Publications

The cost of polymer electrolyte water electrolysis (PEWE) is dominated by the price of electricity used to power the water splitting reaction. We present a liquid water fed polymer electrolyte water electrolyzer cell operated at a cell temperature of 100 °C in comparison to a cell operated at state-of-the-art operation temperature of 60 °C over a 300 h constant current period. The hydrogen conversion efficiency increases by up to 5% at elevated temperature and makes green hydrogen cheaper. However temperature is a stress factor that accelerates degradation causes in the cell. The PEWE cell operated at a cell temperature of 100 °C shows a 5 times increased cell voltage loss rate compared to the PEWE cell at 60 °C. The initial performance gain was found to be consumed after a projected operation time of 3500 h. Elevated temperature operation is only viable if a voltage loss rate of less than 5.8 μV h−1 can be attained. The major degradation phenomena that impact performance loss at 100 °C are ohmic (49%) and anode kinetic losses (45%). Damage to components was identified by post-test electron-microscopic analysis of the catalyst coated membrane and measurement of cation content in the drag water. The chemical decomposition of the ionomer increases by a factor of 10 at 100 °C vs 60 °C. Failure by short circuit formation was estimated to be a failure mode after a projected lifetime 3700 h. At elevated temperature and differential pressure operation hydrogen gas cross-over is limiting since a content of 4% hydrogen in oxygen represents the lower explosion limit.

A range of existing and newly developed hydrogen standards certification and labelling (SCL) schemes aim to promote the role of ‘renewable’ ‘clean’ or ‘green’ hydrogen in decarbonising energy transitions. This paper analyses a sample of these SCLs to assess their role in the scaling up of renewable hydrogen and its derivatives. To analyse these hydrogen SCLs we embellish a novel conceptual framework that brings together Sustainability Systems Thinking and Governance (SSG) literatures. The results reveal noteworthy scheme differences in motivation approach criteria and governance; highlighting the complex interconnected and dynamic reality within which energy systems are embedded. We consider whether the sustainable utilisation of renewable hydrogen is well-served by the proliferation of SCLs and recommend an SSG-informed approach. An SSG approach will better promote collaboration towards an authoritative global multistakeholder compromise on hydrogen certification that balances economic considerations with social and environmental dimensions.

Endeavors have recently been concentrated on minimizing the dependency on fossil fuels in order to mitigate the ever-increasing problem of greenhouse gas (GHG) emissions. Hydrogen energy is regarded as an alternative to fossil fuels due to its cleaner emission attributes. Reforming of hydrocarbon fuels is amongst the most popular and widely used methods for hydrogen production. Hydrogen produced from reforming processes requires additional processes to separate from the reformed gases. In some cases further purification of hydrogen has to be carried out to use the hydrogen in power generation applications. Metallic membranes especially palladium (Pd)-based ones have demonstrated sustainable hydrogen separation potential with around 99.99% hydrogen purity. Comprehensive and critical research investigations must be performed to optimize membrane-assisted reforming as well as to maximize the production of hydrogen. The computational fluid dynamic (CFD) can be an excellent tool to analyze and visualize the flow/reaction/permeation mechanisms at a lower cost in contrast with the experiments. In order to provide the necessary background knowledge on membrane reactor modeling this study reviews summarizes and analyses the kinetics of different fuel reforming processes equations to determine hydrogen permeation and lastly various geometry and operating condition adopted in the literature associated with membrane-reactor modeling works. It is indicated that hydrogen permeation through Pd-membranes depends highly on the difference in hydrogen pressure. It is found that hydrogen permeation can be improved by employing different pressure configuration introducing sweep flow on the permeate side of the membrane reducing retentate side flow rate and increasing the temperature.

This article presents a 3D model of a yellow hydrogen generation system that uses the electricity produced by a photovoltaic carport. The 3D models of all key system components were collected and their characteristics were described. Based on the design of the 3D model of the photovoltaic carport the amount of energy produced monthly was determined. These quantities were then applied to determine the production of low-emission hydrogen. In order to increase the amount of low-emission hydrogen produced the usage of a stationary energy storage facility was proposed. The Metalog family of probability distributions was adopted to develop a strategic model for low-emission hydrogen production. The hydrogen economy of a company that uses small amounts of hydrogen can be based on such a model. The 3D modeling and calculations show that it is possible to design a compact low-emission hydrogen generation system using rapid prototyping tools including the photovoltaic carport with an electrolyzer placed in the container and an energy storage facility. This is an effective solution for the climate and energy transition of companies with low hydrogen demand. In the analytical part the Metalog probability distribution family was employed to determine the amount of monthly energy produced by 6.3 kWp photovoltaic systems located in two European countries: Poland and Italy. Calculating the probability of producing specific amounts of hydrogen in two European countries is an answer to a frequently asked question: In which European countries will the production of low-emission hydrogen from photovoltaic systems be the most profitable? As a result of the calculations for the analyzed year 2023 in Poland and Italy specific answers were obtained regarding the probability of monthly energy generation and monthly hydrogen production. Many companies from Poland and Italy are taking part in the European competition to create hydrogen banks. Only those that offer low-emission hydrogen at the lowest prices will receive EU funding.

Due to the increase in electric energy consumption and the significant growth in the number of electric vehicles (EV) at the level of the distribution network new networks have started using new fuels such as hydrogen to improve environmental indicators and at the same time better efficiency from the excess capacity of renewable resources. In this article the services that can be provided by hydrogen refueling stations and charging electric vehicles in the optimal performance of microgrids have been investigated. The model proposed in this paper includes a two-stage stochastic framework for scheduling resources in microgrids especially hydrogen refueling stations and electric vehicle charging. In this model two main goals of cost minimization and greenhouse gas emissions are considered. In the proposed framework and in the first stage the service range of microgrids is determined precisely according to the electrical limitations of distribution systems in emergency situations. Then in the second stage the problem of energy management in each microgrid will be solved centrally. In this situation various indicators including the output energy of renewable sources smart charging of hydrogen and electric vehicle charging stations (EV/FCV) and flexible loads (FL) are evaluated. The final mathematical model is implemented as a multivariate integer multiple linear problem (MILP) using the GUROBI solver in GAMS software. The simulation results on the modified IEEE 118-Bus network show the positive effect of the presence of flexible loads and smart charging strategies by charging stations. Also the numerical derivation shows that the operating costs of the entire system can be reduced by 4.77% and the use of smart charging strategies can reduce greenhouse gas emissions by 49.13%.

Offshore green hydrogen emerges as a guiding light in the global pursuit of environmental sustainability and net-zero objectives. The burgeoning expansion of offshore wind power faces significant challenges in grid integration. This avenue towards generating offshore green hydrogen capitalises on its ecological advantages and substantial energy potential to efficiently channel offshore wind power for onshore energy demands. However a substantial research void exists in efficiently integrating offshore wind electricity and green hydrogen. Innovative designs of offshore hydrogen platforms present a promising solution to bridge the gap between offshore wind and hydrogen integration. Surprisingly there is a lack of commercially established offshore platforms dedicated to the hydrogen industry. However the wealth of knowledge from oil and gas platforms contributes valuable insights to hydrogen platform design. Diverging from the conventional decentralised hydrogen units catering to individual turbines this study firstly introduces a pioneering centralised Offshore Green Hydrogen Platform (OGHP) which seamlessly integrates modular production storage and offloading modulars. The modular design of facilitates scalability as wind capacity increases. Through a detailed case study centred around a 100-Megawatt floating wind farm the design process of offshore green hydrogen modulars and its floating sub-structure is elucidated. Stability analysis and hydrodynamic analysis are performed to ensure the safety of the OGHP under the operation conditions. The case study will enhance our understanding OGHP and its modularised components. The conceptual design of modular OGHP offers an alternative solution to ‘‘Power-to-X’’ for offshore renewable energy sector.

This paper investigates the feasibility of hydrogen-powered hybrid electric vehicles as a solution to transportation-related pollution. It focuses on optimizing energy use to improve efficiency and reduce emissions. The study details the creation and real-time performance assessment of a hydrogen hybrid electric vehicle (HHEV)system using an STM32F407VG board. This system includes a fuel cell (FC) as the main energy source a battery (Bat) to provide energy during hydrogen supply disruptions and a supercapacitor (SC) to handle power fluctuations. A multi-agent-based artificial intelligence tool is used to model the system components and an energy management algorithm (EMA) is applied to optimize energy use and support decision-making. Real Global Positioning System (GPS) data are analyzed to estimate energy consumption based on trip and speed parameters. The EMA developed and implemented in real-time using Matlab/Simulink(2016) identifies the most energy-efficient routes. The results show that the proposed vehicle architecture and management strategy effectively select optimal routes with minimal energy use.

Conventional turboshaft engines are high power density movers suffering from low efficiency at part power operation and producing significant emissions. This paper presents a design exploration and feasibility assessment of a hybrid hydrogen-fueled powerplant for Urban Air Mobility (UAM) rotorcraft. A multi-disciplinary approach is devised comprising models for rotorcraft performance tank and subsystems sizing and engine performance. The respective trade-offs between payload-range and mission level performance are quantified for kerosene-fueled and hybrid hydrogen tilt-rotor variants. The effects of gas turbine scaling and fuel cell pressurization are evaluated for different hybridization degrees. Gas turbine scaling with hybridization (towards the fuel cell) results in up to 21% benefit in energy consumption relative to the non-scaled case with the benefits being more pronounced at high hybridization degrees. Pressurizing the fuel cell has shown significant potential as cell efficiency can increase up to 10% when pressurized to 6 bar which translates to a 6% increase in overall efficiency. The results indicate that current fuel cells (1 kW/kg) combined with current hydrogen tank technology severely limit the payload range capability of the tilt-rotor. However for advanced fuel cell technology (2.5 kW/kg) and low ranges hybrid powerplant show the potential to reduce energy consumption and reduce emissions footprint.

A new model is presented to predict hydrogen-assisted fatigue. The model combines a phase field description of fracture and fatigue stress-assisted hydrogen diffusion and a toughness degradation formulation with cyclic and hydrogen contributions. Hydrogen-assisted fatigue crack growth predictions exhibit an excellent agreement with experiments over all the scenarios considered spanning multiple load ratios H2 pressures and loading frequencies. These are obtained without any calibration with hydrogen-assisted fatigue data taking as input only mechanical and hydrogen transport material properties the material’s fatigue characteristics (from a single test in air) and the sensitivity of fracture toughness to hydrogen content. Furthermore the model is used to determine: (i) what are suitable test loading frequencies to obtain conservative data and (ii) the underestimation made when not pre-charging samples. The model can handle both laboratory specimens and large-scale engineering components enabling the Virtual Testing paradigm in infrastructure exposed to hydrogen environments and cyclic loading.

This paper presents work undertaken as part of the Hytunnel-CS project a consortium investigating safety considerations for fuel cell hydrogen (FCH) vehicles in tunnels and similar confined spaces. This test programme investigated erosive effects of an ignited high pressure hydrogen jet impinging onto tunnel structural materials specifically concrete as used for tunnel linings and asphalt road surfacing for the road itself. The chosen test conditions mimicked a high-pressure release (700 bar) from an FCH car as a result of activation of the thermal pressure relief device (TPRD) on the fuel tank. These devices typically have a release opening of 2 mm and thus a nozzle diameter of approximately 2 mm was used. The resultant releases were ignited using a propane pilot light and test samples were placed in the jet path at varying standoff distances from the release nozzle.<br/>An initial characterization test of a free unimpeded ignited jet demonstrated a rapid and intense temperature increase up to 1650 °C lasting in the order of 3 - 5 minutes for that fuel inventory (4 kg hydrogen). Five tests were carried out where the ignited jet was impinged onto five structural samples. It was found that erosion occurred in the concrete samples where no fire mitigation namely addition of polypropylene fibres was applied. The road-surface sample was found to become molten but did not progress to combustion.<br/>Post-test material analysis including compressive strength and thermal conductivity measurements was carried out on some of the concrete samples to investigate whether structural deformities had occurred within the sample microstructure. The results suggested that the erosive damage caused by the hydrogen jet was mostly superficial and as such did not present an increased fire risk to the structural integrity to that of conventional hydrocarbon fires i.e. those that would result from petrol or diesel fuel tank releases. In terms of fire resistance standards it is suggested that current fire mitigation strategies and structural testing standards would be adequate for hydrogen vehicles on the road network.

Nowadays high-pressure hydrogen storage is the most commercially used technology owing to its high hydrogen purity rapid charging/discharging of hydrogen and low-cost manufacturing. Despite numerous reviews on hydrogen storage technologies there is a relative scarcity of comprehensive examinations specifically focused on high-pressure gaseous hydrogen storage and its associated materials. This article systematically presents the manufacturing processes and materials used for a variety of high-pressure hydrogen storage containers including metal cylinders carbon fiber composite cylinders and emerging glass material-based hydrogen storage containers. Furthermore it introduces the relevant principles and theoretical studies showcasing their advantages and disadvantages compared to conventional high-pressure hydrogen storage containers. Finally this article provides an outlook on the future development of high-pressure hydrogen storage containers.

Industry is the biggest sector of energy consumption and greenhouse gas emissions whose decarbonisation is essential to achieve the Sustainable Development Goals. Carbon capture energy efficiency improvement and hydrogen are among the main strategies for industrial decarbonization. However novel approaches are needed to address the key requirements and differences between sectors to ensure they can work together to well integrate industrial decarbonisation with heat CO2 and hydrogen. The emerging Calcium Looping (CaL) is attracting interest in designing CO2-involved chemical processes for heat capture and storage. The reversibility relatively high-temperature (600 to 900 ◦C) and high energy capacity output as well as carbon capture function make CaL well-fit for CO2 capture and utilisation and waste heat recovery from industrial flue gases. Meanwhile methane dry reforming (MDR) is a promising technology to produce blue hydrogen via the consumption of two major greenhouse gases i.e. CO2 and CH4. It has great potential to combine the two technologies to achieve insitu CO2 utilization with multiple benefits. In this paper progresses on the reaction conditions and performance of CaL for CO2 capture and industrial waste heat recovery as well as MDR were screened. Secondly recent approaches to CaL-MDR synergy have been reviewed to identify the advantages. The major challenges in such a synergistic process include MDR catalyst deactivation CaL sorbents sintering and system integration. Thirdly the paper outlooks future work to explore a rational design of a multi-function system for the proposed synergistic process.

As part of the United Nations’ (UN) Sustainable Development Goal 7 (SDG7) SDG target 7.1 recognizes universal electrification and the provision of clean cooking fuel as two fundamental challenges for global society. Faltering progress toward SDG target 7.1 calls for innovative technologies to stimulate advancements. Hydrogen has been proposed as a versatile energy carrier to be applied in both pillars of SDG target 7.1: electrification and clean cooking. This paper conducts a semi-systematic literature review to provide the status quo of research on the application of hydrogen in the rationale of SDG 7.1 covering the technical integration pathways as well as the key economic environmental and social aspects of its use. We identify decisive factors for the future development of hydrogen use in the rationale of SDG target 7.1 and by complementing our analysis with insights from the related literature propose future avenues of research. The literature on electrification proposes that hydrogen can serve as a backup power supply in rural off-grid communities. While common electrification efforts aim to supply appliances that use lower amounts of electricity a hydrogen-based power supply can satisfy appliances with higher power demands including electric cook stoves while simultaneously supporting clean cooking efforts. Alternatively with the exclusive aim of stimulating clean cooking hydrogen is proposed to be used as a clean cooking fuel via direct combustion in distribution and utilization infrastructures analogous to Liquid Petroleum Gas (LPG). While expected economic and technical developments are seen as likely to render hydrogen technologies economically competitive with conventional fossil fuels in the future the potential of renewably produced hydrogen usage to reduce climate-change impacts and point-of-use emissions is already evident today. Social benefits are likely when meeting essential safety standards as a hydrogen-based power supply offers service on a high tier that might overachieve SDG 7.1 ambitions while hydrogen cooking via combustion fits into the existing social habits of LPG users. However the literature lacks clear evidence on the social impact of hydrogen usage. Impact assessments of demonstration projects are required to fill this research gap.

Transition to a sustainable energy supply is essential for addressing the challenges of climate change and achieving a low-carbon future. Green hydrogen produced from solar photovoltaic (PV) systems presents a promising solution in Ghana where energy demands are increasing rapidly. The levelized cost of hydrogen (LCOH) is considered a critical metric to evaluate hydrogen production techniques cost competitiveness and economic viability. This study presents a comprehensive analysis of LCOH from solar PV systems. The study considered a 5 MW green hydrogen production plant in Ghana’s capital Accra as a proposed system. The results indicate that the LCOH is about $9.49/kg which is comparable to other findings obtained within the SubSaharan Africa region. The study also forecasted that the LCOH for solar PV-based hydrogen produced will decrease to $5–6.5/kg by 2030 and $2–2.5/kg by 2050 or lower making it competitive with fossil fuel-based hydrogen. The findings of this study highlight the potential of green hydrogen as a sustainable energy solution and its role in driving the country’s net-zero emissions agenda in relation to its energy transition targets. The study’s outcomes are relevant to policymakers researchers investors and energy stakeholders in making informed decisions regarding deploying decentralised green hydrogen technologies in Ghana and similar contexts worldwide.

The aim of this study is to investigate the long-term planning of the Italian power sector from 2021 to 2050. The key role of photovoltaic and wind technologies in combination with power-to-power systems based on hydrogen and batteries is investigated. An updated version of the OSeMOSYS tool is used which employs a clustering method for the representation of time-varying input data. First the potential of variable renewable energy sources (VRES) is assessed. A sensitivity analysis is also performed on the temporal resolution of the model to determine an adequate trade-off between the computation time and the accuracy of the results. Then a technoeconomic optimization scenario is carried out resulting in a total net present cost of about 233.7 B€. A high penetration of VRES technologies is foreseen by 2050 with a total VRES installed capacity of 272.9 GW (mainly photovoltaic and onshore wind). Batteries are found to be the preferable energy storage solution in the first part of the energy transition while the hydrogen storage starts to be convenient from about the year 2040. Indeed the role of hydrogen storage becomes fundamental as the VRES penetration increases thanks to its cost-effective long-term storage capability. By 2050 74.6 % of electricity generation will be based on VRES which will also enable a significant reduction in CO2 emissions of about 87 %.

This paper addresses the problem of the reduction in the huge energy demand of hospitals and health care facilities. The sharp increase in the natural gas price due to the Ukrainian–Russian war has significantly reduced economic savings achieved by combined heat and power (CHP) units especially for hospitals. In this framework this research proposes a novel system based on the integration of a reversible CHP solid oxide fuel cell (SOFC) and a photovoltaic field (PV). The PV power is mainly used for balancing the hospital load. The excess power production is exploited to produce renewable hydrogen. The SOFC operates in electrical tracking mode. The cogenerative heat produced by the SOFC is exploited to partially meet the thermal load of the hospital. The SOFC is driven by the renewable hydrogen produced by the plant. When this hydrogen is not available the SOFC is driven by natural gas. In fact the SOFC is coupled with an external reformer. The simulation model of the whole plant including the reversible SOFC PV and hospital is developed in the TRNSYS18 environment and MATLAB. The model of the hospital is calibrated by means of measured data. The proposed system achieves very interesting results with a primary energy-saving index of 33% and a payback period of 6.7 years. Therefore this energy measure results in a promising solution for reducing the environmental impact of hospital and health care facilities.

The present study comprehensively examines the application of hydro wave tidal undersea current and geothermal energy sources of Canada for green hydrogen fuel production. The estimated potential capacity of each province is derived from official data and acceptable assumptions and is subject to discussion and evaluation in the context of a viable hydrogen economy. According to the findings the potential for green hydrogen generation in Canada is projected to be 48.86 megatons. The economic value of the produced green hydrogen results in an equivalent of 21.30 billion US$. The top three provinces with the highest green hydrogen production potential using hydro resources including hydro wave tidal undersea current and geothermal are Alberta Quebec and British Columbia with 26.13 Mt 7.34 Mt and 4.39 Mt respectively. Quebec is ranked first by only considering the marine sources including 4.14 Mt with hydro 1.46 Mt with wave 0.27 Mt underwater current and 1.45 Mt with tidal respectively. Alberta is listed as the province with the highest capacity for hydrogen production from geothermal energy amounting up to 26.09 Mt. The primary objective is to provide comprehensive hydrogen maps for each province in Canada which will be based on the identified renewable energy potential and the utilization of electrolysers. This may further be examined within the framework of the prevailing policies implemented by local communities and officials in order to develop a sustainable energy plan for the nation.

This work is part of the MULTHYFUEL E.U. research program [1] aiming at enabling the implementation of hydrogen dispersers in refuelling stations. One important challenge is the severity of accidents due to a leakage of hydrogen from a dispenser in the forecourt. The work presented in this paper deals with the quantification of the leakage scenarios in terms of frequencies and severities. The risk analysis exercise although performed by experts showed very large discrepancies between the frequencies of leakages of the same categories and even between the consequences. A large part of the disagreement comes from the failure databases chosen as shown in the paper. The mismatch between the components on which the databases have been settled and the actual hydrogen components may be responsible for this situation. However as it stands limited confidence can be laid on the outcome of the risk analysis.<br/>A new method is being developed to calculate the frequencies of the leakage and the flowrate based on an accurate description of each component and of each hazardous situation. For instance the possibility for a fitting to become untight due to pressure cycling is modelled based on the contact mechanics. Human errors can also be introduced by describing the tasks. In addition of the description of the method the application to a disperser is proposed with some comparison to experiments. One of the outcomes is that leakage cross sections can be much larger than expected.

Low-carbon ammonia has recently received interest as alternative fuel for the maritime sector. This paper presents a techno-economic analysis of the total cost of ownership (TCO) of a Post-Panamax vessel powered by low-carbon ammonia. We also calculate the annual increase in carbon tax needed to compensate for the increment in TCO compared to a vessel powered by very low sulfur fuel oil. The increment in TCO is calculated as function of propulsion efficiency to account for uncertainties in the thermodynamics of ammonia combustion for three different cost scenarios of low-carbon ammonia. We evaluate the benefits and drawbacks of hydrogen and diesel as dual fuel for three types of propulsion systems: a compression ignition engine a spark-ignition engine and a combination of a solid oxide fuel cell (SOFC) system and a spark-ignition engine. We incorporate three different cost levels for ammonia and a variable engine efficiency ranging from 35% to 55%. If the ammonia engine has the efficiency of a conventional marine engine the increment in TCO is 25% in the most optimistic cost scenario. SOFCs can reach a better efficiency and yield no pollutant emissions but the reduction in fuel expenses in comparison to conventional combustion engines only offsets their high investment costs at either low engine efficiency or high fuel prices. The increment in TCO and reduction in GHG emissions depend on whether high combustion efficiencies small dual fuel fractions and low NOx N2O and NH3 emissions can be simultaneously achieved.

In light of growing concerns regarding greenhouse gas emissions and the increasingly severe impacts of climate change the global situation demands immediate action to transition towards sustainable energy solutions. In this sense hydrogen could play a fundamental role in the energy transition offering a potential clean and versatile energy carrier. This paper reviews the recent results of Life Cycle Assessment studies of different hydrogen production pathways which are trying to define the routes that can guarantee the least environmental burdens. Steam methane reforming was considered as the benchmark for Global Warming Potential with an average emission of 11 kgCO2eq/kgH2. Hydrogen produced from water electrolysis powered by renewable energy (green H2 ) or nuclear energy (pink H2 ) showed the average lowest impacts with mean values of 2.02 kgCO2eq/kgH2 and 0.41 kgCO2eq/kgH2 respectively. The use of grid electricity to power the electrolyzer (yellow H2 ) raised the mean carbon footprint up to 17.2 kgCO2eq/kgH2 with a peak of 41.4 kgCO2eq/kgH2 in the case of countries with low renewable energy production. Waste pyrolysis and/or gasification presented average emissions three times higher than steam methane reforming while the recourse to residual biomass and biowaste significantly lowered greenhouse gas emissions. The acidification potential presents comparable results for all the technologies studied except for biomass gasification which showed significantly higher and more scattered values. Regarding the abiotic depletion potential (mineral) the main issue is the lack of an established recycling strategy especially for electrolysis technologies that hamper the inclusion of the End of Life stage in LCA computation. Whenever data were available hotspots for each hydrogen production process were identified.

Energy transition is a key driver to combat climate change and achieve zero carbon future. Sustainable and costeffective hydrogen production will provide valuable addition to the renewable energy mix and help minimize greenhouse gas emissions. This study investigates the performance of in-situ hydrogen production (IHP) process using a full-field compositional model as a precursor to experimental validation The reservoir model was simulated as one geological unit with a single point uniform porosity value of 0.13 and a five-point connection type between cell to minimize computational cost. Twenty-one hydrogen forming reactions were modelled based on the reservoir fluid composition selected for this study. The thermodynamic and kinetic parameters for the reactions were obtained from published experiments due to the absence of experimental data specific to the reservoir. A total of fifty-four simulation runs were conducted using CMG STARS software for 5478 days and cumulative hydrogen produced for each run was recorded. Results generated were then used to build a proxy model using Box-Behnken design of experiment method and Support Vector Machine with RBF kernel. To ascertain accuracy of the proxy models analysis of variance (ANOVA) was conducted on the variables. The average absolute percentage error between the proxy model and numerical simulation was calculated to be 10.82%. Optimization of the proxy model was performed using genetic algorithm to maximize cumulative hydrogen produced. Based on this optimized model the influence of porosity permeability well location injection rate and injection pressure were studied. Key results from this study reveals that lower permeability and porosity reservoirs supports more hydrogen yield injection pressure had a negligible effect on hydrogen yield and increase in oxygen injection rate corelated strongly with hydrogen production until a threshold value beyond which hydrogen yield decreased. The framework developed in the study could be used as tool to assess candidate reservoirs for in-situ hydrogen production.

This article summarizes current research on the life cycle assessment (LCA) of fuel cell electric vehicles (FCEVs) in road transport. Increasing greenhouse gas emissions and climate change are pushing the transport sector to intensify efforts toward decarbonization. One promising solution is the adoption of hydrogen technologies whose development is supported by European Union regulations such as the “Fit for 55” package. FCEVs are characterized by zero emissions during operation but their environmental impact largely depends on the methods of hydrogen production. The use of renewable energy sources in hydrogen production can significantly reduce greenhouse gas emissions while hydrogen produced from fossil fuels can even result in higher emissions compared to internal combustion engine vehicles. This article also discusses the importance of hydrogen refueling infrastructure and the efficiency of fuel storage and transportation systems. In conclusion LCA shows that FCEVs can support the achievement of climate goals provided that the development of hydrogen production technologies based on renewable sources and the corresponding infrastructure is ensured. The authors also highlight the potential of hybrid technologies as a transitional solution in the process of transforming the transport sector.

Hydrogen has emerged as a key element in the transition to a sustainable energy model. Among hydrogen storage and transport technologies liquid organic hydrogen carriers (LOHCs) stand out as a promising alternative for large-scale long-term use. Catalysts essential in these systems are usually composed of platinum group metals (PGMs) over alumina known for their high cost and scarcity. This study analyzes the overall environmental impact of the LOHC benzyltoluene/perhydro-benzyltoluene-based hydrogen supply chain by means of the life cycle assessment (LCA) focusing on the synthesis processes of novel low-PGM catalysts which remain under explored in existing literature. The results identify dehydrogenation as the most impactful step due to significant heat consumption and highlight the substantial environmental footprint associated with the use of platinum in catalyst production. This research provides crucial insights into the environmental implications of LOHC systems particularly the role of novel low-PGM catalysts and offers guidance for their future large-scale applications.

Clean hydrogen is touted as a cornerstone of the global energy transition. It can help to decarbonize hard-to-electrify sectors ship renewable power over great distances and boost energy security. Clean hydrogen’s appeal is increasingly felt in the Global South where countries seek to benefit from production export and consumption opportunities new infrastructures and technological innovations. These geographies are however in the process of taking shape and their associated power configurations spatialities and socio-ecological consequences are yet to be more thoroughly understood and examined. Drawing on political geography perspectives this article proposes the concept of “hydrogen landscape” – or in short H2-scape – to theorize and explore hydrogen transitions as space-making processes imbued with power relations institutional orders and social meanings. In this endeavor it outlines a conceptual framework for understanding the making of H2-scapes and offers three concrete directions for advancing empirical research on hydrogen transitions in the Global South: (1) H2-scapes as resource frontiers; (2) H2-scapes as port-centered arrangements; and (3) H2-scapes as failure. As hydrogen booms in finances projects and visibility the article illuminates conceptual tools and perspectives to think about and facilitate further research on the emergent political geographies of hydrogen transitions particularly in more uneven unequal and vulnerable Global South landscapes.

Low temperature water electrolysers such as Proton Exchange Membrane Water Electrolysers (PEMWEs) Alkaline Water Electrolysers (AWEs) and Anion Exchange Membrane Water Electrolysers (AEMWEs) are known to be sensitive to water quality with a range of common impurities impacting performance hydrogen quality and device lifetime. Purification of feed water adds to cost operational complexity and design limitations while failure of purification equipment can lead to degradation of electrolyser materials and components. Increased robustness to impurities will offer a route to longer device lifetimes and reduced operating costs but understanding of the impact of impurities and associated degradation mechanisms is currently limited. This critical review offers for the first time a comprehensive overview of relevant impurities in operating electrolysers and their impact. Impurity sources degradation mechanisms characterisation techniques water purification technologies and mitigation strategies are identified and discussed. The review generalises already reported mechanisms proposes new mechanisms and provides a framework for consideration of operational implications.

Ammonia production currently contributesalmost 11% of global industrial carbon dioxide emissions or1.3% of global emissions. In the context of global emissiontargets and growing demand decarbonization of this processis highly desirable. We present a method to calculate a firstestimate for the optimum size of an ammonia productionplant (at the process level) the required renewable energy(RE) supply and the levelized cost of ammonia (LCOA) forislanded operation with a hydrogen buffer. A model wasdeveloped to quantitatively identify the key variables thatimpact the LCOA (relative to a ±10 GBP/tonne change inLCOA): levelized cost of electricity (±0.89 GBP/MWh) electrolyzer capital expenditure (±65 GBP/kW) minimum Haber−Bosch (HB) load (±12% of rated power) maximum rate of HB load ramping and RE supply mix. Using 2025/2030 estimatesresults in a LCOA of 588 GBP/tonne for Lerwick Scotland. The application of the model will facilitate and improve theproduction of carbon-free ammonia in the future.

Hydrogen is a carbon-neutral fuel so in theory it holds enormous potential. The use of hydrogen as a fuel for traditional internal combustion engines is becoming increasingly prominent. The authors now have the opportunity to retrofit a single-cylinder diesel research engine to an engine with hydrogen operation. For this reason before that conversion they prepared a comprehensive review study regarding hydrogen. Firstly the study analyzes the most essential properties of hydrogen in terms of mixture formation and combustion compared to diesel. After that it deals with indirect and direct injection and what kind of combustion processes can occur. Since there is a possibility of preignition backfire and knocking the process can be dangerous in the case of indirect mixture formation and so a short subsection is devoted to these uncontrolled combustion phenomena. The next subsection shows how important in many ways a special spark plug and ignition system are for hydrogen operation. The next part of the study provides a detailed presentation of the possible combustion chamber design for operation with hydrogen fuel. The last section reveals how many parameters can be focused on analyzing the hydrogen’s combustion process. The authors conclude that intake manifold injection and a Heron-like combustion chamber design with a special spark plug with an ignition system would be an appropriate solution.

The decarbonization of hard-to-abate industries is crucial for keeping global warming to below 2◦C. Green or renewable hydrogen synthesized through water electrolysis has emerged as a sustainable alternative for fossil fuels in energy-intensive sectors such as aluminum cement chemicals steel and transportation. However the scalability of green hydrogen production faces challenges including infrastructure gaps energy losses excessive power consumption and high costs throughout the value chain. Therefore this study analyzes the challenges within the green hydrogen value chain focusing on the development of nascent technologies. Presenting a comprehensive synthesis of contemporary knowledge this study assesses the potential impacts of green hydrogen on hard-to-abate sectors emphasizing the expansion of clean energy infrastructure. Through an exploration of emerging renewable hydrogen technologies the study investigates aspects such as economic feasibility sustainability assessments and the achievement of carbon neutrality. Additionally considerations extend to the potential for large-scale renewable electricity storage and the realization of net-zero goals. The findings of this study suggest that emerging technologies have the potential to significantly increase green hydrogen production offering affordable solutions for decarbonization. The study affirms that global-scale green hydrogen production could satisfy up to 24% of global energy needs by 2050 resulting in the abatement of 60 gigatons of greenhouse gas (GHG) emissions - equivalent to 6% of total cumulative CO2 emission reductions. To comprehensively evaluate the impact of the hydrogen economy on ecosystem decarbonization this article analyzes the feasibility of three business models that emphasize choices for green hydrogen production and delivery. Finally the study proposes potential directions for future research on hydrogen valleys aiming to foster interconnected hydrogen ecosystems.

Metal hydride-based hydrogen storage (MHHS) has been used for several purposes including mobile and stationary applications. In general the overall MHHS performance for both applications depends on three main factors which are the appropriate selection of metal hydride material uses design configurations of the MHHS based on the heat exchanger and overall operating conditions. However there are different specific requirements for the two applications. The weight of the overall MHHS is the key requirement for mobile applications while hydrogen storage capacity is the key requirement for stationary applications. Based on these requirements several techniques have been recently used to enhance MHHS performance by mostly considering the faster hydrogen absorption/desorption reaction. Considering metal hydride (MH) materials their low thermal conductivity significantly impacts the hydrogen absorption/desorption reaction. For this purpose a comprehensive understanding of these three main factors and the hydrogen absorption/desorption reaction is critical and it should be up to date to obtain the suitable MHHS performance for all related applications. Therefore this article reviews the key techniques which have recently been applied for the enhancement of MHHS performance. In the review it is demonstrated that the design and layout of the heat exchanger greatly affect the performance of the internal heat exchanger. The initial temperature of the heat transfer fluid and hydrogen supply pressure are the main parameters to increase the hydrogen sorption rate and specific heating power. The higher supply pressure results in the improvement in specific heating power. For the metal hydride material selection under the consideration of mobile applications and stationary applications it is important to strike trade-offs between hydrogen storage capacity weight material cost and effective thermal conductivity.

Climate change necessitates the development of sustainable energy systems with hydrogen technologies playing a key role in this transition. Additive manufacturing (AM) offers a significant potential to enhance the efficiency of hydrogen energy components and reduce their costs through rapid prototyping design freedom and functional integration. This review provides the first comprehensive summary of the current state of research on the application of AM processes in the production storage and utilization of hydrogen. It highlights various AM processes such as powder bed fusion directed energy deposition fused filament fabrication and stereolithography for the advancement of hydrogen energy components. Current research trends include the material development multi-material AM hybrid processes and the integration of artificial intelligence and machine learning. At present the technologies presented are mainly at a development stage of TRL 4–5. The next major step towards industrialization is the demonstration of prototypes outside the laboratory.

Continuing from previous episodes about encouraging global investment in green hydrogen Patrick Molloy and Alicia Eastman speak with Ignacio de Calonje Chief Investment Officer IFC Global Infrastructure. Ignacio breaks down the role of the IFC and its relationship with other Multilateral Development Banks (MDBs) to encourage decarbonization and bespoke solutions for the Global South.

The podcast can be found on their website.

The aim of this article is to examine existing technologies for the use of electrical energy and to develop proposals for their improvement on maritime vessels. As a criterion for evaluating the effectiveness of alternative energy sources on ships factors such as greenhouse gas emissions levels production and transportation characteristics onboard storage conditions and technoeconomic indicators have been proposed. The analysis of fuel types reveals that hydrogen has zero greenhouse gas emissions. However transportation and storage issues along with the high investment required for implementation pose barriers to the widespread use of hydrogen as fuel for maritime vessels. This article demonstrates that solar energy can serve as an alternative to gases and liquid fuels in maritime transport. The technologies and challenges in utilizing solar energy for shipping are analyzed trends in solar energy for maritime transport are discussed and future research directions for the use of solar energy in the maritime sector are proposed. The most significant findings include the identification of future research directions in the application of solar energy in the maritime sector including the adaptation of concentrated solar power (CSP) systems for maritime applications; the development of materials and designs for solar panels specifically tailored to marine conditions; the development of methods for assessing the long-term economic benefits of using solar energy on vessels; and the creation of regulatory frameworks and international standards for the use of solar energy on ships. Furthermore for hybrid photovoltaic and diesel power systems promising research directions could include efforts to implement direct torque control systems instead of field-orientated control systems as well as working on compensating higher harmonics in the phase current spectra of asynchronous motors.

Ammonia is a promising hydrogen carrier for enabling the efficient transport of hydrogen as observed by the many hydrogen transport projects using ammonia. For the clean energy future understanding environmental impacts of the transport system is important. This study conducts life cycle assessment (LCA) for the marine transport of renewable hydrogen using ammonia as the hydrogen carrier. The LCA considered renewable hydrogen produced from four systems; wind-powered electrolysis gasification of forest residue anaerobic digestion of food waste and landfill gas reforming; followed by Haber-Bosch ammonia synthesis using the renewable hydrogen and nitrogen produced from air separation. The ammonia was then transported 11000 km by sea to a destination facility where it was decomposed using either Ru or Ni catalysts to obtain hydrogen. Among the four hydrogen transport systems operated with renewable energy electrolysis-hydrogen system presented the highest global warming impact of 3.31 kg CO2 eq/kg H2 due to electricity use for the electrolysis whereas simpler processes based on a landfill gas system led to the lowest impact of 2.27 kg CO2 eq/kg H2. Process energy consumption was the major contributor to global warming impact with 27%–49.2% of contri bution. The consumption of metals and energy during wind turbine construction resulted in the most significant impact in six out of 12 midpoint impact categories for the electrolysis-hydrogen system which also led to the highest endpoint impacts. The endpoint impacts of the four systems were in the order of electrolysis > food waste > forest residue > landfill gas (from high to low) for both endpoint human health and ecosystems impacts. Ammonia decomposition using Ru catalysts exhibited slightly lower global warming impact than Ni catalysts while final purification of hydrogen by vanadium membrane presented 4.8% lower impacts than the purification by pressure swing adsorption. Large-scale hydrogen supply chains can be achieved by technological improve ment and support of policies and financial schemes.

Polymer electrolyte membrane (PEM) fuel cells and electrolysers offer efficient use and production of hydrogen for emission-free transport and sustainable energy systems. Perfluorosulfonic acid (PFSA) membranes like Nafion® and Aquivion® are the state-of-the-art PEMs but there is a need to increase the operating temperature to improve mass transport avoid catalyst poisoning and electrode flooding increase efficiency and reduce the cost and complexity of the system. However PSFAs-based membranes exhibit lower mechanical and chemical stability as well as proton conductivity at lower relative humidities and temperatures above 80 ◦C. One approach to sustain performance is to introduce inorganic fillers and improve water retention due to their hydrophilicity. Alternatively polymers where protons are not conducted as hydrated H3O+ ions through liquid-like water channels as in the PSFAs but as free protons (H+) via Brønsted acid sites on the polymer backbone can be developed. Polybenzimidazole (PBI) and sulfonated polyetheretherketone (SPEEK) are such materials but need considerable acid doping. Different composites are being investigated to solve some of the accompanying problems and reach sufficient conductivities. Herein we critically discuss a few representative investigations of composite PEMs and evaluate their significance. Moreover we present advances in introducing electronic conductivity in the polymer binder in the catalyst layers.

This report provides a comprehensive assessment of progress towards the European Green Deal (EGD) the European Union’s transformative agenda for achieving climate neutrality by 2050. The analysis encompasses 154 quantifiable targets from 44 policy documents between 2019 and 2024 across key sectors such as climate energy circular economy transport agriculture and food ecosystems and biodiversity water soil and air pollution. The study shows that significant achievement has been delivered so far but progress needs to accelerate in many areas. As of mid-2024 32 of the 154 targets are currently “on track” and 64 are identified as “acceleration needed” meaning that more progress is needed to meet the targets on time. Furthermore 15 of the targets are found to be “not progressing” or “regressing” and for 43 of the targets no data is currently available. The timing of the binding policies most of which have been recently agreed and are expected to deliver results in the coming years is a significant factor influencing these assessments. This report integrates all EGD actions and related policies offering an assessment of the EU’s green transition based on robust data and science. It identifies priority areas for intensified efforts to meet short-term implementation goals and contribute to the long-term ambition of a sustainable fair just and climate-neutral Europe by 2050. This collective work serves as a benchmarking tool providing scientifically grounded guidance for future EU policies and programmes.

This report delves into the European renewable hydrogen supply chain to offer recommendations for Europe to become a leader in the hydrogen economy.

The use of alternative fuels is a primary means for decarbonising the maritime industry. Liquefied natural gas (LNG) liquid hydrogen (LH2) and liquid ammonia (LNH3) are liquified gases among the alternative fuels. The safety risks associated with these fuels differ from traditional fuels. In addition to their low-temperature hazards the flammability of LNG and LH2 and the high toxicity of LNH3 present challenges in fuel handlings due to their high likelihood of fuel release during bunkering. This study aims at drawing extensive comparisons of the evaporation and vapour dispersion behaviours for the three fuels after release accidents during bunkering and discuss their safety issues. The study involved the release event of the three fuels on the main deck area of a reference bulk carrier with a deadweight of 208000 tonnes. Two release scenarios were considered: Scenario 1 involved a release of 0.3 m3 of fuel and Scenario 2 involved a release of 100 kg of fuel. An empirical equation was used to calculate the fuel evaporation process and the Computational Fluid Dynamic (CFD) code FDS was employed to simulate the dispersion of vapour clouds. The obtained results reveal that LH2 has the highest evaporation rate followed by LNG and LNH3. The vapour clouds of LNG and LNH3 spread along the main deck surface while the LH2 vapour cloud exhibits upward dispersion. The flammable vapour clouds of LNG and LH2 remain within the main deck area whereas the toxic gas cloud of LNH3 disperses towards the shore and spreads near the ground on the shore side. Based on the dispersion behaviours the hazards of LNG and LH2 are com parable while LNH3 poses significantly higher hazards. In terms of hazard mitigations effective water curtain systems can suppress the vapour dispersion.

A comprehensive analysis of the green hydrogen supply chain is presented in this paper encompassing production storage transportation and consumption with a focus on the application of metaheuristic optimization. The challenges associated with each stage are highlighted and the potential of metaheuristic optimization methods to address these challenges is discussed. The primary method of green hydrogen production water electrolysis through renewable energy is outlined along with the importance of its optimization. Various storage methods such as compressed gas liquid hydrogen and material-based storage are covered with an emphasis on the need for optimization to improve safety capacity and performance. Different transportation options including pipelines trucks and ships are explored and factors influencing the choice of transportation methods in different regions are identified. Various hydrogen consumption methods and their associated challenges such as fuel cell performance optimization hydrogen-based heating systems design and energy conversion technology choice are also discussed. The paper further investigates multi-objective approaches for the optimization of problems in this domain. The significant potential of metaheuristic optimization techniques is highlighted as a key to addressing these challenges and improving overall efficiency and sustainability with respect to future trends in this rapidly advancing area.

To enhance the accommodation capacity of renewable energy and promote the coordinated development of multiple energy this paper proposes a novel economic dispatch method for an integrated electricity–heat–hydrogen energy system on the basis of coupling three energy flows. Firstly we develop a mathematical model for the hydrogen energy system including hydrogen production storage and hydrogen fuel cells. Additionally a multi-device combined heat and power system is constructed incorporating gas boilers waste heat boilers gas turbines methanation reactors thermal storage tanks batteries and gas storage tanks. Secondly to further strengthen the carbon reduction advantages the economic dispatch model incorporates the power-to-gas process and carbon trading mechanisms giving rise to minimizing energy purchase costs energy curtailment penalties carbon trading costs equipment operation and maintenance costs. The model is linearized to ensure a global optimal solution. Finally the experimental results validate the effectiveness and superiority of the proposed model. The integration of electricity–hydrogen coupling devices improves the utilization rate of renewable energy generation and reduces the total system operating costs and carbon trading costs. The use of a tiered carbon trading mechanism decreases natural gas consumption and carbon emissions contributing to energy conservation and emission reduction.

Considering the environmental challenges humanity faces in the 21st century it is obvious that there is an enormous need for change of the global energy map. Under these circumstances new energy sources and intermediates must be considered as options to limit the greenhouse gases emissions and mitigate climate crisis. Biohydrogen production is one of the most appealing options due to hydrogen’s multiple applications and zero emissions as a fuel to empower a future hydrogen circular economy. In this review article we focus on two methods that are not widely used at industrial scale but have many future possibilities and growth margins: (a) photo-fermentation and (b) bio photolysis. Both methods are light dependent and need photobioreactors to function and produce significant amounts of biohydrogen. Based on an extensive literature search and systemic analysis of the findings presentation of the different reactants operating conditions and biohydrogen productions key factors and effecting parameters were discussed. Temperature pH light intensity and photobioreactor operation and design are some of the most significant factors that define the biohydrogen production rates and yields. Innovative solutions and approaches are presented including biotechnological and genetic engineering modifications to microorganisms as well as combinations of some hybrid biohydrogen producing methods especially dark and photo fermentation. For implementing a biohydrogen circular-economy different wastes were explored as potential feedstocks and overcoming of major bottlenecks that biophotolysis and photo-fermentation face in the transition to a sustainable biohydrogen economy were discussed.

Aviation is a major contributor to transportation carbon emissions but aims to reduce its carbon footprint. Sustainable and environmentally friendly green hydrogen fuel is essential for decarbonization of this industry. Using the extremely low temperature of liquid hydrogen in aviation sector unlocks the opportunity for cryoelectric aircraft concept which exploits the advantageous properties of superconductors onboard. A significant barrier for green hydrogen adoption relates to its high cost and the immediate need for large-scale production which Proton Exchange Membrane Water Electrolyzers (PEMWE) can address through optimal dynamic performance high lifetimes good efficiencies and importantly scalability. In PEMWE the cell is a crucial component that facilitates the electrolysis process and consists of a polymer membrane and electrodes. To control the required production rate of hydrogen the output power of cell should be monitored which usually is done by measuring the cell’s potential and current density. In this paper five different machine learning (ML) models based on different algorithms have been developed to predict this parameter. Findings of the work highlight that the model based on Cascade-Forward Neural Network (CFNN) is investigated to accurately predict the cell potential of PEMWE under different anodic material and working conditions with an accuracy of 99.998 % and 0.001884 in terms of R2 and root mean square error respectively. It can predict the cell potential with a relative error of less than 0.65 % and an absolute error of below 0.01 V. The Standard deviation of 0.000061 for 50 iterations of stability analysis indicated that this model has less sensitivity to the random selection of training data. By accurately estimating different cell’s output with one model and considering its ultra-fast response CFNN model has the potential to be used for both monitoring and the designing purposes of green hydrogen production.

The decarbonization of the building stock in this paper focusing the single-family house sector in Germany is essential to achieve the climate goals. In fact as the largest part of the building stock it represents more than 65 % of the entire German residential building stock. Current strategies and regulations have demonstrated low impact on carbon emission reduction due to poor renovation rates particularly in the single-family house typology. The present study analyzes the potential of carbon emission reduction prioritizing local renewable energy generation and storage in combination with improved building energy systems. Through a simulation-based approach it considers reference buildings of different age classes and formulates variants for improving strategies with different levels of retrofit under the premise of a fully renewable locally generated energy supply. Based on the potential for solar energy supply the variants consider the seasonal shift that needs to be stored and particularly the role of hydrogen as an energy storage medium. The study´s goal is quantifying the impacts of the local renewable energy production its required storage capacity depending on the retrofit depth both for estimating the potential of transforming the single-family house stock to net zero carbon emissions.

Fermentation is an oxygen-free biological process that produces hydrogen a clean renewable energy source with the potential to power a low-carbon economy. Bibliometric analysis is crucial in academic research to evaluate scientific production identify trends and contributors and map the development of a field providing valuable information to guide researchers and promote scientific innovation. This review provides an advanced bibliometric analysis and a future perspective on fermentation for hydrogen production. By searching WoS we evaluated and refined 62087 articles to 4493 articles. This allowed us to identify the most important journals countries institutions and authors in the field. In addition the ten most cited articles and the dominant research areas were identified. A keyword analysis revealed five research clusters that illustrate where research is progressing. The outlook indicates that a deeper understanding of microbiology and support from energy policy will drive the development of hydrogen from fermentation.

Solar hydrogen and electricity are promising high energy-density renewable sources. Although photochemistry or photovoltaics are attractive routes special challenge arises in sunlight conversion efficiency. To improve efficiency various semiconductor materials have been proposed with selective sunlight absorption. Here we reported a hybrid system synergizing photo-thermochemical hydrogen and photovoltaics harvesting full-spectrum sunlight in a cascade manner. A simple suspension of Au-TiO2 in water/methanol serves as a spectrum selector absorbing ultraviolet-visible and infrared energy for rapid photo-thermochemical hydrogen production. The transmitted visible and near-infrared energy fits the photovoltaic bandgap and retains the high efficiency of a commercial photovoltaic cell under different solar concentration values. The experimental design achieved an overall efficiency of 4.2% under 12 suns solar concentration. Furthermore the results demonstrated a reduced energy loss in full-spectrum energy conversion into hydrogen and electricity. Such simple integration of photo-thermochemical hydrogen and photovoltaics would create a pathway toward cascading use of sunlight energy.

Green hydrogen will play a key role in the transition to a carbon-neutral energy system. This study addresses the challenge of supplying baseload green hydrogen through an integrated off-grid alkaline water electrolyzer (AWE) plant wind and solar photovoltaic (PV) power a battery energy storage system (BESS) and a hydrogen storage system based on salt and rock cavern geologies. The capacities of the components and the hydrogen storage size are optimized simultaneously with the control of the AWE plant to minimize the levelized cost of hydrogen (LCOH2) of the gas supplied. The operation of the system is simulated over 30 years with a 15 min time resolution considering degradation operating expenses and component replacements. Power generation data collected from a wind farm and a solar PV installation both located in southeastern Finland are used for system simulation. A sensitivity analysis exploring different hydrogen demand rates discount rates and installation years is conducted for both systems considering rock and salt caverns providing the optimal configuration for each case. It is found that for the price scenario of the year 2025 for a combined 100 MW AWE and compressor the optimal hydrogen demand rate is 12 kg/min with an LCOH2 of 3.14 e/kg and 2.77 e/kg in systems including rock and salt caverns respectively.

To achieve deep decarbonization renewable energy generation must be substantially increased. The technologies with the lowest levelized cost of electricity (LCOE) are land-based photovoltaics (PVs) and wind energy. Agri-PVs offer the potential for dual land use combining energy generation with agricultural activities. However the costs of agri-PVs are higher than those of ground-mounted PV. To enhance the competitiveness of agri-PV we investigate the synergies between agri-PVs and hydrogen electrolysis through process simulation. Additionally we analyse current technological developments in agri-PVs based on a market analysis of start-up companies. Our results indicate that the levelized cost of hydrogen (LCOH) can be comparable for agri-PVs and ground-mounted PVs due to the somewhat smoother electricity generation for the same installed capacity. The market analysis reveals the emergence of a technology ecosystem that integrates agri-PVs with next-generation agricultural technologies such as sensors robotics and artificial intelligence (AI) agents along with localized electricity generation forecasting. The integrated agri-PV and hydrogen generation system has significant global scaling potential for renewable energy generation. Furthermore it positively impacts local economies and energy resilience may reduce water scarcity in agriculture and leverages advancements in AI robotics PV and hydrogen generation technologies.

Recently worldwide the attention being paid to hydrogen and its derivatives as alternative carbon-free (or low-carbon) options for the electricity sector the transport sector and the industry sector has increased. Several projects in the field of low-emission hydrogen production (particularly electrolysis-based green hydrogen) have either been constructed or analyzed for their feasibility. Despite the great ambitions announced by some nations with respect to becoming hubs for hydrogen production and export some quantification of the levels at which hydrogen and its derived products are expected to penetrate the global energy system and its various demand sectors would be useful in order to judge the practicality and likelihood of these ambitions and future targets. The current study aims to summarize some of the expectations of the level at which hydrogen and its derivatives could spread into the global economy under two possible future scenarios. The first future scenario corresponds to a business-as-usual (BAU) pathway where the world proceeds with the same existing policies and targets related to emissions and low-carbon energy transition. This forms a lower bound for the level of the role of hydrogen and its penetration into the global energy system. The second future scenario corresponds to an emission-conscious pathway where governments cooperate to implement the changes necessary to decarbonize the economy by 2050 in order to achieve net-zero emissions of carbon dioxide (carbon neutrality) and thus limit the rise in the global mean surface temperature to 1.5 ◦C by 2100 (compared to pre-industrial periods). This forms an upper bound for the level of the role of hydrogen and its penetration into the global energy system. The study utilizes the latest release of the annual comprehensive report WEO (World Energy Outlook—edition year 2023 the 26th edition) of the IEA (International Energy Agency) as well as the latest release of the annual comprehensive report WETO (World Energy Transitions Outlook—edition year 2023 the third edition) of the IRENA (International Renewable Energy Agency). For the IEA-WEO report the business-as-usual situation is STEPS (Stated “Energy” Policies Scenario) and the emissions-conscious situation is NZE (Net-Zero Emissions by 2050). For the IRENA-WETO report the business-asusual situation is the PES (Planned Energy Scenario) and the emissions-conscious situation is the 1.5◦C scenario. Through the results presented here it becomes possible to infer a realistic range for the production and utilization of hydrogen and its derivatives in 2030 and 2050. In addition the study enables the divergence between the models used in WEO and WETO to be estimated by identifying the different predictions for similar variables under similar conditions. The study covers miscellaneous variables related to energy and emissions other than hydrogen which are helpful in establishing a good view of how the world may look in 2030 and 2050. Some barriers (such as the uncompetitive levelized cost of electrolysis-based green hydrogen) and drivers (such as the German H2Global initiative) for the hydrogen economy are also discussed. The study finds that the large-scale utilization of hydrogen or its derivatives as a source of energy is highly uncertain and it may be reached slowly given more than two decades to mature. Despite this electrolysis-based green hydrogen is expected to dominate the global hydrogen economy with the annual global production of electrolysis-based green hydrogen expected to increase from 0 million tonnes in 2021 to between 22 million tonnes and 327 million tonnes (with electrolyzer capacity exceeding 5 terawatts) in 2050 depending on the commitment of policymakers toward decarbonization and energy transitions.

Hydrogen flight is one important part of the way to net zero aviation. However safety challenges around refuelling are not well understood but are paramount to enable airports to be more comfortable with using hydrogen in the airport environment. This study investigates safety considerations of hydrogen aircraft refuelling at airports. Technical and human factor risks are explored as well as risk assessment models. Two focus groups were conducted in 2022. Data was analysed using NVivo revealing major themes including the mental and physical performance of refuellers technical aspects of refuelling stations environmental factors and the use of risk assessment models. These findings contribute significantly to an understanding of hydrogen refuelling challenges in busy airport environments. Recommendations help airports preparing for hydrogen as a fuel source further supporting the transition towards net zero aviation. Future research could focus on carrying out experiments analysing chemical reactions between kerosene and hydrogen vapours and testing the identified risk assessment tools in different airport environments.

Quantitative Risk Assessments (QRA) is an important tool for enabling safe deployment of hydrogen technologies and is increasingly embedded in the permitting process. Following the framework developed in our companion paper we conducted a detailed QRA on the uncontrolled releases from a high-capacity hydrogen fueling station with liquid hydrogen (LH2) storage. We characterized gaseous and liquid hydrogen releases determined the causal pathways that led to them and the frequency of the potential hazardous outcomes. These hazardous scenarios were modeled to estimate their potential harm on station users. The analysis results reveal that the total frequency for a major hydrogen release is 1.48 × 10− 2 times per station-year. However considering the control barriers in the station the expected frequency of ignition events is reduced to 1.35 × 10− 5 ignition per stationyear. The expected fatality risk is within the tolerable limit for hydrogen fueling stations but still remains higher than that of conventional gasoline stations. The most severe scenario identified involves a high-pressure GH2 release leading to a jet fire with jet flames reaching up to 15 m in length. The most probable sources of GH2 releases are from the gaseous hydrogen filters while for LH2 releases cryogenic pumps are the primary contributors. To improve the accuracy of QRAs for LH2 systems we identified critical gaps including the need for improved reliability data that must be addressed.

This study investigates the techno-economic feasibility of a Power-to-X (PtX) system by integrating solarpowered hydrogen electrolysis with carbon capture and Fischer-Tropsch (FT) synthesis processes for e-fuel production in Basra Iraq. To this aim a comprehensive modeling framework is developed to cover the detailed simulation of E-fuel production along with the system cost analysis. The proposed PtX system is supposed to be located near the Hartha power plant which is one of the main sources of electricity in the Basra region allowing for the utilization of captured CO2 from the power plant’s exhaust gas. The PtX plant design shows significant potential producing 2.44 tonnes of (C12-C20) hydrocarbons and 3.36 tonnes of (C21-C40) heavy oils annually. This is achieved by utilizing 7.5 and 74.2 tonnes per year of hydrogen generated from solar electrolysis and captured CO2 respectively. A cash flow analysis covering 25 years shows that an E-fuel market price of $10 per liter is needed to achieve a positive cash flow within 15 years. The study also indicates that implementing a $200 per tonne carbon tax improves the economic feasibility of the project by allowing for earlier positive cash flows from 6 years and a quicker break-even point at the current E-fuel market price of $2 per liter with a NPV of $ 464 million. Sensitivity analysis reveals that higher carbon taxes and e-fuel prices enhance profitability by reducing payback periods and increasing the NPV. However an increase in hydrogen production costs introduces substantial risk with higher costs decreasing economic viability. The feasibility assessment suggests that despite the substantial initial investment needed for various system components the long-term advantages include reduced CO2 emissions and the potential for Iraq to emerge as a leader in renewable fuel production. Stable policies robust carbon taxes and cost-efficient hydrogen production are essential for the successful implementation of PtX project.