Applications & Pathways

Ammonia is a particularly promising hydrogen carrier due to its relatively low cost high energy density its liquid storage and to its production from renewable sources. Thus in recent years great attention is devoted to this fuel for realizing next generation refueling stations according to a carbon-free energy economy. In this paper a distributed onsite refueling station (200 kg/day of hydrogen filling 700-bar HFCEVs (Hybrid Fuel Cell Electric Vehicles) with about 5 kg of hydrogen in 5 min) based on ammonia feeding is studied from the energy and economic point of views. The station is designed with a modular configuration consisting of more sections: i) the hydrogen production section ii) the electric energy supplier section iii) the compression and storage section and the refrigeration/dispenser section. The core of the station is the hydrogen production section that is based on an ammonia cracking reactor and its auxiliaries; the electric energy demand necessary for the station operation (i.e. the hydrogen compression and refrigeration) is satisfied by a PEMFC (Proton-Exchange Membrane Fuel Cell) power module. Energy performance according to the hydrogen daily demand has been evaluated and the estimation of the levelized cost of hydrogen (LCOH) has been carried out in order to establish the cost of the hydrogen at the pump that can assure the feasibility of this novel refueling station.

Hydrogen is a promising fuel to decarbonise aviation. Storage in liquid form is favoured for long-haul aircraft; storage as a high-pressure gas is preferred otherwise. The exergy expended during the compression or liquefaction process is stored as physical exergy in the fuel. Most discussions around hydrogen-fuelled aviation ignore this very significant exergy content. When combusted in an engine the chemical energy of hydrogen can produce around 60 MJ of work per kg. The work that can be extracted from the physical exergy depends strongly on the method used. This paper presents an exergy analysis considering a range of storage conditions operating conditions and work-extraction methods. For reasonable gas-turbine operating conditions upwards of 16 MJ/kg might be extracted from compressed hydrogen (at 700 bar) and 30 MJ/kg from LH2. This additional work representing 25–50 % of the shaft work produced by combustion has been by and large neglected.

Stringent CO2 reduction targets and tightening emission regulations have intensified interest in hydrogen internal combustion engines (H2ICEs) as a clean and robust solution for the heavy-duty (HD) sector. This study experimentally compares port fuel injection (PFI) early low-pressure direct injection (LPDI) and late LPDI strategies on a single-cylinder HD H2ICE under steady-state medium and high loads. The injection timing and fuel pressure are varied to study the overall influences on a single-cylinder heavy-duty H2ICE. PFI and early LPDI deliver high charge homogeneity but reduced volumetric efficiency compared to late LPDI. At medium load all three strategies achieve ~41 % gross indicated thermal efficiency (gITE). Increasing LPDI pressure from 12.8 to 20 bar enhances mixture uniformity cutting BSNOx emissions by up to 75 %. At high load early LPDI reaches 41.7 % gITE with low NOx (0.72 g/kWh) while late LPDI benefits from reduced heat transfer loss and compression work achieving 42.4 % gITE. However late injection also increases BSNOx (9.3 g/kWh) unburnt H2 (435 ppm) and pressure rise rate (19.7 bar/◦CA). These results highlight LPDI’s potential for high efficiency with injection timing and pressure as key levers to balance emissions and performance.

Green hydrogen will play a crucial role in the future of emission reduction in air traffic in the long-term as it will completely eliminate CO2 emissions and significantly reduce other pollutants such as contrails and nitrogen oxides. Hydrogen offers a promising alternative to kerosene for short- and medium-haul flights particularly through direct combustion and hydrogen fuel cell technology in new aircraft concepts. Against the background of the immense capital-intensive infrastructure adjustments that are required at airports for this purpose and the simultaneously high future hydrogen demand for the shipping industry this paper analyses the emission savings potential in Europe if airports near seaports would switch to hydrogen-powered flight connections.

Maritime and aviation transport are widely recognised as sectors where reducing greenhouse gas emissions is particularly challenging due to their reliance on energy-dense fuels and the challenges associated with direct electrification. These sectors face increasing pressure to defossilise and reduce emissions in line with global climate goals while simultaneously facing unique technological operational and economic uncertainties. This study addresses a key research gap by comparing the maritime and aviation sectors for common factors and sector-specific differences in their transition to green e-fuels produced from renewable electricity and sustainable CO2. A techno-economic assessment is conducted to evaluate alternative fuel and propulsion options using the levelised cost of mobility framework. The analysis also incorporates the pricing of non-CO2 greenhouse gases and air pollutant emissions. Results show that e-ammonia or e-LNG combustion is the most cost-effective option for maritime transport when emission costs are excluded whereas hydrogen fuel cells become more economical when these costs are internalised. In aviation e-kerosene use in conventional aircraft presents the lowest costs regardless of the year or emission pricing. The findings highlight the importance of considering unique characteristics of each sector and tailored defossilisation and decarbonisation strategies that consider sector-specific constraints. To sustainably meet the growing demand for transport fuels rapid investments in renewable electricity generation electrolysers and e-fuel synthesis are essential. Development of strong regulatory frameworks and financial instruments will be critical to support early deployment of e-fuels and minimise the risks.

In Southern Italy near the Mediterranean Sea mobility services like cars bicycles scooters and materialhandling forklifts are frequently required in addition to multimodal local transportation services such as trains ferry boats and airplanes. This research proposes an innovative concept of hydrogen valley virtually simulated in Matlab/Simulink environment located in Calabria. As a novelty hydrogen is produced centrally and delivered via fuel cell hybrid trains to seven hydrogen refueling stations serving various mobility hubs. The centralized production facility operates with a nominal capacity of about 4 tons/day producing hydrogen via PEM electrolysis and storing hydrogen at 200 bar with a hydrogen compressor. As the size of vehicle fleets and the cost of acquiring renewable energy through power purchase agreements vary the hydrogen valley is examined from both a technical and an economic perspective analyzing: the values of the levelized cost of hydrogen the energy consumption and the energy efficiency of the energy systems. Specifically the levelized cost of hydrogen reached competitive values close to 5 €/kg of hydrogen under the most optimistic scenarios with fleet conversions of more than 60 % and a power purchase agreement price lower than 150 €/MWh. Then the benefits of hydrogen rail transport in terms of emissions reduction and health from an economic standpoint are compared to conventional diesel trains and fully electric trains saving respectively 3.2 ktons/year and 0.4 ktons/year of carbon dioxide equivalent emissions and corresponding economic benefits of respectively 51 and 0.548 million euros.

The use of aluminum-based products is widespread and growing particularly in industries such as automotive food packaging and construction. Obtaining aluminum is expensive and energy-intensive making the recycling of existing products essential for economic and environmental viability. This work explores the potential of using green hydrogen as a replacement for natural gas in the smelting and refining furnaces in aluminum recycling facilities. The adoption of green hydrogen has the potential to curtail approximately 4.54 Ktons/year of CO2 emissions rendering it a sustainable and economically advantageous solution. The work evaluates the economic viability of a case study through assessing the Net Present Value (NPV) and the Internal Rate of Return (IRR). Furthermore it is employed single- and multi-parameter sensitivity analyses to obtain insight on the most relevant conditions to achieve economic viability. Results demonstrate that integrating on-site green hydrogen generation yields a favorable NPV of €57370 an IRR of 9.83% and a 19.63-year payback period. The primary factors influencing NPV are the initial electricity consumption stack and the H2 price.

The integration of wind and solar energy with green hydrogen technologies represents an innovative approach toward achieving sustainable energy solutions. This review examines state-ofthe-art strategies for synthesizing renewable energy sources aimed at improving the efficiency of hydrogen (H2 ) generation storage and utilization. The complementary characteristics of solar and wind energy where solar power typically peaks during daylight hours while wind energy becomes more accessible at night or during overcast conditions facilitate more reliable and stable hydrogen production. Quantitatively hybrid systems can realize a reduction in the levelized cost of hydrogen (LCOH) ranging from EUR 3.5 to EUR 8.9 per kilogram thereby maximizing the use of renewable resources but also minimizing the overall H2 production and infrastructure costs. Furthermore advancements such as enhanced electrolysis technologies with overall efficiencies rising from 6% in 2008 to over 20% in the near future illustrate significant progress in this domain. The review also addresses operational challenges including intermittency and scalability and introduces system topologies that enhance both efficiency and performance. However it is essential to consider these challenges carefully because they can significantly impact the overall effectiveness of hydrogen production systems. By providing a comprehensive assessment of these hybrid systems (which are gaining traction) this study highlights their potential to address the increasing global energy demands. However it also aims to support the transition toward a carbon-neutral future. This potential is significant because it aligns with both environmental goals and energy requirements. Although challenges remain the promise of these systems is evident.

The use of hydrogen as a source of fuel for marine applications is relatively nascent. As the maritime industry pivots to the use of alternate low and zero-emission fuels to adapt to a changing regulatory landscape hydrogen energy needs to present and substantiate a technical and commercially viable use case to secure its value proposition in the future fuel mix. This paper leverages the technoeconomic and environmental assessment previously performed on HyForce a hydrogen-fuelled harbour tug which has shown encouraging results for both technical and commercial aspects. This study aims to create a digital twin of HyForce to accurately predict her operability in real-world scenarios. The results from this study identify the strengths and drawbacks of the proposed use case. This is achieved by embedding the detailed design of HyForce in a virtual environment to further evaluate its operational performance through Computational Fluid Dynamics (CFD) simulations of realistic environmental conditions such as wind wave sea currents and friction attributed to the properties of seawater. The results from this study indicate a base case power requirement of 93 kW to 1892 kW to achieve speeds of 5 to 12 knots in the absence of external environmental influences. Consequently the speed of HyForce has a profound impact on total resistance peaking at 97.3 kN at 12 knots. Seawater properties such as low seawater temperature of 0C and a high salinity of 50g/kg increased friction. Additionally wind speeds of 10 m/s acting on HyForce delivered a resistance of 3 kN. However these will be well mitigated through the design of the propulsion system which will be able to deliver a thrust power of 1892 kW and with assistance from the energy storage systems produce 2 MW of power to overcome the resistance experienced. The findings presented in this paper can serve as a foundation for constructing a robust model for the development of a predictive controller for future work. This controller has the potential to optimize the configuration of hydrogen and battery energy storage aligning with desired cost functions.

The decarbonization of industrial process heat is one of the bigger challenges of the global energy transition. Process heating accounts for about 20% of final energy demand in Germany and the situation is similar in other industrialized nations around the globe. Process heating is indispensable in the manufacturing processes of products and materials encountered every day ranging from food beverages paper and textiles to metals ceramics glass and cement. At the same time process heating is also responsible for significant greenhouse gas emissions as it is heavily dependent on fossil fuels such as natural gas and coal. Thus process heating needs to be decarbonized. This review article explores the challenges of decarbonizing industrial process heat and then discusses two of the most promising options the use of electric heating technologies and the substitution of fossil fuels with low-carbon hydrogen in more detail. Both energy carriers have their specific benefits and drawbacks that have to be considered in the context of industrial decarbonization but also in terms of necessary energy infrastructures. The focus is on high-temperature process heat (>400 ◦C) in energy-intensive basic materials industries with examples from the metal and glass industries. Given the heterogeneity of industrial process heating both electricity and hydrogen will likely be the most prominent energy carriers for decarbonized high-temperature process heat each with their respective advantages and disadvantages.

Solid oxide fuel cells (SOFC) have developed to a mature technology able to achieve electrical efficiencies beyond 60%. This makes them particularly suitable for off-grid applications where SOFCs can supply both electricity and heat at high efficiency. Concerns related to lifetime particularly when operated dynamically and the high investment cost are however still the main obstacles toward a widespread adoption of this technology. In this paper we propose a hybrid cogeneration system that attempts to overcome these limitations in which the SOFC mainly provides the baseload of the system. Introducing a purification unit allows the production and storage of pure hydrogen from the SOFC anode off-gas. The hydrogen can be stored and used in a proton exchange membrane fuel cell (PEMFC) during peak demands. The SOFC system is completed with a battery used during periods of high electricity production. We propose the use of a mixed integer-linear optimization framework for the sizing of the different components of the system and particularly for identifying the optimal trade-off between round-trip efficiency and investment cost of the battery-based and hydrogen-based storage systems. The proposed system is applied and optimized to two case studies: an off-grid dwelling and a cruise ship. The results show that if the SOFC is used as the main energy conversion technology of the system the use of hydrogen storage in combination with a PEMFC and a battery is more economically convenient compared to the use of the SOFC in stand-alone mode or of pure battery storage. The results show that the proposed hybrid storage solution makes it possible to reduce the investment cost of the system while maintaining the use of the SOFC as the main energy source of the system.

The increasing depletion of fossil fuels and their environmental impact have led to the development of fuel cell hybrid electric vehicles. By combining fuel cells with batteries these vehicles offer greater efficiency and zero emissions. However their energy management remains a challenge requiring advanced strategies. This paper presents a comparative study of two developed energy management strategies: a deterministic rule-based approach and a fuzzy logic approach. The proposed system consists of a proton exchange membrane fuel cell (PEMFC) as the primary energy source and a lithium-ion battery as the secondary source. A comprehensive model of the hybrid powertrain is developed to evaluate energy distribution and system behaviour. The control system includes a model predictive control (MPC) method for fuel cell current regulation and a PI controller to maintain DC bus voltage stability. The proposed strategies are evaluated under standard driving cycles (UDDS and NEDC) using a simulation in MATLAB/Simulink. Key performance indicators such as fuel efficiency hydrogen consumption battery state-of-charge and voltage stability are examined to assess the effectiveness of each approach. Simulation results demonstrate that the deterministic strategy offers a structured and computationally efficient solution while the fuzzy logic approach provides greater adaptability to dynamic driving conditions leading to improved overall energy efficiency. These findings highlight the critical role of advanced control strategies in improving FCHEV performance and offer valuable insights for future developments in hybrid-vehicle energy management.

This study investigates potential solutions for low-carbon power generation with hydrogen firing and carbon capture. Multi-dimensional system modeling was used to assess the effects on plant performance size and cost. The examined cycles include advanced dry- wet- bottoming- oxyfuel cycles with air-separation units and post-combustion carbon capture with exhaust gas recirculation. The results identify three distinct lowcarbon technology pathways. While conventional combined-cycle plants are suitable for hydrogen retrofits hydrogen firing (both blue and green) results in levelized costs of electricity 50%–300% higher than carbon capture solutions making carbon capture more attractive for long-term energy storage. When carbon capture is applied to conventional combined cycles they become suboptimal compared to alternative solutions. The intercooled-recuperated (ICR) gas turbine cycle integrated with post-combustion carbon capture offers superior performance: over 3% higher efficiency 12% lower capital costs and 70% smaller physical footprint compared to conventional combined cycles with carbon capture. The Allam cycle represents a third pathway achieving 100% CO2 capture with efficiency comparable to combined cycles at 90% capture. Gas separation units emerge as the dominant source of both capital costs and efficiency penalties across all carbon capture configurations representing the key area for future optimization to reduce overall electricity costs.

The global transport sector a significant contributor to energy consumption and greenhouse gas (GHG) emissions requires innovative solutions to meet sustainability goals. Artificial intelligence (AI) has emerged as a transformative technology offering opportunities to enhance energy efficiency and reduce GHG emissions in transport systems. This study provides a comprehensive review of AI’s role in optimizing vehicle energy management traffic flow and alternative fuel technologies such as hydrogen fuel cells and biofuels. It explores AI’s potential to drive advancements in electric and autonomous vehicles shared mobility and smart transportation systems. The economic analysis demonstrates the viability of AI-enhanced transport considering Total Cost of Ownership (TCO) and cost-benefit outcomes. However challenges such as data quality computational demands system integration and ethical concerns must be addressed to fully harness AI’s potential. The study also highlights the policy implications of AI adoption underscoring the need for supportive regulatory frameworks and energy policies that promote innovation while ensuring safety and fairness.

Accelerating the transition to a cleaner global energy system is essential for tackling the climate crisis and green hydrogen energy systems hold significant promise for integrating renewable energy sources. This paper offers a thorough evaluation of green hydrogen’s potential as a groundbreaking alternative to achieve near-zero greenhouse gas (GHG) emissions within a renewable energy framework. The paper explores current technological options and assesses the industry’s present status alongside future challenges. It also includes an economic analysis to gauge the feasibility of integrating green hydrogen providing a critical review of the current and future expectations for the levelized cost of hydrogen (LCOH). Depending on the geographic location and the technology employed the LCOH for green hydrogen can range from as low as EUR 1.12/kg to as high as EUR 16.06/kg. Nonetheless the findings suggest that green hydrogen could play a crucial role in reducing GHG emissions particularly in hard-to-decarbonize sectors. A target LCOH of approximately EUR 1/kg by 2050 seems attainable in some geographies. However there are still significant hurdles to overcome before green hydrogen can become a cost-competitive alternative. Key challenges include the need for further technological advancements and the establishment of hydrogen policies to achieve cost reductions in electrolyzers which are vital for green hydrogen production.

The Department of Energy’s (DOE) hydrogen and fuel cell activities are presented focussing on key targets and progress. Recent results on the cost durability and performance of fuel cells are discussed along with the status of hydrogen-related technologies and cross-cutting activities. DOE has deployed fuel cells in key early markets including backup power and forklifts. Recent analyses show that fuel cell electric vehicles (FCEVs) are among the most promising options to reduce greenhouse gas emissions and petroleum use. Preliminary analysis also indicates that the total cost of ownership of FCEVs will be comparable to other advanced vehicle and fuel options.

Energy decarbonisation is essential to achieve Net-Zero emissions goal by 2050. Consequently investments in alternative low-carbon pathways and energy carriers for the heat sector are required. In this study we propose an optimisation framework for the transition of heat sector in Great Britain focusing on hydrogen infrastructure decisions. A spatially-explicit mixed-integer linear programming (MILP) evolution model is developed to minimise the total system’s cost considering investment and operational decisions. The optimisation framework incorporates both long-term planning horizon of 5-year steps from 2035 to 2050 and typical days with hourly resolution. Aiming to alleviate the computational effort of such multiscale model two hierarchical solution approaches are suggested that result in computational time reduction. From the optimisation results it is shown that the installation of gas reforming hydrogen production technologies with CCS and biomass gasification with CCS can provide a cost-effective strategy achieving decarbonisation goal. What-if analysis is conducted to demonstrate further insights for future hydrogen infrastructure investments. Results indicate that as cost is highly dependent on natural gas price Water Electrolysis capacity increases significantly when gas price rises. Moreover the introduction of carbon tax policy can lead to lower CO2 net emissions.

The work carried out in this paper focused on “Machine learning models for the prediction of turbulent combustion speed for hydrogen-natural gas spark ignition engines”. The aim of this work is to develop and verify the ability of machine learning models to solve the problem of estimating the turbulent flame speed for a spark-ignition internal combustion engine operating with a hydrogen-natural gas mixture then evaluate the relevance of these models in relation to the usual approaches. The novelty of this work is the possibility of a direct calculation of turbulent combustion speed with a good precision using only machine learning model. The obtained models are also compared to each other by considering in turn as a comparison criterion: the precision of the result calculation time and the ability to assimilate original data (which has not undergone preprocessing). An important particularity of this work is that the input variables of the machine learning models were chosen among the variables directly measurable experimentally based on the opinion of experts in combustion in internal combustion engines and not on the usual approaches to dimensionality reduction on a dataset. The data used for this work was taken from a MINSEL 380 a 380-cc single-cylinder engine. The results show that all the machine learning models obtained are significantly faster than the usual approach and Random Forest (R2: R-squared = 0.9939 and RMSE: Root Mean Square Error = 0.4274) gives the best results. With a forecasting accuracy of over 90 % both approaches can make reasonable predictions for most industrial applications such as designing engine monitoring and control systems firefighting systems simulation and prototyping tools.

Nowadays several technologies based on powertrain electrification and the exploitation of hydrogen represent valuable options for decarbonizing the on-road public transport sector. The considered alternatives should exhibit an effective benchmark between CO2 reduction potential and production/operational costs. Conducting a comprehensive Total Cost of Ownership (TCO) analysis coupled with a thorough Life Cycle Assessment (LCA) is therefore crucial in shaping the future for cleaner urban mobility. From this perspective this study compares different powertrain configurations for a 12 m urban bus: a conventional diesel Internal Combustion Engine Vehicle (ICEV) a series hybrid diesel two hydrogen-based series hybrid vehicles: a Hydrogen Hybrid Electric Vehicle featuring an H2-ICE (H2-HEV) or a Fuel Cell Electric Vehicle (FCEV) and a Battery Electric Vehicle (BEV). Moreover a sensitivity analysis has been conducted on the carbon footprint for power generation considering also the marginal electricity mix. In addition prospective LCA and TCO elements are introduced by addressing future technological projections for the 2030 horizon. The research reveals that as of today the BEV and hydrogen-fueled vehicles have comparable environmental impacts when the marginal electricity mix is considered. The techno-economic analysis indicates that under current conditions FCEVs and H2-HEVs are not cost-effective for CO₂ reduction unless powered by renewable energy sources. However considering future technological advancements and market evolution FCEVs offer the most promising balance between economic and environmental benefits particularly if hydrogen prices reach €4 per kilogram. If hydrogen-powered vehicles remain a niche market BEVs will be the most viable option for decarbonizing the transport sector in most European countries.

Green hydrogen production and storage are vital in mitigating carbon emissions and sustainable transition. However the high investment cost and management requirements are the bottleneck of utilizing hybrid hydrogen-based systems in microgrids. Given the necessity of cost-effective and optimal design of these systems the present study examines techno-economic feasibility of integrating hybrid hydrogen-based systems into an outdoor test facility. With this perspective several solar-driven hybrid scenarios are introduced at two energy storage levels namely the battery and hydrogen energy storage systems including the high-pressure gaseous hydrogen and metal hydride storage tanks. Dynamic simulations are carried out to address subtle interactions in components of the hybrid system by establishing a TRNSYS model coupled to a Fortran code simulating the metal hydride storage system. The OpenStudio-EnergyPlus plugin is used to simulate the building load validate against experimental data according to the measured data and monitored operating conditions. Aimed at enabling efficient integration of energy storage systems a techno-enviro-economic optimization algorithm is developed to simultaneously minimize the levelized cost of the electricity and maximize the CO2 mitigation in each proposed hybrid scenario. The results indicate that integrating the gaseous hydrogen and metal hydride storages into the photovoltaic-alone scenario enhances 22.6% and 14.4% of the annual renewable factor. Accordingly the inclusion of battery system to these hybrid scenarios gives a 30.4% and 20.3 % boost to the renewable factor value respectively. Although the inclusion of battery energy storage into the hybrid systems increases the renewable factor the results imply that it reduces the hydrogen production rate via electrolysis. The optimized values of the levelized cost of electricity and CO2 emission for different scenarios vary in the range of 0.376–0.789 $/kWh and 6.57–9.75 ton respectively. The multi-criteria optimizations improve the levelized cost of electricity and CO2 emission by up to 46.2% and 11.3% with respect to their preliminary design.

This study investigates hydrogen (H2) as a supplementary fuel in heavy-duty diesel engines using pre-manifold injection. A H2-diesel dual-fuel (H2DF) system was implemented on a commercial class-8 heavy-duty diesel truck without modifying the original diesel injection system and engine control unit (ECU). Tests were conducted on a chassis dynamometer at engine speeds between 1000 and 1400 rpm with driver-demanded torques from 10 to 75%. The hydrogen energy fraction (HEF) was strategically controlled in the range between 10 and 30%. Overall CO2 reduction (comparable to the HEF level) was achieved with similar brake-specific energy consumption (BSEC) at all loads and speeds. To maintain the same shaft torque the driver-demanded torque was reduced in H2DF operation which resulted in a lower boost pressure. At higher loads engine-out BSNOx slightly decreased while BSCO and black carbon (BC) increased significantly due to lower oxygen concentration resulting from the lower boost pressure. At lower loads engine-out BSCO and BSBC decreased moderately while NO2/NO ratio increased substantially in H2DF operation. Deliberate air path and diesel injection control are expected to enable higher HEF and GHG reductions.

As a zero-emission fuel hydrogen provides a promising solution with significant potential to meet the increasing demand for clean energy alternatives. Hydrogen fueling stations are essential infrastructure for the commercialization of hydrogen fuel cells but the flammability of hydrogen poses safety challenges throughout its lifecycle. Past incidents highlight the need for robust risk assessments starting with comprehensive hazard identification and failure scenario analysis.<br/>This paper proposes using Multilevel Flow Modelling (MFM) a functional modeling method integrated with reasoning capability to support safety evaluations. MFM enables the structured representation of system functions and supports tasks such as fault diagnosis and hazard analysis. Previously applied in nuclear offshore and chemical systems MFM is here used to model a liquid hydrogen fueling station. This paper demonstrates that a developed MFM model identifies failure scenarios related to hydrogen leaks overpressure and operational reliability issues.<br/>This paper conducts a comparison between MFM and traditional methods FMEA and FTA and demonstrates MFM's strength in handling the key challenges rooted from complex failure interactions. Results suggest MFM is complementary to traditional methods and can enhance risk assessments. MFM also contributes to digitalization in safety assessment and monitoring systems ultimately improving hydrogen fueling station reliability and safety.

In the future steel products will be reheated for hot working using hydrogen instead of natural gas. This study investigated the differences in oxide scale formation between natural gas/air and hydrogen/air combustion at constant air-fuel-ratio. Samples of a hypo-eutectoid eutectoid and hyper-eutectoid steel grade (dimensions: 30 x 30 x 50 mm W x H x L) were exposed to the two atmospheres in a semi-industrial scale furnace for 180 min at three sample core temperatures (1100 1200 and 1280 °C). Specific mass gain was calculated and the samples were metallographically examined. Switching the fuel increased scale formation depending on the steel. The exponential correlation between temperature and scale formation is more pronounced for the eutectoid and the hyper-eutectoid steel grade. Metallographic investigations revealed similar scale morphologies in both atmospheres but with significant temperature dependence. The decarburization depth is atmosphere-independent. Thus switching fuel does not negatively impact the properties of the steel substrate; it only increases scale formation during reheating.

An analysis of the turbulent premixed combustion speed in an internal combustion engine using natural gas hydrogen and intermediate mixtures as fuels is carried out with different air-fuel ratios and engine speeds. The combustion speed has been calculated by means of a two-zone diagnosis thermodynamic model combined with a geometric model using a spherical flame front hypothesis. 48 operating conditions have been analyzed. At each test point the pressure record of 200 cycles has been processed to calculate the cycle averaged turbulent combustion speed for each flame front radius. An expression of turbulent combustion speed has been established as a function of two parameters: the ratio between turbulence intensity and laminar combustion speed and the second parameter the ratio between the integral spatial scale and the thickness of the laminar flame front increased by instabilities. The conclusion of this initial study is that the position of the flame front has a great influence on the expression to calculate the combustion speed. A unified correlation for all positions of the flame front has been obtained by adding one correction term based on the expansion speed as a turbulence source. This unified correlation is thus valid for all experimental conditions of fuel types air–fuel ratios engine speeds and flame front positions. The correlation can be used in quasi-dimensional predictive models to determine the heat released in an ICE.

This study investigated the cost competitiveness using total cost of ownership (TCO) analysis of hydrogen fuel cell electric vehicles (FCEVs) in heavy duty on and off-road fleet applications as a key enabler in the decarbonisation of the transport sector and compares results to battery electric vehicles (BEVs) and diesel internal combustion engine vehicles (ICEVs). Assessments were carried out for a present day (2021) scenario and a sensitivity analysis assesses the impact of changing input parameters on FCEV TCO. This identified conditions under which FCEVs become competitive. A future outlook is also carried out examining the impact of time-sensitive parameters on TCO when net zero targets are to be reached in the UK and EU. Several FCEVs are cost competitive with ICEVs in 2021 but not BEVs under base case conditions. However FCEVs do have potential to become competitive with BEVs under specific conditions favouring hydrogen including the application of purchase grants and a reduced hydrogen price. By 2050 a number of FCEVs running on several hydrogen scenarios show a TCO lower than ICEVs and BEVs using rapid chargers but for the majority of vehicles considered BEVs remain the lowest in cost unless specific FCEV incentives are implemented. This paper has identified key factors hindering the deployment of hydrogen and conducted comprehensive TCO analysis in heavy duty on and off-road fleet applications. The output has direct contribution to the decarbonisation of the transport sector.

This study aimed to compare hydrogen ammonia methanol and waste-derived biofuels as shipping fuels using life cycle assessment to establish what potential they have to contribute to the shipping industry’s 100% greenhouse gas emission reduction target. A novel approach was taken where the greenhouse gas emissions associated with one year of global shipping fleet operations was used as a common unit for comparison therefore allowing the potential life cycle greenhouse gas emission reduction from each fuel option to be compared relative to Paris Agreement compliant targets for international shipping. The analysis uses life cycle assessment from resource extraction to use within ships with all GHGs evaluated for a 100-year time horizon (GWP100). Green hydrogen waste-derived biodiesel and bio-methanol are found to have the best decarbonisation po tential with potential emission reductions of 74–81% 87% and 85–94% compared to heavy fuel oil; however some barriers to shipping’s decarbonisation progress are identified. None of the alternative fuels considered are currently produced at a large enough scale to meet shipping’s current energy demand and uptake of alternative fuel vessels is too slow considering the scale of the challenge at hand. The decarbonisation potential from alternative fuels alone is also found to be insufficient as no fuel option can offer the 100% emission reduction required by the sector by 2050. The study also uncovers several sensitives within the life cycles of the fuel options analysed that have received limited attention in previous life cycle investigations into alternative shipping fuels. First the choice of allocation method can potentially double the life cycle greenhouse gas emissions of e-methanol due to the carbon ac counting challenges of using waste carbon dioxide streams during fuel production. This leads to concerns related to the true impact of using carbon dioxide captured from fossil-fuelled processes to produce a combustible product due to the resultant high downstream emissions. Second nitrous oxide emissions from ammonia combustion are found to be highly sensitive due to high greenhouse gas potency potentially offsetting any greenhouse reduction potential compared to heavy fuel oil. Further uncertainties are highlighted due to limited available data on the rate of nitrous oxide production from ammonia engines. The study therefore highlights an urgent need for the shipping sector to consider these factors when investing in new ammonia and methanol engines; failing to do so risks jeopardizing the sector’s progress towards decarbonisation. Finally whilst alternative fuels can offer good decarbonisation potential (particularly waste derived biomethanol and bio-diesel and green hydrogen) this cannot be achieved without accelerated investment in new and retrofit vessels and new fuel supply chains: the research concludes that existing pipeline of vessel orders and fuel production facilities is insufficient. Furthermore there is a need to integrate alternative fuel uptake with other decarbonisation strategies such as slow steaming and wind propulsion.

With the escalating global energy demand the pursuit of sustainable energy sources has become increasingly urgent. Among these biofuels have gained significant attention for their potential to provide renewable and eco-friendly alternatives. Biodiesel is recognized for its diverse and cost-effective feedstock options. The study provides a novel approach to the production of biodiesel by employing the use of Dunaliella salina microalgae as a green source. The research suggests the blends provide a future solution to less toxic fuel sources achieving efficiency and minimizing emissions. This research emphasize on the production of biodiesel from Dunaliella salina microalgae a promising resource due to its high energy yield. The microalgae were cultivated in an f/2 nutrient medium enriched with carbon dioxide vitamins and trace metals. A total of 700 mL of bio-oil was extracted using ultrasonication at 50 Hz for 85 minutes. Then the bio-oil was transesterified in a single-stage sodium hydroxide-catalysed process with methanol as a solvent. The process yielded a high extraction efficiency of 94%. The produced biodiesel was characterized through advanced analytical techniques including NMR spectroscopy GC-MS and FTIR test studies confirming its suitability as a fuel. Combustion and emission analyses revealed that the direct substitution of biodiesel blends for diesel in engines significantly reduced hydrocarbon and carbon monoxide emissions although a slight increase in nitrogen oxide (NOx) emissions was noted. The combustion and emission characteristics were influenced by blend composition and calorific value. Additionally the study provides a detailed comparison of the performance of pure diesel biodiesel blends and hydrogen-enriched biodiesel in diesel engines offering valuable insights into their environmental and performance impacts. This study gives additional insights towards future work such as scalability (consisting large scale cultivation of algae for better studies) engine durability (studies on engine wear and tear) and integration with renewable energy sources (integrating renewable sources like solar and wind energies).

As a subdivision of the hydrogen energy application field ship-borne hydrogen fuel cell systems have certain differences from vehicle or other application scenarios in terms of their structural type safety environmental adaptability and test verification. The connection method of the ship-borne hydrogen storage cylinder (SHSC) is very important for the hydrogen fuel cell ship and the structural parameters of the SHSC are particularly important in the hydrogen refueling process. To ensure the safe and reliable operation of the hydrogen-powered ship research on the filling of the SHSC under different connection modes was carried out during refueling. In our study a thermal flow physical model of the SHSC was established to research the hydrogen refueling process of the series and parallel SHSCs. The influence of series and parallel modes of the SHSCs on the hydrogen refueling process was explored and the evolution law of the internal flow field pressure and temperature of series and parallel SHSCs under different filling parameters was analyzed by numerical simulation. Our results confirmed the superiority of the parallel modular approach in terms of thermal safety during refueling. The results can supply a technical basis for the future development of hydrogen refueling stations and ship-board hydrogenation control algorithms.

The maritime industry while indispensable to global trade is a significant contributor to greenhouse gas (GHG) emissions accounting for approximately 3% of global emissions. As international regulatory bodies particularly the International Maritime Organization (IMO) push for ambitious decarbonization targets hydrogen-based technologies have emerged as promising alternatives to conventional fossil fuels. This review critically examines the potential of hydrogen fuels—including hydrogen fuel cells (HFCs) and hydrogen internal combustion engines (H2ICEs)—for maritime applications. It provides a comprehensive analysis of hydrogen production methods storage technologies onboard propulsion systems and the associated techno-economic and regulatory challenges. A detailed life cycle assessment (LCA) compares the environmental impacts of hydrogenpowered vessels with conventional diesel engines revealing significant benefits particularly when green or blue hydrogen sources are utilized. Despite notable hurdles—such as high production and retrofitting costs storage limitations and infrastructure gaps—hydrogen holds considerable promise in aligning maritime operations with global sustainability goals. The study underscores the importance of coordinated government policies technological innovation and international collaboration to realize hydrogen’s potential in decarbonizing the marine sector.

BACKGROUND: Norway is facing the challenge of reducing transport emissions. High speed crafts(HSC) are the means of transport with highest emissions. Currently there is little literature or experienceof using hydrogen systems for HSC.OBJECTIVE: Evaluate the economic feasibility of fuel cell (FC) powered HSC vs diesel and biodieseltoday and in a future scenario based on real world operation profile.<br/>METHOD: Historical AIS position data from the route combined with the speed-power characteristicsof a concept vessel was used to identify the energy and power demand. From the resulting data a suitableFC system was defined and an economic comparison made based on annual costs including annualizedinvestment and operational costs.<br/>RESULTS: HSC with a FC-system has an annual cost of 12.6 MNOK. It is 28% and 12% more expensivethan diesel and biodiesel alternative respectively. A sensitivity analysis with respect to 7 key design pa-rameters indicates that highest impact is made by hull energy efficiency FC system cost and hydrogen fuelcost. In a future scenario (2025–2030) with moderate technology improvements and cost developmentthe HSC with FC-systems can become competitive with diesel and cheaper than biodiesel.<br/>CONCLUSIONS: HSC with FC-systems may reach cost parity with conventional diesel in the period2025–2030.

China’s progress in decarbonizing its transportation particularly vehicle electrification is notable. However the economically effective pathways are underexplored. To find out how much cost is necessary for carbon neutrality for the light-duty vehicle (LDV) sector this study examines twenty decarbonization pathways combining the New Energy and Oil Consumption Credit model and the China-Fleet model. We find that the 2060 zero-greenhouse gas (GHG) emission goal for LDVs is achievable via electrification if the battery pack cost is under CNY483/kWh by 2050. However an extra of CNY8.86 trillion internal subsidies is needed under pessimistic battery cost scenarios (CNY759/kWh in 2050) to eliminate 246 million tonnes of CO2-eq by 2050 ensuring over 80% market penetration of battery electric vehicles (BEVs) in 2050. Moreover the promotion of fuel cell electric vehicles is synergy with BEVs to mitigate the carbon abatement difficulties decreasing up to 34% of the maximum marginal abatement internal investment.

Decarbonising aquaculture support vessels is pivotal to reducing greenhouse gas (GHG) emissions across both the aquaculture and maritime sectors. This study evaluates the technical and economic feasibility of deploying hydrogen as a marine fuel for a 14.95 m net cleaning vessel (NCV) operating in Tasmania Australia. The analysis retains the vessel’s original layout and subdivision to enable a like-for-like comparison between conventional diesel and hydrogen-based systems. Two options are evaluated: (i) replacing both the main propulsion engines and auxiliary generator sets with hydrogen-based systems— either proton exchange membrane fuel cells (PEMFCs) or internal combustion engines (ICEs); and (ii) replacing only the diesel generator sets with hydrogen power systems. The assessment covers system sizing onboard hydrogen storage integration operational constraints lifecycle cost and GHG abatement. Option (i) is constrained by the sizes and weights of PEMFC systems and hydrogen-fuelled ICEs rendering full conversion unfeasible within current spatial and technological limits. Option (ii) is technically feasible: sixteen 700 bar cylinders (131.2 kg H2 total) meet one day of onboard power demand for net-cleaning operations with bunkering via swap-and-go skids at the berth. The annualised total cost of ownership for the PEMFC systems is 1.98 times that of diesel generator sets while enabling annual CO2 reductions of 433 t. The findings provide a practical decarbonisation pathway for small- to medium-sized service vessels in niche maritime sectors such as aquaculture while clarifying near-term trade-offs between cost and emissions.

Fuel-cell flying vehicles suffer from limited endurance while ammonia decomposed onboard to supply hydrogen offers a carbon-free high-density solution to extend flight missions. However the system’s performance is governed by a multi-scale coupling between propulsion and control systems. To this end this paper introduces a novel optimization paradigm termed physics-informed gradient-enhanced multi-objective optimization (PIGEMO) to simultaneously optimize the ammonia decomposition unit (ADU) catalyst composition powertrain sizing and flight control parameters. The PI-GEMO framework leverages a physics-informed neural network (PINN) as a differentiable surrogate model which is trained not only on sparse simulation data but also on the governing differential equations of the system. This enables the use of analytical gradient information extracted from the trained PINN via automatic differentiation to intelligently guide the evolutionary search process. A comprehensive case study on a flying vehicle demonstrates that the PIGEMO framework not only discovers a superior set of Pareto-optimal solutions compared to traditional methods but also critically ensures the physical plausibility of the results.

By integrating Renewable Energy Sources (RES) and storage devices Hybrid Energy Systems (HESs) represent a promising solution for decarbonizing isolated and remote communities. Proper sizing and management of systems comprising a variety of components requires however more advanced methods than conventional energy systems. This study proposes a novel Mixed Integer Linear Programming (MILP) framework for the simultaneous design of a grid-connected HES supported by renewable generators. Unlike the standard design approach based on parametric dispatch strategies this framework simultaneously optimizes the energy management of each system configuration under analysis. The novel approach is applied to size a combination of Li-Ion batteries an alkaline electrolyzer H2 tanks and a PEM fuel cell to maximize the NPV of a system including a wind turbine and a photovoltaic field. Managing thousands of variables at the same time the framework simultaneously optimizes how all components are used to fulfill the load and balance the input/export of power within a limited electrical network. Results show that the combination of BESS and H2 can provide for both the need for short- and long-term energy storage and that the MILP optimization can effectively allocate the energy flows and produce 558 k€ of revenues per year 15.5% of the initial investment cost of 3.6 M€. The investment cost of the system is recovered in six years and presents an NPV of 5.51 M€ after 20 years. Results from the proposed method are also compared to common approaches based on rule-based parametric dispatch strategies demonstrating the superiority of MILP for the design and management of complex HESs.

Air travel demand is rising rapidly and the aviation sector is relying on technology to decouple environmental impacts from its growth. Using Sweden as a case study we assessed the absolute environmental sustainability of medium-distance air travel in 2050 positioning the aviation sector's environmental impacts in relation to the planetary limits. We employed a novel framework that integrates prospective life cycle assessment and absolute environmental sustainability assessment methodologies. Our findings suggest that projected medium-distance air travel powered by e-kerosene or liquid hydrogen could have life cycle environmental impacts that overshoot global climate change and biodiversity loss thresholds by several orders of magnitude. Based on our case results for Sweden for aviation to develop within the planetary limits we recommend cross-sector collaboration to address environmental impacts from fossil-free energy supplies and the establishment of integrated targets that incorporate broader environmental issues. Given the unlikelihood of decoupling growth from environmental impacts policymakers and the aviation sector should consider concurrently supporting technological development and implementing measures to manage air travel demand.

The integration of electric vehicles (EVs) and fuel-cell electric vehicles (FCEVs) requires accessible and profitable facilities for fast charging. To promote fast-charging stations (FCSs) a systematic analysis that encompasses both planning and operation is required including the incorporation of multi-energy resources and uncertainty. This paper presents an optimization framework that addresses a joint strategy for the configuration and operation of an EV/FCEV fast-charging station (FCS) integrated with distributed energy resources (DERs) and hydrogen systems. The framework incorporates uncertainties related to solar photovoltaic (PV) generation and demand for EVs/FCEVs. The proposed joint strategy comprises a four-phase decision-making framework. Phase 1 involves modeling EV/FECE demand while Phase 2 focuses on determining an optimal long-term infrastructure configuration. Subsequently in Phase 3 the operator optimizes daily power scheduling to maximize profit. A real-time uncertainty update is then executed in Phase 4 upon the realization of uncertainty. The proposed optimization framework formulated as mixed-integer quadratic programming (MIQP) considers configuration investment operational maintenance and penalty costs for excessive grid power usage. A heuristic algorithm is proposed to solve this problem. It yields good results with significantly less computational complexity. A case study shows that under the most adverse conditions the proposed joint strategy increases the FCS owner’s profit by 3.32% compared with the deterministic benchmark.

In this study we investigate the dual-fuel operation of compression ignition engines using biodiesel at varying concentrations in combination with biogas with and without hydrogen enrichment. A response surface methodology based on a central composite experimental design was employed to optimize energy efficiency and minimize pollutant emissions. The partial substitution of diesel with gaseous fuel substantially reduces the specific fuel consumption achieving a maximum decrease of 21% compared with conventional diesel operation. Enriching biogas with hydrogen accounting for 13.3% of the total flow rate increases the thermal efficiency by 0.8% compensating for the low calorific value and reduced volumetric efficiency of biogas. Variations in biodiesel concentration exhibits a nonlinear effect yielding an additional average efficiency gain of 0.4%. Regarding emissions the addition of hydrogen to biogas contributes to an average reduction of 5% in carbon monoxide emissions compared to the standard dual-fuel operation. However dual-fuel operation leads to higher unburned hydrocarbon emissions relative to neat diesel; hydrogen enrichment mitigates this drawback by reducing hydrocarbon emissions by 4.1%. Although NOx emissions increase by an average of 26.6% with hydrogen addition dual-fuel strategies achieve NOx reductions of 11.5% (hydrogen-enriched mode) and 33.3% (pure biogas mode) relative to diesel-only operation. Furthermore the application of response surface methodology is robust and reliable with experimental validation showing errors of 0.55–8.66% and an overall uncertainty of 4.84%.

The transport sector is a major contributor to greenhouse gas emissions largely due to its dependence on fossil fuels. Electrifying transport through Battery Electric Vehicles (BEVs) and Hydrogen Fuel Cell Electric Vehicles (FCEVs) is widely recognized as a key pathway to reducing emissions. While both BEVs and FCEVs are zero-emission during operation they still require electricity to function. Sourcing this electricity from solar energy presents a promising opportunity for sustainable operation. The novelty of this work lies in exploring how solar energy can be effectively integrated into both BEV and FCEV systems. The paper examines the potential scope and infrastructure requirements of these vehicle types as well as innovative charging and refuelling strategies. For BEVs charging options include fixed charging stations battery swapping stations and wireless charging. In the context of solar integration photovoltaic (PV) systems can be mounted directly on the vehicle body or used to power charging stations. While current PV efficiency and reliability are insufficient to meet the full energy demand of BEVs they can provide valuable auxiliary power. For FCEVs solar energy can be utilized for hydrogen production enabling the concept of solar-powered FCEVs. Refuelling options include onsite and offsite hydrogen production facilities as well as mobile refuelling units. In both cases land requirements for PV installations are significant. Alternatives to ground-mounted PV such as floating PV or agrivoltaics (agriPV) should be considered to optimize land use. While solar-powered charging or refuelling stations are technically feasible complete reliance on solar power alone is not yet practical. A hybrid approach with grid connections energy storage or backup generation remains necessary to ensure consistent energy availability. For BEVs the cost of charging particularly for long-distance travel where rapid charging is required remains a barrier. For FCEVs challenges include the high cost of hydrogen production and the limited availability of refuelling infrastructure despite their advantage of fast refuelling times. Government policies and incentives are playing a critical role in overcoming these barriers fostering investment in infrastructure and accelerating the transition toward a cleaner transport sector. In summary integrating solar energy into BEV and FCEV infrastructure can advance sustainable mobility by reducing lifecycle emissions. While current PV efficiency storage and hydrogen production limitations require hybrid energy solutions ongoing technological improvements and supportive policies can enable broader adoption. A balanced renewable energy mix with solar as a key component will be essential for realizing truly sustainable zero-emission transport.

Against the dual backdrop of intensifying carbon emission constraints and the large-scale integration of renewable energy integrated electricity–hydrogen energy systems (EH-ESs) have emerged as a crucial technological pathway for decarbonising energy systems owing to their multi-energy complementarity and cross-scale regulation capabilities. This paper proposes an operational optimisation and carbon reduction capability assessment framework for EH-ESs focusing on revealing their operational response mechanisms and emission reduction potential under multi-disturbance conditions. A comprehensive model encompassing an electrolyser (EL) a fuel cell (FC) hydrogen storage tanks and battery energy storage was constructed. Three optimisation objectives—cost minimisation carbon emission minimisation and energy loss minimisation—were introduced to systematically characterise the trade-offs between economic viability environmental performance and energy efficiency. Case study validation demonstrates the proposed model’s strong adaptability and robustness across varying output and load conditions. EL and FC efficiencies and costs emerge as critical bottlenecks influencing system carbon emissions and overall expenditure. Further analysis reveals that direct hydrogen utilisation outperforms the ‘electricity–hydrogen–electricity’ cycle in carbon reduction providing data support and methodological foundations for low-carbon optimisation and widespread adoption of electricity–hydrogen systems.

Hydrogen is the key to decarbonising heavy-duty transport. Understanding the distribution of hydrogen demand is crucial for effective planning and development of infrastructure. However current data on future hydrogen demand is often coarse and aggregated limiting its utility for detailed analysis and decision-making. This study developed a spatial disaggregation approach to estimating hydrogen demand for heavy-duty trucks and mapping the spatial distribution of hydrogen demand across multiple scales in Australia. By integrating spatial datasets with economic factors market penetration rates and technical specifications of hydrogen fuel cell vehicles the approach disaggregates the projected demand into specific demand centres allowing for the mapping of regional hydrogen demand patterns and the identification of key centres of hydrogen demand based on heavy-duty truck traffic flow projections under different scenarios. This approach was applied to Australia and the findings offered valuable insights that can help policymakers and stakeholders plan and develop hydrogen infrastructure such as optimising hydrogen refuelling station locations and support the transition to a low-carbon heavy-duty transport sector.

As an energy-intensive sector China’s iron and steel industry is crucial for achieving “Dual Carbon” goals. This study fills the research gap in systematically comparing the synergistic effects of multiple policies by evaluating five key measures (2020–2023) in ultra-low-emission retrofits and clean energy alternatives. Using public macro-data at the national level this study quantified cumulative reductions in air pollutants (SO2 NOx PM VOCs) and CO2. A synergistic control effect coordinate system and a normalized synergistic emission reduction equivalent (APeq) model were employed. The results reveal significant differences: Sintering machine desulfurization and denitrification (SDD) showed the highest APeq but increased CO2 emissions in 2023. Dust removal equipment upgrades (DRE) and unorganized emission control (UEC) demonstrated stable co-reduction effects. While electric furnace short-process steelmaking (ES) and hydrogen metallurgy (HM) showed limited current benefits they represent crucial deep decarbonization pathways. The framework provides multi-dimensional policy insights beyond simple ranking suggesting balancing short-term pollution control with long-term transition by prioritizing clean alternatives.

Hydrogen fuel cell systems are a viable option for electrified aero engines due to their efficiency and environmental benefits. However integrating these systems presents challenges notably in terms of overall system weight and thermal management. Heat exchangers are crucial for the effective thermal management system of electric propulsion systems in commercial electrified aviation. This paper provides a comprehensive review of various heat exchanger types and evaluates their potential applications within these systems. Selection criteria are established based on the specific requirements for air and hydrogen heat exchangers in electrified aircraft. The study highlights the differences in weighting criteria for these two types of heat exchangers and applies a weighted point rating system to assess their performance. Results indicate that extended surface microchannel and printed circuit heat exchangers exhibit significant promise for aviation applications. The paper also identifies key design challenges and research needs particularly in enhancing net heat dissipation increasing compactness improving reliability and ensuring effective integration with aircraft systems.

The passive combination of fuel cells and supercapacitors possesses promising applications in the automotive industry due to its ability to decrease stack size maintain peak power capacity improve system productivity and go away with the need for additional control all without Direct current to Direct Current (DC/DC) converters. This research describes the steps to create and evaluate a fuel cell (FC) and supercapacitor (SC) passive hybrid electrical system for a 60-V lightweight vehicle. Also study offers a thorough design approach and model and experimentally to validate every passive hybrid testing station component. When both concepts are stable the voltage errors are about 2 % and 3 % respectively for fuel cells and supercapacitors. The results of the experiments provide more evidence that the passive design is effective under step loads and driving cycles. The results of the measurements match the models used to simulate the passive hybrid system if a step load voltage is used. A smaller FC stack is possible since the fuel cell controls the steady-state current. Alternatively the supercapacitors provide varying currents because of their reduced resistance. This study use a driving cycle to show that the FC stack can lower its output to 25 % of the peak power required by the load.

The inherent randomness and intermittency of offshore renewable energy sources such as wind and solar power pose significant challenges to the stable and secure operation of the power grid. These fluctuations directly affect the performance of grid-connected systems particularly in terms of harmonic distortion and load response. This paper addresses these challenges by proposing a novel harmonic control strategy and load response optimization approach. An integrated three-winding transformer filter is designed to mitigate high-frequency harmonics and a control strategy based on converter-side current feedback is implemented to enhance system stability. Furthermore a hybrid PI-VPI control scheme combined with feedback filtering is employed to improve the system’s transient recovery capability under fluctuating load and generation conditions. Experimental results demonstrate that the proposed control algorithm based on a transformer-oriented model effectively suppresses low-order harmonic currents. In addition the system exhibits strong anti-interference performance during sudden voltage and power variations providing a reliable foundation for the modulation and optimization of offshore wind–solar coupled hydrogen production power supply systems.

With the increasing maturity of renewable energy technologies and the pressing need to address climate change urban power systems are striving to integrate a higher proportion of low-carbon renewable energy sources. However the inherent variability and intermittency of wind and solar power pose significant challenges to the stability and reliability of urban power grids. Existing research has primarily focused on short-term energy storage solutions or small-scale integrated energy systems which are insufficient to address the long-term large-scale energy storage needs of urban areas with high renewable energy penetration. This paper proposes a mid-to-long-term capacity expansion model for hydrogen energy storage in urban-scale power systems using Shanghai as a case study. The model employs mixed-integer linear programming (MILP) to optimize the generation portfolios from the present to 2060 under two scenarios: with and without hydrogen storage. The results demonstrate that by 2060 the installed capacity of hydrogen electrolyzers could reach 21.5 GW and the installed capacity of hydrogen power generators could reach 27.5 GW accounting for 30% of the total installed capacity excluding their own. Compared to the base scenario the electricity–hydrogen collaborative energy supply system increases renewable penetration by 11.6% and utilization by 12.9% while reducing the levelized cost of urban comprehensive electricity (LCOUCE) by 2.514 cents/kWh. These findings highlight the technical feasibility and economic advantages of deploying long-term hydrogen storage in urban grids providing a scalable solution to enhance the stability and efficiency of high-renewable urban power systems.

Hydrogen (H2) fuel is one of eco-friendly resources for delivering de-carbonized and sustainable electricity supply in line with the UN’s Sustainable Development Goals 7 and 13 for affordable and clean energy and climate change action respectively. This paper presents a state-of-the art review of the H2 energy resource in terms of its history and evolution production techniques global economy market perspective and application to microgrid systems. It also introduces a systematic classification of the fuel. The production techniques examined include: the thermal approach such as the reforming gasification and thermochemical processes; the photocatalytic approach otherwise called artificial photosynthesis; the biological and photonic approach that involves the photolysis photo-fermentation dark fermentation CO gas fermentation and biomass valorization processes to produce H2 while the electrical approach is based on the chemical dissociation of electrolytes into their constituent ions by the passage of electric current. A particular attention is paid to the potential of the H2 resource in running some energy generators in microgrid systems such as the internal combustion engines microturbines and the fuel cells that are useful for combined heat and power application. The paper introduces different technical configurations topologies and processes that involve the use of green H2 fuel in generating systems and the connection of bus bars power converters battery bank and the electrical and thermal loads. The paper also presents hybrid fuel cell (FC) and PV system simulation using System Advisor Model (SAM) to showcase the use of H2 fuel in a micogrid. The paper provides insightful directions into the H2 economy smart electrical grid and the future prospects.

Zero-emission fuels are expected to drive the maritime sector decarbonisation with hydrogen emerging as a long-term solution. This study aims to investigate by using CFD modelling a hydrogen fuelled marine dual-fuel engine to identify operating settings ranges for different hydrogen energy fractions (HEF) as well as parametrically optimise the diesel fuel injection timing and temperature at inlet valve closing (IVC). A large marine four-stroke engine with nominal power of 10.5 MW at 500 rev/m is considered assuming operation at 90 % load and hydrogen injection in the cylinders intake ports. CFD models are developed for several operating scenarios in both diesel and dual-fuel modes. The models are validated against measured data for the engine diesel mode and literature data for a hydrogen-fuelled light-duty engine. A convergence study is conducted to select the grid compromising between computational effort and accuracy. Parametric runs for 20 % 40 % and 60 % HEF with different IVC temperature and diesel start of injection are modelled to quantify the engine performance emissions and combustion characteristics. A single parameter optimisation is conducted to determine the most effective pilot diesel injection timings. The results reveal the IVC temperature range for stable hydrogen combustion to avoid incomplete combustion at low IVC temperature and knocking above 360 K. The proposed settings lead to higher peak heat release rate and in-cylinder pressure compared to the diesel mode without exceeding the permissible in-cylinder pressure rise limits for 60 % HEF. However NOx emissions increase to 12.9 g/kWh in the dual-fuel mode. The optimal start of injection (SOI) for the diesel fuel in the case of 60 % HEF is found 8 ◦CA BTDC resulting in an indicated thermal efficiency of 43.2 % and stable combustion. Advancing SOI beyond the optimal value results in incomplete combustion. This is the first study on hydrogen use in large marine four-stroke engines providing insights for the engine design and operation and as such it contributes to the maritime industry decarbonisation efforts.

This work studies the feasibility of integrating a hydrogen-powered propulsion system in a regional aircraft at the conceptual design level. The developed system consists of fuel cells which will be studied at three technological levels and batteries also studied for four hybridization factors (X = 0 0.05 0.10 0.20). Hydrogen can absorb great thermal loads since it is stored in the tank at cryogenic temperatures and is used as fuel in the fuel cells at around 80 ◦C. Taking advantage of this characteristic two thermal management system (TMS) architectures were developed to ensure the proper functioning of the aircraft during the designated mission: A1 which includes a vapor compression system (VCS) and A2 which omits it for a simpler design. The models were developed in MATLAB® and consist of different components and technologies commonly used in such systems. The analysis reveals that A2 due to the exclusion of the VCS outperformed A1 in weight (10–23% reduction) energy consumption and drag. A1’s TMS required significantly more energy due to the VCS compressor. Hybridization with batteries increased system weight substantially (up to 37% in A2) and had a greater impact on energy consumption in A2 due to additional fan work. Hydrogen’s heat sink capacity remained underutilized and the hydrogen tank was deemed suitable for a non-integral fuselage design. A2 had the lowest emissions (10–20% lower than A1 for X = 0) but hybridization negated these benefits significantly increasing emissions in pessimistic scenarios.

Hydrogen internal combustion engines are pivotal components of the power industry for achieving zero-carbon emissions. However the development of hydrogen engines is still in its infancy and experimental research on their injection strategies lacks systematization. In this study the individual impacts of hydrogen injection pressure (within low-pressure ranges) and injection timing as well as their coupling effects on combustion characteristics engine efficiency and exhaust emissions were experimentally investigated. Results show that under fixed timing an injection pressure of 25–27.5 bar yields the highest and earliest peak in-cylinder pressures whereas at 15 bar the ignition delay increases to 14.7°CA the flame development duration extends to 8.57°CA and the late combustion duration shortens to 41.37°CA; the exhaust gas temperature peaks at 628 K at 20 bar and NOX peaks at 537 ppm at 25 bar. BTE (brake thermal efficiency) exhibits a U-shaped relationship with pressure with the minimum efficiency occurring near 25 bar when timing is held constant; advancing start of injection from 130° BTDC to 170° BTDC reduces both NOX and exhaust gas temperature with the optimal fuel economy at 140° BTDC and a peak in-cylinder pressure that is approximately 7 % higher and occurs 2–3°CA earlier at 130–140° BTDC. In the pressure–timing maps IMEP (indicated mean effective pressure) is maximized at 30 bar and 90° BTDC; BTE reaches 33.5 % at 25 bar and 100° BTDC; NOX attains a minimum at 25 bar and 110° BTDC while the exhaust gas temperature is lowest at 25 bar and 120° BTDC. Injection pressure is the primary lever for regulating fuel economy and emissions while injection timing mainly adjusts combustion phasing and IMEP. The results provide clear guidance for calibrating low-pressure hydrogen injection systems supply benchmark data for model validation and support the development of practical control strategies for hydrogen engines.

This study investigates the effects of varying hydrogen percentages in fuel blends on combustion dynamics engine performance and emissions. Experimental data and analytical equations were used to evaluate combustion parameters such as equivalent lambda in-cylinder pressure heat release rate and ignition timing. The findings demonstrate that hydrogen blending enhances combustion stability shortens ignition delay and shifts peak heat release to be closer to the top dead center (TDC). These changes improve thermal efficiency and reduce cycle-to-cycle variation. Hydrogen blending also significantly lowers carbon dioxide (CO2) and hydrocarbon (HC) emissions particularly at higher blend levels (H0–H5) while lower blends increase nitrogen oxides (NOx) emissions and risk pre-ignition due to advanced start of combustion (SOC). Engine performance improved with an average hydrogen energy contribution of 12% under a constant load. However the optimal hydrogen blending range is crucial to balancing efficiency gains and emission reductions. These results underline the potential of hydrogen as a cleaner additive fuel and the importance of optimizing blend ratios to harness its benefits effectively.