Publications

The use of hydrogen as an energy carrier within the scope of the decarbonisation of the world’s energy production and utilisation is seen by many as an integral part of this endeavour. However the discussion around hydrogen technologies often lacks some perspective on the currently available technologies their Technology Readiness Level (TRL) scope of application and important performance parameters such as energy density or conversion efficiency. This makes it difficult for the policy makers and investors to evaluate the technologies that are most promising. The present study aims to provide help in this respect by assessing the available technologies in which hydrogen is used as an energy carrier including its main challenges needs and opportunities in a scenario in which fossil fuels still dominate global energy sources but in which renewables are expected to assume a progressively vital role in the future. The production of green hydrogen using water electrolysis technologies is described in detail. Various methods of hydrogen storage are referred including underground storage physical storage and material-based storage. Hydrogen transportation technologies are examined taking into account different storage methods volume requirements and transportation distances. Lastly an assessment of well-known technologies for harnessing energy from hydrogen is undertaken including gas turbines reciprocating internal combustion engines and fuel cells. It seems that the many of the technologies assessed have already achieved a satisfactory degree of development such as several solutions for high-pressure hydrogen storage while others still require some maturation such as the still limited life and/or excessive cost of the various fuel cell technologies or the suitable operation of gas turbines and reciprocating internal combustion engines operating with hydrogen. Costs below 200 USD/kWproduced lives above 50 kh and conversion efficiencies approaching 80% are being aimed at green hydrogen production or electricity production from hydrogen fuel cells. Nonetheless notable advances have been achieved in these technologies in recent years. For instance electrolysis with solid oxide cells may now sometimes reach up to 85% efficiency although with a life still in the range of 20 kh. Conversely proton exchange membrane fuel cells (PEMFCs) working as electrolysers are able to sometimes achieve a life in the range of 80 kh with efficiencies up to 68%. Regarding electricity production from hydrogen the maximum efficiencies are slightly lower (72% and 55% respectively). The combination of the energy losses due to hydrogen production compression storage and electricity production yields overall efficiencies that could be as low as 25% although smart applications such as those that can use available process or waste heat could substantially improve the overall energy efficiency figures. Despite the challenges the foreseeable future seems to hold significant potential for hydrogen as a clean energy carrier as the demand for hydrogen continues to grow particularly in transportation building heating and power generation new business prospects emerge. However this should be done with careful regard to the fact that many of these technologies still need to increase their technological readiness level before they become viable options. For this an emphasis needs to be put on research innovation and collaboration among industry academia and policymakers to unlock the full potential of hydrogen as an energy vector in the sustainable economy.

This study identifies limitations and research and development (R&D) gaps at both the component and system levels for hydrogen energy systems (HESs) and specifies how these limitations impact HES adoption within the electric power system (EPS) decarbonization roadmap. To trace these limitations and potential solutions an analytical review is conducted in electrification and integration of HESs renewable energy sources (RESs) and multi-carrier energy systems (MCESs) in sequence. The study also innovatively categorizes HES integration challenges into component and system levels. At the component level technological aspects of hydrogen generation storage transportation and refueling are explored. At the system level HES coordination hydrogen market frameworks and adoption challenges are evaluated. Findings highlight R&D gaps including misalignment between HES operational targets and techno-economic development integration insufficiency model deficiencies and challenges in operational complexity. This study provides insights for sustainable energy integration by supporting the transition to a decarbonized energy system.

It is essential to use alternative fuels if we are to reach the emission reduction targets set by the IMO. Hydrogen carriers are classified as zero-emission while having a higher energy density (including packing factor) than pure hydrogen. They are often considered as safe alternative fuels. The exact definition of what safety entails is often lacking both for hydrogen carriers as well as for ship safety. The aim of this study is to review the safety of hydrogen carriers from two perspectives investigating potential connections between the chemical and maritime approaches to safety. This enables a reasoned consideration between safety aspects and other design drivers in ship design and operation. The hydrogen carriers AB NaBH4 KBH4 and two LOHCs (NEC and DBT) are taken into consideration together with a couple reference fuels (ammonia methanol and MDO). After the evaluation of chemical properties related to safety and the scope of the current IMO safety framework it can be concluded that safety remains a vague and non-explicit concept from both perspectives. Therefore further research is required to prove the safe application of hydrogen carriers onboard ships.

The pressure to move to sustainable energy sources is obvious in today's fast changing energy environment. In this context green hydrogen appears as a beacon of hope with the potential to reinvent the paradigms of energy consumption particularly in the transportation and aviation sectors. Hydrogen has long been intriguing owing to its unique characteristics. It is not only an energy transporter; it has the power to alter the game. Its growing significance is due to its capacity to decarbonize energy generation. Traditional hydrogen generation techniques have contributed considerably to world CO2 emissions accounting for over 2% of total emissions. This environmental problem is successfully addressed by the development of green hydrogen which is created from renewable energy sources. The International Energy Agency (IEA) predicts a 25 to 30 percent increase in global energy consumption by 2040 which is a very grim scenario. If continue to rely on coal and oil this growing demand will result in greater CO2 emissions exacerbating climate change's consequences. In this situation green hydrogen is not only an option but a need. Because green hydrogen has properties with conventional fuels it can be simply integrated into current infrastructure. This harmonic integration ensures that the shift to hydrogen-based solutions in these sectors would not demand a complete redesign of the present systems assuring cost-effectiveness and practicality. However like with any energy source green hydrogen has obstacles. Its combustibility and probable explosiveness have been cited as causes for concern. However developments in safety measures have successfully mitigated these dangers ensuring that hydrogen may be used safely and efficiently across various applications. A further difficulty is its energy density particularly in comparison to conventional fuels. While its energy-to-weight ratio may be good its bulk poses challenges particularly in the aviation industry where space is at a premium. Beyond its direct use as a fuel green hydrogen has potential in auxiliary capacities. It may be used as a dependable backup energy source during power outages as well as in a variety of different sectors and uses ranging from manufacturing to residential. Green hydrogen's adaptability demonstrates its potential to infiltrate all sectors of our economy. Storage is an important enabler for broad hydrogen use. Effective hydrogen storage technologies guarantee not only its availability but also its viability as a source of energy. Current research and advancements in this field are encouraging which strengthens the argument for green hydrogen. At conclusion green hydrogen is in the vanguard of sustainable energy solutions particularly for the transportation and aviation industries. In our collaborative quest of a sustainable future its unique features and environmental advantages make it a vital asset. As we explore further into the complexities of green hydrogen in this publication we want to shed light on its potential obstacles and future route.

This study uses a multi-method design to investigate the media’s role in shaping Germans’ attitudes toward green hydrogen. It combines an automatized content analysis of 7649 German newspaper articles published between July 2021 and June 2024 and a three-wave panel survey of the German population conducted between June 2023 and June 2024 with an initial sample of 2701 participants. The findings show that the intensity of media reporting on hydrogen was low compared to other energy-related topics. Nevertheless participants’ assessments of relative topic presence are rather accurate (rho: 0.50–0.80). A considerable number of participants were unable to position themselves toward the potential and challenges of hydrogen (23%–35%). Overall the results indicate that media and communication tend to stabilize or change existing attitudes rather than contribute to the formation or loss of attitudes leading to implications for the communication of relevant stakeholders.

Despite Iran’s considerable renewable energy (RE) potential and excellent wind capacity and high solar radiation levels these sources contribute only a small fraction of the country’s total energy production. This paper addresses the techno-economic viability of gray hydrogen production by these renewables with a particular focus on solar energy. Given the considerable potential of solar energy and the strategic location of Shahrekord it would be an optimal site for a hydrogen generation plant integrated with a solar field. HOMER Pro 3.18.3 software was utilized to model and optimize the levelized cost of hydrogen (LCOH) of steam reforming using different hydrocarbons in various scenarios. The results of this study indicate that natural gas (NG) reforming represents the most cost-effective method of gray hydrogen production in this city with an LCOH of −0.423 USD/kg. Other hydrocarbons such as diesel gasoline propane methanol and ethanol have a price per kilogram of produced hydrogen as follows: USD −0.4 USD −0.293 USD 1.17 USD 1.48 and USD 2.15. In addition integrating RE sources into hydrogen production was found to be viable. Moreover by implementing RE technologies CO2 emissions can be significantly reduced and energy security can be achieved.

Inspired by the announcement of the new Hydrogen Strategy for the UK in 2021 this study aimed to determine how the oil and gas industry responds and adapts to the changes. This paper analyses qualitative and quantitative data from the companies’ annual and energy reports. Four oil and gas companies involved in hydrogen projects in the UK were selected as case studies. The responses from the companies were collected using the content analysis research strategy in 2019–2021. A steady increase was observed based on the code frequency reflecting the increasing discussions and actions the companies took regarding this hydrogen pathway. Although only one company appears to be at the forefront of this transition progress with a score of almost 90% based on the strategy management analysis other companies continue to demonstrate their commitment to supporting the national target.

With the continuous development of hydrogen storage systems power-to-gas (P2G) and combined heat and power (CHP) the coupling between electricity–heat–hydrogen–gas has been promoted and energy conversion equipment has been transformed from an independent operation with low energy utilization efficiency to a joint operation with high efficiency. This study proposes a low-carbon optimization strategy for a multi-energy coupled IES containing hydrogen energy storage operating jointly with a two-stage P2G adjustable thermoelectric ratio CHP. Firstly the hydrogen energy storage system is analyzed to enhance the wind power consumption ability of the system by dynamically absorbing and releasing energy at the right time through electricity–hydrogen coupling. Then the two-stage P2G operation process is refined and combined with the CHP operation with an adjustable thermoelectric ratio to further improve the low-carbon and economic performance of the system. Finally multiple scenarios are set up and the comparative analysis shows that the addition of a hydrogen storage system can increase the wind power consumption capacity of the system by 4.6%; considering the adjustable thermoelectric ratio CHP and the twostage P2G the system emissions reduction can be 5.97% and 23.07% respectively and the total cost of operation can be reduced by 7.5% and 14.5% respectively.

For the safe and efficient utilization of hydrogen-enriched natural gas combustion in industrial gas-fired boilers the present study adopted a combination of numerical simulation and field tests to investigate its adaptability. Firstly the combustion characteristics of hydrogen-enriched natural gas with different hydrogen blending ratios and equivalence ratios were evaluated by using the Chemkin Pro platform. Secondly a field experimental study was carried out based on the WNS2- 1.25-Q gas-fired boiler to investigate the boiler’s thermal efficiency heat loss and pollutant emissions after hydrogen addition. The results show that at the same equivalence ratio with the hydrogen blending ratio increasing from 0% to 25% the laminar flame propagation speed of the fuel increases the extinction strain rate rises and the combustion limit expands. The laminar flame propagation speed of premixed methane/air gas reaches the maximum value when the equivalence ratio is 1.0 and the combustion intensity of the flame is the highest at this time. In the field tests as the hydrogen blending ratio increases from 0% to nearly 10% with the increasing excess air ratio the boiler’s thermal efficiency decreases as well as the NOx emission. This indicates that there exists a tradeoff between the boiler thermal efficiency and NOx emission in practice.

In this paper we aim to analyse the impact of hydrogen production decarbonisation and electrification scenarios on the infrastructure development generation mix CO2 emissions and system costs of the European power system considering the retrofit of the natural gas infrastructure. We define a reference scenario for the European power system in 2050 and use scenario variants to obtain additional insights by breaking down the effects of different assumptions. The scenarios were analysed using the European electricity market model COMPETES including a proposed formulation to consider retrofitting existing natural gas networks to transport hydrogen instead of methane. According to the results 60% of the EU’s hydrogen demand is electrified and approximately 30% of the total electricity demand will be to cover that hydrogen demand. The primary source of this electricity would be non-polluting technologies. Moreover hydrogen flexibility significantly increases variable renewable energy investment and production and reduces CO2 emissions. In contrast relying on only electricity transmission increases costs and CO2 emissions emphasising the importance of investing in an H2 network through retrofitting or new pipelines. In conclusion this paper shows that electrifying hydrogen is necessary and cost-effective to achieve the EU’s objective of reducing long-term emissions.

In recent years new chemical release agents based on silane are being used in the tire industry. Silane is an inorganic chemical compound consisting of a silicon backbone and hydrogen. Silanes can be thermally decomposed into high-purity silicon and hydrogen. If silane is stored and transported in Intermediate Bulk Containers (IBCs) equipped with safety valves in vented semi-confined spaces such as ISO-Containers hydrogen can be accumulated and become explosive mixture with air. A conservative CFD analysis using the GASFLOW-MPI code has been carried out to assess the hydrogen risk inside the vented containers. Two types of containers with different natural ventilation systems were investigated under various hypothetical accident scenarios. A continuous release of hydrogen due to the chemical decomposition of silane from IBCs was studied as the reference case. The effect of the safety valves on hydrogen accumulation in the container which results in small pulsed releases of hydrogen was investigated. The external effects of the sun and wind on hydrogen distribution and ventilation were also evaluated. The results can provide detailed information on hydrogen dispersion and mixing within the vented enclosures and used to evaluate the hydrogen risks such as flammability. Based on the assumptions used in this study it indicates that the geometry of ventilation openings plays a key role in the efficiency of the indoor air exchange process. In addition the use of safety valves makes it possible to reduce the concentration of hydrogen by volume in air compared to the reference case. The effect of the sun which results in a temperature difference between two container walls allows a strong mixing of hydrogen and air which helps to obtain a concentration lower than both the base case and the case of the pulsed releases. But the best results for the venting process are obtained with the wind that can drive the mixture to the downwind wall vent holes.

Hydrogen plays a pivotal role in global efforts to decarbonize energy and industrial sectors. The European Union particularly Germany anticipate a significant reliance on hydrogen imports in the medium to long term identifying the Middle East and North Africa (MENA) region as a key potential producer and exporter of green hydrogen and its downstream products. Yet investment risks pose significant challenges to advancing the region’s green hydrogen and synthetic fuel industries. However systematic comparative risk analyses for these sectors across MENA countries remain limited. This study addresses the research gap by conducting a comparative risk assessment for renewable energy and green hydrogen and synthetic fuel development in 17 MENA countries. A comprehensive framework evaluating macro and micro risks was applied along with two contrasting risk scenarios to explore future developments under different risk conditions. The findings reveal that while MENA countries hold promise most face at least moderate risks underscoring the complexity of fostering these industries regionally.

Green hydrogen produced by water electrolysis using renewable energy sources (RES) is an emerging technology that aligns with sustainable development goals and efforts to address climate change. In addition to energy electrolyzers require ultrapure water to operate. Although seawater is abundant on the Earth it must be desalinated and further purified to meet the electrolyzer’s feeding water quality requirements. This paper reviews seawater purification processes for electrolysis. Three mature and commercially available desalination technologies (reverse osmosis multiple-effect distillation and multi-stage flash) were examined in terms of working principles performance parameters produced water quality footprint and capital and operating expenditures. Additionally pretreatment and post-treatment techniques were explored and the brine management methods were investigated. The findings of this study can help guide the selection and design of water treatment systems for electrolysis.

Unlike the typical low-temperature (< 150 °C) continental geothermal systems usually characterized by high N2 CH4 and CO2 concentrations but a trace H2 concentration the sandstone-dominated Jimo hot spring on China's eastern coast exhibits: (1) abnormally high H2 concentrations (2.4–12.5 vol%) and H2/CH4 (up to 46.5); (2) depleted δD-H2 (−822 to −709‰) comparable to the Kansas hot springs near the Mid-Continent rift system with the most depleted δD-H2 (−836 to −740‰) recorded in nature; and (3) dramatic gas concentration and isotope ratio variations within an area of 0.2 km2 . Gas chemistry and H-C-He-Ne isotope ratios are studied with reference to published H2 isotope data from various systems. The origin of the gas is most likely attributed to: (a) allochthonous abiotic H2 generated by the reduction of water and oxidation of FeII-rich pyroxene and olivine (serpentinization) in the basalt located 2 km away under near-surface conditions and migration to the deep sandstone reservoir; (b) primary thermogenic CH4 produced in the sandstone; (c) mixing with a considerable amount of microbial H2 from shallow fresh and marine sediments; and (d) biotic CH4 with typical abiotic signatures resulting from isotope exchanges with fluids high in H2/CH4 and CO2/CH4 ratios. Allochthonous abiotic H2 in a sandstone-dominated continental geothermal system and massive microbial fermentation-based H2 production in shallow fresh and residual marine sediments with insignificant but differential consumption activity are highlighted. The published hydrogen isotope ratios for H2 produced under various natural geological environmental and experimental conditions have been collected systematically to provide a fundamental framework and an initial tool for restricting the dominant origin of H2.

Hydrogen is viewed as a potential energy solution for the 21st century with capabilities to tackle issues relating to environmental emissions sustainability energy shortages and security. Even though there are potential benefits of renewable hydrogen towards transitioning to net-zero emissions there is a limited study on the current use ongoing development and future directions of renewable hydrogen in Australia. Thus this study conducts a systematic review of studies for exploring Australia’s renewable hydrogen energy transition current trends strategies developments and future directions. By using the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines earlier studies from 2005 to 2024 from two major databases such as ProQuest and Web of Science are gathered and analyzed. The study highlights significant issues relating to hydrogen energy technologies and opportunities/challenges in production storage distribution utilization and environmental impacts. The study found that Australia’s ambition for a strong hydrogen economy is made apparent with its clear strategic actions to develop a clean technology-based hydrogen production storage and distribution system. This study provides several practical insights on Australia’s hydrogen energy transition hydrogen energy technologies investments and innovation as well as strategies/recommendations for achieving a more environment friendly secure affordable and sustainable energy future.

To address the challenges of multi-energy coupling decision-making caused by the complex interactions and significant conflicts of interest among multiple entities in integrated energy systems an energy management strategy for integrated energy systems with electricity heat and hydrogen multi-energy storage is proposed. First based on the coupling relationship of electricity heat and hydrogen multi-energy flows the architecture of the integrated energy system is designed and the mathematical model of the main components of the system is established. Second evaluation indexes in three dimensions including energy storage device life load satisfaction rate and new energy utilization rate are designed to fully characterize the economy stability and environmental protection of the system during operation. Then an improved radar chart model considering multi-evaluation index comprehensive optimization is established and an adaptability function is constructed based on the sector area and perimeter. Combined with the operation requirements of the electric–thermal–hydrogen integrated energy system constraint conditions are determined. Finally the effectiveness and adaptability of the strategy are verified by examples. The proposed strategy can obtain the optimal decision instructions under different operation objectives by changing the weight of evaluation indexes while avoiding the huge decision space and secondary optimization problems caused by multiple non-inferior solutions in conventional optimization and has multiscenario adaptability.

Due to the small characteristic molecular size of hydrogen small leaks are more common in hydrogen systems compared to similar systems with hydrocarbons. This together with the high reactivity makes an efficient ventilation system very important in hydrogen applications. There are several models available for ventilation sizing that are based on either a well-mixed assumption or a fully stratified situation. However experiments show that many realistic releases will be neither and therefore additional models are needed. One possibility is to use CFD-models but the small release sizes for pinhole releases (<<1 mm) make it difficult to find an appropriate mesh without excessive computational time (especially since the simulations need to be iterated to find the optimum ventilation size). An alternative approach which is described and benchmarked in the current paper is to use a multi-zone model where the domain is divided into several large cells where the mass exchange is simplified compared to CFD and thus simulation time is reduced. The flow in the model is governed by mass conservation and density differences due to concentration gradients using the Bernoulli equation. The release of gas generates a plume which is modelled based on an empirical plume model which gives the entrainment and hydrogen source term for each cell. The model has a short run time and will therefore allow optimization in a short time frame. The model is benchmarked against five experiments with helium at the Canadian Nuclear Laboratories (CNL) in Canada and one hydrogen experiment performed at Lodz University of Technology in Poland. The result shows that the model can reasonably well reproduce accumulation in the experiments with small release without ventilation but appears to slightly underestimate the level of stratification and the interface height for ventilated cases where the source is elevated from the floor level.

We conduct a techno-economic assessment of two low-emissions steel production technologies and evaluate their deployment in emissions mitigation scenarios utilizing the MIT Economic Projection and Policy Analysis (EPPA) model. Specifically we assess direct reduced iron-electric arc furnace with carbon capture and storage (DRI-EAF with CCS) and H2-based direct reduced iron-electric arc furnace (H2 DRI-EAF) which utilizes low carbon hydrogen to reduce CO2 emissions. Our techno-economic analysis based on the current state of technologies found that DRI-EAF with CCS increased costs ~7% relative to the conventional steel technology. H2 DRI-EAF increased costs by ~18% when utilizing Blue hydrogen and ~79% when using Green hydrogen. The exact pathways for hydrogen production in different world regions including the extent of CCS and hydrogen deployment in steelmaking are highly speculative at this point. In illustrative scenarios using EPPA we find that using base cost assumptions switching from BF-BOF to DRI-EAF or scrap EAF can provide significant emissions mitigation within steelmaking. With further reductions in the cost of advanced steelmaking we find a greater role for DRI-EAF with CCS whereas reductions in both the cost of advanced steelmaking and hydrogen production lead to a greater role for H2 DRI-EAF. Our findings can be used to help decision-makers assess various decarbonization options and design economically efficient pathways to reduce emissions in the steel industry. Our cost evaluation can also be used to inform other energy-economic and integrated assessment models designed to provide insights about future decarbonization pathways.

The NREL Hydrogen Sensor Laboratory was commissioned in 2010 as a resource for sensor developers end-users and regulatory agencies within the national and international hydrogen community. The Laboratory continues to provide as its core capability the unbiased verification of hydrogen sensor performance to assure sensor availability and their proper use. However the mission and strategy of the NREL Sensor Laboratory has evolved to meet the needs of the growing hydrogen market. The Sensor Laboratory program has expanded to support research in conventional and alternative detection methods as hydrogen use expands to large-scale markets as envisioned by the DOE National Clean Hydrogen Strategy and Roadmap. Current research encompasses advanced methods of hydrogen leak detection including stand-off and wide area monitoring approaches for large scale and distributed applications. In addition to safety applications low-level detection strategies to support the potential environmental impacts of hydrogen and hydrogen product losses along the value chain are being explored. Many of these applications utilize detection strategies that supplement and may supplant the use of traditional point sensors. The latest results of the hydrogen detection strategy research at NREL will be presented.

The Gulf Cooperation Council (GCC) comprising: Saudi Arabia United Arab Emirates Kuwait Qatar Oman and Bahrain is home to an abundant number of resources including natural gas and solar and wind energy (renewables). Because of this the region is favourably positioned to become a significant player in both blue and green hydrogen production and their export. Current dependence on fossil fuels and ambitious national targets for decarbonisation have led the region and world to research the feasibility of switching to a hydrogen economy. This literature review critically examines the current advantages and strategies adopted by the GCC to expedite the implementation of hydrogen supply chains as well as investigation into the methodologies employed in current research for the modelling and optimisation of hydrogen supply chains. Insight into these endeavours is critical for stakeholders to assess the inherent challenges and opportunities in establishing a sustainable hydrogen economy. Despite a substantial global effort establishing a solid hydrogen supply chain presently faces various obstacles including the costs of clean hydrogen production. Scaling-up storage and transport methods is an issue that affects all types of hydrogen including carbon-intensive (grey) hydrogen. However the current costs of green hydrogen production mostly via the process of electrolysis is a major obstacle hindering the widescale deployment of clean hydrogen. Research in this literature review found that compressed gas and cryogenic liquid options have the highest storage capacities for hydrogen of 39.2 and 70.9 kg/m3 respectively. Meanwhile for hydrogen transportation pipelines and cryogenic tankers are the most conventional and efficient options with an efficiency of over 99 %. Cryogenic ships to carry liquid hydrogen also show potential due to their large storage capacities of 10000 tonnes per shipment However costs per vessel are currently still very expensive ranging between $ 465 and $620 million.

Hydrogen plays an important role in the global transition towards Net-Zero emission. While pipelines are a viable option to transport large quantities of compressed hydrogen over long distances it is not always practical in many applications. In such situations a viable option is to transport and deliver large quantities of hydrogen as cryogenic liquid. The liquefaction process cools hydrogen to cryogenic temperatures below its boiling point of -259.2 0C. Such extreme low temperature implies specific hazards and risks which are different from those associated with the relatively well-known compressed gaseous hydrogen. Managing these specific issues brings new challenges for the stakeholders.<br/>Furthermore the transfer of liquid hydrogen (LH2) and its technical handling is relatively well known for industrial gas or space applications. Experience with LH2 in public and populated areas such as truck and aircraft refuelling stations or port bunkering stations for example is limited or non-existent. Safety requirements in these applications which involve or are in proximity of untrained public are different from rocket/aerospace industry.<br/>The manuscript reviews knowhow already gained by the international hydrogen safety community; and on such basis elucidate the gaps which are yet to be filled to meet industry needs to design and operate inherently safe LH2 operations including the implications for regulations codes and standards (RCS). Where relevant the associated gaps in some underpinning sciences will be mentioned; and the need to contextualise the information and safety practices from NASA1/ESA2/JAXA3 to inform risk adoption will be summarised.

The European Union aims to increase its climate ambition and achieve climate neutrality by 2050. This necessitates expanding offshore wind energy and green hydrogen production especially for hard-to-abate industrial sectors. A study examines the impact of green hydrogen on offshore wind projects specifically focusing on a potential future North Sea offshore grid. The study utilizes data from the TYNDP 2020 Global Ambition scenario 2040 considering several European countries. It aims to assess new transmission and generation capacity utilization and understand the influencing factors. The findings show that incorporating green hydrogen production increases offshore wind utilization and capture prices. The study estimates that by 2040 the levelized cost of hydrogen could potentially decrease to e1.2-1.6/kg H2 assuming low-cost electricity supply and declining capital costs of electrolysers. These results demonstrate the potential benefits and cost reductions of integrating green hydrogen production into North Sea offshore wind projects.

Hydrogen energy the cleanest fuel presents extensive applications in renewable energy technologies such as fuel cells. However the transition process from carbon-based (fossil fuel) energy to desired hydrogen energy is usually hindered by inevitable scientific technological and economic obstacles which mainly involves complex hydrocarbon reforming reactions. Hence this paper provides a systematic and comprehensive analysis focusing on the hydrocarbon reforming mechanism. Accordingly recent related studies are summarized to clarify the intrinsic difference among the reforming mechanism. Aiming to objectively assess the activated catalyst and deactivation mechanism the rate-determining steps of reforming process have been emphasized summarized and analyzed. Specifically the effect of metals and supports on individual reaction processes is discussed followed by the metalsupport interaction. Current tendency and research map could be established to promote the technology development and expansion of hydrocarbon reforming field. This review could be considered as the guideline for academics and industry designing appropriate catalysts.

The Paris Climate Agreement seeks to keep global temperature increases under 2° Celsius ideally 1.5° Celsius. This goal necessitates significant emission reductions. By 2030 emissions are expected to range between 52 and 58 GtCO2e from their 2016 level of approximately 52 GtCO2e. This review paper explores a number of low and zero-carbon renewable fuels such as hydrogen green ammonia green methanol biomethane natural gas and synthetic methane (with natural gas and synthetic methane subject to CCUS both at processing and at final use) as alternative solutions for providing a way to rebalance transition paths in order to achieve the goals of the Paris Agreement while also reaping the benefits of other sustainability targets. The results show renewables will need to account for approximately 90% of total electricity generation by 2050 and approximately 25% of non-electric energy usage in buildings and industry. However low and zero-carbon renewable fuels currently only contributes about 15% to the global energy shares and it will take about 10% more capacity to reach the 2050 goal. The transportation industry will need to take important steps toward energy efficiency and fuel switching in order to achieve the 20% emission reduction. Therefore significant new commitments to efficient low-carbon alternatives will be necessary to make this enormous change. According to this paper investing in energy efficiency and lowcarbon alternative energy must rise by a factor of about five by 2050 in comparison to 2015 levels if the 1.5 °C target is to be realised.

In the context of reducing the global emissions of greenhouse gaseshydrogen (H2) has become an attractive alternative to substitute the current fossil fuels.However its properties seasonal fluctuations and the lack of extended energy stabilitymade it extremely difficult to be economically and safely stored for a long term in recentyears. Therefore this paper investigated the potential of shale gas reservoirs (rich andlow clay−rich silica minerals) to store hydrogen upon demand. Density functional theorymolecular simulation was employed to explore hydrogen adsorption on the silica−kaolinite interface and the physisorption of hydrogen on the shale surface is revealed.This is supported by low adsorption energies on different adsorption configurations(0.01 to −0.21 eV) and the lack of charge transfer showed by Bader charge analysis.Moreover the experimental investigation was employed to consider the temperature(50−100 °C) and pressure (up to 20 bar) impact on hydrogen uptake on Midra shalespecifically palygorskite (100%) which is rich in silicate clay minerals (58.83% SiO2).The results showed that these formations do not chemically or physically maintainhydrogen; hence hydrogen can be reversibly stored. The results highlight the potential of shale gas reservoirs to store hydrogen asno hydrogen is adsorbed on the shale surface so there will be no hydrogen loss and no adverse effect on the shale’s structuralintegrity and it can be safely stored in shale reservoirs and recovered upon demand.

Concerns related to climate change have shifted global attention towards advanced sustainable and decarbonized energy systems. While renewable resources such as wind and solar energy offer environmentally friendly alternatives their inherent variability and intermittency present significant challenges to grid stability and reliability. The integration of renewable energy sources requires innovative solutions to effectively balance supply and demand in the electricity grid. This review explores the critical role of electrolyzer systems in addressing these challenges by providing ancillary services to modern electricity grids. Electrolyzers traditionally used only for hydrogen production have now emerged as versatile tools capable of responding quickly to grid load variations. They can consume electricity during excess periods or when integrated with fuel cells generate electricity during peak demand contributing to grid stability. Therefore electrolyzer systems can fulfill the dual function of producing hydrogen for the end-user and offering grid balancing services ensuring greater economic feasibility. This review paper aims to provide a comprehensive view of the electrolyzer systems’ role in the provision of ancillary services including frequency control voltage control congestion management and black start. The technical aspects market projects challenges and future prospects of using electrolyzers to provide ancillary services in modern energy systems are explored.

Hydrogen presents the UK with a substantial opportunity to drive economic growth and secure skilled jobs by leveraging our natural geological and geographical advantages robust supply chain and existing energy expertise. Hydrogen UK’s most recent Economic Impact Assessment estimates that the hydrogen sector in the UK could support approximately 30000 direct jobs and contribute more than £7 billion gross value added annually by 2030. On a global scale the hydrogen market is projected to be worth $2.5 trillion by 2050.

With international competition increasing the UK must act now to capitalise on this potential. These projections are supported by a recognition that hydrogen is one of the key solutions to decarbonising the UK economy complementing other low-carbon solutions such as electrification carbon capture biofuels and energy efficiency. Additionally hydrogen will play a vital role in enhancing the UK’s energy security by storing domestically produced energy to balance intermittent renewable sources like wind and solar. As a critical component of the clean energy transition hydrogen is indispensable to achieving net zero.

As it stands the UK is well placed to capitalise on the hydrogen opportunity and emerge as a global leader. We have made early strides in establishing a framework for hydrogen development with various pilot projects and strategic investments already underway. However the next five years will be critical for the sector as we move from strategy and planning to development and delivery. It is imperative to get the first lowcarbon production projects over the line and into construction as a matter of urgency and then deliver substantial infrastructure development regulatory clarity and sustained financial support to scale-up production and distribution. A new Government presents an opportunity for policymakers to solidify commitments and accelerate the deployment of hydrogen technology ensuring the UK remains competitive in the global race.

Our manifesto outlines policy recommendations for the new UK Government to take across production distribution and storage infrastructure end use applications trade and beyond which will support a thriving British industrial base that creates jobs and growth for British people. To achieve this the UK hydrogen industry calls on policymakers to speed up the deployment of hydrogen through the recommendations set out in this Manifesto.

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

The affordability and availability of water and energy have a huge impact on food production. Research has shown that there exists a direct and indirect link between power production and clean water generation. Hence the inclusion/importance given to the energy-water-food (EWF) nexus in the United Nations’ sustainable development goals. Acknowledging the importance of decarbonization to the global future there exists a gap in literature on the development of models that can enhance the EWF nexus reduce energy poverty and achieve 100% renewable energy in the electricity sector. Therefore the technical and economic prospect of geothermal energy for bridging the aforementioned gaps in existing works of literature is presented in this study. The energy poverty/wealthy status of a country has been confirmed to have a significant impact on economic development as economic development is largely reflected in the food-water availability. Ditto this study is focused on the interconnectivity of the EWF nexus while incorporating global decarbonization targets. Geothermal energy is of the utmost significance in East Africa due to its abundant potential and distinctive geological features. Located in the Great Rift Valley the region has an abundance of geothermal reservoirs making it an ideal location for geothermal power generation. This study is novel as a comprehensive assessment framework for energy poverty is developed and innovative models utilizing primarily the geothermal resource in the East African region to mitigate this problem are proposed and analyzed. The role of hydrogen generation from critical excess electricity production is also analyzed. The East Africa region is considered the case study for implementing the models developed. A central renewable energy grid is proposed/modelled to meet the energy demand for seven East African countries namely; Ethiopia Tanzania Uganda Djibouti Comoros Eritrea and Rwanda. This study considers 2030 2040 and 2050 as the timestamp for the implementation of the proposed models. The hybrid mix of the biomass power plant solar photovoltaic (PV) pumped hydro storage system and onshore wind power is considered to furthermore show the potency of renewable energy resources in this region. Results showed that the use of geothermal energy to meet energy demands in the case study will mitigate energy poverty and enhance the region’s EWF.

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.

Long-duration energy storage is the key challenge facing renewable energy transition in the future of well over 50% and up to 75% of primary energy supply with intermittent solar and wind electricity while up to 25% would come from biomass which requires traditional type storage. To this end chemical energy storage at grid scale in the form of fuel appears to be the ideal option for wind and solar power. Renewable hydrogen is a much-considered fuel along with ammonia. However these fuels are not only difficult to transport over long distances but they would also require totally new and prohibitively expensive infrastructure. On the other hand the existing natural gas pipeline infrastructure in developed economies can not only transmit a mixture of methane with up to 20% hydrogen without modification but it also has more than adequate long-duration storage capacity. This is confirmed by analyzing the energy economies of the USA and Germany both possessing well-developed natural gas transmission and storage systems. It is envisioned that renewable methane will be produced via well-established biological and/or chemical processes reacting green hydrogen with carbon dioxide the latter to be separated ideally from biogas generated via the biological conversion of biomass to biomethane. At the point of utilization of the methane to generate power and a variety of chemicals the released carbon dioxide would be also sequestered. An essentially net zero carbon energy system would be then become operational. The current conversion efficiency of power to hydrogen/methane to power on the order of 40% would limit the penetration of wind and solar power. Conversion efficiencies of over 75% can be attained with the on-going commercialization of solid oxide electrolysis and fuel cells for up to 75% penetration of intermittent renewable power. The proposed hydrogen/methane system would then be widely adopted because it is practical affordable and sustainable.

A gas turbine is usually installed inside an acoustic enclosure where the fuel gas supply system is also placed. It is common practice using CFD analysis to simulate the accidental fuel gas release inside the enclosure and the consequent dispersion. These numerical studies are used to properly design the gas detection system according to specific safety criteria which are well defined when the fuel gas is a conventional natural gas. Package design is done to prevent that any sparking items and hot surfaces higher than auto-ignition temperature could be a source of ignition in case of leak. Nevertheless it is not possible to exclude that a leakage from a theoretical point of view could be ignited and for this reason a robust design requires that the enclosure structure is able to withstand the overpressure generated by a gas cloud ignition. Moving to hydrogen as fuel gas makes this design constraint much more relevant for its known characteristics of reactiveness large range of flammability maximum burning velocity etc. In such context gas leak and dispersion analysis become even more crucial because a correct prediction of these scenarios can guide the design to a safe configuration. The present work shows a comparison of the dispersion of different leakages inside a gas turbine enclosure carried out with two different CFD tools Ansys CFX and FLACS. This verification is considered essential since dispersion analysis results are used as initial conditions for gas cloud ignition simulations strictly necessary to predict the consequence in term of overpressure without doing experimental tests.

Polymeric materials are widely used in hydrogen energy system such as FCEV and hydrogen refueling stations under high-pressure condition. The permeation property (coefficients of permeation diffusion and solubility) of polymers under high-pressure hydrogen condition should be discussed as parameters to develop those devices. Also the property should be determined to understand influence of the compression by the pressure on polymer materials. A device which can measure gas permeation property of polymer materials accurately in equilibrium state under high-pressure environment is developed and the reliability of the measurements is ensured. High-pressure hydrogen gas permeability characteristics up to 100 MPa are measured for high-density polyethylene. An advantage of the method is discussed comparing with the non-equilibrium state method focusing on the hydrostatic pressure effect. Deterioration of hydrogen permeability is observed along with the decrease of diffusion coefficient which is supposedly affected by hydrostatic compression effect with the increase of environment pressure.

Hydrogen can manage intermittent Renewable Energy Sources (RES) especially in high-RES share systems. The energy transition calls for mature low cost low space solutions bringing the attention to unitized items such as the reversible Solid Oxide Cell (rSOC). This device made of a single unit can work as an electrolyzer and as fuel cell with high efficiency fuel flexibility and producing combined heat. The objective of this review is to identify and classify rSOC applications to the building sector as an effective solution and to show how much this technology is near to its commercialisation. Research & Development projects were analysed and discussed for a comprehensive overview. Conclusions show an increasing interest in the reversible technology although it is still at pre industrialisation stage with few real applications in the building sector of which the majority is reported commented and compared in this paper for the first time.

Hydrogen is emerging as a critical component in the global energy transition providing a low-carbon alternative for sectors such as industry and transportation. This paper aims to comprehensively address water usage in hydrogen production by exploring the water demands of different production methods and their implications for water management particularly in Texas. Key variables influencing water consumption are identified and potential water demands under different hydrogen market scenarios are estimated. Using spatial analysis regions where hydrogen production may stress local water resources are identified alongside policy recommendations for sustainable water use.

This report explores how hydrogen could be taken up in the UK and how this in turn translates to each sector from both global and UK perspectives to understand the practical implications of global and UK targets and projections on hydrogen innovation opportunities:

♦ Assessing demand for hydrogen sets out the context and the approach taken in the assessment of global and UK sector hydrogen needs including the development of specific UK scenarios for hydrogen deployment and innovation across the energy system and supply chain.

♦ Key insights discusses the insights and an overview of the outputs from the implementation of the UK deployment scenarios in whole energy system modelling.

♦ Hydrogen production storage and distribution and demand explore these areas in more detail setting out the current state and potential trajectories for hydrogen in each sector both globally and in the UK up to 2050.

This report can also be downloaded free on the Hydrogen Innovation Initative website.

A viable green energy source for heavy industries and transportation is hydrogen. The internal combustion engine (ICE) when powered by hydrogen offers an economical and adaptable way to quickly decarbonize the transportation industry. In general two techniques are used to inject hydrogen into the ICE combustion chamber: port injection and direct injection. The present work examined direct injection technology highlighting the need to understand and manage hydrogen mixing within an ICE’s combustion chamber. Before combusting hydrogen it is critical to study its propagation and mixture behavior just immediately before burning. For this purpose the DI-CHG.2 direct injector model by BorgWarner was used. This injector operated at 35 barG and 20 barG as maximum and minimum upstream pressures respectively; a 5.8 g/s flow rate; and a maximum tip nozzle temperature of 250 ◦C. Experiments were performed using a high-pressure and hightemperature visualization vessel available at our facility. The combustion mixture prior to burning (spray) was visually controlled by the single-pass high-speed Schlieren technique. Images were used to study the spray penetration (S) and spray volume (V). Several parameters were considered to perform the experiments such as the injection pressure (Pinj) chamber temperature (Tch) and the injection energizing time (Tinj). With pressure ratio and injection time being the parameters commonly used in jet characterization the addition of temperature formed a more comprehensive group of parameters that should generally aid in the characterization of this type of gas jets as well as the understanding of the combined effect of the rate of injection on the overall outcome. It was observed that the increase in injection pressure (Pinj) increased the spray penetration depth and its calculated volume as well as the amount of mass injected inside the chamber according to the ROI results; furthermore it was also observed that with a pressure difference of 20 bar (the minimum required for the proper functioning of the injector used) cyclic variability increased. The variation in temperature inside the chamber had less of an impact on the spray shape and its penetration; instead it determined the velocity at which the spray reached its maximum length. In addition the injection energizing time had no effect on the spray penetration.

In recent years global efforts towards a future with sustainable energy have intensified the development of renewable energy sources (RESs) such as offshore wind solar photovoltaics (PVs) hydro and geothermal. Concurrently green hydrogen produced via water electrolysis using these RESs has been recognized as a promising solution to decarbonizing traditionally hard-to-abate sectors. Furthermore hydrogen storage provides a long-duration energy storage approach to managing the intermittency of RESs which ensures a reliable and stable electricity supply and supports electric grid operations with ancillary services like frequency and voltage regulation. Despite significant progress the hydrogen economy remains nascent with ongoing developments and persistent uncertainties in economic technological and regulatory aspects. This paper provides a comprehensive review of the green hydrogen value chain encompassing production transportation logistics storage methodologies and end-use applications while identifying key research gaps. Particular emphasis is placed on the integration of green hydrogen into both grid-connected and islanded systems with a focus on operational strategies to enhance grid resilience and efficiency over both the long and short terms. Moreover this paper draws on global case studies from pioneering green hydrogen projects to inform strategies that can accelerate the adoption and large-scale deployment of green hydrogen technologies across diverse sectors and geographies.

Liquid hydrogen has the potential to significantly reduce in-flight carbon emissions in the aviation industry. Among the most promising aircraft configurations for future hydrogen-powered aviation are the blended wing body and the pure flying wing configurations. However their tapered and flattened airframe designs pose a challenge in accommodating liquid hydrogen storage tanks. This paper presents a design guide to tapered conformable pressure tanks for liquid hydrogen storage. The proposed tank configurations feature a multi-bubble layout and are subject to low internal differential pressure. The objective is to provide tank designers with simple geometric rules and practical guidelines to simplify the design process of tapered multi-bubble pressure tanks. Various tank configurations are discussed starting with a simple tapered two-bubble tank and advancing to more complex tapered configurations with a multi-segment and multi-bubble layout. A comprehensive design methodology is established providing tank designers with a step-by-step design procedure and highlighting the practical guidelines in each step of the design process.

This study aims to elucidate the behavior of diffusible hydrogen and delayed fracture in martensitic steel with 1500 MPa strength during automotive painting process and under vehicle service conditions. A sequential process of automotive pretreatment line and vehicle service environment is simulated to evaluate the hydrogen pick up in each process. In case of the automotive painting line the absorption of hydrogen is within the common range in the process of phosphating treatment and electrodeposition. The baking process plays an effective role for desorbing the diffusible hydrogen absorbed during the automotive pre-treatment such as zinc-phosphating and electrodeposition process. In case of the corrosion environment under the automotive driving conditions hydrogen induced delayed fracture is accelerated as the exposure time increases. Further it is clarified that severe plastic deformation are the significant factors for hydrogen induced delayed fracture under with low pH value and present of chloride ion in a chemical solution parameter. In summary hydrogen is transported constantly during electrodeposition sequential line process of automobile manufacturing below the hydrogen content of 0.5 ppm which is not critical value for leading to hydrogen delayed fracture based on results of slow strain rate tensile tests. However exposure to extreme conditions under service environment of vehicle such as acidic solution and chloride chemistry solution that result in high level of hydrogen absorption severe plastic deformation in the sheared edge and constantly applied internal or external stresses can cause the hydrogen induced delayed fracture in the fully martensitic steels.

Water electrolysis is considered as an important technology for an increased renewable energy penetration. This perspective on low-temperature water electrolysis joins the dots between the interdisciplinary fields of fundamental science describing physicochemical processes engineering for the targeted design of cell components and the development of operation strategies. Within this aim the mechanisms of ion conduction gas diffusion corrosion and electrocatalysis are reviewed and their influence on the optimum design of separators electrocatalysts electrodes and other cell components are discussed. Electrocatalysts for the water splitting reactions and metals for system components are critically accessed towards their stability and functionality. On the basis of the broad scientific analysis provided challenges for the design of water electrolyzers are elucidated with special regard to the alkaline or acidic media of the electrolyte.

Renewable hydrogen has emerged as a potentially critical energy carrier for achieving climate change mitigation goals. International trade could play a key role in meeting hydrogen demand in a globally decarbonized energy system. To better understand this role we have developed a modelling framework that incorporates hydrogen supply and demand curves and a market equilibrium model to maximize social welfare. Applying this framework we investigate two scenarios: an unrestricted trade scenario where hydrogen trade is allowed between all regions globally and a regional independence scenario where trade is restricted to be intra-regional only. Under the unrestricted trade scenario global hydrogen demand could reach 234 Mt by 2050 with 31.2% met through international trade. Key trade routes identified include North Africa to Europe the Middle East to Developing Asia and South America to Japan and South Korea. In the regional independence scenario most regions could meet their demand domestically except for Japan and South Korea due to self-insufficiency. Finally this analysis reveals that producers in North Africa and South America are likely to gain more economic value from international trade compared to other producing regions. The results offer key insights for policymakers and investors for shaping future hydrogen trade policies and investment decisions.

Chapters:<br/>♦ Introduction by Rainer Quitzow and Yana Zabanova<br/>♦ The EU in the Global Hydrogen Race: Bringing Together Climate Action Energy Security and Industrial Policy by Yana Zabanova<br/>♦ Germany’s Hydrogen Strategy: Securing Industrial Leadership in a Carbon–Neutral Economy by Almudena Nunez and Rainer Quitzow<br/>♦ France’s Hydrogen Strategy: Focusing on Domestic Hydrogen Production to Decarbonise Industry and Mobility by Ines Bouacida<br/>♦ International Dimension of the Polish Hydrogen Strategy. Conditions and Potential for Future Development by Michał Smoleń and Wojciech Żelisko<br/>♦ Hydrogen Affairs in Hungary’s Politically Confined Ambition byJohn Szabo<br/>♦ Spain’s Hydrogen Ambition: Between Reindustrialisation and Export-Led Energy Integration with the EU by Ignacio Urbasos and Gonzalo Escribano<br/>♦  Italian Hydrogen Policy: Drivers Constraints and Recent Developments by Andrea Prontera<br/>♦  Hydrogen Policy in the Netherlands: Laying the Foundations for a Scalable Hydrogen Value Chain by Roelof Stam Coby van der Linde and Pier Stapersma<br/>♦ Hydrogen Strategy of Sweden: Unpacking the Multiple Drivers and Potential Barriers to Hydrogen Development by Stefan Ćetković and Janek Stockburger<br/>♦  Norway’s Hydrogen Strategy: Unveiling Green Opportunities and Blue Export Ambitions by Jon Birger Skjærseth Per Ove Eikeland Tor Håkon Jackson Inderberg and Mari Lie Larsen<br/>♦ The Geopolitics of Hydrogen in Europe: The Interplay between EU and Member State Policies by Rainer Quitzow and Yana Zabanova

Reducing the gap between the electrodes and diaphragm to zero is an often adopted strategy to reduce the ohmic drop in alkaline water electrolyzers for hydrogen production. We provide a thorough account of the current–voltage relationship in such a zero-gap configuration over a wide range of electrolyte concentrations and current densities. Included are voltage components that are not often experimentally quantified like those due to bubbles hydroxide depletion and dissolved hydrogen and oxygen. As is commonly found for zero-gap configurations the ohmic resistance was substantially larger than that of the separator. We find that this is because the relatively flat electrode area facing the diaphragm was not active likely due to separator pore blockage by gas the electrode itself and or solid deposits. Over an e-folding time-scale of ten seconds an additional ohmic drop was found to arise likely due to gas bubbles in the electrode holes. For electrolyte concentrations below 0.5 M an overpotential was observed associated with local depletion of hydroxide at the anode. Finally a high supersaturation of hydrogen and oxygen was found to significantly increase the equilibrium potential at elevated current densities. Most of these voltage losses are shown to be easily avoidable by introducing a small 0.2 mm gap greatly improving the performance compared to zero-gap.

A promising energy carrier and storage solution for integrating renewable energies into the power grid currently being investigated is hydrogen produced via electrolysis. It already serves various purposes but it might also enable the development of hydrogen-based electricity storage systems made up of electrolyzers hydrogen storage systems and generators (fuel cells or engines). The adoption of hydrogen-based technologies is strictly linked to the electrification of end uses and to multicarrier energy grids. This study introduces a generic method to integrate and optimize the sizing and operation phases of hydrogen-based power systems using an energy hub optimization model which can manage and coordinate multiple energy carriers and equipment. Furthermore the uncertainty related to renewables and final demands was carefully assessed. A case study on an urban microgrid with high hydrogen demand for mobility demonstrates the method’s applicability showing how the multi-objective optimization of hydrogen-based power systems can reduce total costs primary energy demand and carbon equivalent emissions for both power grids and mobility down to  −145%. Furthermore the adoption of the uncertainty assessment can give additional benefits allowing a downsizing of the equipment.

The current global energy environment is experiencing a substantial shift towards minimizing carbon emissions and enhancing sustainability due to persistent problems. Demand for sustainable end-to-end energy solutions has boosted green hydrogen as the solution to decarbonize the world. The current study has identified and evaluated 7 main criteria of 27 sub-criteria for enabling the hydrogen supply Chains for decarbonization using the Fuzzy DEMATEL technique. The results show that the most prominent enablers criteria under causal factors are: cluster-based approach for developing a green hub Cost and investment decisions Hydrogen trade policy and regulatory actions and Technology. The effect group factors include: Assessment of ecological concerns- Ecology effect Availability of Energy sources and Awareness and public outreach. This study offers insights to understand the dynamics of the hydrogen supply chains and its way ahead towards decarbonization and transition towards a low-carbon economy. This research helps various academic and industrial stakeholders to give pace to green hydrogen uptake as a vital decarbonization tool and act as a base for strategic and collaborative decisions for a resilient and responsible energy landscape.

Transitioning from carbon-intensive steam methane reforming to low-carbon hydrogen production is essential for decarbonizing the European industrial sector. However the employment impact of such a transition remains unclear. Here we estimate the effects using a transition pathways optimization model and industrial survey data. The results show that an electrolysis-based hydrogen sector transition would create 40000 jobs in the hydrogen sector by 2050. However these jobs are not equally distributed with Western Europe hosting the largest share (40%) and 20% of current hydrogen-producing regions experiencing net job decreases. Even after accounting for renewable energy jobs created by electrolysis-driven electricity demand growth the 2050 low-carbon hydrogen workforce would provide only 10% of the jobs currently offered by European fossil fuel production. Numerous uncertainties and regional development inequities suggest the need for sector-diversified workforce transition plans and training programs to foster skills suited to multiple low-carbon opportunities.

Natural gas (NG) is favored for transportation due to its availability and lower CO2 emissions than fossil fuels despite drawbacks like poor lean combustion ability and slow burning. According to a few recent studies using hydrogen (H2 ) alongside NG and diesel in Tri-fuel mode addresses these drawbacks while enhancing efficiency and reducing emissions making it a promising option for diesel engines. Due to the importance and novelty of this the continuation of ongoing research and insufficient literature studies on HNG–diesel engine emissions that are considered helpful to researchers this research has been conducted. This review summarizes the recent research on the HNG–diesel Tri-fuel engines utilizing hydrogen-enriched natural gas (HNG). The research methodology involved summarizing the effect of engine design operating conditions fuel mixing ratios and supplying techniques on the CO CO2 NOx and HC emissions separately. Previous studies show that using natural gas with diesel increases CO and HC emissions while decreasing NOx and CO2 compared to pure diesel. However using hydrogen with diesel reduces CO CO2 and HC emissions but increases NOx. On the other hand HNG–diesel fuel mode effectively mitigates the disadvantages of using these fuels separately resulting in decreased emissions of CO CO2 HC and NOx. The inclusion of hydrogen improves combustion efficiency reduces ignition delay and enhances heat release and in-cylinder pressure. Additionally operational parameters such as engine power speed load air–fuel ratio compression ratio and injection parameters directly affect emissions in HNG–diesel Tri-fuel engines. Overall the Tri-fuel approach offers promising emissions benefits compared to using natural gas or hydrogen separately as dual-fuels.

This study reviews existing simulation models and describes a selected model for analysing combustion dynamics in hydrogen and natural gas mixtures specifically within non-ferrous melting furnaces. The primary objectives are to compare the combustion characteristics of these two energy carriers and assess the impact of hydrogen integration on furnace operation and efficiency. Using computational fluid dynamics (CFD) simulations incorporating actual furnace geometries and a detailed combustion and NOx emission prediction model this research aims to accurately quantify the effects of hydrogen blending. Experimental tests on furnaces using only natural gas confirmed the validity of these simulations. By providing precise predictions for temperature distribution and NOx emissions this approach reduces the need for extensive laboratory testing facilitates broader exploration of design modifications accelerates the design process and ultimately lowers product development costs.

The dynamic response characteristics between the multiple energy flows of electricity-hydrogen-heat in the renewable energy DC off-grid hydrogen production system are highly coupled and nonlinear which leads to the complexity of its energy conversion and transmission law. This study proposes a model to describe the dynamic nonlinear energy conversion and transmission laws specific to such systems. The model develops a nonlinear admittance framework and a conversion characteristic matrix for multi-heterogeneous energy flow subsystems based on the operational characteristics of each subsystem within the DC off-grid hydrogen production system. Building upon this foundation an energy hub model for the hydrogen production system is established yielding the electrical thermal and hydrogen energy outputs along with their respective conversion efficiencies for each subsystem. By discretizing time the energy flow at each time node within the hydrogen production system is computed revealing the system’s dynamic energy transfer patterns. Experiments were conducted using measured wind speed and irradiance data from a specific location in eastern China. Results from selected typical days were analyzed and discussed revealing that subsystem characteristics exhibit nonlinear variation patterns. This highlights the limitations of traditional models in accurately capturing these dynamics. Finally a simulation platform incorporating practical control methods was constructed to validate the model’s accuracy. Validation results demonstrate that the model possesses high accuracy providing a solid theoretical foundation for further in-depth analysis of DC off-grid hydrogen production systems.

The conversion of solar to chemical energy is one of the central processes considered in the emerging renewable energy economy. Hydrogen production from water splitting over particulate semiconductor catalysts has often been proposed as a simple and a cost-effective method for largescale production. In this review we summarize the basic concepts of the overall water splitting (in the absence of sacrificial agents) using particulate photocatalysts with a focus on their synthetic methods and the role of the so-called “co-catalysts”. Then a focus is then given on improving light absorption in which the Z-scheme concept and the overall system efficiency are discussed. A section on reactor design and cost of the overall technology is given where the possibility of the different technologies to be deployed at a commercial scale and the considerable challenges ahead are discussed. To date the highest reported efficiency of any of these systems is at least one order of magnitude lower than that deserving consideration for practical applications.