Publications

The strategic importance of hydrogen has gained significant recognition as nations across the world have committed to achieving net zero. Here in the UK there’s a widespread consensus that hydrogen is critical to achieving our net zero target. This commitment culminated in the launch of the UK’s first Hydrogen Strategy and has been reaffirmed by Chris Skidmore’s Independent Review of Net Zero. Both these documents highlight hydrogen’s importance not only to net zero but growing the UK industrial base1 . Analysis by Hydrogen UK estimates up to 20000 jobs could be created by 2030 contributing £26bn in cumulative GVA2. These economic benefits flow from all areas of the value chain ranging from production storage network development and off-taker markets. However with large scale projects still to take final investment decisions current volumes of low-carbon hydrogen produced and consumed fall well below the government’s 2030 ambitions. Encouragingly the UK has a positive track record of deploying low carbon technologies. The combination of the UK’s world leading policies and incentive schemes alongside our vibrant RD&I and engineering environment has enabled rapid deployment of technologies like offshore wind and electric vehicles. Yet despite being world leaders in deployment early opportunities for regional supply chain growth and job creation were not fully realised and taken advantage of from inception. The hydrogen sector is therefore at a tipping point. To capitalise on the economic opportunity hydrogen offers the UK must learn from prior technology deployments and build a strong domestic hydrogen supply chain in parallel to championing deployment. This report delivers on a recommendation from the Hydrogen Champion Report which encouraged industry to create an industry led supply chain strategy3 . With Hydrogen UK steering the work on behalf of the UK hydrogen industry this study focusses on identifying the actions needed to mature a local supply chain that can support the initial deployment of hydrogen technologies across the value chain. The report is segmented into two sections. The first section outlines a voluntary ambition for local content from industry alongside the potential intervention mechanisms needed to achieve the ambition. The second section exploresthe challenges companies across the hydrogen value chain face in maximising UK supply chain opportunities.

This report can be found on Hydrogen UK's website.

Hydrogen primarily produced from steam methane reforming plays a crucial role in oil refining and provides a solution for the oil and gas industry's long-term energy transition by reducing CO2 emissions. This paper examines hydrogen’s role in this transition. Firstly experiences from oil and gas exploration including in-situ gasification can be leveraged for hydrogen production from subsurface natural hydrogen reservoirs. The produced hydrogen can serve as fuel for generating steam and heat for thermal oil recovery. Secondly hydrogen can be blended into gas for pipeline transportation and used as an alternative fuel for oil and gas hauling trucks. Additionally hydrogen can be stored underground in depleted gas fields. Lastly oilfield water can be utilized for hydrogen production using geothermal energy from subsurface oil and gas fields. Scaling up hydrogen production faces challenges such as shared use of oil and gas infrastructures increased carbon tax for promoting blue hydrogen and the introduction of financial incentives for hydrogen production and consumption hydrogen leakage prevention and detection.

A unique hydrogen leak detection strategy is the use of powerless indicator wraps for fittings and other pneumatic elements within a hydrogen facility. One transduction mechanism of such indicators is a color change that is induced by a reaction between a pigment and released hydrogen. This is an effective way to detect hydrogen leaks and to identify their source before they become a safety event however this technology requires visual (manual) inspection to identify a color change or leak. One improvement in this strategy would be to improve the communication of the visual response to an end-user. Element One (E1) has previously developed and introduced DetecTape® a self-fusing silicone non-reversible hydrogen leak detecting tape for application to potential leak sites in hydrogen piping valves and fittings and it has been successfully commercialized with excellent feedback. Element One’s sensors can be fabricated using either pigments or thin films which both change color and conductivity. Neither change requires an external power source. The conductivity change may be communicated as a wireless transmission such as passive radio frequency identification devices (RFID) to an appropriate receiving system where it may be remotely monitored to achieve higher levels of safety and reliability at low cost. Element One will report on its recent progress in the commercial development of remotely monitored hydrogen leak detection using several wireless protocols including passive RFID.

During the last decade developing more sustainable transportation modes has become a primary objective for car manufacturers and governments around the world to mitigate environmental issues such as climate change the continuous increase in greenhouse gas (GHG) emissions and energy depletion. The use of hydrogen fuel cell technology as a source of energy in electric vehicles is considered an emerging and promising technology that could contribute significantly to addressing these environmental issues. In this study the effects of Hydrogen Fuel Cell Battery Electric Vehicles (HFCBEVs) on global GHG emissions compared to other technologies such as BEVs were determined based on different relevant factors such as predicted sales for 2050 (the result of the developed prediction model) estimated daily traveling distance estimated future average global electricity emission factors future average Battery Electric Vehicle (BEV) emission factors future global hydrogen production emission factors and future average HFCBEV emission factors. As a result the annual GHG emissions produced by passenger cars that are expected to be sold in 2050 were determined by considering BEV sales in the first scenario and HFCBEV replacement in the second scenario. The results indicate that the environmental benefits of HFCBEVs are expected to increase over time compared to those of BEVs due to the eco-friendly methods that are expected to be used in hydrogen production in the future. For instance in 2021 HFCBEVs could produce more GHG emissions than BEVs by 54.9% per km of travel whereas in 2050 BEVs could produce more GHG emissions than HFCBEVs by 225% per km of travel.

Fuel cell electric vehicles (FCEVs) have received significant attention in recent times due to various advantageous features such as high energy efficiency zero emissions and extended driving range. However FCEVs have some drawbacks including high production costs; limited hydrogen refueling infrastructure; and the complexity of converters controllers and method execution. To address these challenges smart energy management involving appropriate converters controllers intelligent algorithms and optimizations is essential for enhancing the effectiveness of FCEVs towards sustainable transportation. Therefore this paper presents emerging energy management strategies for FCEVs to improve energy efficiency system reliability and overall performance. In this context a comprehensive analytical assessment is conducted to examine several factors including research trends types of publications citation analysis keyword occurrences collaborations influential authors and the countries conducting research in this area. Moreover emerging energy management schemes are investigated with a focus on intelligent algorithms optimization techniques and control strategies highlighting contributions key findings issues and research gaps. Furthermore the state-of-the-art research domains of FCEVs are thoroughly discussed in order to explore various research domains relevant outcomes and existing challenges. Additionally this paper addresses open issues and challenges and offers valuable future research opportunities for advancing FCEVs emphasizing the importance of suitable algorithms controllers and optimization techniques to enhance their performance. The outcomes and key findings of this review will be helpful for researchers and automotive engineers in developing advanced methods control schemes and optimization strategies for FCEVs towards greener transportation.

In 2015 during the lead up to the Paris Climate Agreement the United States set forth a Nationally Determined Contribution that outlines national goals for greenhouse gas emission reductions. It was not until 2021 that the US put forth a long-term strategy that lays out the pathway to reach these goals. The US long-term strategy lays the framework for research needs to meet the greenhouse gas emission reduction goals and incentivizes industry to meet the goals using a variety of policies. The five US long term strategy core elements are to decarbonize electricity electrify end uses and switch to clean fuels cut energy waste reduce methane and other non-carbon dioxide greenhouse gas emissions and to scale up carbon dioxide removal. Implementation of the long term strategy has generally been funded by tax incentives and government grants that were approved as part of the Inflation Reduction Act. Political headwinds societal Not in My Backyard resistance long-term economic funding cumbersome permitting requirements and incentives vs. taxation debate are significant policy/nontechnical hurdles. Technical challenges remain regarding effective energy efficiency implementation the use of hydrogen as a fuel cost effective carbon emission treatment nuclear energy expansion renewables expansion and grid integration biofuel integration efficient and safe energy storage and electrical grid adequacy/expansion. This review article condenses the multitude of technical and policy issues facing the US long-term strategy providing readers with an overview of the extent and magnitude of the challenges while outlining possible solutions.

This study presents and analyses three plant configurations of the Ocean Thermal Energy Conversion (OTEC) technology. All the solutions are based on using the OTEC system to obtain hydrogen through an electrolyzer. The hydrogen is then compressed and stored. In the first and second layouts a Rankine cycle with ammonia and a mixture of water and ethanol is utilised respectively; in the third layout a Kalina cycle is considered. In each configuration the OTEC cycle is coupled with a polymer electrolyte membrane (PEM) electrolyzer and the compression and storage system. The water entering the electrolyzer is pre-heated to 80 ◦C by a solar collector. Energy exergy and exergo-economic studies were conducted to evaluate the cost of producing compressing and storing hydrogen. A parametric analysis examining the main design constraints was performed based on the temperature range of the condenser the mass flow ratio of hot and cold resource flows and the mass fraction. The maximum value of the overall exergy efficiency calculated is equal to 93.5% for the Kalina cycle and 0.524 €/kWh is the minimum cost of hydrogen production achieved. The results were compared with typical data from other hydrogen production systems.

This review presents a broad exploration of the techno economic evaluation of different technologies utilized in the production of hydrogen from both renewable and non-renewable sources. These encompass methods ranging from extracting hydrogen from fossil fuels or biomass to employing microbial processes electrolysis of water and various thermochemical cycles. A rigorous techno-economic evaluation of hydrogen production technologies can provide a critical cost comparison for future resource allocation priorities and trajectory. This evaluation will have a great impact on future hydrogen production projects and the development of new approaches to reduce overall production costs and make it a cheaper fuel. Different methods of hydrogen production exhibit varying efficiencies and costs: fast pyrolysis can yield up to 45% hydrogen at a cost range of $1.25 to $2.20 per kilogram while gasification operating at temperatures exceeding 750°C faces challenges such as limited small-scale coal production and issues with tar formation in biomass. Steam methane reforming which constitutes 48% of hydrogen output experiences cost fluctuations depending on scale whereas auto-thermal reforming offers higher efficiency albeit at increased costs. Chemical looping shows promise in emissions reduction but encounters economic hurdles and sorptionenhanced reforming achieves over 90% hydrogen but requires CO2 storage. Renewable liquid reforming proves effective and economically viable. Additionally electrolysis methods like PEM aim for costs below $2.30 per kilogram while dark fermentation though cost-effective grapples with efficiency challenges. Overcoming technical economic barriers and managing electricity costs remains crucial for optimizing hydrogen production in a low-carbon future necessitating ongoing research and development efforts.

Currently modern hydrogen technologies due to their low or zero emissions constitute one of the key elements of energy transformation and sustainable development. The growing interest in hydrogen is driven by the European climate policy aimed at limiting the use of fossil fuels for energy purposes. Although not all opinions regarding the technical and economic potential of hydrogen energy are positive many prepared forecasts and analyses show its prospective importance in several areas of the economy. The aim of this article is to provide a comprehensive review of modern materials current hydrogen technologies and strategies and show the opportunities problems and challenges Poland faces in the context of necessary energy transformation. The work describes the latest trends in the production transportation storage and use of hydrogen. The environmental social and economic aspects of the use of green hydrogen were discussed in addition to the challenges and expectations for the future in the field of hydrogen technologies. The main goals of the development of the hydrogen economy in Poland and the directions of actions necessary to achieve them were also presented. It was found that the existence of the EU CO2 emissions allowance trading system has a significant impact on the costs of hydrogen production. Furthermore the production of green hydrogen will become economically justified as the costs of energy obtained from renewable sources decrease and the costs of electrolysers decline. However the realisation of this vision depends on the progress of scientific research and technical innovations that will reduce the costs of hydrogen production. Government support mechanisms for the development of hydrogen infrastructure and technologies will also be of key importance.

In recent years traditional fossil fuels such as coal oil and natural gas have historically dominated various applications but there has been a growing shift towards cleaner alternatives. Among these alternatives hydrogen (H2) stands out as a highly promising substitute for all other conventional fuels. Today hydrogen (H2) is actively taking on a significant role in displacing traditional fuel sources. The utilization of hydrogen in gas turbine (GT) power generation offers a significant advantage in terms of lower greenhouse gas emissions. The performance of hydrogen-based gas turbines is influenced by a range of variables including ambient conditions (temperature and pressure) component efficiency operational parameters and other factors. Additionally incorporating an intercooler into the gas turbine system yields several advantages such as reducing compression work and maintaining power and efficiency. Many scholars and researchers have conducted comprehensive investigations into the components mentioned above within context of gas turbines (GTs). This study provides an extensive examination of the research conducted on hydrogen-powered gas turbine and intercooler with employed different methods and techniques with a specific emphasis on the different case studies of a hydrogen gas turbine and intercooler. Moreover this study not only examined the current state of research on hydrogen-powered gas turbine and intercooler but also covered its influence by offering the effective recommendations and insightful for guiding for future research in this field.

Promoting the development of China’s hydrogen energy industry is crucial for achieving green energy transition. However existing research lacks systematic studies on the spatial layout of the hydrogen industry chain. This study constructed a comprehensive theoretical framework encompassing hardware infrastructure software systems and soft power. Using multi-source heterogeneous data GIS analysis and NVivo text coding methods the current regional layout and challenges of China’s hydrogen infrastructure industry chain were systematically evaluated. The findings determined that economically developed eastern regions lead in infrastructure and soft power while central and western regions leverage their resource and manufacturing advantages. Major challenges include regional imbalances in hardware infrastructure uneven distribution of soft power and misalignment between software systems and actual needs. Analysis of the “14th Five-Year Plan” of various regions elucidated deep insights into the diversity of local hydrogen energy development strategies identifying five types of hydrogen cities: resource-advantaged market-oriented regionally collaborative innovation-driven and policy-supported. Accordingly strategies to enhance industry chain synergy clarify city roles and optimize regional ecosystems were proposed. It is recommended to integrate hydrogen infrastructure with urban planning and incorporate environmental impact assessments into spatial optimization decisions. This study provides a systematic analytical framework and progressive policy recommendations for the efficient and green layout of China’s hydrogen infrastructure offering important implications for the sustainable development of the hydrogen industry and other rapidly developing economies.

Following a desktop study undertaken in 2021 to identify hazard scenarios associated with the use of liquid and compressed hydrogen on commercial shipping Shell has started a programme of large-scale experiments on the consequences of a release of liquid hydrogen. This work will compliment on-going research Shell has sponsored within several joint industry projects but will also address immediate concerns that the maritime industry has for the transportation of liquid hydrogen (LH2). This paper will describe the first phase of experiments involving the release of LH2 onto various substrates as well as dispersion across an instrumented test pad. These results will be used to address the following uncertainties in risk assessments within the hydrogen economy such as (1) Quantify the impact of low wind speed and high humidity on the buoyancy of both a passive and momentum jet dispersion cloud (2) Gather additional data on liquid hydrogen jet fires (3) Understand the likelihood for the formation of a sustained pool of hydrogen (4) Characterise materials especially passive fire protective coatings that are exposed to LH2. Not only will these experiments generate validation data to provide confidence in the Shell consequence tool FRED but they will also be used by Shell to support updates and new regulations developed by the International Maritime Organisation as it seeks to reduce CO2 intensity in the maritime industry.

This work undertakes a techno‑economic comparative analysis of the design of photo‑ voltaic panel/wind turbine/electrolyzer‑H2 tank–fuel cell/electrolyzer‑H2 tank (configuration 1) and photovoltaic panel/wind turbine/battery/electrolyzer‑H2 tank (configuration 2) to supply electricity to a simulated house and a hydrogen‑powered vehicle on Jeju Island. The aim is to find a system that will make optimum use of the excess energy produced by renewable energies to power the hydrogen vehicle while guaranteeing the reliability and cost‑effectiveness of the entire system. In addition to evaluating the Loss of Power Supply Probability (LPSP) and the Levelized Cost of Energy (LCOE) the search for achieving that objective leads to the evaluation of two new performance indicators: Loss of Hydrogen Supply Probability (LHSP) and Levelized Cost of Hydrogen (LCOH). After anal‑ ysis for 0 < LPSP < 1 and 0 < LHSP < 1 used as the constraints in a multi‑objective genetic algorithm configuration 1 turns out to be the most efficient loads feeder with an LCOE of 0.3322 USD/kWh an LPSP of 0% concerning the simulated house load an LCOH of 11.5671 USD/kg for a 5 kg hydrogen storage and an LHSP of 0.0043% regarding the hydrogen vehicle load.

Much has been learned about natural hydrogen (H2) seepages and accumulation but present knowledge of hydrogen behavior in the crust is so limited that it is not yet possible to consider exploitation of this resources. Hydrogen targeting requires a shift in the long-standing paradigms that drive oil and gas exploration. This paper describes the foundation of an integrated source-to-sink view of the hydrogen cycle and propose preliminary practical guidelines for hydrogen exploration.

Hydrogen is regarded as an ideal zero-carbon fuel for an internal combustion engine. However the low mass flow rate of the hydrogen injector and the low volume heat value of the hydrogen strongly restrict the enhancement of the hydrogen engine performance. This experimental study compared the effects of single-injectors and double-injectors on the engine performance combustion pressure heat release rate and the coefficient of variation (CoVIMEP) based on a singlecylinder 0.5 L port fuel injection hydrogen engine. The results indicated that the number of hydrogen injectors significantly influences the engine performance. The maximum brake power is improved from 4.3 kW to 6.12 kW when adding the injector. The test demonstrates that the utilization of the double-injector leads to a reduction in hydrogen obstruction in the intake manifold consequently minimizing the pumping losses. The pump mean effective pressure decreased from −0.049 MPa in the single-injector condition to −0.029 MPa in the double-injector condition with the medium loads. Furthermore the double-injector exhibits excellent performance in reducing the coefficient of variation. The maximum CoVIMEP decreased from 2.18% in the single-injector configuration to 1.92% in the double-injector configuration. This result provides new insights for optimizing hydrogen engine injector design and optimizing the combustion process.

Hydrogen flames are much thinner than hydrocarbon flames. They have a higher propensity to wrinkle and are subject to thermo-diffusive instabilities in lean conditions. The large scale experiments of Sherman under partially vented conditions have shown that the transition to detonation is possible with only modest flame acceleration to approximately 200 m/s which is much lower than the commonly accepted limits corresponding to choked flames. At present the reason for this transition is not known. Vented H2-air explosions have also demonstrated the role played by expansion/flame interactions in deforming the flame. The state of the art on flame burning rate enhancement by expansion waves will be provided along with the recent experimental and numerical results of head on interaction of flames with an expansion wave conducted in our group. We show that the expansion wave interaction can generate local burning rate increases by more than an order of magnitude. The role of thermo-diffusive instability is also assessed. The mechanism of flame deformation is via the vorticity generation by the misaligned pressure gradient controlled by the expansion wave and the density gradient of the flame. Expansion waves originating from the unburned gas severely elongate the cells until the flame folds burn out. Expansion waves originating from the burned gas side first invert the flames then elongate them by the same mechanism. The rate of elongation is controlled by the volumetric expansion of the gas and the curvature-enhanced growth.

The chances of a global hydrogen economy becoming a reality have increased significantly since the COVID pandemic and the war in Ukraine and for net zero carbon emissions. However intercontinental hydrogen transport is still a major issue. This study suggests transporting hydrogen as a gas at atmospheric pressure in balloons using the natural flow of wind to carry the balloon to its destination. We investigate the average wind speeds atmospheric pressure and temperature at different altitudes for this purpose. The ideal altitudes to transport hydrogen with balloons are 10 km or lower and hydrogen pressures in the balloon vary from 0.25 to 1 bar. Transporting hydrogen from North America to Europe at a maximum 4 km altitude would take around 4.8 days on average. Hydrogen balloon transportation cost is estimated at 0.08 USD/kg of hydrogen which is around 12 times smaller than the cost of transporting liquified hydrogen from the USA to Europe. Due to its reduced energy consumption and capital cost in some locations hydrogen balloon transportation might be a viable option for shipping hydrogen compared to liquefied hydrogen and other transport technologies.

The capabilities of an OpenFOAM solver to reproduce the transition of stoichiometric H2-air mixtures to detonation in obstructed 2-D channels were tested. The process is challenging numerically as it involves the ignition of a flame kernel its subsequent propagation and acceleration interaction with obstacles formation of shock waves ahead and detonation onset (DO). Two different obstacle configurations were considered in 10-mm high × 1-m long channels: (i) wavy walls (WW) that mimic the behavior of fencetype obstacles but prevent abrupt area changes. In this case flame acceleration (FA) is strongly affected by shock-flame interactions and DO often results from the compression of the gas present between the accelerating flame front and a converging section of the channel. (ii) Fence-type (FT) obstacles. In this case FA is driven by the increase in flame surface area as a result of the interaction of the flame front with the unburned gas flow field ahead particularly downstream of obstacles; shock-flame interactions play a role at the later stages of FA and DO takes place upon reflection of precursor shocks from obstacles. The effect of initial pressure p0 = 25 50 and 100 kPa at constant blockage ratio (BR = 0.6) was investigated and compared for both configurations. Results show that for the same initial pressure (p0 = 50 kPa) the obstacle configurations could lead to different final propagation regimes: a quasi-detonation for WW and a choked-flame for FT due to the increased losses for the latter. At p0 = 25 kPa however while both configurations result in choked flames WW seem to exhibit larger velocity deficits than FT due to longer flame-precursor shock distances during quasi-steady propagation and to the increased presence of unburnt mixture downstream of the tip of the flame that homogeneously explodes providing additional support to the propagation of the flame.

The depletion of reliable energy sources and the environmental and climatic repercussions of polluting energy sources have become global challenges. Hence many countries have adopted various renewable energy sources including hydrogen. Hydrogen is a future energy carrier in the global energy system and has the potential to produce zero carbon emissions. For the non-fossil energy sources hydrogen and electricity are considered the dominant energy carriers for providing end-user services because they can satisfy most of the consumer requirements. Hence the development of both hydrogen production and storage is necessary to meet the standards of a “hydrogen economy”. The physical and chemical absorption of hydrogen in solid storage materials is a promising hydrogen storage method because of the high storage and transportation performance. In this paper physical hydrogen storage materials such as hollow spheres carbon-based materials zeolites and metal– organic frameworks are reviewed. We summarize and discuss the properties hydrogen storage densities at different temperatures and pressures and the fabrication and modification methods of these materials. The challenges associated with these physical hydrogen storage materials are also discussed.

Blending hydrogen to existing fuel mix represents a major opportunity for decarbonisation. One important consideration for this application is the chemical interaction between hydrogen and hydrocarbon fuels arising from their different combustion chemistries and varying considerably with combustion processes. This paper conducted an exploratory study of hydrogen’s impact on autoignition in several combustion processes where hydrogen is used as a blending component or the main fuel. Case studies are presented for spark ignition engines (H2/natural gas) compression ignition engines (H2/diesel) moderate or intense low-oxygen dilution (MILD) combustors (H2/natural gas) and rotational detonation engines (H2/natural gas). Autoignition reactivity as a function of the hydrogen blending level is investigated numerically using the ignition delay iso-contours and state-of-the-art kinetic models at time scales representative of each application. The results revealed drastically different impact of hydrogen blending on autoignition due to different reaction temperature pressure and time scale involved in these applications leaving hydrocarbon interacting with hydrogen at different ignition branches where the negative pressure/temperature dependency of oxidation kinetics could take place. The resulted non-linear and at times non-monotonic behaviours indicate a rich topic for combustion chemistry and also demonstrates ignition delay iso-contour as a useful tool to scope autoignition reactivity for a wide range of applications.

This work formed part of the H21 programme whose objective is to reach the point whereby it is feasible to convert the existing natural gas (NG) distribution network to 100% hydrogen (H2) and provide a contribution to decarbonising the UK’s heat and power sectors with the focus on decarbonised fuel at point of use. Hydrogen has an ATEX Gas Group of IIC compared to IIA for natural gas which means further precautions are necessary to prevent the ignition of hydrogen during network operations. Both electrostatic and friction ignition risks were considered. Network operations considered include electrostatic precautions for polyethylene (PE) pipe and cutting and drilling of metallic pipes. As a result of the updated basis of safety from ignition considerations existing flow stopping methods were reviewed to see if they were compatible. Commonly used flow stopping methods were tested under laboratory conditions with hydrogen following the methodologies specified in the Gas Industry Standards (GIS). A new basis of safety for flow stopping has been proposed that looks at the flow past the secondary stop as double isolations are recommended for use with hydrogen.

Feedstock-to-fuel conversion or “Fuel Production” is a major contributor to greenhouse gas (GHG) emissions in life cycle assessment (LCA) of sustainable aviation fuels (SAF) from wastes. Here we construct and demonstrate an original mass and energy conserved chemically rigorous LCA methodology for the production of Hydroprocessed Esters and Fatty Acids-Synthetic Paraffinic Kerosene (HEFA-SPK) from Used Cooking Oil (UCO). This study proposes and demonstrates the use of; (i) the chemical composition of the UCO (ii) the ASTM properties of HEFA-SPK and (iii) the elemental mass and energy conserved reaction mechanism which converts one to the other as physical constraints for the specific LCA of any UCO derived HEFA-SPK. With application of these constraints the emissions embodied in UCO HEFA-SPK Fuel Production is found to range from 4.2 to 15.7 gCO2e/MJSAF depending on the renewability of the energy and hydrogen utilized. Imposition of (i)-(iii) as modelling constraints derives a HEFA-SPK yield of 49 mass% a priori. This finding aligns with experimental literature but brings attention to the higher yield estimations of 70–81% observed in current LCA tools. We show that this impacts the end LCA significantly as it adjusts allocation of emissions. A replication study of CORSIA’s (10.5 gCO2e/MJSAF) default core LCA value for Fuel Production quantifies the increase at +5.3 gCO2e/MJSAF or 15.8 gCO2e/MJSAF as total for Fuel Production. As the embodied emissions are significantly dependent on the specifics of the scenario assessed we highlight reporting a definitive GHG intensity for any UCO derived HEFA-SPK as generic will be inaccurate to an extent.

Accelerated decarbonisation of steelmaking oil refining and petrochemical industries is essential for climate change mitigation. Drawing on three longitudinal case studies of these industries in the UK this synthesis article makes a comparative analysis of their varying low-carbon reorientation speeds. The paper uses the triple embeddedness framework to analyse five factors (policy support international competition financial health technical feasibility corporate strategy and mindset) that explain why UK oil refineries have in recent years been comparatively the fastest in their low-carbon reorientation and UK steelmakers the slowest. We find that policy support has been more beneficial for refining and petrochemicals than for steel although recent government deals with steelmakers addressed this imbalance. International competition has been high for steel and petrochemicals and comparatively lower for refining (meaning that decarbonisation costs are less detrimental for international competitiveness). Financial performance has comparatively been worst for steel and best for oil refining which shapes the economic feasibility of low-carbon options. Hydrogen and carbon-capture-and-storage are technologically feasible for refining and petrochemicals while Electric Arc Furnaces are technically feasible for steelmakers but face wider feasibility problems (with scrap steel supply electricity grids and electricity prices) which is why we question the recent government deals. Corporate strategy and perceptions changed in oil refining with firms seeing economic opportunities in decarbonisation while steelmakers and petrochemical firms still mostly see decarbonisation as a burden and threat. The paper ends with comparative conclusions a discussion of political considerations and future outlooks for the three UK industries policy and research.

This study focuses on development of a CFD model able to simulate the experimentally observed critical nozzle diameter for hydrogen non-premixed flames. The critical diameter represents the minimum nozzle size through which a free jet flame will remain stable at all driving pressures. Hydrogen non-premixed flames will not blow-out at diameters equal to or greater than the critical diameter. Accurate simulation of this parameter is important for assessment of thermally activated pressure relief device (TPRD) performance during hydrogen blowdown from a storage tank. At TPRD diameters below the critical value there is potential for a hydrogen jet flame to blow-out as the storage tank vents potentially leading to hydrogen accumulation in an indoor release scenario. Previous experimental studies have indicated that the critical diameter for hydrogen is approximately 1 mm. In this study flame stability is considered across a range of diameters and overpressures from 0.1 mm to 2 mm and from 0.2 MPa to 20 MPa respectively. The impact of turbulent Schmidt number Sct which is the ratio of momentum diffusivity (kinematic viscosity) and mass diffusivity on the hydrogen concentration profile in the region near the nozzle exit and subsequent influence on critical diameter was investigated and discussed. For lower Sct values the enhanced mass mixing resulted in smaller predicted critical diameters. The use of value Sct=0.61 in the model demonstrated the best agreement with experimental values of the critical diameter. The model reproduced the critical diameter of 1 mm and then was applied to predict flame stability for under-expanded hydrogen jets.

The steel industry which relies heavily on primary energy is one of the industries with the highest CO2 emissions in China. It is urgent for the industry to identify ways to embark on the path to “green steel”. Hydrogen metallurgy technology uses hydrogen as a reducing agent and its use is an important way to reduce CO2 emissions from long-term steelmaking and ensure the green and sustainable development of the steel industry. Previous research has demonstrated the feasibility and emission reduction effects of hydrogen metallurgy technology; however further research is needed to dynamically analyze the overall impact of the large-scale development of hydrogen metallurgy technology on future CO2 emissions from the steel industry. This article selects the integrated MARKAL-EFOM system (TIMES) model as its analysis model constructs a China steel industry hydrogen metallurgy model (TIMES-CSHM) and analyzes the resulting impact of hydrogen metallurgy technology on CO2 emissions. The results indicate that in the business-as-usual scenario (BAU scenario) applying hydrogen metallurgy technology in the period from 2020 to 2050 is expected to reduce emissions by 203 million tons and make an average 39.85% contribution to reducing the steel industry’s CO2 emissions. In the carbon emission reduction scenario applying hydrogen metallurgy technology in the period from 2020 to 2050 is expected to reduce emissions by 353 million tons contributing an average of 41.32% to steel industry CO2 reduction. This study provides an assessment of how hydrogen metallurgy can reduce CO2 emissions in the steel industry and also provides a reference for the development of hydrogen metallurgy technology.

New hypotheses for reusing platforms reaching their end-of-life have been investigated in several works discussing the potential conversions of these infrastructures from recreational tourism to fish farming. In this perspective paper we discuss the conversion options that could be of interest in the context of the current energy transition with reference to the off-shore Italian scenario. The study was developed in support of the development of a national strategy aimed at favoring a circular economy and the reuse of existing infrastructure for the implementation of the energy transition. Thus the investigated options include the onboard production of renewable energy hydrogen production from seawater through electrolyzers CO2 capture and valorization and platform reuse for underground fluid storage in depleted reservoirs once produced through platforms. Case histories are developed with reference to a typical fictitious platform in the Adriatic Sea Italy to provide an engineering-based approach to these different conversion options. The coupling of the platform with the underground storage to set the optimal operational conditions is managed through the forecast of the reservoir performance with advanced numerical models able to simulate the complexity of the phenomena occurring in the presence of coupled hydrodynamic geomechanical geochemical thermal and biological processes. The results of our study are very encouraging because they reveal that no technical environmental or safety issues prevent the conversion of offshore platforms into valuable infrastructure contributing to achieving the energy transition targets as long as the selection of the conversion option to deploy is designed taking into account the system specificity and including the depleted reservoir to which it is connected when relevant. Socio-economic issues were not investigated as they were out of the scope of the project.

The overuse of fossil fuels has caused a serious energy crisis and environmental pollution. Due to these challenges the search for alternative energy sources that can replace fossil fuels is necessary. Hydrogen is a widely acknowledged future energy carrier because of its nonpolluting properties and high energy density. To realize a hydrogen economy in the future it is essential to construct a comprehensive hydrogen supply chain that can make hydrogen a key energy carrier. This paper reviews the various technologies involved in the hydrogen supply chain encompassing hydrogen production storage transportation and utilization technologies. Then the challenges of constructing a hydrogen supply chain are discussed from techno-economic social and policy perspectives and prospects for the future development of a hydrogen supply chain are presented in light of these challenges.

This paper presents work undertaken by the HSE as part of the Hytunnel-CS project a consortium investigating safety considerations for fuel cell hydrogen (FCH) vehicles in tunnels and similar confined spaces. The sudden failure of a pressurised hydrogen vessel was identified as a scenario of concern due to the severity of the consequences associated with such an event. In order to investigate this scenario experimentally HSE designed a bespoke and reusable ‘sudden release’ vessel. This paper presents an overview of the vessel and the results of a series of 13 tests whereby hydrogen was released from the bespoke vessel into a tunnel at pressures up to 65 MPa. The starting pressure and the volume of hydrogen in the vessel were altered throughout the campaign. Four of the tests also included congestion in the tunnel. The tests reliably autoignited. Overpressure measurements and flame arrival times measured with exposed-tip thermocouples enabled analysis of the severity of the events. A high-pressure fast-acting pressure transducer in the body of the vessel showed the pressure decay in the vessel which shows that 90% of the hydrogen was evacuated in between 1.8 and 3.2 ms (depending on the hydrogen inventory). Schlieren flow imagery was also used at the release point of the hydrogen showing the progression of the shock front following initiation of the tests. An assessment of the footage shows an estimated initial velocity of Mach 3.9 at 0.4 m from the release point. Based on this an ignition mechanism is proposed based upon the temperature behind the initial shock front.

Trains have been a crucial part of modern transport and their high energy efficiency and low greenhouse gas emissions make them ideal candidates for the future transport system. Transitioning from diesel trains to hydrogen fuel cell electric trains is a promising way to decarbonize rail transport. That’s because the fuel cell electric trains have several advantages over other electric trains such as lower life-cycle emissions and shorter refueling time than battery ones and less requirements for wayside infrastructure than the ones with overhead electric wires. However hydrogen fuel technology still needs to be advanced in areas including hydrogen production storage refueling and on-board energy management. Currently there are several pilot projects of hydrogen fuel cell electric trains across the globe especially in developed countries including one commercialized and permanent route in Germany. The experiences from the pilot projects will promote the technological and economic feasibility of hydrogen fuel in rail transport.

The seasonally varying potential to produce electricity from renewable sources such as wind PV and hydropower is a challenge for the continuous supply of hydrogen for transport and mobility. Seasonal storage of energy allows to avoid the use of grid electricity when it is scarce; storage systems can thus increase the resilience of the energy system. For grid-neutral and renewable hydrogen production an electrolyser is considered together with a Power-to-Gas seasonal storage system which consists of a methanation the gas grid as intermediate storage and a steam reformer. As feed stream electricity from an own photovoltaic (PV) system is considered and for some cases additional electricity from the grid or from a wind turbine. The dynamic operation of the plant during a year is simulated. It is possible to safely supply fuel cell vehicles with hydrogen from the grid-neutral plant without using electricity when it is scarce and expensive. To supply 135 kgH2/day unit sizes of 1 MW–2.9 MW for the PV system and 0.9 MW–2.6 MW for the electrolysis are required depending on the amount of available grid-electricity. The usage of grid-electricity increases the capacity factor of the electrolysis which results in decreased unit sizes and in a better economic performance. Seasonal storage of energy is required which results in an increased hydrogen production in summer of approximately 50% more than directly needed by the fuel cell vehicles. The overall efficiency from electricity to hydrogen is decreased due to the storage path by 10%-points to 56% based on the higher heating value. Assuming a cost-equivalent hydrogen price per driven kilometre in comparison to the actual diesel price and electricity costs of 10 Ct/kWhel from the grid the revenues of the system are higher than the operating costs.

Logistics is becoming more cost competitive while customers and regulatory bodies pressure businesses to disclose their carbon footprints creating interest in alternative fuels as a decarbonization strategy. This paper provides a thematic review of the role of alternative fuels in sustainable air land and sea logistics their challenges and potential mitigations. Through an extensive literature survey we determined that biofuels synthetic kerosene natural gas ammonia alcohols hydrogen and electricity are the primary alternative fuels of interest in terms of environmental sustainability and techno-economic feasibility. In air logistics synthetic kerosene from hydrogenated esters and fatty acids is the most promising route due to its high technical maturity although it is limited by biomass sourcing. Electrical vehicles are favorable in road logistics due to cheaper green power and efficient vehicle designs although they are constrained by recharging infrastructure deployment. In sea logistics liquified natural gas is advantageous owing to its supply chain maturity but it is limited by methane slip control and storage requirements. Overall our examination indicates that alternative fuels will play a pivotal role in the logistics networks of the future.

The article presents the application of the metalog family of probability distributions to predict the energy production of photovoltaic systems for the purpose of generating small amounts of green hydrogen in distributed systems. It can be used for transport purposes as well as to generate energy and heat for housing purposes. The monthly and daily amounts of energy produced by a photovoltaic system with a peak power of 6.15 kWp were analyzed using traditional statistical methods and the metalog probability distribution family. On this basis it is possible to calculate daily and monthly amounts of hydrogen produced with accuracy from the probability distribution. Probabilistic analysis of the instantaneous power generated by the photovoltaic system was used to determine the nominal power of the hydrogen electrolyzer. In order to use all the energy produced by the photovoltaic system to produce green hydrogen the use of a stationary energy storage device was proposed and its energy capacity was determined. The calculations contained in the article can be used to design home green hydrogen production systems and support the climate and energy transformation of small companies with a hydrogen demand of up to ¾ kg/day.

Chemical looping dry reforming of methane (CLDRM) using perovskites as a catalyst is considered a promising option for producing hydrogen from biogas. In this work the life-cycle performance of a system compiling a CLDRM unit paired with a water gas shift unit a pressure swing adsorption unit and a combined cycle scheme to provide steam and electricity was assessed. The main data needed to reflect the behavior of the reforming reaction was obtained experimentally and implemented in an Aspen Plus® simulation. Inventory data was obtained through process simulation and used to assess the environmental performance of the process in terms of carbon footprint acidification freshwater eutrophication ozone depletion photochemical ozone formation and depletion of minerals and metals. Overall the environmental viability of the production of green hydrogen from biogas was found to be heavily dependent on the biogas leakage in anaerobic digestion plants. The CLDRM system was benchmarked against a conventional DRM implementation for the same feedstock. While the conventional DRM plant environmentally outperformed the perovskite-based CLDRM the latter might present advantages from an implementation point of view.

The refining industry is shifting from decarbonization to hydrogenation for processing heavy fractions to reduce pollution and improve efficiency. However the carbon footprint of hydrogen production presents significant environmental challenges. This study couples refinery linear programming models with life cycle assessment to evaluate from a long-term perspective the role of low-carbon hydrogen in promoting sustainable and profitable hydrogenation refining practices. Eight hydrogen-production pathways were examined including those based on fossil fuels and renewable energy providing hydrogen for three representative refineries adopting hydrogenation decarbonization and co-processing routes. Learning curves were used to predict future hydrogen cost trends. Currently hydrogenation refineries using fossil fuels benefit from significant cost advantages in hydrogen production demonstrating optimal economic performance. However in the long term with increasing carbon taxes hydrogenation routes will be affected by the high carbon emissions associated with fossil-based hydrogen losing economic advantages compared to decarbonization pathways. With increasing installed capacity and technological advancements low-carbon hydrogen is anticipated to reach cost parity with fossil-based hydrogen before 2060. Coupling renewable hydrogen is expected to yield the most significant economic advantages for hydrogenation refineries in the long term. Renewable hydrogen drives the transition of refining processing routes from a decarbonization-oriented approach to a hydrogenation-oriented paradigm resulting in cleaner refining processes and enhanced competitiveness under emission-reduction pressures.

Hydrogen has gained tremendous momentum worldwide as an energy carrier to transit to a net zero emission energy sector. It has been widely adopted as a promising large-scale renewable energy (RE) storage solution to overcome RE resources’ variability and intermittency nature. The fuel cell (FC) technology became in focus within the hydrogen energy landscape as a cost-effective pathway to utilize hydrogen for power generation. Therefore FC technologies’ research and development (R&D) expanded into many pathways such as cost reduction efficiency improvement fixed and mobile applications lifetime safety and regulations etc. Many publications and industrial reports about FC technologies and applications are available. This raised the necessity for a holistic review study to summarize the state-of-the-art range of FC stacks such as manufacturing the balance of plant types technologies applications and R&D opportunities. At the beginning the principal technologies to compare the well known types followed by the FC operating parameters are presented. Then the FC balance of the plant i.e. building components and materials with its functionality and purpose types and applications are critically reviewed with their limitations and improvement opportunities. Subsequently the electrical properties of FCs with their key features including advantages and disadvantages were investigated. Applications of FCs in different sectors are elaborated with their key characteristics current status and future R&D opportunities. Economic attributes of fuel cells with a pathway towards low cost are also presented. Finally this study identifies the research gaps and future avenues to guide researchers and the hydrogen industry.

Hydrogen offers the UK a unique opportunity to deliver on our Net Zero ambitions enabling deep decarbonisation of the parts of the energy system that are challenging to electrify balancing the energy system by providing large scale long duration energy storage and reducing pressure on electricity infrastructure. The UK Government in recognition of the centrality of hydrogen to the future energy system has set a 10GW hydrogen production ambition to be achieved by 2030. This ambition and its supporting policies such as the Hydrogen Business Model the Low Carbon Hydrogen Standard and the Hydrogen Transport and Storage Business Models will unlock private sector investment and kick-start the UK’s hydrogen activity. Encouragingly the UK has a positive track record of deploying low carbon technologies. The  combination of the UK’s world leading policies and incentive schemes alongside a vibrant  Research Development and Innovation (RD&I)  and engineering environment has enabled rapid  deployment of technologies such as offshore wind  and electric vehicles. Yet despite being world leaders  in deployment early opportunities for regional  supply chain growth and job creation were not fully  realised and taken advantage of from inception. The  hydrogen sector is therefore at a tipping point. To  capitalise on the economic opportunity hydrogen  offers the UK must learn from prior technology  deployments and build a strong domestic hydrogen  supply chain in parallel to championing deployment.

Hydrogen is unique amongst low carbon  technologies. It represents a significant economic  opportunity with future hydrogen markets estimated  by the Hydrogen Innovation Initiative to be worth  $8tn and hydrogen technology markets estimated to reach $1tn by 20501 but crucially it is also still a nascent market. Unlike many other low carbon technologies where supply chains are already well established hydrogen supply chains are embryonic meaning that the UK has an opportunity to anchor these supply chains here and establish itself as a global leader.

The UK is well placed to capitalise on this opportunity with favourable geography and geology  that enables us to produce and store hydrogen cost effectively coupled with a strong pipeline of hydrogen projects a stable policy environment that is attractive to investors and a wealth of transferable skills and expertise from the oil and gas industry.

We must ensure that alongside our focus on deployment we are also investing in technology and supply chains. Not only will this deliver exponential economic benefits from the projects supported by Government but it will also enable us to tackle increasing global supply chain constraints. Hydrogen UK estimated in its Economic Impact Assessment that hydrogen could deliver 30000 jobs annually and £7bn of GVA by 2030

It is important to be targeted and strategic in our investment and activities and recognise that hydrogen represents a wide range of technologies and the UK should not expect to lead in every area. Hydrogen UK with the support of the Hydrogen Delivery Council has undertaken analysis of the hydrogen value chain building on UK strengths and identifying the high value items that can deliver significant impact and benefit to the UK. We have also conducted widespread engagement with project developers to identify the barriers to utilising UK technology in projects and with technology developers to identify the challenges and barriers to investing and siting development and manufacturing in the UK.

The report can be found on Hydrogen UK's website.

Salt caverns have great potential to store relevant amounts of hydrogen as part of the energy transition. However the durability and suitability of commonly used steels for piping in hydrogen salt caverns is still under research. In this work aging effects focusing on corrosion and cracking patterns of casing steel API 5CT J55 and “H2ready” pipeline steel API 5L X56 were investigated with scanning electron microscopy and energy dispersive X-ray spectroscopy after accelerated stress tests with pressure/temperature cycling under hydrogen salt cavern-like conditions. Compared to dry conditions significant more corrosion by presence of salt ions was detected. However compared to X56 only for J55 an intensification of corrosion and cracking at the surface due to hydrogen atmosphere was revealed. Pronounced surface cracks were observed for J55 over the entire samples. Overall the results strongly suggest that X56 is more resistant than J55 under the conditions of a hydrogen salt cavern.

Hydrogen is one of the key solutions to decarbonising the UK economy along with other carbon abatement solutions such as electrification CCUS biofuels and energy efficiency. It provides a low carbon alternative to fossil fuels that has many of the same desirable features such as burning with a high temperature flame without producing carbon emissions during combustion. Hydrogen will be particularly valuable in hard-to-decarbonise sectors that have few cost-effective alternatives including elements of industry heavy transport and dispatchable power generation. However it’s use could be much more widespread depending on how costs preferences and policy for different low carbon solutions develop. The Government’s Hydrogen Strategy estimates that based on analysis from the Climate Change Committee (CCC) in 2050 between 20% and 35% of the UK’s final energy demand could be met with low carbon hydrogen1 . While hydrogen provides a promising solution to reducing emissions current deployment of low carbon hydrogen is low with almost all hydrogen in the UK produced from unabated fossil fuels resulting in high emissions. In the UK hydrogen production must meet the Low Carbon Hydrogen Standard (LCHS) to access government support. This is currently set at 20g CO2 e/MJ(LHV) and will ensure that future deployment will deliver significant emissions reductions when switching from fossil fuels2. The period to 2030 will be a critical time for the UK to seize the economic opportunity presented by low carbon hydrogen sector. Internationally increasing attention has been placed on hydrogen as a solution to global emissions. In the USA the Inflation Reduction Act (IRA) has provided fixed rate tax credits of up to $3/kg (£2.4/kgII) for clean hydrogen production3. Closer to home the EU is targeting 10 million tonnes of domestic electrolytic production and an additional 10 million tonnes of electrolytic hydrogen imports by 20304. This will be achieved through a variety of policy levers including an auction for fixed price subsidy support for electrolytic production with a ceiling of €4.5/kg5 (£3.84/kgIII). In the UK Government have set an ambitious target of up to 10 GW of low carbon hydrogen production by 2030 with at least half of this from electrolytic sources6. This will be supported by the Hydrogen Production Business Model (HPBM) a two-way variable CfD which could potentially provide hydrogen for a price as low as the natural gas price7 . As global supply chains investment and skills are in international competition the UK must continue its ambitious hydrogen aspirations to ensure the decarbonisation and economic opportunity presented by low carbon hydrogen is captured. This study estimates the economic impact of the low carbon hydrogen sector in the UK by 2030. The impact is assessed by estimating the costs of hydrogen deployment and applying employment and GVA multipliers to these costs based on historic economic activity. These estimates are broken down by different forms of low carbon hydrogen production and end use as well as the enabling infrastructure required to connect production and demand namely hydrogen networks and storage. Both the employment and GVA are estimated for each of these value chain elements for every year between 2024 and 2030. Employment and economic growth from the hydrogen sector will be created across the UK with many benefits arising in regions that have faced historic underinvestment such as the industrial clusters and Scotland. Beyond the high-level economic benefits estimated in this study the hydrogen sector creates an opportunity for the hundreds of thousands oil and gas sector jobs in the UK to transition to a low carbon alternative.

This report can be found on Hydrogen UK's website.

The transformation of fossil fuel-based power generation systems towards greenhouse gas-neutral ones based on renewable energy sources is one of the key challenges facing contemporary society. The temporal volatility that accompanies the integration of renewable energy (e.g. solar radiation and wind) must be compensated to ensure that at any given time a sufficient supply of electrical energy for the demands of different sectors is available. Green hydrogen which is produced using renewable energy sources via electrolysis can be used to chemically store electrical energy on a seasonal basis. Reconversion technologies are needed to generate electricity from stored hydrogen during periods of low renewable electricity generation. This study presents a detailed technoeconomic assessment of hydrogen gas turbines. These technologies are also superior to fuel cells due to their comparatively low investment costs especially when it comes to covering the residual loads. As of today hydrogen gas turbines are only available in laboratory or small-scale settings and have no market penetration or high technology readiness level. The primary focus of this study is to analyze the effects on gas turbine component costs when hydrogen is used instead of natural gas. Based on these findings an economic analysis addressing the current state of these turbine components is conducted. A literature review on the subsystems is performed considering statements from leading manufactures and researchers to derive the cost deviations and total cost per installed capacity (€/kWel). The results reveal that a hydrogen gas turbine power plant has an expected cost increase of 8.5% compared to a conventional gas turbine one. This leads to an average cost of 542.5 €/kWel for hydrogen gas turbines. For hydrogen combined cycle power plants the expected cost increase corresponds to the cost of the gas turbine system as the steam turbine subsystem remains unaffected by fuel switching. Additionally power plant retrofit potentials were calculated and the respective costs in the case of an upgrade were estimated. For Germany as a case study for an industrialized country the potential of a possible retrofit is between 2.7 and 11.4 GW resulting to a total investment between 0.3 and 1.1 billion €.

Acting in accordance with the requirements of the 2015 Paris Agreement Poland as well as other European Union countries have committed to achieving climate neutrality by 2050. One of the solutions to reduce emissions of harmful substances into the environment is the implementation of large-scale hydrogen technologies. This article presents the cost of producing green hydrogen produced using an alkaline electrolyzer with electricity supplied from a photovoltaic farm. The analysis was performed using the Monte Carlo method and for baseline assumptions including an electricity price of 0.053 EUR/kWh the cost of producing green hydrogen was 5.321 EUR/kgH2 . In addition this article presents a sensitivity analysis showing the impact of the electricity price before and after the energy crisis and other variables on the cost of green hydrogen production. The large change occurring in electricity prices (from 0.035 EUR/kWh to 0.24 EUR/kWh) significantly affected the levelized cost of green hydrogen (LCOH) which could change by up to 14 EUR/kgH2 in recent years. The results of the analysis showed that the parameters that successively have the greatest impact on the cost of green hydrogen production are the operating time of the plant and the unit capital expenditure. The development of green hydrogen production facilities along with the scaling of technology in the future can reduce the cost of its production.

In the present work we present the results of numerical simulations involving the dispersion and combustion of a hydrogen cloud released in an empty tunnel. The simulations were conducted with the use of ADREA-HF CFD code and the results are compared with measurements from experiments conducted by HSE in a tunnel with the exact same geometry. The length of the tunnel is equal to 70 m and the maximum height from the floor is equal to 3.25 m. Hydrogen release is considered to occur from a train containing pressurized hydrogen stored at 580 bars. The release diameter is equal to 4.7 mm and the release direction is upwards. Initially dispersion simulation was performed in order to define the initial conditions for the deflagration simulations. The effect of the initial wind speed and the effect of the ignition delay time were investigated. An extensive grid sensitivity study was conducted in order to achieve grid independent results. The CFD model takes into account the flame instabilities that are developed as the flame propagates inside the tunnel and turbulence that exists in front of the flame front. Pressure predictions are compared against experimental measurements revealing a very good performance of the CFD model.

A growing share of renewable energy production in the energy supply systems is key to reaching the European political goal of zero CO2 emission in 2050 highlighted in the green deal. Linked to the irregular production of solar and wind energies which have the highest potential for development in Europe massive energy storage solutions are needed as energy buffers. The European project HyPSTER [1] (Hydrogen Pilot STorage for large Ecosystem Replication) granted by the Clean Hydrogen Partnership addresses this topic by demonstrating a cyclic test in an experimental salt cavern filled with hydrogen up to 3 tons using hydrogen that is produced onsite by a 1 MW electrolyser. One specific objective of the project is the assessment of the risks and environmental impacts of cyclic hydrogen storage in salt caverns and providing guidelines for safety regulations and standards. This paper highlights the first outcome of the task WP5.5 of the HyPSTER project addressing the regulatory and normative frameworks for the safety of hydrogen storage in salt caverns from some selected European Countries which is dedicated to defining recommendations for promoting the safe development of this industry within Europe.

Hydrogen refueling stations rely on pressure vessels capable of withstanding pressures up to 90 MPa while mitigating concerns related to hydrogen embrittlement. However a gap exists in understanding the long-term fatigue behavior of these vessels under real operational conditions. This study focuses on evaluating the safety of SA372 pressure vessels using operational data from a hydrogen refueling station in Pyeongtaek South Korea. A predictive reinspection methodology is proposed based on this evaluation. Parameters including hydrogen-induced stress intensity factor (KIH) initial crack size (a0 c0) and pressure vessel specifications are considered to assess critical crack depth (ac) critical usage cycles (Nc) and allowable usage cycles (Nallowed). Leveraging operational data collected between August and November 2023 fatigue analysis and Rainflow counting inform reinspection schedules. Results indicate a need for mid-bank vessel reinspection within the second year high-bank vessel reinspection every 20 years and low-bank vessel reinspection every 143 years in accordance with safety regulations. Additionally a revised refueling logic is proposed to optimize vehicle charging methods and pressure ranges enhancing operational safety. This study serves as a preliminary investigation highlighting the need for broader data collection and analysis to generalize findings across multiple stations.

Hydrogen and carbon capture and storage are pivotal to decarbonize the European energy system in a broad range of pathway scenarios. Yet their timely uptake in different sectors and distribution across countries are affected by supply options of renewable and fossil energy sources. Here we analyze the decarbonization of the European energy system towards 2060 covering the power heat and industry sectors and the change in use of hydrogen and carbon capture and storage in these sectors upon Europe’s decoupling from Russian gas. The results indicate that the use of gas is significantly reduced in the power sector instead being replaced by coal with carbon capture and storage and with a further expansion of renewable generators. Coal coupled with carbon capture and storage is also used in the steel sector as an intermediary step when Russian gas is neglected before being fully decarbonized with hydrogen. Hydrogen production mostly relies on natural gas with carbon capture and storage until natural gas is scarce and costly at which time green hydrogen production increases sharply. The disruption of Russian gas imports has significant consequences on the decarbonization pathways for Europe with local energy sources and carbon capture and storage becoming even more important. Given the highlighted importance of carbon capture and storage in reaching the climate targets it is essential that policymakers ameliorate regulatory challenges related to these value chains.

H2 production via membrane-assisted steam methane reforming (MA-SMR) can ensure higher energy efficiency and lower emissions compared to conventional reforming processes (SMR). Ceramic-supported Pd–Ag membranes have been extensively investigated for membrane-assisted steam methane reforming applications with outstanding performance. However costs sealings for integration in the reactor structure and resistance to solicitations remain challenging issues. In this work the surface quality of a low-cost porous Hastelloy-X filter is improved by asymmetric filling with α-Al2O3 of decreasing size and deposition of γ-Al2O3 as an interdiffusion barrier. On the modified support a thin Pd–Ag layer was deposited via electroless plating (ELP) resulting in a membrane with H2/N2 selectivity >10000. The permeation characteristics of the membrane were studied followed by testing for membrane-assisted methane steam reforming. The results showed the ability of the membrane reactor to overcome thermodynamic conversion of the conventional process for all explored operating conditions as well as ensuring 99.3% H2 purity in the permeate stream at 500 ◦C and 4 bar.

Research on proton exchange membrane water electrolysis for renewable hydrogen production is rapidly advancing worldwide driven by the imperative to reduce costs and enhance efficiency through development of novel materials. However to effectively evaluate and validate these advancements standardized testing methods are essential extending beyond single-cell analysis to encompass stack-level characterization. This paper proposes comprehensive characterization methods tailored for analysis of electrolysis stacks and their performance characteristics. Each method is introduced with a focus on its practical applicability accompanied by detailed procedural guidelines for implementation. Furthermore variations within each method are discussed offering possibilities for gathering additional insights. Presenting a portfolio of different methods ranging from standard to advanced techniques applicable at the stack level the paper showcases results obtained through their application. These results normalized to cell area demonstrate the significance of each method in obtaining stack characteristics crucial for informed design de cisions on material selection and subsequent integration into electrolysis systems. By illustrating results derived from various stacks this study contributes valuable insights for evaluating design material suitability and operational performance thereby advancing the development and deployment of proton exchange membrane water electrolysis technology for sustainable hydrogen production.

Direct solar hydrogen generation via a combination of photovoltaics (PV) andwater electrolysis can potentially ensure a sustainable energy supply whileminimizing greenhouse emissions. The PECSYS project aims at demonstrating asolar-driven electrochemical hydrogen generation system with an area >10 m 2with high efficiency and at reasonable cost. Thermally integrated PV electrolyzers(ECs) using thin-film silicon undoped and silver-doped Cu(InGa)Se 2 and siliconheterojunction PV combined with alkaline electrolysis to form one unit aredeveloped on a prototype level with solar collection areas in the range from 64 to2600 cm 2 with the solar-to-hydrogen (StH) efficiency ranging from 4 to 13%.Electrical direct coupling of PV modules to a proton exchange membrane EC totest the effects of bifaciality (730 cm 2 solar collection area) and to study the long-term operation under outdoor conditions (10 m 2 collection area) is also inves-tigated. In both cases StH efficiencies exceeding 10% can be maintained over thetest periods used. All the StH efficiencies reported are based on measured gasoutflow using mass flow meters.

Biomass gasification produces syngas composed mainly of hydrogen carbon monoxide carbon dioxide methane water and higher hydrocarbons till C4 mainly ethane. The hydrocarbon content can be upgraded into richer hydrogen streams through the steam reforming reaction. This study assessed the steam reforming process at the thermodynamic equilibrium of five streams with different compositions from the gasification of three different biomass sources (Lignin Miscanthus and Eucalyptus). The simulations were performed on Aspen Plus V12 software using the Gibbs energy minimization method. The influence of the operating conditions on the hydrogen yield was assessed: temperature in the range of 200 to 1100 ◦C pressures of 1 to 20 bar and steamto‑carbon (S/C) molar ratios from 0 (only dry reforming) to 10. It was observed that operating conditions of 725 to 850 ◦C 1 bar and an S/C ratio of 3 enhanced the streams’ hydrogen content and led to nearly complete hydrocarbon conversion (>99%). Regarding hydrogen purity the stream obtained from the gasification of Lignin and followed by a conditioning phase (stream 5) has the highest hydrogen purity 52.7% and an hydrogen yield of 48.7%. In contrast the stream obtained from the gasification of Lignin without any conditioning (stream 1) led to the greatest increase in hydrogen purity from 19% to 51.2% and a hydrogen yield of 61.8%. Concerning coke formation it can be mitigated for S/C molar ratios and temperatures >2 and 700 ◦C respectively. Experimental tests with stream 1 were carried out which show a similar trend to the simulation results particularly at high temperatures (700–800 ◦C).

Anion exchange membrane water electrolysis (AEMWE) is a potentially low-cost and sustainable technology for hydrogen production that combines the advantages of proton exchange membrane water electrolysis and traditional alkaline water electrolysis systems. Despite considerable research efforts in recent years the medium-term (100 h) stability of Aemion™ membranes needs further investigation. This work explores the chemical and electrochemical durability (>100 h) of Aemion™ anion exchange membranes in a flow cell using nickel felt as the electrode material on the anode and cathode sides. Remixing the electrolytes between the AEMWE galvanostatic tests was very important to enhance electrolyte refreshment and the voltage stability of the system. The membranes were analyzed by NMR spectroscopy after the AEMWE tests and the results showed no sign of severe chemical degradation. In a separate experiment the chemical stability and mechanical integrity of the membranes were studied by soaking them in a strongly alkaline electrolyte for a month (>700 h) at 90 C followed by NMR analysis. A certain extent of ionic loss was observed due to chemical degradation and the membranes disintegrated into small pieces.

Climate change necessitates urgent action to decarbonize the transport sector. Sustainable vehicles represent crucial alternatives to traditional combustion engines. This study comprehensively compares four prominent sustainable vehicle technologies: biofuel-powered vehicles (BPVs) fuel cell vehicles (FCVs) electric vehicles (EVs) and solar vehicles. We examine each technology’s history development classification key components and operational principles. Furthermore we assess their sustainability through technical factors environmental impacts cost considerations and policy dimensions. Moreover the discussion section addresses the challenges and opportunities associated with each technology and assesses their social impact including public perception and adoption. Each technology offers promise for sustainable transportation but faces unique challenges. Policymakers industry stakeholders and researchers must collaborate to address these challenges and accelerate the transition toward a decarbonized transport future. Potential future research areas are identified to guide advancements in sustainable vehicle technologies.