Publications

Hydrogen is poised to play a pivotal role in achieving net-zero targets and advancing green economies. However a range of complex operational challenges hinders its planning production delivery and adoption. At the same time numerous drivers within the hydrogen value chain present significant opportunities. This paper investigates the intricate relationships between these drivers and barriers associated with hydrogen supply chain (HSC). Utilising expert judgment in combination Grey-DEMATEL technique we propose a framework to assess the interplay of HSC drivers and barriers. Gaining insight into these relationships not only improves access to hydrogen but also foster innovation in its development as a low-carbon resource. The use of prominence scores and net influence rankings for each driver and barrier in the framework provides a comprehensive understanding of their relative significance and impact. Our findings demonstrate that by identifying and accurately mapping these attributes clear cause-and-effect relationships can be established contributing to a more nuanced understanding of the HSC. These insights have broad implications across operational policy scholarly and social domains. For instance this framework can aid stakeholders in recognizing the range of opportunities available by addressing key barriers to hydrogen adoption.

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.

Renewable hydrogen offers compelling climate mitigation prospects with Norway possessing the opportunity to become a main global producer given its unique combination of wind energy potential available infrastructure and political motivation. However comprehensive environmental impact assessments of hydrogen from offshore wind are lacking and hydrogen leakage rates remain uncertain. A life-cycle assessment of hydrogen production from offshore wind farms in Norway is presented where different combinations of turbines (floating or bottomfixed) storage options (tank or salt cavern) and distribution methods (trucks or pipelines) are considered. Climate change impacts are assessed across the supply chain using global warming potential 100 (GWP100) and 20 (GWP20) and include hydrogen leakage contributions. The results range from 1.56 ± 0.14–2.28 ± 0.14 kg CO2-eq/kg H2 for GWP100 and 2.96 ± 0.76 and 3.75 ± 0.76 kg CO2-eq/kg H2 for GWP20 and are on average 55 % and 45 % lower than those of blue hydrogen respectively. At a default rate of 5 % hydrogen leakage contributes 50–63 % of the total impact for GWP20 and 25–37 % for GWP100. If higher-end leakage rates from literature are considered the impacts increase to 3.46 kg CO2-eq/kg H2 for GWP100 which is still lower than that of blue hydrogen. The scenario combining bottom-fixed turbines salt cavern storage and pipeline distribution presents the lowest environmental impacts. However while bottom-fixed turbines generally offer lower impacts floating turbines pose lesser risk to marine biodiversity. Overall infrastructure represents the main driver of environmental impacts. Mitigation in this area will improve potential benefits.

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.

Many countries of the Global South struggle to achieve inclusive growth paths despite investment in the exploitation of rich resources. Resource-based industrialization literature stresses the potential for achieving broader development effects via the development of production linkages with local enterprises. The focus lies on market-driven outsourcing dynamics that foster linkage development such as efficiency location-specific knowledge and technology and scale complexity. However little is known about the opportunity space for both policy making and local firms to create these linkages. To address this issue we incorporate the concept of change agency stemming from the path development literature into the discussion on production linkages to show how both (local) firm agency and system-level agency can achieve linkage creation for inclusive path transplantation. We illustrate the framework by scrutinizing the potential inclusion of solar energy companies in Namibia’s emerging green hydrogen economy. The study finds that while the potential for renewable energy companies in Namibia to participate in the value chain is limited an integrated bundle of measures relying on firm- and system-level agency could address peripheral contextual factors overcome entry barriers and leverage further potential for linkage creation in the solar energy sector: mobilizing the local workforce fostering inter-firm cooperation leveraging local advantages creating knowledge institutions enhancing the regulatory framework upgrading infrastructure and enforcing local content regulations.

Hydrogen shaft injection into blast furnaces (BFs) has a large potential to eliminate carbon dioxide emissions yet the temporal evolution of thermal and chemical states following shaft-injected hydrogen utilisation has not been reported in the open literature. In this research a recently developed transient-state multifluid BF model is applied to elucidate the temporal evolution of in-furnace phenomena. Besides a domain-average method is adopted to analyse the extensive simulation data to determine the time required to attain the next steady-like state. The results show that the evolution of thermal and chemical conditions varies across different regions with distinct characteristics near the furnace wall. The shifts in iron oxide reduction behaviour are completed within 10 to 20 h after the new operation and the transition time points to the next steady-like states of thermal and chemical conditions are different. As the hydrogen flow rate increases the average transition time decreases. However 2 to 4 days are required for the studied BF to reach a new steady-like state in the considered scenarios. The model offers a cost-effective approach to investigating the transient smelting characteristics of an ironmaking BF with hydrogen injection.

Underground hydrogen storage (UHS) in depleted oil and gas fields is pivotal for balancing large-scale renewable-energy systems yet the wettability of reservoir rocks in contact with hydrogen after decades of Enhanced Oil Recovery (EOR) operations remains poorly quantified. This work experimentally investigates how two common EOR legacies cationic surfactant (city-trimethyl-ammonium bromide CTAB) and supercritical carbon dioxide (SC–CO2) flooding alter rock–water–Hydrogen (H2) wettability in carbonate formations. Contact angles were measured on dolomite and limestone rock slabs at 30–75 ◦C and 3.4–17.2 MPa using a high-pressure captive-bubble cell. Crude-oil aging shifted clean dolomite from strongly water-wet (θ ~ 28–29◦) to intermediate-wet (θ ≈ 84◦). Subsequent immersion in dilute CTAB solutions (0.5–2 wt %) fully reversed this effect restoring or surpassing the original water-wetness (θ ≈ 21–28◦). Limestone samples exposed to SC-CO2 at 60–80 ◦C became more hydrophilic (θ ≈ 18–30◦) relative to untreated controls; moderate carbonate dissolution (≤6 × 103 ppm Ca2+) produced the most significant improvement in water-wetness whereas severe dissolution yielded diminishing returns. These findings show that many mature reservoirs are already water-wet (post-CO2) or can be easily re-wetted (via residual CTAB). Across all scenarios sample wettability showed little sensitivity to pressure but higher temperature consistently promoted stronger water-wetness. Future work should include dynamic core-flooding experiments with realistic reservoir.

In the context of the evolving energy landscape the need to harness renewable energy sources (RESs) has become increasingly imperative. Within this framework hydrogen emerges as a promising energy storage vector offering a viable solution to the flexibility challenges caused by the inherent variability of RESs. This work investigates the feasibility of integrating a hydrogen-based energy storage system within an energy community in Barcelona using surplus electricity from photovoltaic (PV) panels. A power-to-power configuration is modelled through a comprehensive methodology that determines optimal component sizing based on high-resolution real-world data. This analysis explores how different operational strategies influence the system’s cost-effectiveness. The methodology is thus intended to assist in the early-stage decision-making process offering a flexible approach that can be adapted to various market conditions and operational scenarios. The results show that under the current conditions the combination of PV generation energy storage and low-cost grid electricity purchases yield the most favourable outcomes. However in a long-term perspective considering projected cost reductions for hydrogen technologies strategies including energy sales back to the grid become more profitable. This case study offers a practical example of balancing engineering and economic considerations providing replicable insights for designing hydrogen storage systems in similar energy communities.

This study evaluated the economic feasibility of producing hydrogen from natural gas via thermal degradation in a plasma reactor. Plasma pyrolysis where natural gas passes through the space between electrodes and serves as the working medium enables high hydrogen yields without emitting carbon monoxide or carbon dioxide. Instead the primary products are hydrogen and solid carbon. Unlike conventional methods this approach requires no catalysts addressing a major technological limitation. A thermodynamic equilibrium model based on Gibbs free energy minimization was used to analyze the process over a temperature range of 500–2500 K. The results indicate an optimal temperature of approximately 1500 K which achieved a 99.5% methane conversion by mass. Considering the capital and operating costs and profit margins the hydrogen production cost was estimated at 3.49 EUR/kg. The sensitivity analysis revealed that the price of solid carbon had the most significant impact which potentially raised the hydrogen cost to 4.53 EUR/kg or reduced it to 1.70 EUR/kg.

The aim of this study is to review and identify H2 storage suitability in geological reservoirs of the Republic of Lithuania. Notably Lithuania can store clean H2 effectively and competitively because of its wealth of resources and well-established infrastructure. The storage viability in Lithuanian geological contexts is highlighted in this study. In addition when it comes to injectivity and storage capacity salt caverns and saline aquifers present less of a challenge than other kinds of storage medium. Lithuania possesses sizable subterranean reservoirs (Cambrian rocks) that can be utilized to store H2. For preliminary assessment the cyclic H2 injection and production simulation is performed. A 10-year simulation of hydrogen injection and recovery in the Syderiai saline aquifer demonstrated the feasibility of UHS though efficiency was reduced by nearly 50% when using a single well for both injection and production. The study suggests using separate wells to improve efficiency. However to guarantee economic injectivity and containment security a detailed assessment of the geological structures is required specifically at the pore scale level. The volumetric approach estimated a combined storage capacity of approximately 898.5 Gg H2 (~11 TWh) for the Syderiai and Vaskai saline aquifers significantly exceeding previous estimates. The findings underscore the importance of detailed geological data and further research on hydrogen-specific factors to optimize UHS in Lithuania. Addressing technical geological and environmental challenges through multidisciplinary research is essential for advancing UHS implementation and supporting Lithuania’s transition to a sustainable energy system. UHS makes it possible to maximize the use of clean energy reduce greenhouse gas emissions and build a more sustainable and resilient energy system. Hence intensive research and advancements are needed to optimize H2 energy for broader applications in Lithuania.

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.

The use of hydrogen as a fuel for piston engines enables environmentally friendly and efficient operation. However several challenges arise in the combustion process limiting the development of hydrogen engines. These challenges include abnormal combustion the high burning velocity of hydrogen-enriched mixtures increased nitrogen oxide emissions and others. A rational organization of hydrogen combustion can partially or fully mitigate these issues through the use of advanced methods such as late direct injection charge stratification dual injection jet-guided operation and others. However mathematical models describing hydrogen combustion for these methods are still under development complicating the optimization and refinement of hydrogen engines. Previously we proposed a mathematical model based on Wiebe functions to describe premixed and diffusion combustion as well as relatively slow combustion in lean-mixture zones behind the flame front and near-wall regions. This study further develops the model by accounting for the combined influence of the mixture composition and engine speed mixture stratification and the effects of injection and ignition parameters on premixed and diffusion combustion. Special attention is given to combustion modeling in an engine with single injection and jet-guided operation.

Green hydrogen is viewed as a promising pathway to future decarbonized energy systems. However hydrogen production depends on a few critical minerals particularly platinum and iridium. Here we examine how the supply of these minerals is subject to vulnerabilities hidden in interdependent global networks of trade and investment. We develop an index to quantify these vulnerabilities for a combination of a target country an investing country an intermediary country and a commodity. Focusing on the US as the target country for the import of platinum and iridium we show how vulnerability-inducing investing countries changed between 2010 and 2019. We find that the UK is consistently among investing countries that can potentially induce US vulnerabilities via intermediary exporters of platinum and iridium with South Africa being the primary intermediary country. Future research includes incorporating geopolitical factors and technological innovations to move the index closer from potential to real-world vulnerabilities.

Solid oxide electrolysis cells (SOECs) represent a promising technology because they have the potential to achieve greater efficiency than existing electrolysis methods making them a strong candidate for sustainable hydrogen production. SOECs utilize a solid oxide electrolyte which facilitates the migration of oxygen ions while maintaining gas impermeability at temperatures between 600 ◦C and 900 ◦C. This review provides an overview of the recent advancements in research and development at the intersection of machine learning and SOECs technology. It emphasizes how data-driven methods can improve performance prediction facilitate material discovery and enhance operational efficiency with a particular focus on materials for cathode-supported cells. This paper also addresses the challenges associated with implementing machine learning for SOECs such as data scarcity and the need for robust validation techniques. This paper aims to address challenges related to material degradation and the intricate electrochemical behaviors observed in SOECs. It provides a description of the reactions that may be involved in the degradation mechanisms taking into account thermodynamic and kinetic factors. This information is utilized to construct a fault tree which helps categorize various faults and enhances understanding of the relationship between their causes and symptoms.

As part of global decarbonization efforts hydrogen has emerged as a key energy carrier that can achieve deep emission reductions in various sectors. This review critically assesses the role of hydrogen in the low-carbon energy transition and highlights the interlinked challenges within the Techno-Enviro-Socio-Political (TESP) framework. It examines key aspects of deployment including production storage safety environmental impacts and socio-political factors to present an integrated view of the opportunities and barriers to large-scale adoption. Despite growing global interest over 90 % of the current global hydrogen production originated from fossilbased processes resulting in around 920 Mt of CO2 emissions two-thirds of which were attributable to fossil fuels. The Life Cycle Assessment (LCA) shows that coal-based electrolysis resulted in the highest GHG emission (144 - 1033 g CO2-eq/MJ) and an energy consumption (1.55–10.33 MJ/MJ H2). Without a switch to low-carbon electricity electrolysis cannot deliver significant climate benefits. Conversely methanol steam reforming based on renewable feedstock offered the lowest GHG intensity (23.17 g CO2-eq/MJ) and energy demand (0.23 MJ/ MJ) while biogas reforming proved to be a practical short-term option with moderate emissions (51.5 g CO2-eq/ MJ) and favourable energy figures. Catalytic ammonia cracking which is suitable for long-distance transport represents a compromise between low energy consumption (2.93 MJ/MJ) and high water intensity (8.34 L/km). The thermophysical properties of hydrogen including its low molecular weight high diffusivity and easy flammability lead to significant safety risks during storage and distribution which are exacerbated by its sensitivity to ignition and jet pulse effects. The findings show that a viable hydrogen economy requires integrated strategies that combine decarbonised production scalable storage harmonised safety protocols and cross-sector stakeholder engagement for better public acceptance. This review sets out a multi-dimensional approach to guide technological innovation policy adaptation and infrastructure readiness to support a scalable and environmentally sustainable hydrogen economy.

With the intensification of the global energy crisis hydrogen has attracted significant attention as a high-energy-density and zero-emission clean energy source. Traditional hydrogen production methods are dependent on fossil fuels and simultaneously contribute to environmental pollution. The aqueous phase reforming (APR) of renewable biomass and its derivatives has emerged as a research hotspot in recent years due to its ability to produce green hydrogen in an environmentally friendly manner. This review provides an overview of the advancements in APR of lignocellulosic biomass as a sustainable and environmentally friendly method for hydrogen production. It focuses on the reaction pathways of various biomass feedstocks (such as glucose cellulose and lignin) as well as the types and performance of catalysts used in the APR process. Finally the current challenges and future prospects in this field are briefly discussed.

The global emphasis on clean energy has increased interest in producing hydrogen from petroleum reservoirs through in situ combustion-based processes. While field practices have demonstrated the feasibility of co-producing hydrogen and oil the question of which offers greater economic potential oil or hydrogen remains central to ongoing discussions especially as researchers explore ways to produce hydrogen exclusively from petroleum reservoirs. This study presents the first integrated techno-economic model comparing oil and hydrogen production under varying injection strategies using CMG STARS for reservoir simulations and GoldSim for economic modeling. Key technical factors including injection compositions well configurations reservoir heterogeneity and formation damage (issues not addressed in previous studies) were analyzed for their impact on hydrogen yield and profitability. The results indicate that CO2-enriched injection strategies enhance hydrogen production but are economically constrained by the high costs of CO2 procurement and recycling. In contrast air injection although less efficient in hydrogen yield provides a more cost-effective alternative. Despite the technological promise of hydrogen oil revenue remains the dominant economic driver with hydrogen co-production facing significant economic challenges unless supported by policy incentives or advancements in gas lifting separation and storage technologies. This study highlights the economic trade-offs and strategic considerations crucial for integrating hydrogen production into conventional petroleum extraction offering valuable insights for optimizing hydrogen co-production in the context of a sustainable energy transition. Additionally while the present work focuses on oil reservoirs future research should extend the approach to natural gas and gas condensate reservoirs which may offer more favorable conditions for hydrogen generation.

This perspective sheds light on emerging research priorities crucial for advancing the low-carbon hydrogen sector considered critical for achieving net zero greenhouse gas emissions targets especially for hard-to-abate sectors. Our analysis follows a five-step process including drawing from news media academic discourse and expert consultations. We identify twenty-one major research challenges. Among the top priorities highlighted by experts are: (i) Evaluating the trade-offs of hydrogen-fueled power generation compared to hydrocarbon fuels and renewables with alternative storage solutions and the feasibility of co-firing hydrogen and ammonia with hydrocarbon fuels for backup or independent power generation; (ii) Exploring how global hydrogen trade could be shaped by market forces such as price volatility geopolitical dynamics and international collaborations; (iii) Examining the financial considerations for investors from developed nations pursuing hydrogen projects in resource-rich developing countries balancing costs investment risks and expected returns. We find statistically significant differences in opinions on hydrogen/ammonia co-firing for power generation between experts from China and those from the U.S. and Germany.

The rapid increase in global warming requires that sustainable energy choices aimed at achieving net-zero greenhouse gas emissions be implemented as soon as possible. This objective emerging from the European Green Deal and the UN Climate Action could be achieved by using clean and efficient energy sources such as hydrogen produced from nuclear power. “Renewable” hydrogen plays a fundamental role in decarbonizing both the energy-intensive industrial and transport sectors while addressing the global increase in energy consumption. In recent years several strategies for hydrogen production have been proposed; however nuclear energy seems to be the most promising for applications that could go beyond the sole production of electricity. In particular nuclear advanced reactors that operate at very high temperatures (VHTR) and are characterized by coolant outlet temperatures ranging between 550 and 1000 ◦C seem the most suitable for this purpose. This paper describes the potential use of nuclear energy in coordinated and coupled configurations to support clean hydrogen production. Operating conditions energy requirements and thermodynamic performance are described. Moreover gaps that require additional technology and regulatory developments are outlined. The intermediate heat exchanger which is the key component for the integration of nuclear hybrid energy systems was studied by varying the thermal power to determine physical parameters needed for the feasibility study. The latter consisting of the comparative cost evaluation of some nuclear hydrogen production methods was carried out using the HEEP code developed by the IAEA. Preliminary results are presented and discussed.

Model predictive control (MPC) requires high accuracy of the model. However the actual power system has complex dynamic characteristics. There must be unmodeled dynamics in the system modeling process which makes it difficult for MPC to perform the function of optimal control. ESO has the ability to observe and suppress errors combining the both can solve this problem. Thus this paper proposes a coordinated control strategy of hydrogen-energy storage system based on disturbance-rejection model predictive controller. Firstly this paper constructs the state-space model of the system and improves MPC. By connecting ESO and MPC in series this paper designs a matched disturbance-rejection model predictive controller and analyzes the robustness of the research system. Finally this paper verifies the effectiveness and feasibility of the disturbance-rejection model predictive controller under various working conditions. Compared with the method using only MPC the dynamic response time of the system frequency regulation under the proposed strategy in this paper is increased by about 29.9 % and the frequency drop rate is slowed down by 13.5 %. In addition under the AGC command and continuous load disturbance working conditions the maximum frequency deviation of the system under the proposed strategy is reduced by about 54.01 % and 48.96 %. The results clearly show that the proposed strategy in this paper significantly improves the dynamic response ability of the system and reduces the frequency fluctuation of the system after disturbance.

In response to growing environmental concerns hydrogen production has emerged as a critical element in the transition to a sustainable global economy. We evaluate the impact of hydrogen production on both the financial performance and market value of energy sector companies using balanced panel data from 288 European-listed firms over the period of 2018 to 2022. The findings reveal a paradox. While hydrogen production imposes significant financial constraints it is positively recognized by market participants. Despite short-term financial challenges companies engaged in hydrogen production experience higher market value as investors view these activities as a long-term growth opportunity aligned with global sustainability goals. We contribute to the literature by offering empirical evidence on the financial outcomes and market valuation of hydrogen engagement distinguishing between production and storage activities and further categorizing production into green blue and gray hydrogen. By examining these nuances we highlight the complex relationship between financial market results. While hydrogen production may negatively impact short-term financial performance its potential for long-term value creation driven by decarbonization efforts and sustainability targets makes it attractive to investors. Ultimately this study provides valuable insights into how hydrogen engagement shapes corporate strategies within the evolving European energy landscape.

Hydrogen blending into natural gas networks is a promising pathway to decarbonize the gas sector but requires bespoke fluid-dynamic models to accurately capture the properties of hydrogen and assess its feasibility. This paper introduces a generalizable optimal transient gas flow model for transporting homogeneous natural gashydrogen mixtures in large-scale networks. Designed for preliminary planning the model assesses whether a network can operate under a given hydrogen blending ratio without violating existing constraints such as pressure limits pipeline and compressor capacity. A distinguishing feature of the model is a multi-day linepack management strategy that engenders realistic linepack profiles by precluding mathematically feasible but operationally unrealistic solutions thereby accurately reflecting the flexibility of the gas system. The model is demonstrated on Western Australia’s 7560 km transmission network using real system topology and demand data from several representative days in 2022. Findings reveal that the system can accommodate up to 20 % mol hydrogen potentially decarbonizing 7.80 % of gas demand.

The integration of renewable energy into industrial processes is crucial for reducing the carbon footprint of conventional hydrogen production. This work presents detailed design optical–thermal simulation and performance analysis of a solar parabolic dish (SPD) system for supplying high-temperature steam to a Steam Methane Reforming (SMR) plant. A 5 m diameter dish with a focal length of 3 m was designed and optimized using COMSOL Multiphysics (version 6.2) and MATLAB (version R2023a). Optical ray tracing confirmed a geometric concentration ratio of 896× effectively focusing solar irradiation onto a helical cavity receiver. Thermal–fluid simulations demonstrated the system’s capability to superheat steam to 551 ◦C at a mass flow rate of 0.0051 kg/s effectively meeting the stringent thermal requirements for SMR. The optimized SPD system with a 5 m dish diameter and 3 m focal length was designed to supply 10% of the total process heat (≈180 GJ/day). This contribution reduces natural gas consumption and leads to annual fuel savings of approximately 141000 SAR (Saudi Riyal) along with a substantial reduction in CO2 emissions. These quantitative results confirm the SPD as both a technically reliable and economically attractive solution for sustainable blue hydrogen production.

The spark-ignited (SI) hydrogen combustion engine has the potential to noticeably reduce greenhouse gas emissions from passenger cars. To prevent nitrogen oxide emissions and to increase fuel efficiency and power output complex air paths and operating strategies are utilized. This makes the engine control problem more complex challenging the conventional engine calibration process. This work combines and extends the state-of-the-art in real-time combustion engine modeling and optimal control presenting a novel control concept for the efficient operation of a hydrogen combustion engine. The extensive experimental validation with a 1.5 l three-cylinder hydrogen SI engine and a dynamically operated engine test bench with emission and in-cylinder pressure measurements provides a comprehensible comparison to conventional engine control. The results demonstrate that the proposed optimal control decreased the load tracking errors by a factor of up to 2.8 and increased the engine efficiency during lean operation by up to 10 percent while decreasing the calibration effort compared to conventional engine control.

This study employs first principles calculations and thermodynamic analyses to investigate the dissociative adsorption of hydrogen on the Fe(110) surface. The results show that the adsorption energies of hydrogen at different sites on the iron surface are −1.98 eV (top site) −2.63 eV (bridge site) and −2.98 eV (hollow site) with the hollow site being the most stable adsorption position. Thermodynamic analysis further reveals that under operational conditions of 25 ◦C and 12 MPa the Gibbs free energy change (∆G) for hydrogen dissociation is −1.53 eV indicating that the process is spontaneous under pipeline conditions. Moreover as temperature and pressure increase the spontaneity of the adsorption process improves thus enhancing hydrogen transport efficiency in pipelines. These findings provide a theoretical basis for optimizing hydrogen transport technology in natural gas pipelines and offer scientific support for mitigating hydrogen embrittlement improving pipeline material performance and developing future hydrogen transportation strategies and safety measures.

Under the UK’s carbon neutrality goals for 2050 the Liverpool City Region’s (LCR) strategic positioning with its rich industrial heritage and infrastructure assets such as extensive port facilities and proximity to vast renewable energy resources positions it as a potential leader in the UK’s shift towards a hydrogen economy. Given this the regional hydrogen industry and stakeholders in decarbonisation initiatives intend to undertake a critical review of the opportunities challenges and uncertainties to local hydrogen supply and demand systems to assist in their decision-making. To achieve this goal this study reviews the readiness of the hydrogen supply chain infrastructure within the LCR which highlights four sectors in the hydrogen economy i.e. production storage transportation and utilisation. Subsequently to offer the first-hand data in practice a multi-faceted approach that incorporates a broad array of stakeholders through the Triple Helix (TH) model is adopted. Special attention is given to hydrogen’s role in transforming heavy industry transportation and heating sectors supported by significant local projects like HyNet North West. During a roundtable discussion industry-academia-government stakeholders identify challenges in scaling up infrastructure and assess the economic and technological landscape for hydrogen adoption. To the best of our knowledge this will be the first regional academic endeavour to comprehensively examine the alignment between hydrogen supply and demand theory and practice. Based on a detailed SWOT analysis this study outlines the region’s strengths including established industrial clusters and technological capabilities in manufacturing. It also highlights weaknesses such as the high costs associated with emerging hydrogen technologies technological immaturity and gaps in necessary infrastructure. The opportunities presented by national policy incentives and growing global demand for sustainable energy solutions are considered alongside threats including regulatory complexities and the slow pace of public acceptance. This comprehensive examination not only maps the current landscape but also sets the stage for strategic interventions needed to realise hydrogen’s full potential within the LCR aiming to guide policymakers industry leaders and researchers in their efforts to foster a viable hydrogen economy. Moreover the findings offer valuable insights that can inform the development of hydrogen strategies in other regions and cities.

The paper approaches a computational evaluation of the 100% hydrogen fueled DLR micro-Gas Turbine (mGT) burner F400S.3 through high-fidelity Large Eddy Simulations (LES). Sensitivity analyses on the thermal boundary conditions of the burner walls and the turbulent combustion model were conducted. The experimental OH*-Chemiluminescence distribution was compared with numerical results obtained using the Partially Stirred Reactor (PaSR) and the Extended Flamelet Generated Manifold (ExtFGM) combustion models. The results showed good agreement regarding the flame shape and reactivity prediction when non-adiabatic thermal boundary conditions were applied at the burner walls and the PaSR model was implemented. On the contrary the ExtFGM model exhibited underprediction in flame length and flame lift-off overestimating flame reactivity. Finally after selecting the combustion model that best retrieved the experimental data a pressurized LES was performed on the combustor domain to evaluate its performance under real operating conditions for mGT.

Blue hydrogen production typically achieved by combining steam methane reforming with amine-based CO2 capture is widely considered an economical route towards clean hydrogen. However it suffers from high energy demands associated with solvent regeneration. To overcome this limitation we propose a novel hybrid approach integrating steam methane reforming with membrane-based CO2 capture and O2-enriched combustion. Using process simulations we conducted comprehensive techno-economic and environmental analyses to assess critical parameters affecting the levelised cost of hydrogen (LCOH) and CO2 emissions. Optimal results were obtained at an enriched oxygen level of 30% using vacuum pumping and CO2 capture via feed compression at 11 bar. This configuration achieved an LCOH of ~$1.8/kg H2 and total specific CO2 emissions of ~4.9 kg CO2/kg H2. This aligns closely with conventional blue hydrogen benchmarks with direct emissions significantly reduced to around 1 kg CO2/kg H2. Additionally sensitivity analysis showed robust economic performance despite variations in energy prices. Anticipated advancements in membrane technology could reduce the LCOH further to approximately $1.5/kg H2. Thus this hybrid membrane-based process presents a competitive and sustainable strategy supporting the achievement of the 2050 net-zero emissions goals in hydrogen production.

Methane pyrolysis offers a compelling pathway for low-carbon hydrogen production by avoiding CO2 emissions and enabling distributed deployment in locations with natural gas supply thereby eliminating the need for costly hydrogen transport. While promising the commercial deployment is constrained by the lack of detailed reactor modeling and technoeconomic assessment at small production scales. This study addresses these gaps by designing and modeling a small-scale (1–10 t-H2/day) bubble column reactor employing molten Ni–Bi alloy catalyst for methane pyrolysis. A coupled kinetic–hydrodynamic model was developed to simulate gas holdup bubble behavior and conversion under different operating conditions. The reactor design was integrated into an Aspen Plus simulation of the full process including heat recovery and hydrogen purification. Optimization of pressure temperature and single-pass conversion revealed that operation at 1100 ◦C 15 bar and 70–75 % conversion minimized reactor volume and cost. The lowest levelized cost of hydrogen (LCOH) achieved was $3.06/kg-H2 without sale of carbon significantly lower than green H2 produced from water electrolysis and competitive with blue H2 produced via centralized reforming when transportation costs are included. Sensitivity analysis reveals that carbon byproduct is a key economic lever; carbon sale at $250/t-C reduces LCOH by 25 % while a price of $700/t-C would meet U.S. DOE $1/kg-H₂ target. These results demonstrate the technoeconomic viability of molten metal methane pyrolysis and highlight future opportunities.

The transition to hydrogen as an aviation fuel as outlined in current decarbonization roadmaps is expected to result in the entry into service of hydrogen-powered aircraft in 2035. To achieve this evolution certification regulations are key enablers. Due to the disruptive nature of hydrogen aircraft technologies and their associated hazards it is essential to assess the maturity of the existing regulatory framework for certification to ensure its availability when manufacturers apply for aircraft certification. This paper presents the work conducted under the Clean Aviation CONCERTO project to advance certification readiness by comprehensively identifying gaps in the current European regulations. Generic methodologies were developed for regulatory gap and risk analyses and applied to a hydrogen turbine aircraft with non-propulsive fuel cells as the APU. The gap analysis conducted on certification specifications for large and normal-category airplanes as well as engines confirmed the overall adequacy of many existing requirements. However important gaps exist to appropriately address hydrogen hazards particularly concerning fire and explosion hydrogen storage and fuel systems crashworthiness and occupant survivability. The paper concludes by identifying critical areas for certification and highlighting the need for complementary hydrogen phenomenology data which are key to guiding future research and regulatory efforts for certification readiness maturation.

Achieving global net-zero emissions by 2050 demands integrated and scalable strategies that unite decarbonization technologies across sectors. This review provides a forwardlooking synthesis of carbon capture and storage and hydrogen systems emphasizing their integration through artificial intelligence to enhance operational efficiency reduce system costs and accelerate large-scale deployment. While CCS can mitigate up to 95% of industrial CO2 emissions and hydrogen particularly blue hydrogen offers a versatile low-carbon energy carrier their co-deployment unlocks synergies in infrastructure storage and operational management. Artificial intelligence plays a transformative role in this integration enabling predictive modeling anomaly detection and intelligent control across capture transport and storage networks. Drawing on global case studies (e.g. Petra Nova Northern Lights Fukushima FH2R and H21 North of England) and emerging policy frameworks this study identifies key benefits technical and regulatory challenges and innovation trends. A novel contribution of this review lies in its AI-focused roadmap for integrating CCS and hydrogen systems supported by a detailed analysis of implementation barriers and policy-enabling strategies. By reimagining energy systems through digital optimization and infrastructure synergy this review outlines a resilient blueprint for the transition to a sustainable low-carbon future.

Towards low-carbon buildings with resilient energy performance renewable energy resources and flexible energy assets play key roles in managing the electrical and heat demands. Hydrogen-based systems represent a promising solution through renewable hydrogen production and long-term storage. This paper systematically reviews 35 peer-reviewed studies (1990–2024) on hydrogen integration in buildings focusing on demand-side management (DSM) optimization methods and system performance. The review covers the environmental impacts feasibility and economic viability of integrating different hydrogen systems for supplying energy. Across critical reviews case studies hydrogen supplementary systems achieved CO2 reductions between 12 % and 87 % operational cost decreases of up to 40 % and efficiency gains exceeding 80 %. Payback periods varied widely between 9 and 20 years demonstrating high investment costs. Key gaps include limited field validation economic feasibility and public acceptance of hydrogen homes. One key area for future investigation is optimizing energy flows across production storage and demand particularly in Vehicle-to-Building (V2B) applications. This review paper highlights opportunities especially the potential of hydrogen system in decarbonization of buildings by long-term energy storage barriers and policy needs for implementing hydrogen technologies in grid-connected and remote areas to enhance sustainable and resilient buildings.

Electrifying heat supply in chemical processes offers a strategic pathway to reduce CO2 emissions associated with fossil fuel combustion. This study investigates the retrofit of an existing terrace-wall Steam Methane Reformer (SMR) in an ammonia plant by replacing fuel-fired burners with electric resistance heaters in the radiant section. The proposed e-REFORMER concept is applied to a real-world case producing hydrogen-rich syngas at 29000 Nm3 /h with simulation and energy analysis performed using Aspen HYSYS®. The results show that electric heating reduces total thermal input by 3.78 % lowers direct flue gas CO2 emissions by 91.56 % and improves furnace thermal efficiency from 85.6 % to 88.9 % (+3.3 %). The existing furnace design and convection heat recovery system are largely preserved maintaining process integration and plant operability. While the case study reflects a medium-scale plant the methodology applies to larger facilities and supports integration with decarbonised power grids and Carbon Capture Utilisation and Storage (CCUS) technologies. This work advances current literature by addressing full-system integration of electrification within hydrogen and ammonia production chains offering a viable pathway to improve energy efficiency and reduce industrial emissions.

Hydrogen as a clean energy source has enormous potential in addressing global climate change and energy security challenges. This paper discusses different hydrogen production methodologies (steam methane reforming and water electrolysis) focusing on the electrolysis process as the most promising method for industrial-scale hydrogen generation. The review delved into three main electrolysis methods including alkaline water electrolysis proton exchange membrane electrolysis and anion exchange membrane electrolysis cells. Also the production of hydrogen as a by-product by means of membrane cells and mercury cells. The process of reforming natural gas (mainly methane) using steam is currently the predominant technique comprising approximately 96% of the world’s hydrogen synthesis. However it is carbon intensive and therefore not sustainable over time. Water as a renewable resource carbon-free and rich in hydrogen (11.11%) offers one of the best solutions to replace hydrogen production from fossil fuels by decomposing water. This article highlights the fundamental principles of electrolysis recent membrane studies and operating parameters for hydrogen production. The study also shows the amount of pollutant emissions (g of CO2/g of H2) associated with a hydrogen color attribute. The integration of water electrolysis with renewable energy sources constitutes an efficient and sustainable strategy in the production of green hydrogen minimizing environmental impact and optimizing the use of clean energy resources.

Hydrogen can play a key role as short- and long-term energy storage solution in an energy grid with fluctuating renewable sources. In technologies using hydrogen there is always the risk of unintended leakages due to the low density of gaseous hydrogen. The risk becomes specifically high in confined areas where leaking hydrogen could easily mix with air and form flammable gas mixtures. In the maritime transportation large and congested geometries can be subject to accumulation of hydrogen. A mitigation measure for areas where venting is insufficient or even impossible is the installation of catalytic recombiners. The operational behavior can be described with numerical models which are required to optimize the location and to assess the efficiency of the mitigation solution. In the present study we established an experimental procedure in the REKO-4 facility a 5.5 m³ vessel to determine the recombination rate obtained from a recombiner. Based on the experimental data an engineering correlation was developed to be used for simulations in safety assessments.

Hydrogen blending in natural gas pipelines facilitates renewable energy integration and cost-effective hydrogen transport. Due to hydrogen’s lower density and higher leakage potential compared to natural gas understanding hydrogen concentration distribution is critical. This study employs ANSYS Fluent 2022 R1 with a realizable k-ε model to analyze flow dynamics of hydrogen–methane mixtures in horizontal and undulating pipelines. The effects of hydrogen blending ratios pressure (3–8 MPa) and pipeline geometry were systematically investigated. Results indicate that in horizontal pipelines hydrogen concentrations stabilize near initial values across pressure variations with minimal deviation (maximum increase: 1.6%). In undulating pipelines increased span length of elevated sections reduces maximum hydrogen concentration while maintaining proximity (maximum increase: 0.65%) to initial levels under constant pressure. Monitoring points exhibit concentration fluctuations with changing pipeline parameters though no persistent stratification occurs. However increasing the undulating height elevation difference leads to an increase in the maximum hydrogen concentration at the top of the pipeline rising from 3.74% to 9.98%. The findings provide theoretical insights for safety assessments of hydrogen–natural gas co-transport and practical guidance for pipeline design optimization.

The development of new energy vehicles particularly electric vehicles (EVs) and hydrogen fuel cell vehicles (HFCVs) represents a strategic initiative to address climate change and foster sustainable development. Integrating PV with hydrogen production into hybrid electricity-hydrogen energy stations enhances land and energy efficiency but introduces scheduling challenges due to uncertainties. A multi-time scale scheduling framework which includes day-ahead and intraday optimization is established using fuzzy chance-constrained programming to minimize costs while considering the uncertainties of PV generation and charging/refueling demand. Correspondingly trapezoidal membership function and triangular membership function are used for the fuzzy quantification of day-ahead and intraday predictions of photovoltaic power generation and load demands. The system achieves 29.37% lower carbon emissions and 17.73% reduced annualized costs compared to day-ahead-only scheduling. This is enabled by real-time tracking of PV/load fluctuations and optimized electrolyzer/fuel cell operations maximizing renewable energy utilization. The proposed multi-time scale framework dynamically addresses short-term fluctuations in PV generation and load demand induced by weather variability and temporal dynamics. By characterizing PV/load uncertainties through fuzzy methods it enables formulation of chance-constrained programming models for operational risk quantification. The confidence level – reflecting decision-makers’ reliability expectations – progressively increases with refined temporal resolution balancing economic efficiency and operational reliability.

According to the international standard ISO 14687:2019 for hydrogen fuel quality the maximum allowable concentration of water in hydrogen for use in refueling stations and storage systems must not exceed 5 µmol/mol. Therefore an adsorption purification process following the electrolyzer is necessary. This study numerically investigates the adsorption of water and the corresponding water loading on zeolite 13X BFK based on the mass flows entering the adsorption column from three 5 MW electrolyzers coupled to a 15 MW offshore wind turbine. As the mass flow is influenced by wind speed a direct comparison between realistic wind speeds and adsorption loading is presented. The presented numerical discretization of the model also accounts for perturbations in wind speed and consequently mass flows. In addition adsorption isobars were measured for water on zeolite 13X BFK within the required pressure and temperature range. The measured data was utilized to fit parameters to the Langmuir–Freundlich isotherm.

The growing demand for low-emission urban freight has intensified efficiency challenges in lastmile delivery especially in dense city centres. This study assesses hydrogen-powered cargo bikes as a scalable zero-emission alternative to fossil fuel vans and battery-electric cargo bikes. Using real-world logistics data from Rome we apply simulation models including Monte Carlo cost analysis Artificial Intelligence driven routing K-means station placement and fleet scaling. Results show hydrogen bikes deliver 15% more parcels daily than electric counterparts reduce refuelling detours by 31.4% and lower per-trip fuel use by 32%. They can cut up to 120 metric tons of CO2 annually per 100-bike fleet. While battery-electric cargo bikes remain optimal for short trips hydrogen bikes offer superior uptime range and rapid refuelling—ideal for highfrequency mid-distance logistics. Under supportive pricing and infrastructure hydrogen cargo bikes represent a resilient and sustainable solution for decarbonizing last-mile delivery in city areas.

Life Cycle Assessments (LCAs) are predominantly conducted using a static approach which aggregates emissions over time without considering emissions timing. Additionally LCAs often assume biogenic carbon neutrality neglecting site-specific forest carbon fluxes and temporal trade-offs. This study applies both static and dynamic LCA and incorporates biogenic carbon to evaluate the climate change impact of hydrogen production. It focuses on gasification of eucalyptus woodchips cultivated on former marginal grasslands (BIO system) which avoids competition with land used for food production. A case study is presented in western Andalusia (Spain) with the aim to replace hydrogen produced via the conventional steam methane reforming (SMR) pathway (BAU system) at La Rabida ´ refinery. The CO2FIX model was used to simulate biogenic carbon fluxes providing insights into carbon sequestration dynamics and it was found that the inclusion of biogenic carbon flows from eucalyptus plantations dramatically reduced CO₂ equivalent emissions (176 % in the static approach and 369 % in the dynamic approach) primarily due to soil and belowground biomass carbon sequestration. The dynamic LCA showed significantly lower CO₂ emissions than the static LCA (106 % reduction) shifting emissions from − 1.79 kg CO₂/kg H₂ in the static approach to − 3.69 kg CO₂/kg H₂ in the dynamic approach. These findings highlight the need to integrate emission dynamics and biogenic carbon flows into LCA methodologies to support informed decision-making and the development of more effective environmental policies.

The escalating global demand for electricity coupled with environmental concerns and economic considerations has driven the exploration of alternative energy sources creating competition for land with other sectors. A comprehensive analysis of a 10 MW floating photovoltaic (FPV) system deployed across different Köppen climate zones along with techno-economic analysis involves evaluating technical efficiency and economic viability. Technical parameters are assessed using PVsyst simulation and HOMER Pro. While economic analysis considers return on investment net present value internal rate of return and payback period. Results indicate that temperate and dry zones exhibit significant electricity generation potential from an FPV. The study outlines the payback period with the lowest being 5.7 years emphasizing the system’s environmental benefits by reducing water loss in the form of evaporation. The system is further integrated with hydrogen generation while estimating the number of cars that can be refueled at each location with the highest amount of hydrogen production being 292817 kg/year refueling more than 100 cars per day. This leads to an LCOH of GBP 2.84/kg for 20 years. Additionally the comparison across different Koppen climate zones suggests that even with the high soiling losses dry climate has substantial potential; producing up to 18829587 kWh/year of electricity and 292817 kg/year of hydrogen. However factors such as high inflation can reduce the return on investment to as low as 13.8%. The integration of FPV with hydropower plants is suggested for enhanced power generation reaffirming its potential to contribute to a sustainable energy future while addressing the UN’s SDG7 SDG9 SDG13 and SDG15.

The transition to decarbonized energy systems positions hydrogen as a critical vector for achieving climate neutrality yet its large-scale transportation and storage remain key challenges. This study presents a comprehensive life cycle assessment (LCA) and economic analysis of large-scale H2 supply chains evaluating the liquid organic hydrogen carrier (LOHC) system based on benzyltoluene/perhydro-benzyltoluene (H0-BT/H12-BT) against conventional technologies: compressed gaseous hydrogen (CGH2) liquid hydrogen (LH2) and liquid ammonia (LNH3). The analysis includes multiple H2 transportation scenarios across Europe considering the steps: conditioning sea transportation post-processing and land distribution by truck or pipeline. Environmentally LOHC currently faces higher environmental impacts than CGH2 driven by energy-intensive dehydrogenation process. Truck-based distribution further amplifies impacts particularly over long distances while pipeline-based distribution significantly reduces the environmental burdens where infrastructure exists. Sensitivity analysis reveals that using H2 for dehydrogenation heat lowers process-level impacts but increases overall supply chain impacts questioning its net environmental benefit. Economically LOHC remains competitive despite high dehydrogenation costs benefiting from low sea transportation expenses compatibility with existing fossil fuel infrastructure and potential for future CAPEX and OPEX improvements. While CGH2 outperforms LH2 and LNH3 avoiding energy-intensive liquefaction and cracking its storage requirements add considerable costs. For land distribution LOHC trucks are optimal at lower capacities whereas repurposed natural gas pipelines favour CGH2 at higher scale reducing costs by up to 84 %. Despite current trade-offs the scalability flexibility and synergies with existing infrastructure position LOHC as a promising solution for long-distance H2 transport contingent on technological maturation to mitigate dehydrogenation impacts.

Creating a hydrogen market in Africa is a great opportunity to assist in the promotion of sustainable energy solutions and economic growth. This article addresses the legislation and regulations that need to be developed to facilitate growth in the hydrogen market and allow local green hydrogen offtake across the continent. By reviewing current policy and strategy within particular African countries and best practices globally from key hydrogen economies the review establishes compelling issues challenges and opportunities unique to Africa. The study identifies the immense potential in Africa for renewable energy and in particular for solar and wind as the foundation for the production of green hydrogen. It examines how effective policy frameworks can establish a vibrant hydrogen economy by bridging infrastructural gaps cost hurdles and regulatory barriers. The paper also addresses how local offtake contracts for green hydrogen can be used to stimulate economic diversification energy security and sustainable development. Policy advice is provided to assist African authorities and stakeholders in the deployment of enabling regulatory frameworks and the mobilization of funds. The paper contributes to global hydrogen energy discussions by introducing Africa as an eligible stakeholder in the emerging hydrogen economy and outlining prospects for its inclusion into regional and global energy supply chains.

This study explores the safety problems of hydrogen leakage and explosion in hydrogen fuel cell buses through Computational Fluid Dynamics simulations. The research investigates the diffusion behavior of hydrogen in the passenger cabin depending on the leakage position and flow rates identifying a stratified constant-concentration layer formed at the top of the cabin. Leakage near the rear wall of the vehicle provided the highest hydrogen concentration while at higher flow rates the diffusive process accelerated the spreading of flammable hydrogen concentrations. Hydrogen ignition simulations showed a fast internal pressure increase and secondary explosions outside the vehicle. Thermal hazards in the cases were higher than overpressure. The research’s additional analysis of ignition timing and source location shows that overpressure peaked initially with delayed ignition but declined afterward while rear-ignited flames exhibited the farthest high-temperature hazard range at 10.88 m. These findings are fundamental for giving insight into hydrogen behavior in confined spaces and thus guiding risk assessment and emergency response planning for the development of safety protocols in hydrogen fuel cell buses contributing to the safer implementation of hydrogen energy in public transportation.

Natural hydrogen is generated via serpentinization radiolysis and organic metagenesis in geological settings. After expulsion from the source and along its upward migration path the free gas may encounter hydratebearing sediments. To simulate this natural scenario CH4 hydrate and CH4 + C3H8 hydrate were synthesized at 5.0 MPa and exposed to a hydrogen-containing gas mixture. In-situ Raman spectroscopic measurements demonstrated the incorporation of H2 molecules into the hydrate phase even at a partial pressure of 0.5 MPa. Exsitu Raman spectroscopic characterization of hydrates formed from a CH4 + H2 gas mixture at 5.0 MPa confirmed the H2 inclusion within the large cavities of structure I. The results show that the interactions between H2 and the natural gas hydrate phase range from the incorporation of H2 molecules into the hydrate phase to the rapid dissociation of the gas hydrate depending on thermodynamic conditions and H2 concentration in the coexisting gas phase.

Infrastructure projects can act as niches for innovation development contribute to strategic goals of network owners and drive broader systemic transitions. However limited research has examined how sustainability transitions are shaped through narratives and counternarratives around infrastructure projects. Using a case study of the port of Rotterdam we analyze how three embedded projects - Maasvlakte 2 RDM Campus and the Hydrogen Pipeline - reflected and shaped evolving narratives and counter-narratives over a 20-year sustainability transition. Grounded in the Multi-Level Perspective (MLP) the study demonstrates how an infrastructure owner like the Port of Rotterdam Authority (PoRA) strategically mobilized narrative framing to reshape existing regimes over time. The study contributes to the debate on project management and transition studies by highlighting how infrastructure project owners respond to transition-related tensions by shaping defending and adapting project narratives over time thereby influencing sustainability trajectories.

In order to minimize emissions of the aerospace sector and thus its impact on the climate several novel concepts of propulsion systems for aircraft are being developed. Many of these concepts do not use an energy source based on the combustion of hydrocarbons but other means of energy generation and storage like hydrogen fuel cells and corresponding hydrogen storage systems. The use of hydrogen as a primary energy carrier in aircraft poses novel and different hazards when compared to conventional propulsion and fuel storage systems. The study described in the present paper identifies analyzes and evaluates failure conditions and corresponding hazards that are associated with the electrified propulsion systems. Mitigation strategies to prevent failures to occur or decrease their severity are recommended. The effects of the assessed failures on aircraft crew and occupants are classified as catastrophic hazardous or major as defined in the according Certification Specifications. Failure Conditions occurring at the aircraft system and subsystem levels are considered and their effect on the aircraft and propulsion system is assessed. The hazards identified mostly emerge due to the properties of the gaseous or liquid hydrogen. They include the flammability of gaseous hydrogen and the very low temperatures of cryogenic liquid hydrogen as well as the installation of high voltage power infrastructure and high capacity heat exchangers.

Hydrogen is increasingly recognised as a potential critical energy carrier in decarbonising global energy systems. Australia is positioning itself as a potential leader in offshore renewable hydrogen production by leveraging existing liquified natural gas export infrastructure activating its abundant renewable energy resources and harnessing its extensive offshore marine acreage. Despite this there is limited research on the techno-economic and regulatory pathways for offshore hydrogen development in Australia as an enabler of its net zero manufacturing and export ambitions. This study offers a multidisciplinary assessment and review of Australia’s offshore renewable hydrogen potential. It aims to examine the technical legal and economic challenges and opportunities to enable and adapt the existing Australian offshore electricity regulatory regime and enable policy to facilitate future renewable offshore hydrogen licensing and production. Overall the findings provide practical insights for advancing Australia’s offshore hydrogen transition including technical innovations needed to scale offshore wind development. The study demonstrates how a specific offshore hydrogen licensing framework could reduce legal uncertainties to create economies of scale and reduce hydrogen investment risk to unlock the full potential of developing offshore renewable hydrogen projects.

This paper provides authors’ perspective on the current advances and challenges in utilising polymers and composites in hydrogen economy. It has originated from ‘Polymers and Composites for Hydrogen Economy’ symposium organised in March 2025 at the University of Warwick. This paper presents views from the event and thus provides a perspective from academia and industry on the ongoing advances and challenges for those materials in hydrogen applications.

The utilisation of renewable energy sources for hydrogen production is increasingly vital for ensuring the long-term sustainability of global energy systems. Currently the Sultanate of Oman is actively integrating renewable energy particularly through the deployment of solar photovoltaic (PV) systems as part of its ambitious targets for the forthcoming decades. Also Oman has target to achieve 1 million tonnes of green-H2 production annually. Leveraging Oman's abundant solar resources to produce green hydrogen and promote the clean transportation industry could significantly boost the country's sustainable energy sector. This paper outlines a standalone bifacial solar-powered system designed for large-scale green hydrogen (H2) production and storage to operate both a hydrogen refuelling station and an electric vehicle charging station in Sohar Oman. Using HOMER software three scenarios: PV/Hydrogen/Battery PV/Hydrogen PV/Battery systems were compared from a techno-economic perspective. Also the night-time operation (Battery/Hydrogen) was investigated. Varying cost of electricity were obtained depending on the system from $3.91/kWh to $0.0000565kWh while the bifacial PV/Hydrogen/Battery system emerged as the most efficient option boasting a unit cost of electricity (COE) of $3.91/kWh and a levelized cost of hydrogen (LCOH) value of $6.63/kg with net present cost 199M. This system aligns well with Oman's 2030 objectives with the capacity to generate 1 million tonnes of green-H2 annually. Additionally the findings show that the surplus electricity from the system could potentially cover over 30% of Oman's total energy consumption with zero harmful emissions. The implementation of this system promises to enhance Oman's economic and transportation industries by promoting the adoption of electric and fuel cell vehicles while reducing reliance on traditional energy sources.