Publications

The road transport sector is one of the major contributors to greenhouse gas emissions as it still largely relies on traditional powertrain solutions. While some progress has been made in the passenger car sector with the diffusion of battery electric vehicles heavy-duty transport remains predominantly dependent on diesel internal combustion engines. This research aims to evaluate and compare three potential solutions for the decarbonisation of heavy-duty freight transport from an economic perspective: Battery Electric Trucks (BETs) Fuel Cell Electric Trucks (FCETs) and Hydrogen-fuelled Internal Combustion Engine Trucks (H2ICETs). The study focuses on the Finnish market and road network where affordable and low-carbon electricity creates an ideal environment for the development of alternative powertrain vehicles. The analysis employs the Total Cost of Ownership (TCO) method which allows for a comprehensive assessment of all cost components associated with the vehicles throughout their entire lifecycle encompassing both initial expenses and operational costs. Among the several factors affecting the results the impact of the three powertrain technologies on the admissible payloads has been taken into account. The study specifically focuses on the costs directly incurred by the truck owner. Additionally to evaluate the cost effectiveness of the proposed powertrain technologies under different scenarios a sensitivity analysis on electricity and hydrogen prices is conducted. The outcomes of this study reveal that no single powertrain solution emerges as universally optimal as the most cost-effective choice depends strongly on the truck type and its use (i.e. daily mileage). For relatively small trucks (18 t) covering short driving distances (approximately 100 to 200 km/day) BETs prove to be the best solution due to their higher efficiency and lower vehicle costs compared to FCETs. Conversely for larger trucks (42 and 76 t) engaged in longer hauls (>300 km/day) H2ICETs exhibit larger cost benefits due to their lower vehicle costs among the three options under investigation. Finally for small trucks (18 t) travelling long distances (200 km/day or more) FCETs represent a competitive choice due to their high efficiency and costeffective energy storage system. Considering future advancements in FCETs and BETs in terms of improved performance and reduced investment cost the fuel cell-based solution is expected to emerge as the best option across various combinations of truck sizes and daily mileages.

The present paper offers a thorough examination of the safety measures enforced at hydrogen filling stations emphasizing their crucial significance in the wider endeavor to advocate for hydrogen as a sustainable and reliable substitute for conventional fuels. The analysis reveals a wide range of crucial safety aspects in hydrogen refueling stations including regulated hydrogen dispensing leak detection accurate hydrogen flow measurement emergency shutdown systems fire-suppression mechanisms hydrogen distribution and pressure management and appropriate hydrogen storage and cooling for secure refueling operations. The paper therefore explores several aspects including the sophisticated architecture of hydrogen dispensers reliable leak-detection systems emergency shut-off mechanisms and the implementation of fire-suppression tactics. Furthermore it emphasizes that the safety and effectiveness of hydrogen filling stations are closely connected to the accuracy in the creation and upkeep of hydrogen dispensers. It highlights the need for materials and systems that can endure severe circumstances of elevated pressure and temperature while maintaining safety. The use of sophisticated leak-detection technology is crucial for rapidly detecting and reducing possible threats therefore improving the overall safety of these facilities. Moreover the research elucidates the complexities of emergency shut-off systems and fire-suppression tactics. These components are crucial not just for promptly managing hazards but also for maintaining the station’s structural soundness in unanticipated circumstances. In addition the study provides observations about recent technical progress in the industry. These advances effectively tackle current safety obstacles and provide the foundation for future breakthroughs in hydrogen fueling infrastructure. The integration of cutting-edge technology and materials together with the development of upgraded safety measures suggests a positive trajectory towards improved efficiency dependability and safety in hydrogen refueling stations.

Climate change is a major concern for the sustainable development of global energy systems. Hydrogen produced through water electrolysis offers a crucial solution by storing and generating renewable energy with minimal environmental impact thereby reducing carbon emissions in the energy sector. Our research evaluates current hydrogen production technologies such as alkaline water electrolysis (AWE) proton exchange membrane water electrolysis (PEMWE) solid oxide electrolysis (SOEC) and anion exchange membrane water electrolysis (AEMWE). We systematically review life cycle assessments (LCA) for these technologies analyzing their environmental impacts and recent technological advancements. This study fills essential gaps by providing detailed LCAs for emerging technologies and evaluating their scalability and environmental footprints. Our analysis outlines the strengths and weaknesses of each technology guiding future research and assisting stakeholders in making informed decisions about integrating hydrogen production into the global energy mix. Our approach highlights operational efficiencies and potential sustainability enhancements by employing comparative analyses and reviewing advancements in membrane technology and electrocatalysts. A significant finding is that PEMWE when integrated with renewable energy sources offers rapid response capabilities that are vital for adaptive energy systems and reducing carbon footprints.

Future power systems in which generation will come almost entirely from variable Renewable Energy Sources (vRES) will be characterized by weather-driven supply and flexible demand. In a simulation of the future Dutch power system we analyze whether there are sufficient incentives for market-driven investors to provide a sufficient level of security of supply considering the profit-seeking and myopic behavior of investors. We cosimulate two agent-based models (ABM) one for generation expansion and one for the operational time scale. The results suggest that in a system with a high share of vRES and flexibility prices will be set predominantly by the demand’s willingness to pay particularly by the opportunity cost of flexible hydrogen electrolyzers. The demand for electric heating could double the price of electricity in winter compared to summer and in years with low vRES could cause shortages. Simulations with stochastic weather profiles increase the year-to-year variability of cost recovery by more than threefold and the year-to-year price variability by more than tenfold compared to a scenario with no weather uncertainty. Dispatchable technologies have the most volatile annual returns due to high scarcity rents during years of low vRES production and diminished returns during years with high vRES production. We conclude that in a highly renewable EOM investors would not have sufficient incentives to ensure the reliability of the system. If they invested in such a way to ensure that demand could be met in a year with the lowest vRES yield they would not recover their fixed costs in the majority of years.

Blending hydrogen in existing natural gas pipelines compromises steel integrity because it increases fatigue crack growth promotes subcritical cracking and decreases fracture toughness. In this regard several laboratories reported that the fracture toughness measured in a hydrogen containing gaseous atmosphere KIH can be 50% or less than KIC the fracture toughness measured in air. From a pipeline integrity perspective fracture mechanics predicts that injecting hydrogen in a natural gas pipeline decreases the failure pressure and the size of the critical flaw at a given pressure level. For a pipeline with a given flaw size as shown in this work the effect of hydrogen embrittlement (HE) in the predicted failure pressure is largest when failure occurs by brittle fracture. The HE effect on failure pressure diminishes with a decreasing crack size or increasing fracture toughness. The safety margin after a successful hydrostatic test is reduced and therefore the time between hydrotests should be decreased. In this work all those effects were quantified using a crack assessment methodology (level 2 API 579-ASME FFS) considering literature values for KIH and KIC reported for an API 5L X52 pipeline steel. To characterize different scenarios various crack sizes were assumed including a small crack with a size close to the detection limit of current in-line inspection techniques and a larger crack that represents the largest crack size that could survive a hydrotest to 100% of the steel specified minimum yield stress. The implications of a smaller failure pressure and smaller critical crack size on pipeline integrity are discussed in this paper.

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.

Fuel cell hybrid systems due to their combination of the high energy density of fuel cells and the rapid response capability of power batteries have become an important category of new energy vehicles. This paper discusses energy management strategies in hydrogen fuel cell vehicles. Firstly a detailed comparative analysis of existing PID control strategies and Adaptive Equivalent Consumption Minimization Strategies (A-ECMSs) is conducted. It was found that although A-ECMS can balance the energy utilization of the fuel cell and power battery well the power fluctuations of the fuel cell are significant leading to increased hydrogen consumption. Therefore this paper proposes an improved Adaptive Low-Pass Filter Equivalent Consumption Minimization Strategy (A-LPF-ECMS). By introducing low-pass filtering technology transient changes in fuel cell power are smoothed effectively reducing fuel consumption. Simulation results show that under the 6*FTP75 cycle the energy loss of A-LPF-ECMS is reduced by 10.89% (compared to the PID strategy) and the equivalent hydrogen consumption is reduced by 7.1%; under the 5*WLTC cycle energy loss is reduced by 5.58% and equivalent hydrogen consumption is reduced by 3.18%. The research results indicate that A-LPF-ECMS performs excellently in suppressing fuel cell power fluctuations under idling conditions significantly enhancing the operational efficiency of the fuel cell and showing high application value.

The low-carbon development of China’s iron and steel industry (ISI) is important but challenging work for the attainment of China’s carbon neutrality by 2060. However most previous studies related to the low-carbon development of China’s ISI are fragmented from different views such as production-side mitigation demand-side mitigation or mitigation technologies. Additionally there is still a lack of a comprehensive overview of the long-term pathway to the low-carbon development of China’s ISI. To respond to this gap and to contribute to better guide policymaking in China this paper conducted a timely and comprehensive review following the technology roadmap framework covering the status quo future vision and key actions of the low-carbon development of the world and China’s ISI. First this paper provides an overview of the technology roadmap of low-carbon development around the main steel production countries in the world. Second the potential for key decarbonization actions available for China’s ISI are evaluated in detail. Third policy and research recommendations are put forward for the future low-carbon development of China’s ISI. Through this comprehensive review four key actions can be applied to the low-carbon development of China’s ISI: improving energy efficiency shifting to Scrap/EAF route promoting material efficiency strategy and deploying radical innovation technologies.

Multi-energy systems that combine different energy sources and carriers to improve the overall technical economic and environmental performance can boost the energy transition. In this paper we posit an innovative multi-energy system for green hydrogen production that achieves negative carbon emissions by combining bio-fuel membraneintegrated steam reforming and renewable electricity electrolysis. The system produces green hydrogen and carbon dioxide both at high purity. We use thermo-chemical models to determine the system performance and optimal working parameters. Specifically we focus on its ability to achieve negative carbon emissions. The results show that in optimal operating conditions the system can capture up to 14.1 g of CO2 per MJ of stored hydrogen and achieves up to 70% storage efficiency. Therefore we prove that a multi-energy system may reach the same efficiency of an average electrolyzer while implementing carbon capture. In the same optimal operating conditions the system converts 7.8 kg of biogas in 1 kg of hydrogen using 3.2 kg of oxygen coming from the production of 6.4 kg of hydrogen through the electrolyzer. With such ratios we estimate that the conversion of all the biogas produced in Europe with our system could result in the installation of additional dedicated 800 GWp - 1280 GWp of photovoltaic power or of 266 GWp - 532 GWp of wind power without affecting the distribution grid and covering yearly the 45% of the worldwide hydrogen demand while removing from the atmosphere more than 2% of the European carbon dioxide emissions.

Wind-solar hybrid hydrogen production is an effective technique route by converting the fluctuate renewable electricity into high-quality hydrogen. However the intermittency of wind and solar resources also exert chal lenges to the efficient hydrogen production. In order to address this issue this paper developed a day-ahead scheduling strategy based on multi-state transitions of the alkaline electrolyzer(AEL) which improves system flexibility by coordinating the operation of the electrolyzer with the battery. Meanwhile K-means+ + algorithm is also applied to scenario clustering and then proposed a capacity configuration method. Based on the adopted case study the wind-solar installed capacity of the designed hydrogen production system it first optimized and the power fluctuation is mitigated with the complementarity index considering volatility of 12.49%. Moreover the adopted scheduling strategy effectively reduces idle and standby states of the electrolyzer with the daily average energy utilization rate of 12 typical scenarios reaching 92.83%. In addition the wind-solar hydrogen system exhibits favorable economic potential the internal return rate and the investment payback period reach to 6.81% and 12.87 years respectively. This research provides valuable insights for efficiently producing hydrogen using renewable energy sources and promoting their synergistic operation.

This study aims to determine the most cost-effective approach for production of green hydrogen a crucial element for global decarbonization efforts despite its high production costs. The primary research question addresses the optimal and economically viable strategy for green hydrogen production considering various scenarios and technologies. Through a comprehensive analysis of eight scenarios the study employs economic parameters such as net present value minimum production cost payback period and sensitivity analysis. The analysis is validated using estab lished economic metrics and real-world considerations to ensure feasibility. The results suggest that a hybrid system combining solar photovoltaic (PV) with storage and onshore wind turbines is a promising approach yielding a minimum cost of $3.01 per kg of green hydrogen an internal rate of return (IRR) of 5.04% and 8-year payback period. These findings provide a practical so lution for cost-effective green hydrogen production supporting the transition to sustainable en ergy sources. The study also highlights the future potential of integrating solar thermal (CSP) with an organic Rankine cycle (ORC) system for waste heat recovery in hydrogen production. The sensitivity analysis provides the importance of capacity factor levelized cost of hydrogen capital expenditure and discount rate in influencing production costs.

In order to meet the energy demand energy production must be done continuously. Hydrogen seems to be the best alternative for this energy production because it is both an environmentally friendly and renewable energy source. In this study the hydrogen fuel production of the peaceful nuclear explosives (PACER) fusion blanket as the energy source integrated with Fe–Cl thermochemical water splitting cycle have been investigated. Firstly neutronic analyzes of the PACER fusion blanket were performed. Necessary neutronic studies were performed in the Monte Carlo calculation method. Molten salt fuel has been considered mole-fractions of heavy metal salt (ThF4 UF4 and ThF4+UF4) by 2 6 and 12 mol. % with Flibe as the main constituent. Secondly potential of the hydrogen fuel production as a result of the neutronic evaluations of the PACER fusion blanket integrated with Fe–Cl thermochemical cycle have been performed. In these calculations tritium breeding (TBR) energy multi plication factor (M) thermal power ratio (1 − ψ) total thermal power (Phpf) and mass flow rate of hydrogen (m˙ H2 ) have been computed. As a results the amount of the hydrogen production (m˙ H2 ) have been obtained in the range of 232.24x106 kg/year and 345.79 x106 kg/year for the all mole-fractions of heavy metal salts using in the blanket.

In the quest for decarbonisation alternative clean fuels for propulsion systems are sought. There is definite advantage in retaining the well-established principles of operation of combustion engines at the core of future developments with hydrogen as a fuel. Hydrogen is envisaged as a clean source of energy for propulsion of heavy and off-road vehicles as well as in marine and construction sectors. A source of concern is the unexplored effect of hydrogen combustion on dilution and degradation of engine lubricants and their additives and consequently upon tribology of engine contact conjunctions. These potential problems can adversely affect engine efficiency durability and operational integrity. Use of different fuels and their method of delivery produces distinctive combustion characteristics that can affect the energy losses associated with in-cylinder components and their durability. Therefore detailed predictive analysis should support the developments of such new generation of eco-friendly engines. Different fundamental physics underpin the various aspects of a pertinent detailed analysis. These include thermodynamics of combustion in-cylinder tribological interactions of contacting surfaces and blowby of generated gasses. This paper presents such an integrated multi-physics analysis of internal combustion engines with focus on hydrogen as the fuel. Such an in-depth and computationally efficient analysis has not hitherto been reported in the literature. The results show implications for lubricant degradation due to the use of hydrogen in the performance of in-cylinder components and the underlying physical principles.

The flammable hydrogen-blended methane–air and natural gas–air mixtures raise specific safety and environmental issues in the industry and transportation; therefore their explosion characteristics such as the explosion limits explosion pressures and rates of pressure rise have significant importance from a safety point of view. At the same time the laminar burning velocities are the most useful parameters for practical applications and in basic studies for the validation of reaction mechanisms and modeling turbulent combustion. In the present study an experimental and numerical study of the effect of hydrogen addition on the laminar burning velocity (LBV) of methane–air and natural gas–air mixtures was conducted using mixtures with equivalence ratios within 0.90 and 1.30 and various hydrogen fractions rH within 0.0 and 0.5. The experiments were performed in a 14 L spherical vessel with central ignition at ambient initial conditions. The LBVs were calculated from p(t) data determined in accordance with EN 15967 by using only the early stage of flame propagation. The results show that hydrogen addition determines an increase in LBV for all examined binary flammable mixtures. The LBV variation versus the fraction of added hydrogen rH follows a linear trend only at moderate hydrogen fractions. The further increase in rH results in a stronger variation in LBV as shown by both experimental and computed LBVs. Hydrogen addition significantly changes the thermal diffusivity of flammable CH4–air or NG–air mixtures the rate of heat release and the concentration of active radical species in the flame front and contribute thus to LBV variation.

In recent years the use of alternative fuels in thermal engine power plants has gained more and more attention becoming of paramount importance to overcome the use of fuels from fossil sources and to reduce polluting emissions. The present work deals with the analysis of the response to two different gas fuels—i.e. hydrogen and a syngas from agriculture product—of a 30 kW micro gas turbine integrated with a solar field. The solar field included a thermal storage system to partially cover loading requests during night hours reducing fuel demand. Additionally a Heat Recovery Unit was included in the plant considered and the whole plant was simulated by Thermoflex® code. Thermodynamics analysis was performed on hour-to-hour basis for a given day as well as for 12 months; subsequently an evaluation of cogeneration efficiency as well as energy saving was made. The results are compared against plant performance achieved with conventional natural gas fueling. After analyzing the performance of the plant through a thermodynamic analysis the study was complemented with CFD simulations of the combustor to evaluate the combustion development and pollutant emissions formation particularly of NOx with the two fuels considered using Ansys-Fluent code and a comparison was made.

Many countries have announced hydrogen promotion strategies to achieve net zero CO2 emissions around 2050. The cost of producing low-carbon (green and blue) hydrogen has been projected to fall considerably as production is scaled up although more so for green hydrogen than for blue hydrogen. This article uses a global computable general equilibrium (CGE) model to explore whether the cost reduction of green and blue hydrogen production can mitigate the use of fossil fuels and related carbon emissions. The results show that cost reduction can raise low-carbon hydrogen consumption markedly in relative terms but marginally in absolute terms resulting in a modest decrease in fossil fuel use and related carbon emissions. The cost reduction of low-carbon hydrogen slightly lowers the use of coal and gas but marginally increases the use of oil. If regional CO2 taxes are introduced the increase in green hydrogen production is considerably larger than in the case of low-carbon hydrogen cost reduction alone. However if cost reduction in low-carbon hydrogen is introduced in addition to the CO2 tax the emissions from fossil fuels are only marginally reduced. Hence synergy efects between the two measures on emissions are practically absent. A low-carbon hydrogen cost reduction alone is efective but insufcient to have a substantial climate impact. This study also calls for modeling development to capture special user preferences for low-carbon hydrogen related to climate mitigation when phasing in new energy carriers like hydrogen.

Nowadays one of the hottest topic in the automotive engineering community is the reduction of fossil fuels. Hydrogen is an alternative energy source that is already providing clean renewable and efficient power being used in fuel cells. Despite being developed since a few decades fuel cells are affected by several hurdles the most impacting one being their cost per unit power. While waiting for their cost reduction and mass-market penetration hydrogen-fueled internal combustion engines (H2ICEs) can be a rapidly applicable solution to reduce pollution caused by the combustion of fossil fuels. Such engines benefit from the advanced technology of modern internal combustion engines (ICEs) and the advantages related to hydrogen combustion although some modifications are needed for conventional liquid-fueled engines to run on hydrogen. The gaseous injection of hydrogen directly into the combustion chamber is a challenge both for the designers and for the injection system suppliers. To reduce uncertainties time and development cost computational fluid dynamics (CFD) tools appear extremely useful since they can accurately predict mixture formation and combustion before the expensive production/testing phase. The high-pressure gaseous injection which takes place in Direct-Injected H2ICEs promotes a super-sonic flow with very high gradients in the zone between the bulk of the injected hydrogen and the flow already inside the combustion chamber. To develop a methodology for an accurate simulation of these phenomena the SoPHy Engine of the Engine Combustion Network group (ECN) is used and presented. This engine is fed through a single nozzle H2-injector; planar laser-induced fluorescence (PLIF) data are available for comparison with the CFD outcomes.

The global population is predicted to increase from ~7.3 billion to over 9 billion people by 2050.Together with rising economic growth this is forecast to result in a 50% increase in fueldemand which will have to be met while reducing carbon dioxide (CO 2 ) emissions by 50–80%to maintain social political energy and climate security. This tension between rising fuel demandand the requirement for rapid global decarbonization highlights the need to fast-track thecoordinated development and deployment of efficient cost-effective renewable technologies forthe production of CO 2 neutral energy. Currently only 20% of global energy is provided aselectricity while 80% is provided as fuel. Hydrogen (H 2) is the most advanced CO 2 -free fuel andprovides a ‘common’ energy currency as it can be produced via a range of renewabletechnologies including photovoltaic (PV) wind wave and biological systems such as microalgaeto power the next generation of H 2 fuel cells. Microalgae production systems for carbon-basedfuel (oil and ethanol) are now at the demonstration scale. This review focuses on evaluating thepotential of microalgal technologies for the commercial production of solar-driven H2 fromwater. It summarizes key global technology drivers the potential and theoretical limits ofmicroalgal H2 production systems emerging strategies to engineer next-generation systems andhow these fit into an evolving H 2 economy.

Currently the massive use of fossil fuels which still serve as the dominant global energy has led to the release of large amounts of greenhouse gases. Providing abundant clean and safe renewable energy is one of the major technical challenges for humankind. Nowadays hydrogen-based energy is widely considered a potentially ideal energy carrier that could provide clean energy in the fields of transportation heat and power generation and energy storage systems almost without any impact on the environment after consumption. However a smooth energy transition from fossil-fuel-based energy to hydrogen-based energy must overcome a number of key challenges that require scientific technological and economic support. To accelerate the hydrogen energy transition advanced efficient and cost-effective methods for producing hydrogen from hydrogen-rich materials need to be developed. Therefore in this study a new alternative method based on the use of microwave (MW) heating technology in enhanced hydrogen production pathways from plastic biomass low-carbon alcohols and methane pathways compared with conventional heating methods is discussed. Furthermore the mechanisms of MW heating MW-assisted catalysis and MW plasma are also discussed. MW-assisted technology usually has the advantages of low energy consumption easy operation and good safety practices which make it a promising solution to supporting the future hydrogen society

Thanks to the advantages of cleanliness high efficiency extensive sources and renewable energy hydrogen energy has gradually become the focus of energy development in the world’s major economies. At present the natural gas transportation pipeline network is relatively complete while hydrogen transportation technology faces many challenges such as the lack of technical specifications high safety risks and high investment costs which are the key factors that hinder the development of hydrogen pipeline transportation. This paper provides a comprehensive overview and summary of the current status and development prospects of pure hydrogen and hydrogen-mixed natural gas pipeline transportation. Analysts believe that basic studies and case studies for hydrogen infrastructure transformation and system optimization have received extensive attention and related technical studies are mainly focused on pipeline transportation processes pipe evaluation and safe operation guarantees. There are still technical challenges in hydrogen-mixed natural gas pipelines in terms of the doping ratio and hydrogen separation and purification. To promote the industrial application of hydrogen energy it is necessary to develop more efficient low-cost and low-energy-consumption hydrogen storage materials.

Steam methane reforming (SMR) currently supplies 76% of the world’s hydrogen (H2) demand totaling ∼70 million tonnes per year. Developments in H2 production technologies are required to meet the rising demand for cleaner less costly H2. Therefore palladium membrane reactors (Pd-MR) have received significant attention for their ability to increase the efficiency of traditional SMR. This study performs novel economic analyses and constrained nonlinear optimizations on an intensified SMR process with a Pd-MR. The optimization extends beyond the membrane’s operation to present process set points for both the conventional and intensified H2 processes. Despite increased compressor and membrane capital costs along with electric utility costs the SMR-MR design offers reductions in the natural gas usage and annual costs. Economic comparisons between each plant show Pd membrane costs greater than $25 000/m2 are required to break even with the conventional design for membrane lifetimes of 1–3 years. Based on the optimized SMR-MR process this study concludes with sensitivity analyses on the design operational and cost parameters for the intensified SMR-MR process. Overall with further developments of Pd membranes for increased stability and lifetime the proposed SMR-MR design is thus profitable and suitable for intensification of H2 production.

Hydrogen storage technologies are key enablers for the development of low-emission sustainable energy supply chains primarily due to the versatility of hydrogen as a clean energy carrier. Hydrogen can be utilized in both stationary and mobile power applications and as a lowenvironmental-impact energy source for various industrial sectors provided it is produced from renewable resources. However efficient hydrogen storage remains a significant technical challenge. Conventional storage methods such as compressed and liquefied hydrogen suffer from energy losses and limited gravimetric and volumetric energy densities highlighting the need for innovative storage solutions. One promising approach is hydrogen storage in metal hydrides which offers advantages such as high storage capacities and flexibility in the temperature and pressure conditions required for hydrogen uptake and release depending on the chosen material. However these systems necessitate the careful management of the heat generated and absorbed during hydrogen absorption and desorption processes. Thermal energy storage (TES) systems provide a means to enhance the energy efficiency and cost-effectiveness of metal hydride-based storage by effectively coupling thermal management with hydrogen storage processes. This review introduces metal hydride materials for hydrogen storage focusing on their thermophysical thermodynamic and kinetic properties. Additionally it explores TES materials including sensible latent and thermochemical energy storage options with emphasis on those that operate at temperatures compatible with widely studied hydride systems. A detailed analysis of notable metal hydride–TES coupled systems from the literature is provided. Finally the review assesses potential future developments in the field offering guidance for researchers and engineers in advancing innovative and efficient hydrogen energy systems.

: The global demand for energy and the need to mitigate climate change require a shift from traditional fossil fuels to sustainable and renewable energy alternatives. Hydrogen is recognized as a significant component for achieving a carbon-neutral economy. This comprehensive review examines the underground hydrogen storage and particularly laboratory-scale studies related to rock– hydrogen interaction exploring current knowledge. Using bibliometric analysis of data from the Scopus and Web of Science databases this study reveals an exponential increase in scientific publications post-2015 which accounts for approximately 85.26% of total research output in this field and the relevance of laboratory experiments to understand the physicochemical interactions of hydrogen with geological formations. Processes in underground hydrogen storage are controlled by a set of multi-scale parameters including solid properties (permeability porosity composition and geomechanical properties) and fluid properties (liquid and gas density viscosity etc.) together with fluid–fluid and solid–fluid interactions (controlled by solubility wettability chemical reactions etc.). Laboratory experiments aim to characterize these parameters and their evolution simulating real-world storage conditions to enhance the reliability and applicability of findings. The review emphasizes the need to expand research efforts globally to comprehensively address the currently existing issues and knowledge gaps.

Studies estimating the production cost of hydrogen-based fuels known as e-fuels often use renewable power profile time series obtained from open-source simulation tools that rely on meteorological reanalysis and satellite data such as Renewables.ninja or PVGIS. These simulated time series contain errors compared to real on-site measured data which are reflected in e-fuels cost estimates plant design and operational performance increasing the risk of inaccurate plant design and business models. Focusing on solar-powered e-fuels this study aims to quantify these errors using high-quality on-site power production data. A state-of-the-art optimization techno-economic model was used to estimate e-fuel production costs by utilizing either simulated or high-quality measured PV power profiles across four sites with different climates. The results indicate that in cloudy climates relying on simulated data instead of measured data can lead to an underestimation of the fuel production costs by 36 % for a hydrogen user requiring a constant supply considering an original error of 1.2 % in the annual average capacity factor. The cost underestimation can reach 25 % for a hydrogen user operating between 40 % and 100 % load and 17.5 % for a fully flexible user. For comparison cost differences around 20 % could also result from increasing the electrolyser or PV plant costs by around 55 % which highlights the importance of using high-quality renewable power profiles. To support this an open-source collaborative repository was developed to facilitate the sharing of measured renewable power profiles and provide tools for both time series analysis and green hydrogen techno-economic assessments.

The adoption of liquid hydrogen (LH2) holds promise for decarbonising long-range aviation. LH2 aircraft could weigh less than Jet-A aircraft thereby reducing the thrust requirement. However the lower volumetric energy density of LH2 can adversely impact the aerodynamic performance and energy consumption of tube-wing aircraft. In a first this work conducts an energy performance modelling of a futuristic (2030+) LH2 blendedwing-body (BWB) aircraft (301 passengers and 13890 km) using conceptual aircraft design-optimisation approach employing weight-sizing methods while considering the realistic gravimetric and volumetric energy density effects of LH2 on aircraft design and the resulting reduction in aircraft thrust requirement. This study shows that at the design point the futuristic LH2 BWB aircraft reduces the specific energy consumption (SEC MJ/ tonne-km) by 51.7–53.5% and 7.3–10.8% compared to (Jet-A) Boeing 777-200LR and Jet-A BWB respectively. At the off-design points this study shows that by increasing the load factor for a given range and/or increasing range for all load factor cases the SEC (or energy efficiency) of this LH2 BWB concept improves. The results of this work will inform future studies on use-phase emissions and contrails modelling LH2 aircraft operations for contrail reduction estimation of operating costs and lifecycle climate impacts.