (transition region) and 100 (fully turbulent regime). Experiments were conducted to determine the appropriate velocities for each regime ensuring optimal fluidization conditions across reduction temperatures ranging from 500 to 700 ⚬C. The results reveal that conversion rates increase significantly with gas velocities. At 500 ⚬C operating at approximately six times higher velocity leads to a sixfold improvement in conversion when using iron-oxide particles with a Sauter mean diameter of 61 µm. However while enhanced velocities improve reaction efficiency challenges remain at elevated temperatures (T ≥ 500 ⚬C) where iron undergoes defluidization when exposed to hydrogen. Once defluidization occurs refluidization proves impossible with either hydrogen or nitrogen raising concerns about process stability. These insights highlight the potential for optimizing fluidized bed reduction through velocity control while also underscoring the need for additional measures to mitigate unstable fluidization during high-temperature iron oxide reduction.

Refrigeration units in semi-trucks or rigged-body trucks have an energy demand of 8.2–12.4 MWh/y and emit 524.26 kt CO2e/y in Germany. Electrification with fuel cell systems reduces the CO2 emission but an increase of efficiency is necessary because of rapidly increasing hydrogen costs. A metal hydride refrigeration system can increase the efficiency. Even though it was already demonstrated in lab scale with 900 W this power is not sufficient to support a truck refrigeration system and the power output of the lab system was not controllable. Here we show the design and validation of a MATLAB© Simulink model of this metal hydride refrigeration system and its suitability for high power applications with a scaled-up reactor. It was scaled up to rated power of 5 kW and efficiency improvements with an advanced valve switching as well as a controlled cooling pump were implemented. Two application-relevant use cases with hydrogen mass flows from hydrogen fuel cell truck systems were analyzed. The simulation results of these use cases provide an average cooling power of 4.2 and 6.1 kW. Additionally the control of the coolant mass flow at different temperature levels a controlled hydrogen mass flow with a bypass system and an advanced valve switching mechanism increased the system efficiency of the total refrigeration system by 30 % overall.

The growing demand for air connectivity coupled with the forecasted increase in passengers by 2040 implies an exigency in the aviation sector to adopt sustainable approaches for net zero emission by 2050. Sustainable Aviation Fuel (SAF) is currently the most promising short-term solution; however ensuring its overall sustainability depends on reducing the life cycle carbon footprints. A key challenge prevails in hydrogen usage as a reactant for the approved ASTM routes of SAF. The processing conversion and refinement of feed entailing hydrodeoxygenation (HDO) decarboxylation hydrogenation isomerisation and hydrocracking requires substantial hydrogen input. This hydrogen is sourced either in situ or ex situ with the supply chain encompassing renewables or non-renewables origins. Addressing this hydrogen usage and recognising the emission implications thereof has therefore become a novel research priority. Aside from the preferred adoption of renewable water electrolysis to generate hydrogen other promising pathways encompass hydrothermal gasification biomass gasification (with or without carbon capture) and biomethane with steam methane reforming (with or without carbon capture) owing to the lower greenhouse emissions the convincing status of the technology readiness level and the lower acidification potential. Equally imperative are measures for reducing hydrogen demand in SAF pathways. Strategies involve identifying the appropriate catalyst (monometallic and bimetallic sulphide catalyst) increasing the catalyst life in the deoxygenation process deploying low-cost iso-propanol (hydrogen donor) developing the aerobic fermentation of sugar to 14 dimethyl cyclooctane with the intermediate formation of isoprene and advancing aqueous phase reforming or single-stage hydro processing. Other supportive alternatives include implementing the catalytic and co-pyrolysis of waste oil with solid feedstocks and selecting highly saturated feedstock. Thus future progress demands coordinated innovation and research endeavours to bolster the seamless integration of the cutting-edge hydrogen production processes with the SAF infrastructure. Rigorous technoeconomic and life cycle assessments alongside technological breakthroughs and biomass characterisation are indispensable for ensuring scalability and sustainability

The paper studies and analyzes electric vehicle engines powered by hydrogen under the WLTP standard driving protocol. The driving range extension is estimated using a specific protocol developed for FCEV compared with the standard value for battery electric vehicles. The driving range is extended by 10 km averaging over the four protocols with a maximum of 11.6 km for the FTP-75 and a minimum of 7.7 km for the WLTP. This driving range extension represents a 1.8% driving range improvement on average. Applying the FCEV current weight the driving range is extended to 18.9 km and 20.4 km on average when using power source energy capacity standards for BEVs and FCEVs.

Aiming at the problems of poor transient characteristics of converter output DC voltage and large DC current ripple caused by alkaline electrolyzer (AEL) switching operation in the wind power-hydrogen coupled integrated system this paper proposes an interleaved parallel VDCM control method to improve the stable operation of the system. Firstly a refined mathematical-physical model of the wind power-hydrogen coupled integrated system including HD-PMSG interleaved parallel buck and AEL is constructed. Then the VDCM control strategy is introduced into the interleaved parallel buck converter which provides reliable inertia and damping support for the output voltage of the hydrogen production system by simulating the DC motor power regulation characteristics and effectively improving the current ripple of the output current. Meanwhile the influence of rotational inertia and the damping coefficient on the dynamic stability of the system in the control strategy is analyzed based on the small signal method. Finally the proposed method is validated through MATLAB/SIMULINK simulation experiments and RCP + HIL hardware-in-the-loop experiments. The results show that the proposed method can improve the dynamic stability of the wind power-hydrogen coupled integrated system effectively.