Publications

The escalating global energy demand has intensified research into sustainable hydrogen production particularly through water splitting. A highly promising avenue involves photocatalytic water splitting which leverages readily available earth-abundant materials to generate clean hydrogen from water using only renewable energy sources. Among the various catalytic materials investigated metal-organic frameworks (MOFs) have recently attracted considerable interest. Their tunable porosity high crystallinity as well as the customisable molecular structures position them as a transformative class of catalysts for efficient and sustainable photocatalytic hydrogen generation. This review examines MOFs detailing their structural characteristics unique properties and diverse synthetic routes. The discussion extends to the various composite materials that can be derived from MOFs with particular emphasis on their application in photocatalytic hydrogen production via water splitting. Furthermore the review identifies current challenges hindering MOF implementation and proposes modification strategies to overcome these limitations. The concluding section summarises the presented information and future perspectives on the continued development of MOF composites for enhanced photocatalytic hydrogen production from water.

This paper presents TwinP2G a software application for optimal planning of investments in power-to-gas (PtG) systems. TwinP2G provides simulation and optimization services for the techno-economic analysis of user-customized energy networks. The core of TwinP2G is based on power flow simulation; however it supports energy sector coupling including electricity green hydrogen natural gas and synthetic methane. The framework provides a user-friendly user interface (UI) suitable for various user roles including data scientists and energy experts using visualizations and metrics on the assessed investments. An identity and access management mechanism also serves the security and authorization needs of the framework. Finally TwinP2G revolutionizes the concept of data availability and data sharing by granting its users access to distributed energy datasets available in the EnerShare Data Space. These data are available to TwinP2G users for conducting their experiments and extracting useful insights on optimal PtG investments for the energy grid.

The reliability and sustainability of multi-energy networks are increasingly critical in addressing modern energy demands and environmental concerns. Hydrogen-based hybrid energy systems can mitigate the challenges of renewable energy utilization such as intermittency grid stability and energy storage by integrating hydrogen generation and electricity storage from renewable sources such as solar and wind. Therefore this review offers a comprehensive evaluation of the environmental economic and technological aspects of green hydrogen-based hybrid energy systems particularly highlighting improvements in terms of the economics of fuel cell and electrolysis procedures. It also highlights new approaches such as hybrid energy management strategies and power-to-gas (PtG) conversion to enhance the system’s dependability and resilience. Analyzing the role of green hydrogen-based hybrid energy systems in supporting global climate goals and improving energy security underscores their high potential to make a significant contribution to carbon-neutral energy networks and provide policymakers with useful recommendations for developing guidelines. In addition the social aspect of hydrogen systems like energy equity and community engagement towards a hydrogen-based society provides reasons for the continued development of next-generation energy systems.

Hydrogen-powered aircraft constitute a transformative innovation in aviation motivated by the imperative for sustainable and environmentally friendly transportation solutions. This paper aims to concentrate on the design of hydrogen powertrains employing a system approach to propose representative design models for distribution and propulsion systems. Initially the requirements for powertrain design are formalized and a usecase-driven analysis is conducted to determine the functional and physical architectures. Subsequently for each component pertinent to preliminary design an analytical model is proposed for multidisciplinary analysis and optimization for powertrain sizing. A doublewall pipe model incorporating foam and vacuum multi-layer insulation was developed. The internal and outer pipes sizing were performed in accordance with standards for hydrogen piping design. Valves sizing is also considered in the present study following current standards and using data available in the literature. Furthermore models for booster pumps to compensate pressure drop and high-pressure pumps to elevate pressure at the combustion chamber entrance are proposed. Heat exchanger and evaporator models are also included and connected to a burning hydrogen engine in the sizing process. An optimal liner pipe diameter was identified which minimizes distribution systems weight. We also expect a reduction in engine length and weight while maintaining equivalent thrust.

This extensive study delves into analyzing carbon dioxide (CO2)-capturing green hydrogen plant exploring its operation using multiple electrolysis techniques and examining their efficiency and impact on environment. The solar energy is used for the electrolysis to make hydrogen. Emitted CO2 from thermal power plants integrate with green hydrogen and produces methanol. It is a process crucial for mitigating environmental damage and fostering sustainable energy practices. The findings demonstrated that solid oxide electrolysis is the most effective process by which hydrogen can be produced with significant rate of 90 % efficiency. Moreover proton exchange membrane (PEM) becomes a viable and common method with an 80 % efficiency whereas the alkaline electrolysis has a moderate level of 63 % efficiency. Additionally it was noted that the importance of seasonal fluctuations where the capturing of CO2 is maximum in summer months and less in the winter is an important factor to consider in order to maximize the working of the plant and the allocation of resources.

While hydrogen production through pure water splitting remains a key focus in solar hydrogen research photocatalytic seawater splitting presents a more sustainable alternative better aligned with global development goals amid increasing freshwater scarcity. Nevertheless the deactivation of the photocatalyst by the corrosion of various ions present in seawater as well as the chloride ions’ redox side reaction limits the practical use of the photocatalytic seawater splitting process. In this context sulfur has emerged as a crucial component in photocatalytic composites for seawater splitting owing to its unique chemical properties. It acts as a chlorine-repulsive agent effectively suppressing chloride ion oxidation which mitigates corrosion enhances structural stability and significantly improves overall photocatalytic performance in saline environments. This review offers a thorough explanation of the basic ideas of solar-driven seawater splitting delves into various synthesis strategies and explores recent advancements in sulfur-based composites for efficient hydrogen generation using seawater. Optimizing synthesis techniques and incorporating strategies like doping cocatalyst and heterojunctions significantly enhance the performance of sulfur-based photocatalysts for seawater splitting. Future advances include integrating AI-guided material discovery sustainable use of industrial sulfur waste and precise control of sacrificial agents to ensure long-term efficiency and stability.

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.

The transition to cleaner hydrogen-containing fuels is critical for reducing the environmental impact of marine infrastructure yet their potential effects on the durability and mechanical reliability of engine components remain a significant engineering challenge. Although aluminum alloys are generally regarded as less susceptible to hydrogeninduced degradation and are widely applied in internal combustion engine components experimental data obtained under real operating conditions with hydrogen-containing fuel mixtures remain insufficient to fully assess all potential risks. In the present study two identical low-power gasoline engine–generators were operated for 220 h on fuels with and without hydrogen. Post-test analysis included mechanical testing and microstructural characterization of aluminum alloy pistons for comparative assessment. The measured values of ultimate tensile strength elongation and deflection maximum bending force and effective stress concentration factor revealed pronounced property degradation in the piston operated on the gasoline–hydrogen mixture compared to both the new piston and the one run on pure gasoline. Microstructural analysis provided a plausible explanation for this degradation. The results of this preliminary study provide insights into the effects of hydrogen-containing fuel on the mechanical performance of engine component alloys contributing to the development of safer and more reliable marine energy systems.

The transition to a low-carbon energy future requires a multi-faceted approach including the enhancement of existing power generation technologies. This study provides a comprehensive experimental evaluation of hydrogen enrichment as a strategy to improve the performance and reduce the emissions of a power generator. A 3.65 kW power generator that is equipped with spark-ignition engine is systematically tested with five distinct base fuels: gasoline propane methane ethanol and methanol. Each fuel is volumetrically blended with pure hydrogen in ratios of 5 % 10 % 15 % and 20 % using a custom-developed dual-fuel carburetor. The key parameters including exhaust emissions (CO2 CO HC NOx) cylinder exit temperature electrical power output and thermodynamic efficiencies (energy and exergy) are meticulously measured and analyzed. The results reveal that hydrogen enrichment is a powerful tool for decarbonization consistently reducing carbon-based emissions across all fuels. At a 20 % hydrogen blend CO2 emissions are reduced by 22–31 % CO emissions by 39–60 % and HC emissions by 21–60 %. This environmental benefit however is accompanied by a critical trade-off: a severe increase in NOx emissions which rose by 200–420 % due to significantly elevated combustion temperatures. The power outputs are increased by 2–16 % with hydrogen addition enabling lower-energy–density fuels like methane and propane to achieve performance parity with gasoline. Thermodynamic analysis confirms these gains with energy efficiency showing marked improvement particularly for methane which has increased from 42.0 % to 49.9 %. While hydrogen enrichment presents a viable pathway for enhancing engine performance and reducing the carbon emissions of power generators the profound increase in NOx necessitates the integration of advanced control and after-treatment systems for its practical and environmentally responsible deployment.

The U.S. produces 10 million metric tons (MMT) of hydrogen annually emitting about 41 MMT of carbon dioxide equivalents (CO2-eqs). With rising hydrogen demand and new emission regulations integrating conventional and novel hydrogen production systems is crucial. This study presents an integrated optimization framework to model diversified hydrogen economies as mixed integer linear programs (MILPs). Moreover the accounting of emissions extends to the system exterior (scope 3) thus providing a comprehensive sustainability assessment. The primary focus of the presented computational example is to analyze the impact of scope 3 emissions particularly material emissions during the construction phase on process system optimization while complying with stringent environmental constraints such as carbon limits. By evaluating emission reduction scenarios the model highlights the role of power purchase agreements (PPAs) from renewable sources and the trade-offs between conventional and novel hydrogen production technologies. The key findings indicate that while electrolyzer-based systems (PEM and AWE) offer potential for emission reduction their high energy demand and significant scope 3 material emissions pose challenges for a complete transition in the near term. The study identified two optimal design configurations: one utilizing PPAs as the primary energy source coupled with the conventional SMR-CCS process and another that combines both conventional (SMR-CCS) and novel hydrogen production technologies under a hybrid purview. Ultimately the findings contribute toward the ongoing efforts to achieve true net-carbon neutrality.

Hydrogen embrittlement (HE) threatens the structural integrity of industrial components exposed to hydrogenrich environments. This review critically explores hydrogen barrier coatings (HBCs) polymeric metallic ceramic and composite their application and assessment focusing on measured effectiveness in limiting hydrogen permeation and hydrogen embrittlement. Also coating application methods and permeation assessment techniques are evaluated. Recent advances in nanostructured and hybrid coatings are emphasized highlighting the pressing need for durable scalable and environmentally sustainable hydrogen barrier coatings to ensure the reliability of emerging hydrogen-based energy solutions. This comprehensive critical review further distinguishes itself by linking coating deposition methods to defect-driven transport behaviour critically assessing permeation test approaches. It also highlights the emerging role of polymeric and hybrid multilayer coatings with direct implications for advanced and reliable hydrogen production storage and transport infrastructure.

The electrochemical modelling of proton exchange membrane electrolyzers (PEMEZs) relies on the precise determination of several unknown parameters. Achieving this accuracy requires addressing a challenging optimization problem characterized by nonlinearity multimodality and multiple interdependent variables. Thus a novel approach for determining the unknown parameters of a detailed PEMEZ electrochemical model is proposed using the weighted mean of vectors algorithm (WMVA). An objective function based on mean square deviation (MSD) is proposed to quantify the difference between experimental and estimated voltages. Practical validation was carried out on three commercial PEMEZ stacks from different manufacturers (Giner Electrochemical Systems and HGenerators™). The first two stacks were tested under two distinct pressure-temperature settings yielding five V–J data sets in total for assessing the WMVA-based model. The results demonstrate that WMVA outperforms all optimizers achieving MSDs of 1.73366e−06 1.91934e−06 1.09306e−05 6.18248e−05 and 4.41586e−06 corresponding to improvements of approximately 88% 82.9% 82.4% 54.5% and 59.5% over the poorest-performing algorithm in each case respectively. Moreover comparative analyses statistical studies and convergence curves confirm the robustness and reliability of the proposed optimizer. Additionally the effects of temperature and hydrogen pressure variations on the electrical and physical steady-state performance of the PEMEZ are carefully investigated. The findings are further reinforced by a dynamic simulation that illustrates the impact of temperature and supplied current on hydrogen production. Accordingly the article facilitates better PEMEZ modelling and optimizing hydrogen production performance across various operating conditions.

Hydrogen is the energy carrier for a sustainable future without fossil fuels. As this requires a reliable transportation infrastructure the conversion of existing natural gas (NG) grids is an essential part of the worldwide individual national hydrogen strategies in addition to newly erected pipelines. In view of the known effect of hydrogen embrittlement the compatibility of the materials already in use (typically low-alloy steels in a wide range of strengths and thicknesses) must be investigated. Initial comprehensive studies on the hydrogen compatibility of pipeline materials indicate that these materials can be used to a certain extent. Nevertheless the material compatibility for hydrogen service is currently of great importance. However pipelines require frequent maintenance and repair work. In some cases it is necessary to carry out welding work on pipelines while they are under pressure e.g. the well-known tapping of NG grids. This in-service welding brings additional challenges for hydrogen operations in terms of additional hydrogen absorption during welding and material compatibility. The challenge can be roughly divided into two parts: (1) the possible austenitization of the inner piping material exposed to hydrogen which can lead to additional hydrogen absorption and (2) the welding itself causes an increased temperature range. Both lead to a significantly increased hydrogen solubility in the respective materials compared to room temperature. In that connection the knowledge on hot tapping on hydrogen pipelines is rare so far due to the missing service experiences. Fundamental experimental investigations are required to investigate the possible transferability of the state-of-the-art concepts from NG to hydrogen pipeline grids. This is necessary to ensure that no critical material degradation occurs due to the potentially increased hydrogen uptake. For this reason the paper introduces the state of the art in pipeline hot tapping encompassing current research projects and their individual solution strategies for the problems that may arise for future hydrogen service. Methods of material testing their limitations and possible solutions will be presented and discussed.

The urgency for sustainable and efficient hydrogen production has increased interest in heterostructured nanomaterials known for their excellent photocatalytic properties. Traditional synthesis methods often rely on trial-and-error resulting in inefficiencies in material discovery and optimization. This work presents a new AI-driven framework that overcomes these challenges by integrating advanced machine-learning techniques specific to heterostructured nanomaterials. Graph Neural Networks (GNNs) enable accurate representations of atomic structures predicting material properties like bandgap energy and photocatalytic efficiency within ±0.05 eV. Reinforcement Learning optimises synthesis parameters reducing experimental iterations by 40% and boosting hydrogen yield by 15–20%. Physics-Informed Neural Networks (PINNs) successfully predict reaction pathways and intermediate states minimizing synthesis errors by 25%. Variational Autoencoders (VAEs) generate novel material configurations improving photocatalytic efficiency by up to 15%. Additionally Bayesian Optimisation enhances predictive accuracy by 30% through efficient hyperparameter tuning. This holistic framework integrates material design synthesis optimization and experimental validation fostering a synergistic data flow. Ultimately it accelerates the discovery of novel heterostructured nanomaterials enhancing efficiency scalability and yield thus moving closer to sustainable hydrogen production with improvements in photolytic efficiency setting a benchmark for AI-assisted research.

Liquid organic hydrogen carriers (LOHCs) are a promising class of hydrogen storage media in which hydrogen is reversibly bound to organic molecules. In this work we focus explicitly on cyclic LOHCs (both homocyclic and heterocyclic organic compounds) and their catalytic dehydrogenation. We clarify that other carriers (e.g. alcohols like methanol or carboxylic acids like formic acid) exist but are not the focus here; these alternatives are discussed only in comparative context. Cyclic LOHCs typically enable safe ambient-temperature hydrogen storage with hydrogen contents around 6–8 wt%. Key challenges include the high dehydrogenation temperatures (often 200–350 °C) catalyst costs and catalyst deactivation via coke formation. We introduce a comparative analysis table contrasting cyclic LOHCs with alternative carriers in terms of hydrogen density operating conditions catalyst types toxicity and cost. We also expand the catalyst discussion to highlight coke formation mechanisms and the use of mesoporous metal-oxide supports to mitigate deactivation. Finally a techno-economic analysis is provided to address system costs of LOHC storage and regeneration. Finally we underscore the viability and limitations of cyclic LOHCs including practical storage capacities catalyst life and projected costs.

This study presents the design and techno-economic optimization of a hybrid renewable energy system (HRES) for a coastal hotel in Manavgat Türkiye. The system integrates photovoltaic (PV) panels wind turbines (WT) pumped hydro storage (PHS) hydrogen storage (electrolyzer tank and fuel cell) batteries a fuel cell-based combined heat and power (CHP) unit and a boiler to meet both electrical and thermal demands. Within this broader optimization framework six optimal configurations emerged representing gridconnected and standalone operation modes. Optimization was performed in HOMER Pro to minimize net present cost (NPC) under strict reliability (0% unmet load) and renewable energy fraction (REF > 75%) constraints. The grid-connected PHS–PV–WT configuration achieved the lowest NPC ($1.33 million) and COE ($0.153/kWh) with a renewable fraction of ~96% and limited excess generation (~21%). Off-grid PHS-based and PHS–hydrogen configurations showed competitive performance with slightly higher costs. Hydrogen integration additionally provides complementary storage pathways coordinated operation waste heat utilization and redundancy under component unavailability. Battery-only systems without PHS or hydrogen storage resulted in 37–39% higher capital costs and ~53% higher COE confirming the economic advantage of long-duration PHS. Sensitivity analyses indicate that real discount rate variations notably affect NPC and COE particularly for battery-only systems. Component cost sensitivity highlights PV and WT as dominant cost drivers while PHS stabilizes system economics and the hydrogen subsystem contributes minimally due to its small scale. Overall these results confirm the techno-economic and environmental benefits of combining seawater-based PHS with optional hydrogen and battery storage for sustainable hotel-scale applications.

On the path to an emission free energy economy proton exchange membrane water electrolysis (PEMWE) is a promising technology for a sustainable production of green hydrogen at high current densities and thus high production rates. Long lifetime increasing the current density and the reduction of platinum group metal loadings are major challenges for a widespread implementation of PEMWE. In this context this work investigates the aging of a PEMWE stack operating at 4 A cm-2 which is twice the nominal current density of commercial electrolyzers. Specifically an 8-cells PEMWE stack using catalyst coated membranes (CCMs) with different platinum group metal (PGM) loading was operated for 2200 h. To understand degradation phenomena physical ex-situ analyses such as scanning electron microscopy (SEM) atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS) were carried out. The same aging mechanism were observed in all cells independent on their position in stack or the specific PGM loading of the membrane electrode assembly (CCM): (i) a decrease of ohmic resistance over time related to membrane thinning (ii) a significant loss of ionomer at anodes (iii) loss of noble metal from the electrodes leading to deposition of small Ir and Pt concentrations in the membrane (iv) heterogeneous enrichment of Ti on the cathode side likely originating from the cathode-side of the Ti bipolar plates (BPPs). These results are in good agreement with the electrochemical performance loss. Thus we were able to identify the degradation phenomena that dominate under high-current operation and their impact on performance.

The gas equation of state (EOS) serves as a critical tool for analyzing the thermal effects within the hydrogen storage tank during refueling processes. It quantifies the dynamic relationships among pressure temperature and volume playing a vital role in numerical simulations of hydrogen refueling the development of refueling protocols and ensuring refueling safety. This study first establishes a lumped-parameter thermodynamic model for the hydrogen refueling process which combines a zero-dimensional gas model with a one-dimensional tank wall model (0D1D). The model’s accuracy was validated against experimental data and will be used in combination with different EOSs to simulate hydrogen temperature and pressure. Subsequently parameter values are derived for the van der Waals EOS and its modified forms—Redlich–Kwong Soave and Peng–Robinson. The accuracy of the modified forms is evaluated using the Joule–Thomson inversion curve. A polynomial EOS is formulated and its parameters are numerically determined. Finally the hydrogen temperatures and pressures calculated using the van der Waals EOS Redlich– Kwong EOS polynomial EOS and the National Institute of Standards and Technology (NIST) database are compared. Within the initial and boundary conditions set in this study the results indicate that among the modified forms for van der Waals EOS the Redlich– Kwong EOS exhibits higher accuracy than the Soave and Peng–Robinson EOSs. Using the NIST-calculated hydrogen pressure as a benchmark the relative error is 0.30% for the polynomial EOS 1.83% for the Redlich–Kwong EOS and 17.90% for the van der Waals EOS. Thus the polynomial EOS exhibits higher accuracy followed by the Redlich–Kwong EOS while the van der Waals EOS demonstrates lower accuracy. This research provides a theoretical basis for selecting an appropriate EOS in numerical simulations of hydrogen refueling processes.

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.

Hydrogen propulsion technologies are emerging as a key enabler for decarbonizing the aviation sector especially for regional commercial aircraft. The evolution of aircraft propulsion technologies in recent years raises the question of the feasibility of a hydrogen propulsion system for beyond regional aircraft. This paper presents a comprehensive review of hydrogen propulsion technologies highlighting key advancements in component-level performance metrics. It further explores the technological transitions necessary to enable hydrogen-powered aircraft beyond the regional category. The feasibility assessment is based on key performance parameters including power density efficiency emissions and integration challenges aligned with the targets set for 2035 and 2050. The adoption of hydrogen-electric powertrains for the efficient transition from KW to MW powertrains depends on transitions in fuel cell type thermal management systems (TMS) lightweight electric machines and power electronics and integrated cryogenic cooling architectures. While hydrogen combustion can leverage existing gas turbine architectures with relatively fewer integration challenges it presents its technical hurdles especially related to combustion dynamics NOx emissions and contrail formation. Advanced combustor designs such as micromix staged and lean premixed systems are being explored to mitigate these challenges. Finally the integration of waste heat recovery technologies in the hydrogen propulsion system is discussed demonstrating the potential to improve specific fuel consumption by up to 13%.

The transition to low-carbon energy systems demands robust strategies that leverage existing fossil resources while integrating renewable technologies. In this work a single-cycle Gaussian-based producibility model is developed to forecast natural gas production profiles domestic consumption export potential hydrogen production and revenues adaptive for untapped natural gas discoveries. Annual natural gas production is represented by a bell curve defined by peak year and maximum capacity allowing flexible adaptation to different reserve sizes. The model integrates renewable energy adoption and steam–methane reforming to produce hydrogen while tracking revenue streams from domestic sales exports and hydrogen markets alongside carbon taxation. Applicability is demonstrated through a case study of Eastern Mediterranean gas discoveries where combined reserves of 2399 bcm generate a production peak of 100 bcm/year in 2035 and deliver 40.71 billion kg of hydrogen by 2050 leaving 411.87 bcm of reserves. A focused Cyprus scenario with 411 bcm of reserves peaks at 10 bcm/year produces 4.07 billion kg of hydrogen and retains 212.29 bcm of reserves. Cumulative revenues span from USD 84.37 billion under low hydrogen pricing to USD 247.29 billion regionally while the Cyprus-focused case yields USD 1.79 billion to USD 18.08 billion. These results validate the model’s versatility for energy transition planning enabling strategic insights into infrastructure deployment market dynamics and resource management in gas-rich regions.

The transition toward environmentally friendly steelmaking using hydrogen direct reduced iron as feed material in electric arc furnaces will eventually require process adjustments due to changes in the pellet properties when compared to e.g. blast furnace pellets. To this end the melting of hydrogen direct reduced iron pellets with 68 and 100% reduction degrees and Fe content of 67.24% was investigated in a laboratory-scale electric arc furnace. The presence of iron oxide-rich slag had a significant effect on the arc movement on the melt and an inhibiting effect on iron evaporation. The melting was monitored with video recording and optical emission spectroscopy. The videos were used to monitor the melting behavior whereas optical emissions revealed iron gangue elements and hydrogen from the pellets radiating in the plasma. Furthermore the flow of the melt is well seen in the videos as well as the movement of slag droplets on the melt surface. After the experiments the metal had silica-rich inclusions whereas slag had mostly penetrated into the crucible. The most notable differences in melting behavior can be attributed to the iron oxide-rich slag its interaction with the arc and penetration into the crucible and how it affects the arc movement and heat transfer.

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.

This study presents a comparative techno-economic and environmental assessment of three leading stationary energy storage technologies: lithium-ion batteries lead-acid batteries and hydrogen systems (electrolyzer–tank–fuel cell). The analysis integrates Life Cycle Assessment (LCA) and Levelized Cost of Storage (LCOS) to provide a holistic evaluation. The LCA covers the full cradle-to-grave stages while LCOS accounts for capital and operational expenditures efficiency and cycling frequency. The results indicate that lithium-ion batteries achieve the lowest LCOS (120–180 EUR/MWh) and high round-trip efficiency (90–95%) making them optimal for short- and medium-duration storage. Lead-acid batteries though characterized by low capital expenditures (CAPEX) and high recyclability (>95%) show limited cycle life and lower efficiency (75–80%). Hydrogen systems remain costly (>250 EUR/MWh) and less efficient (30–40%) yet they demonstrate clear advantages for long-term and seasonal storage particularly under scenarios with “green” hydrogen production and reduced CAPEX. These findings provide practical guidance for policymakers investors and industry stakeholders in selecting appropriate storage solutions aligned with decarbonization and sustainability goals.