Publications

This study investigates the impact of including (or neglecting) the variable efficiency of hydrogen electrolyzers as a function of operating power in the modelling of green hydrogen produced from variable renewable energy sources. Results show that neglecting the variable electrolyzer efficiency as is commonly done in studies of green hydrogen leads to significant overestimation of hydrogen production in the range of 5–24%. The effects of the time resolution used in models are also investigated as well as the impact of including the option for the electrolyzer to switch to stand-by mode instead of powering down and electrolyzer ramp rate constraints. Results indicate that these have a minor effect on overall hydrogen production with the use of hour resolution data leading to overestimation in the range of 0.2–2% relative to using 5-min data. This study used data from three solar farms and three wind in Australia from which it is observed that wind farms produced 55% more hydrogen than the solar farms. The results in this study highlight the critical importance of including the variable efficiency of electrolyzers in the modelling of green hydrogen production. As this industry scales continuing to neglect this effect would lead to the overestimation of hydrogen production by tens of megatonnes.

With the unprecedented development of green and renewable energy sources the proportion of clean hydrogen (H2 ) applications grows rapidly. Since H2 has physicochemical properties of being highly permeable and combustible high-performance H2 sensors to detect and monitor hydrogen concentration are essential. This review discusses a variety of fiber-optic-based H2 sensor technologies since the year 1984 including: interferometer technology fiber grating technology surface plasma resonance (SPR) technology micro lens technology evanescent field technology integrated optical waveguide technology direct transmission/reflection detection technology etc. These technologies have been evolving from simply pursuing high sensitivity and low detection limits (LDL) to focusing on multiple performance parameters to match various application demands such as: high temperature resistance fast response speed fast recovery speed large concentration range low cross sensitivity excellent long-term stability etc. On the basis of palladium (Pd)-sensitive material alloy metals catalysts or nanoparticles are proposed to improve the performance of fiberoptic-based H2 sensors including gold (Au) silver (Ag) platinum (Pt) zinc oxide (ZnO) titanium oxide (TiO2 ) tungsten oxide (WO3 ) Mg70Ti30 polydimethylsiloxane (PDMS) graphene oxide (GO) etc. Various microstructure processes of the side and end of optical fiber H2 sensors are also discussed in this review.

As a case study on sustainable energy use in educational institutions this study examines the design and integration of a solar–hydrogen storage system within the energy management framework of Kangwon National University’s Samcheok Campus. This paper provides an extensive analysis of the architecture and integrated design of such a system which is necessary given the increasing focus on renewable energy sources and the requirement for effective energy management. This study starts with a survey of the literature on hydrogen storage techniques solar energy storage technologies and current university energy management systems. In order to pinpoint areas in need of improvement and chances for progress it also looks at earlier research on solar–hydrogen storage systems. This study’s methodology describes the system architecture which includes fuel cell integration electrolysis for hydrogen production solar energy harvesting hydrogen storage and an energy management system customized for the needs of the university. This research explores the energy consumption characteristics of the Samcheok Campus of Kangwon National University and provides recommendations for the scalability and scale of the suggested system by designing three architecture systems of microgrids with EMS Optimization for solar–hydrogen hybrid solar–hydrogen and energy storage. To guarantee effective and safe functioning control strategies and safety considerations are also covered. Prototype creation testing and validation are all part of the implementation process which ends with a thorough case study of the solar–hydrogen storage system’s integration into the university’s energy grid. The effectiveness of the system its effect on campus energy consumption patterns its financial sustainability and comparisons with conventional energy management systems are all assessed in the findings and discussion section. Problems that arise during implementation are addressed along with suggested fixes and directions for further research—such as scalability issues and technology developments—are indicated. This study sheds important light on the viability and efficiency of solar–hydrogen storage systems in academic environments particularly with regard to accomplishing sustainable energy objectives.

In this study a theoretical–experimental methodology for determining the stress–strain state in pipeline systems taking into account the hydrogen environment was developed. A complex of theoretical and experimental studies was conducted to determine the specific energy of destruction as an invariant characteristic of the material’s resistance to strain at different hydrogen concentrations. The technique is based on the construction of complete diagrams of the destruction of the material based on the determination of true strains and stresses in the local volume using the method involving the optical–digital correlation of speckle images. A complex of research was carried out and true diagrams of material destruction were constructed depending on the previous elastic–plastic strain and the action of the hydrogen environment. The change in the concentration of hydrogen absorbed by the material was estimated depending on the value of the specific energy of destruction. A study was conducted on tubular samples and the degree of damage to the material of the inner wall under the action of hydrogen and stress from the internal pressure was evaluated according to the change in specific energy depending on the value of the true strain established with the help of an optical–digital correlator on the outer surface and the degree of damage was determined. It has been established that the specific fracture energy of 17G1S steel decreases by 70–90% under the influence of hydrogen. The effect of the change in the amount of strain energy on the thickness of the pipe wall is illustrated.

Due to the increased interest in alternative energy sources hydrogen device safety has become paramount. In this study we induced the explosion of a hydrogen tank from a fuel cell electric vehicle (FCEV) by igniting a fire beneath it and disabling the built-in temperature pressure relief device. Three Type 4 tanks were injected gaseous hydrogen at pressures of 700 350 and 10 bar respectively. The incident pressure generated by the tank explosion was measured by pressure transducers positioned at various points around the tank. A protective barrier was installed to examine its effect on the resulting damage and the reflected pressure was measured along the barrier. The internal pressure and external temperature of the tanks were measured in multiple locations. The 700- and 350-bar hydrogen tanks exploded approximately 10 and 16 min after burner ignition respectively. The 10-bar hydrogen tank did not explode but ruptured approximately 29 min after burner ignition The explosions generated blast waves fireballs and fragments. The impact on the surrounding area was evaluated and we verified that the blast pressure fireballs and fragments were almost completely blocked by the protective barrier. The results of this study are expected to improve safety on an FCEV accident scene.

With a limited global carbon budget it is imperative that decarbonisation decisions are based on accurate holistic accounts of all greenhouse gas (GHG) emissions produced to assess their validity. Here the upstream GHG emissions of potential UK offshore Green and Blue hydrogen production are compared to GHG emissions from hydrogen produced through electrolysis using UK national grid electricity and the ‘business-as-usual’ case of continuing to combust methane. Based on an operational life of 25 years and producing 0.5MtH2 per year for each hydrogen process the results show that Blue hydrogen will emit between 200-262MtCO2e of GHG emissions depending on the carbon capture rates achieved (39%–90%) Green hydrogen produced via electrolysis using 100% renewable electricity from offshore wind will emit 20MtCO2e and hydrogen produced via electrolysis powered by the National Grid will emit between 103-168MtCO2e depending of the success of its NetZero strategy. The ‘business-as-usual’ case of continuing to combust methane releases 250MtCO2e over the same lifetime. This study finds that Blue hydrogen at scale is not compatible with the Paris Agreement reduces energy security and will require a substantial GHG emissions investment which excludes it from being a ‘low carbon technology’ and should not be considered for any decarbonisation strategies going forward.

This study evaluates the levelised cost of hydrogen (LCOH) dynamically produced using the two dominant electrolysis technologies directly connected to wind turbines or photovoltaic (PV) panels in regions of Australia designated as hydrogen hubs. Hourly data are utilised to size the components required to meet the hydrogen demand. The dynamic efficiency of each electrolysis technology as a function of input power along with its operating characteristics and overload capacity are employed to estimate flexible hydrogen production. A sensitivity analysis is then conducted to capture the behaviour of the LCOH in response to inherent uncertainty in critical financial and technical factors. Additionally the study investigates the trade-offs between carbon cost and lifecycle emissions of green hydrogen. This approach is applied to ascertain the impact of internalising environmental costs on the cost-competitiveness of green hydrogen compared to grey hydrogen. The economic modelling is developed based on the Association for the Advancement of Cost Engineering (AACE) guidelines. The findings indicate that scale-up is key to reducing the LCOH by a meaningful amount. However scale-up alone is insufficient to reach the target value of AUD 3 (USD 2) except for PV-based plant in the Pilbara region. Lowered financial costs from scale-up can make the target value achievable for PV-based plants in Gladstone and Townsville and for wind-based plants in the Eyre Peninsula and Pilbara regions. For other hubs a lower electricity cost is required as it accounts for the largest portion of the LCOH.

This narrative document sets out the main rationale for hydrogen storage development at scale in the UK: - To meet net zero the UK will need considerable energy storage - Hydrogen storage will be a major and essential part of this - Physical hydrogen storage is needed in the UK - Only geological hydrogen storage can deliver at the scale needed within the timescales for net zero - Geological hydrogen storage should be supported through a viable business model now to ensure it comes online in the 2030s.

To enhance renewable energy (RE) generation and maintain power balance energy storage systems are of utmost importance. This research introduces a cutting-edge Power-to-Hydrogen (PtH) framework that harnesses hydrogen as a clean and versatile energy storage medium. The primary focus of this study lies in optimizing power flow within a microgrid (G) equipped with RE and energy storage systems considering various factors such as RE generation power demand battery charge cycles and operational costs. To achieve the optimal balance between power generation and consumption a sophisticated mathematical solution is devised. This solution governs the charging and discharging patterns for both battery and electrolyzer ensuring a harmonious power equilibrium. The use of short-term forecasting further refines the optimization process adapting the parameters based on anticipated RE sources and load requirements. To fine-tune the power management solution for day-to-day operations an artificial neural fuzzy inference system (ANFIS)-based shortterm prediction model is employed. The predictive analysis provides confidence intervals for crucial aspects including power generation demand battery charging cycles and hydrogen generation. This facilitates precise cost estimation across various hydrogen and heat price ranges. the proposed PtH optimization framework offers an efficient approach to balance power generation and consumption in Gs driven by RE sources and energy storage. To validate the proposed approach numerical simulations are performed based on data from wind and solar farms load requirements and cost of energy. The results show that the proposed energy management strategy significantly reduces operational costs and optimizes PtH generation while maintaining power balance within the microgrid (G). The predictive approach helps fine-tune the optimization process improving efficiency and cost-effectiveness. The research convincingly demonstrate the economic advantages of adopting hydrogen as an energy storage medium paving the way for a cleaner and more sustainable energy future.

Hydrogen energy technologies are envisioned to play a critical supporting role in global decarbonisation. While low-carbon hydrogen is primarily targeted for reducing industrial emissions alongside decarbonising parts of the transport sector environmental benefits could also be achieved in the residential context. Presently gasdependent countries such as Japan and the United Kingdom are assessing the feasibility of deploying hydrogen home appliances as part of their national energy strategies. However prospects for the transition will hinge on consumer acceptance alongside an array of other socio-technical factors. To support potential ambitions for large-scale and sustained technology diffusion this study advances a Unified Theory of Domestic Hydrogen Acceptance. Through an integrative comparative literature review targeting hydrogen and domestic energy studies the paper proposes a novel Domestic Hydrogen Acceptance Model (DHAM) which accounts for the cognitive and emotional dimensions of human perceptions. Through this dual interplay the proposed framework can increase the predictive power of hydrogen acceptance models.

The influence of hydrogen-enriched natural gas (HENG) and CO2 on the mechanical property of X80 pipeline steel were investigated via fatigue crack growth rate (FCGR) tests and density functional theory (DFT) calculations. The results show that the FCGR in H2 was slightly faster than that in HENG while it was slower than that in the N2/CO2/H2 mixtures. The enhanced FCGR by CO2 further increased with the increasing CO2 content. DFT calculation results show that the adsorbed CO2 on the iron surface significantly increased the migration rate of H atoms from surface to subsurface. This promotes the entry of hydrogen into the steel.

With the world-wide decision to reduce carbon emissions through the Paris Agreement (2015) the demand for hydrogen-fuelled vehicles has been increasing. Although hydrogen is not a toxic gas it has a wide flammable range (4e75%) and can explode due to static electricity. Therefore studies on hydrogen safety are urgently required. In this study an explosion was induced by applying fire to the lower part of a fuel cell electric vehicle (FCEV). Out of three compressed hydrogen storage tanks installed in the vehicle two did not have hydrogen fuel and one was filled with compressed gaseous hydrogen of 700 bar and forcedly deactivated its temperature-activated pressure relief device. The side-on overpressure transducers were installed by distance in main directions to measure the side-on overpressure generated by the vehicle explosion. A 10 m-long protective barrier was installed on which reflected overpressure displacement and acceleration were measured to examine the effect of attenuation of explosion damage in the event of an accident. The vehicle exploded approximately 11 min after ignition generating a blast wave fireballs and fragments. The results of the experiment showed that the protective barrier could almost completely block explosive pressure smoke and scattering generated during an explosion. Through Probit function analysis the probabilities of an accident occurring were derived based on peak overpressure peak impulse and scattering. The results of this study can be used to develop standard operating procedures (SOPs) for firefighters as the base data for setting the initial operation location and deriving the safe separation distance.

This work addresses the energy efficiency of hydrogen refueling stations (HRS) using a first principles model and optimal control methods to find minimal entropy production operating paths. The HRS model shows good agreement with experimental data achieving maximum state of charge and temperature discrepancies of 1 and 7% respectively. Model solution and optimization is achieved at a relatively low computational time (40 s) when compared to models of the same degree of accuracy. The entropy production mapping indicates the flow control valve as the main source of irreversibility accounting for 85% of the total entropy production in the process. The minimal entropy production refueling path achieves energy savings from 20 to 27% with respect to the SAE J2601 protocol depending on the ambient temperature. Finally the proposed method under nearreversible refueling conditions shows a theoretical reduction of 43% in the energy demand with respect to the SAE J2601 protocol.

Hydrogen’s wide availability and versatile production methods establish it as a primary green energy source driving substantial interest among the public industry and governments due to its future fuel potential. Notable investment is directed toward hydrogen research and material innovation for transmission storage fuel cells and sensors. Ensuring safe and dependable hydrogen facilities is paramount given the challenges in accident control. Addressing material compatibility issues within hydrogen systems remains a critical focus. Challenges roadmaps and scenarios steer long-term planning and technology outlooks. Strategic visions align actions and policies encompassing societal and ecological dimensions. The confluence of hydrogen’s promise with material progress holds the prospect of reshaping our energy landscape sustainably. Forming collective future perspectives to foresee this emerging technology’s potential benefits is valuable. Our review article comprehensively explores the forthcoming challenges in hydrogen technology. We extensively examine the challenges and opportunities associated with hydrogen production incorporating CO2 capture technology. Furthermore the interaction of materials and composites with hydrogen particularly in the context of hydrogen transmission pipeline and infrastructure are discussed to understand the interplay between materials and hydrogen dynamics. Additionally the exploration extends to the embrittlement phenomena during storage and transmission coupled with a comprehensive examination of the advancements and hurdles intrinsic to hydrogen fuel cells. Finally our exploration encompasses addressing hydrogen safety from an industrial perspective. By illuminating these dimensions our article provides a panoramic view of the evolving hydrogen landscape.

Hydrogen recombination catalyst is useful tool for reducing hydrogen in closed area. The catalyst is known to be poisoned under wet condition in long time use. The study is focused on the behavior of pre-oxidized Pd nanoparticle as the hard-used catalyst in high humidity environment by comparison of alumina and titanium oxide supports using in situ X-ray absorption spectroscopy technique. The reduction of surface oxide layer of Pd/TiO2 was promoted by water during hydrogen recombination although the reduction reaction of Pd/Al2O3 was inhibited by water.

The average temperature of the Earth has risen due to the accumulation of greenhouse gases emitted from the usage of fossil fuels. The consequential climate changes have caused various problems fueling the growing demand for environmentally friendly energy sources that can replace fossil fuels. Batteries and hydrogen have thus been utilized as substitute energy sources for automobiles to reduce fossil fuel consumption. Consequently the number of hydrogen refueling stations is increasing due to an increase in the number of hydrogen-powered vehicles. However several incidents have been reported in the United States of America and Japan where hydrogen refueling stations have been operating for a long time. A risk assessment of hydrogen refueling stations operating in urban areas was performed in this study by calculating the risk effect range using a process hazard analysis tool (PHAST) v8.7 from DNV-GL and a hydrogen risk assessment model (HyRAM) from Sandia National Laboratories (SNL). The societal risk was assessed through a probit model based on the calculation results. The assessment results showed that the risk caused by jet fire and overpressure in an incident is lower than the ‘as low as reasonably practicable’ (ALARP) level.

Hydrogen (H2) has rapidly become a topic of great attention when discussing routes to net-zero carbon emissions. About 14% of CO2 emissions globally are directly associated with domestic heating in buildings. Replacing natural gas (NG) with H2 for heating has been highlighted as a rapid alternative for mitigating these emissions. To realise this not only the production challenges but also potential obstacles in the transmission/distribution and combustion of H2 must be technically identified and discussed. This review in addition to delineating the challenges of H2 in NG grid pipelines and H2 combustion also collates the results of the state-of-the-art technologies in H2-based heating systems. We conclude that the sustainability of water and renewable electricity resources strongly depends on sizing siting service life of electrolysis plants and post-electrolysis water disposal plans. 100% H2 in pipelines requires major infrastructure upgrades including production transmission pressurereduction stations distribution and boiler rooms. H2 leakage instigates more environmental risks than economic ones. With optimised boilers burning H2 could reduce GHG emissions and obtain an appropriate heating efficiency; more data from boiler manufacturers must be provided. Overall green H2 is not the only solution to decarbonise heating in buildings and it should be pursued abreast of other heating technologies.

Energy transition will reshape the power sector and hydrogen is a key energy carrier that could contribute to energy security. The inclusion of sustainability criteria is crucial for the adequate design/deployment of resilient hydrogen networks. While cost and environmental metrics are commonly included in hydrogen models social aspects are rarely considered. This paper aims to identify the social criteria related to the hydrogen economy by using a systematic hybrid literature review. The main contribution is the identification of twelve social aspects which are described ranked and discussed. “Accessibility” “Information” “H2 markets” and “Acceptability” are now emerging as the main themes of hydrogen-related social research. Identified gaps are e.g. lack of the definition of the value of H2 for society insufficient research for “socio-political” aspects (e.g. geopolitics wellbeing) scarce application of social lifecycle assessment and the low amount of works with a focus on social practices and cultural issues.

This review presents a state-of-the-art of geochemical geomechanical and hydrodynamic modelling studies in the Underground Hydrogen Storage (UHS) domain. Geochemical modelling assessed the reactivity of hydrogen and res pective fluctuations in hydrogen losses using kinetic reaction rates rock mineralogy brine salinity and the integration of hydrogen redox reactions. Existing geomechanics studies offer an array of coupled hydromechanical models suggesting a decline in rock failure during the withdrawal phase in aquifers compared to injection phase. Hydrodynamic modelling evaluations indicate the critical importance of relative permeability hysteresis in determining the UHS performance. Solubility and diffusion of hydrogen gas appear to have minimal impact on UHS. Injection and production rates cushion gas deployment and reservoir heterogeneity however significantly affect the UHS performance stressing the need for thorough modelling and experimental studies. Most of the current UHS modelling efforts focus on assessing the hydrodynamic aspects which are crucial for understanding the viability and safety of UHS. In contrast the lesser-explored geochemical and geomechanical considerations point to potential research gaps. A variety of modelling software tools such as CMG Eclipse COMSOL and PHREEQC evaluated those UHS underlying effects along with a few recent applications of datadriven-based Machine Learning (ML) techniques for enhanced accuracy. This review identified several unresolved challenges in UHS modelling: pronounced lack of expansive datasets leading to a gap between model predictions and their practical reliability; need robust methodologies capable of capturing natural subsurface heterogeneity while upscaling from precise laboratory data to field-scale conditions; demanding intensive computational resources and novel strategies to enhance simulation efficiency; and a gap in addressing geological uncertainties in subsurface environments suggesting that methodologies from oil reservoir simulations could be adapted for UHS. This comprehensive review offers a critical synthesis of the prevailing approaches challenges and research gaps in the domain of UHS thus providing a valuable reference document for further modelling efforts facilitating the informed advancements in this critical domain towards the realization of sustainable energy solutions.

Currently meeting the global energy demand is largely dependent on fossil fuels such as natural gas coal and oil. Fossil fuels represent a danger to the Earth’s environment and its biological systems. The utilisation of these fuels results in a rise in atmospheric CO2 levels which in turn triggers global warming and adverse changes in the climate. Furthermore these represent finite energy resources that will eventually deplete. There is a pressing need to identify and harness renewable energy sources as a replacement for fossil fuels in the near future. This shift is expected to have a minimal environmental impact and would contribute to ensuring energy security. Hydrogen is considered a highly desirable fuel option with the potential to substitute depleting hydrocarbon resources. This concise review explores diverse methods of renewable hydrogen production with a primary focus on solar wind geothermal and mainly water-splitting techniques such as electrolysis thermolysis photolysis and biomass-related processes. It addresses their limitations and key challenges hampering the global hydrogen economy’s growth including clean value chain creation storage transportation production costs standards and investment risks. The study concludes with research recommendations to enhance production efficiencies and policy suggestions for governments to mitigate investment risks while scaling up the hydrogen economy.

In an era characterised by political instability economic uncertainty and mounting environmental pressures hydrogen fuel is being positioned as a critical piece of the global energy security and clean energy agenda. The policy push is noteworthy in the United Kingdom where the government is targeting industrial decarbonisation via hydrogen while exploring a potential role for hydrogen-fuelled home appliances. Despite the imperative to secure social acceptance for accelerating the diffusion of low-carbon energy technologies public perceptions of hydrogen homes remain largely underexplored by the researcher community. In response this analysis draws on extensive focus group data to understand the multi-dimensional nature of social acceptance in the context of the domestic hydrogen transition. Through an integrated mixed-methods multigroup analysis the study demonstrates that socio-political and market acceptance are strongly interlinked owing to a trust deficit in the government and energy industry coupled to underlying dissatisfaction with energy markets. At the community level hydrogen homes are perceived as a potentially positive mechanism for industrial regeneration and local economic development. Households consider short-term disruptive impacts to be tolerable provided temporary disconnection from the gas grid does not exceed three days. However to strengthen social acceptance clearer communication is needed regarding the spatial dynamics and equity implications of the transition. The analysis concludes that existing trust deficits will need to be overcome which entails fulfilling not only a ‘price promise’ on the cost of hydrogen appliances but also enacting a ‘price pledge’ on energy bills. These deliverables are fundamental to securing social acceptance for hydrogen homes.

Renewable energies such as the wind energy and solar energy generate low-carbon electricity which can directly charge battery electric vehicles (BEVs). Meanwhile the surplus electricity can be used to produce the “green hydrogen” which provides zero-emission hydrogen fuels to those fuel cell electric vehicles (FCEVs). In order to charge/refuel multi-energy vehicles we propose a novel scheme of hybrid hydrogen/electricity supply using cryogenic and superconducting technologies. In this scheme the green hydrogen is further liquefied into the high-density and low-pressure liquid hydrogen (LH2) for bulk energy storage and transmission. Taking the advantage of the cryogenic environment of LH2 (20 K) it can also be used as the cryogen to cool down super conducting cables to realize the virtually zero-loss power transmission from 100 % renewable sources to vehicle charging stations. This hybrid LH2/electricity energy pipeline can realize long-distance large-capacity and high efficiency clean energy transmission to fulfil the hybrid energy supply demand for BEVs and FCEVs. For the case of a 100 MW-class hybrid hydrogen/electricity supply station the system principle and energy management strategy are analyzed through 9 different operating sub-modes. The corresponding static and dynamic economic modeling are performed and the economic feasibility of the hybrid hydrogen/electricity supply is verified using life-cycle analysis. Taking an example of wind power capacity 1898 MWh and solar power capacity 1619 MWh per day the dynamic payback period is 15.06 years the profitability index is 1.17 the internal rate of return is 7.956 % and the accumulative NPV is 187.92 M$. The system design and techno-economic analysis can potentially offer a technically/economically superior solution for future multi-energy vehicle charging/refueling systems.

The Integrated Energy System (IES) that coordinates multiple energy sources can effectively improve energy utilization and is of great significance to achieving energy conservation and emission reduction goals. In this context a low-carbon and economic dispatch model for IES is proposed. Firstly a hydrogen energy-based IES (H2-IES) is constructed to refine the utilization process of hydrogen energy. Secondly the carbon emissions of different energy chains throughout their life cycle are analyzed using the life cycle assessment method (LCA) and the carbon emissions of the entire energy supply and demand chain are considered. Finally a staged carbon trading mechanism is adopted to promote energy conservation and emission reduction. Based on this an IES low-carbon and economic dispatch model is constructed with the optimization goal of minimizing the sum of carbon trading costs energy procurement costs and hydrogen sales revenue while considering network constraints and constraints on key equipment. By analyzing the model under different scenarios the introduction of life cycle assessment staged carbon trading and hydrogen energy utilization is shown to promote low-carbon and economic development of the comprehensive energy system.

The intermittency of renewable energy sources necessitates energy storage to meet the full demand and balancing requirements of the grid. Green hydrogen (H2) is a chemical energy carrier that can be used in a flexible manner and store large amounts of energy for long periods of time. This techno-economic analysis investigates H2 production from wind using commercially available desalination and electrolysis units. Proton exchange membrane and alkaline electrolyser units are utilised and compared. The intermittency of wind is examined with comparison against grid-bought electricity. A model is developed to determine the selling price required to ensure profitability over a 10-year period. Firstly where H2 is produced using energy from the grid with electricity purchased when below a specified price point or between specified hours. In the second scenario a wind turbine is owned by the user and the electricity price is not considered while the turbine capital expenditure is. The price of H2 production from wind is found to be comparable with natural gas derived H2 at a larger scale with a minimum selling price calculated to be 4.85 £/kg at a setpoint of 500 kg of H2/hr. At a setpoint of 50 kg of H2/hr this is significantly higher at 12.10 £/kg. In both cases the alkaline electrolyser produced cheaper H2. This study demonstrates an economy of scale with H2 prices decreasing with increased scale. H2 prices are also closely linked to the capital expenditure with the equipment size space and safety identified as limiting factors.

With the clear adverse impacts of fossil fuel-based energy systems on the climate and environment ever-growing interest and rapid developments are taking place toward full or nearly full dependence on renewable energies in the next few decades. Estonia is a European country with large demands for electricity and thermal energy for district heating. Considering it as the case study this work explores the feasibility and full potential of optimally sized photovoltaic (PV) wind and PV/wind systems equipped with electric and thermal storage to fulfill those demands. Given the large excess energy from 100% renewable energy systems for an entire country this excess is utilized to first meet the district heating demand and then to produce hydrogen fuel. Using simplified models for PV and wind systems and considering polymer electrolyte membrane (PEM) electrolysis a genetic optimizer is employed for scanning Estonia for optimal installation sites of the three systems that maximize the fulfillment of the demand and the supply–demand matching while minimizing the cost of energy. The results demonstrate the feasibility of all systems fully covering the two demands while making a profit compared to selling the excess produced electricity directly. However the PV-driven system showed enormous required system capacity and amounts of excess energy with the limited solar resources in Estonia. The wind system showed relatively closer characteristics to the hybrid system but required a higher storage capacity by 75.77%. The hybrid PV/wind-driven system required a total capacity of 194 GW most of which belong to the wind system. It was also superior concerning the amount (15.05 × 109 tons) and cost (1.42 USD/kg) of the produced green hydrogen. With such full mapping of the installation capacities and techno-economic parameters of the three systems across the country this study can assist policymakers when planning different country-scale cogeneration systems.

This paper introduces a value chain design for transportation fuels and a respective business case taking into account hybrid PV-Wind power plants electrolysis and hydrogen-to-liquids (H2tL) based on hourly resolved full load hours (FLh). The value chain is based on renewable electricity (RE) converted by power-to-liquids (PtL) facilities into synthetic fuels mainly diesel. Results show that the proposed RE-diesel value chains are competitive for crude oil prices within a minimum price range of about 79 - 135 USD/barrel (0.44 – 0.75 €/l of diesel production cost) depending on the chosen specific value chain and assumptions for cost of capital available oxygen sales and CO2 emission costs. A sensitivity analysis indicates that the RE-PtL value chain needs to be located at the best complementing solar and wind sites in the world combined with a de-risking strategy and a special focus on mid to long-term electrolyser and H2tL efficiency improvements. The substitution of fossil fuels by hybrid PV-Wind power plants could create a PV-wind market potential in the order of terawatts.

This article investigates the potential of renewable and low-carbon fuel production for the maritime shipping sector using Sweden as a case in focus. Techno-economic modelling and socio-technical transition studies are combined to explore the conditions opportunities and barriers to decarbonising the maritime shipping industry. A set of scenarios have been developed considering demand assumptions and potential instruments such as carbon price energy tax and blending mandate. The study finds that there are opportunities for decarbonising the maritime shipping industry by using renewable marine fuels such as advanced biofuels (e.g. biomethanol) electrofuels (e.g. e-methanol) and hydrogen. Sweden has tremendous resource potential for bio-based and hydrogen-based renewable liquid fuel production. In the evaluated system boundary biomethanol presents the cheapest technology option while e-ammonia is the most expensive one. Green electricity plays an important role in the decarbonisation of the maritime sector. The results of the supply chain optimisation identify the location sites and technology in Sweden as well as the trade flows to bring the fuels to where the bunker facilities are potentially located. Biomethanol and hydrogen-based marine fuels are cost-effective at a carbon price beyond 100 €/tCO2 and 200 €/tCO2 respectively. Linking back to the socio-technical transition pathways the study finds that some shipping companies are in the process of transitioning towards using renewable marine fuels thereby enabling niche innovations to break through the carbon lock-in and eventually alter the socio-technical regime while other shipping companies are more resistant. Overall there is increasing pressure from (inter)national energy and climate policy-making to decarbonise the maritime shipping industry.

The rapid expansion of renewable energies has the potential to decarbonize the electricity supply. This is more challenging in difficult-to-electrify sectors. The use of hydrogen provides a massive potential for this issue. However expanding hydrogen production increases electricity demand while providing additional flexibility to the electricity market. This paper mainly aims to analyze the economic effects of this sector coupling between the European electricity and national hydrogen markets. The developed energy market model jointly considers both markets to reach an overall welfare optimum. A novel modeling approach allows the interaction of these markets without the need for several iterative optimization runs. This allows for a detailed analysis of various market participants’ changes in consumer and producer surpluses. The optimization is conducted in 13 connected Central European countries to account for various power plant fleets generation mixes and electricity prices. Results show an overall welfare increase of EUR 4 to 28 billion in 2030 and an EUR 5 to 158 billion increase in 2040. However there is a surplus shift from consumers to producers. The consumer surplus is reduced by up to EUR 44 billion in 2030 and EUR 60 billion while producers benefit to achieve the overall welfare benefits. The reduction of consumer surplus changes if significant price peaks occur. Fuel cell applications can avoid these price peaks resulting in a surplus shift from thermal power plants to consumers. Hence consumer surplus can increase by up to EUR 146 billion in the respective 2040 scenarios. Pink hydrogen accounts for a sizable portion of total hydrogen production up to 58 percent in 2030 and up to 30 percent in 2040. As a result nuclear power plants that are nearly entirely allocated in France stand to benefit greatly from this sector coupling. Additional efforts could be made to address the link between hydrogen and natural gas prices. Furthermore the potential for cross-border hydrogen trade and the implementation of national legal and regulatory frameworks could be assessed.

A proton exchange membrane (PEM) electrolyzer is fed with water and powered by electric power to electrochemically produce hydrogen at low operating temperatures and emits oxygen as a by-product. Due to the complex nature of the performance of PEM electrolyzers the application of an artificial neural network (ANN) is capable of predicting its dynamic characteristics. A handful of studies have examined and explored ANN in the prediction of the transient characteristics of PEM electrolyzers. This research explores the estimation of the transient behavior of a PEM electrolyzer stack under various operational conditions. Input variables in this study include stack current oxygen pressure hydrogen pressure and stack temperature. ANN models using three differing learning algorithms and time delay structures estimated the hydrogen mass flow rate which had transient behavior from 0 to 1 kg/h and forecasted better with a higher count (>5) of hidden layer neurons. A coefficient of determination of 0.84 and a mean squared error of less than 0.005 were recorded. The best-fitting model to predict the dynamic behavior of the hydrogen mass flow rate was an ANN model using the Levenberg–Marquardt algorithm with 40 neurons that had a coefficient of determination of 0.90 and a mean squared error of 0.00337. In conclusion optimally fit models of hydrogen flow from PEM electrolyzers utilizing artificial neural networks were developed. Such models are useful in establishing an agile flow control system for the electrolyzer system to help decrease power consumption and increase efficiency in hydrogen generation.

This paper presents the HEGIT (Heat Electricity and Gas Infrastructure and Technology) model for optimal infrastructure planning for decarbonising heating in buildings. HEGIT is an optimisation model based on Mixed Integer Linear Programming. The model co-optimises the integrated operation and capacity expansion planning of electricity and gas grids as well as heating technologies on the consumer side while maintaining the security of supply and subject to different environmental operational and system-wide constraints. The three main features of the HEGIT model are: • It incorporates an integrated unit commitment and capacity expansion problem for coordinated operation and long-term investment planning of the electricity and gas grids. • It incorporates the flexible operation of heating technologies in buildings and demand response in operation and long-term investment planning of gas and electricity grids. • It incorporates a multi-scale techno-economic representation of heating technologies design features into the whole energy system modelling and capacity planning. These features enable the model to quantify the impacts of different policies regarding decarbonising heating in buildings on the operation and long-term planning of electricity and gas grids identify the cost-optimal use of available resources and technologies and identify strategies for maximising synergies between system planning goals and minimising trade-offs. Moreover the multi-scale feature of the model allows for multi-scale system engineering analysis of decarbonising heating including system-informed heating technology design identifying optimal operational setups at the consumer end and assessing trade-offs between consumer investment in heating technologies and infrastructure requirements in different heat decarbonisation pathways.

This work evaluates the effectiveness of chemical-based solutions for storing large amounts of renewable electricity. Four “Power-to-X-to-Power” pathways are examined comprising hydrogen methane methanol and ammonia as energy carriers. The pathways are assessed using a model scenario where they are produced with electricity from an onshore wind farm stored in suitable facilities and then reconverted to electricity to meet the energy demand of a chemical site. An energy management and storage capacity estimation tool is used to calculate the annual load coverage resulting from each pathway. All four pathways offer a significant increase in load coverage compared to a scenario without storage solution (56.19%). The hydrogen-based pathway has the highest load coverage (71.88%) and round-trip efficiency (36.93%) followed by the ammonia-based (69.62% 31.37%) methanol-based (67.85% 27.00%) and methane-based (67.64% 26.47% respectively) pathways. The substantially larger storage capacity required for gaseous energy carriers to ensure a steady supply to the consumer could be a decisive factor. The hydrogen pathway requires a storage volume up to 10.93 times larger than ammonia and 16.87 times larger than methanol. Notably ammonia and methanol whose load coverages are only 2.26 and 4.03 percentage points lower than that of hydrogen offer the possibility of implementing site-specific storage solutions avoiding potential bottlenecks due to limited pipeline and cavern capacities.

Investing in green hydrogen systems has become a global objective to achieve the net-zero emission goal. Therefore it is seen as the primary force behind efforts to restructure the world’s energy lessen our reliance on gas attain carbon neutrality and combat climate change. This paper proposes a power management for a net zero emission PV microgrid-based decentralized green hydrogen system. The hybrid microgrid combines a fuel cell battery PV electrolyzer and compressed hydrogen storage (CHSU) unit aimed at power sharing between the total components of the islanded DC microgrid and minimizing the equivalent hydrogen consumption (EHC) by the fuel cell and the battery. In order to minimize the EHC and maintain the battery SOC an optimization-based approach known as the Equivalent Consumption Minimization Strategy (ECMS) is used. A rulebased management is used to manage the power consumed by the electrolyzer and the CHSU by the PV system in case of excess power. The battery is controlled by an inverse droop control to regulate the dc bus voltage and the output power of the PV system is maximized by the fuzzy logic controller-based MPPT. As the hybrid microgrid works in the islanded mode a two-level hierarchical control is applied in order to generate the voltage and the frequency references. The suggested energy management approach establishes the operating point for each system component in order to enhance the system’s efficiency. It allows the hybrid system to use less hydrogen while managing energy more efficiently.

This is a summary report of a study which aimed to understand the safety feasibility cost and impacts for 7 industrial sites to switch from natural gas to 100% hydrogen for heating. The volunteer industrial sites:<br/>♦ are located away from industrial clusters<br/>♦ use natural gas to meet most of their energy demand<br/>♦ will likely be most impacted by decisions on the future of the natural gas grid<br/>We have published the report in order to share its findings with other industrial sites and wider industry in particular those considering hydrogen as an option for decarbonisation.<br/>Note that:<br/>♦ some work was carried out on a non-hydrogen alternative energy source but to a lesser level of detail and not to determine the optimal decarbonisation solution<br/>♦ the findings do not apply to other end user environments because of differences between these environments and the consumption of gas<br/>The study was commissioned in 2022 by the former Department for Business and Energy and undertaken by AECOM and their safety sub-contractor ESR.<br/>The evidence will inform strategic decisions in 2026 on the role of low carbon hydrogen as a replacement for natural gas heating.

A proton exchange membrane fuel cell (PEMFC) system requires an adequate hydrogen supply and circulation to achieve its expected performance and operating life. An ejector-based hydrogen circulation system can reduce the operating and maintenance costs noise and parasitic power consumption by eliminating the recirculation pump. However the ejector’s hydrogen entrainment capability restricted by its geometric parameters and flow control variability can only operate properly within a relatively narrow range of fuel cell output power. This research introduced the optimal design and operation control methods of a dual-ejector hydrogen supply/circulation system to support the full range of PEMFC system operations. The technique was demonstrated on a 70 kW PEMFC stack with an effective hydrogen entrainment ratio covering 8% to 100% of its output power. The optimal geometry design ensured each ejector covered a specific output power range with maximized entrainment capability. Furthermore the optimal control of hydrogen flow and the two ejectors’ opening and closing times minimized the anode gas pressure fluctuation and reduced the potential harm to the PEMFC’s operation life. The optimizations were based on dedicated computational fluid dynamics (CFD) and system dynamics models and simulations. Bench tests of the resulting ejector-based hydrogen supply/circulation system verified the simulation and optimization results.

The world is facing an urgent global climate challenge and hydrogen (H2) is increasingly valued as a carbon-free energy carrier that can play a prominent role in decarbonising economies. However the environmental impact of the different methods for hydrogen production are sometimes overlooked. This work provides a comprehensive overview of the environmental impacts and costs of a diverse range of methods for producing hydrogen. Ninety nine life cycle assessments (LCAs) of hydrogen production published between 2015 and 2022 are categorised by geography production method energy source goal and scope and compared by data sources and methodology. A meta-analysis of methodological choices is used to identify a subset of mutually comparable studies whose results are then compared initially by global warming potential (GWP) then low-GWP scenarios are compared by other indicators. The results show that the lowest GWP is achieved by methods that are currently more expensive (~US $4–9/kg H2) compared to the dominant methods of producing hydrogen from fossil fuels (~US $1–2/kg H2). The research finds that data are currently limited for comparing environmental indicators other than GWP such as terrestrial acidification or freshwater eutrophication. Recommendations are made for future LCAs of hydrogen production.

To reach the decarbonisation goals a zero CO2 emissions large ship propulsion system is proposed in this work. The ship selected is a large ferry propelled by an internal combustion engine fuelled by an ammonia-hydrogen blend. The only fuel loaded in the vessel will be ammonia. The hydrogen required for the combustion in the engine will be produced onboard employing ammonia decomposition. The heat required for this decomposition section will be supplied by using the hot flue gases of the combustion engine. To address the issues regarding NOx emissions a selective catalytic reduction (SCR) reactor was designed. The main operating variables for all the equipment were computed for engine load values of 25% 50% 75% and 100%. Considering the lowest SCR removal rate (91% at an engine load of 100%) the NOx emissions of the vessel were less than 0.5 g/kWh lower than the IMO requirements. An energy analysis of the system proposed to transform ammonia into energy for shipping was conducted. The global energy and exergy efficiencies were 42.4% and 48.1%. In addition an economic analysis of the system was performed. The total capital cost (CAPEX) for the system can be estimated at 8.66 M€ (784 €/kW) while the operating cost (OPEX) ranges between 210 €/MWh (engine load 100%) and 243 €/MWh (engine load of 25%). Finally a sensitivity analysis for the price of ammonia was performed resulting in the feasibility of reducing the operating cost to below 150 €/MWh in the near horizon.

Liquid hydrogen is one of the high-quality energy carriers but a large leak of liquid hydrogen can pose significant safety risks. Understanding its diffusion law after accidental leakage is an important issue for the safe utilization of hydrogen energy. In this paper a series of open-space large-volume liquid hydrogen release experiments are performed to observe the evolution of visible clouds during the release and an array of hydrogen concentration sensors is set up to monitor the fluctuation in hydrogen concentration at different locations. Based on the experimental conditions the diffusion of hydrogen clouds in the atmosphere under different release hole diameters and different ground materials is compared. The results show that with the release of liquid hydrogen the white visible cloud formed by air condensation or solidification is generated rapidly and spread widely and the visible cloud is most obvious near the ground. With the termination of liquid hydrogen release solid air is deposited on the ground and the visible clouds gradually shrink from the far field to the release source. Hydrogen concentration fluctuations in the far field in the case of the cobblestone ground are more dependent on spontaneous diffusion by the hydrogen concentration gradient. In addition compared with the concrete ground the cobblestone ground has greater resistance to liquid hydrogen extension; the diffusion of hydrogen clouds to the far field lags. The rapid increase stage of hydrogen concentration at N8 in Test 7 lags about 3 s behind N12 in Test 6 N3 lags about 7.5 s behind N1 and N16 lags about 8.25 s behind N14. The near-source space is prone to high-concentration hydrogen clouds. The duration of the high-concentration hydrogen cloud at N12 is about 15 s which is twice as long as the duration at N8 increasing the safety risk of the near-source space.

To achieve carbon neutrality in Japan by 2050 renewable energy needs to be used as the main energy source. Based on the constraints of various renewable energies the importance of hydrogen cannot be ignored. This study aimed to investigate the diffusion of hydrogen demand technologies in various sectors and used projections and assumptions to investigate the hydrogen supply side. By performing simulations with the E3ME-FTT model and comparing various policy scenarios with the reference scenario the economic and environmental impacts of the policy scenarios for hydrogen diffusion were analyzed. Moreover the impact of realizing carbon neutrality by 2050 on the Japanese economy was evaluated. Our results revealed that large-scale decarbonization via hydrogen diffusion is possible (90% decrease of CO2 emissions in 2050 compared to the reference) without the loss of economic activity. Additionally investments in new hydrogen-based and other low-carbon technologies in the power sector freight road transport and iron and steel industry can improve the gross domestic product (1.6% increase in 2050 compared to the reference) as they invoke economic activity and require additional employment (0.6% increase in 2050 compared to the reference). Most of the employment gains are related to decarbonizing the power sector and scaling up the hydrogen supply sector while a lot of job losses can be expected in the mining and fossil fuel industries.

This study develops a an optimization model focused on the layout and dispatch of a low-carbon hydrogen supply chain. The objective is to identify the lowest Levelized Cost of Hydrogen for a given demand. The model considers various elements including electricity supply from the local grid and renewable sources (photovoltaic and wind) alongside hydrogen production compression storage and transportation to end users. Applied to an industrial case study in Sweden the findings indicate that the major cost components are linked to electricity generation and investment in electrolyzers with the LCOH reaching 5.2 EUR/kgH2 under typical demand conditions. Under scenarios with higher peak demands and greater demand volatility the LCOH increases to 6.8 EUR/kgH2 due to the need for additional renewable energy capacity. These results highlight the critical impact of electricity availability and demand fluctuations on the LCOH emphasizing the complex interdependencies within the hydrogen supply chain. This study provides valuable insights into the feasibility and cost-effectiveness of adopting hydrogen as an energy carrier for renewable electricity in the context of decarbonizing industrial processes in the energy system.

Green hydrogen produced by water electrolysis is one of the most promising technologies to realize the efficient utilization of intermittent renewable energy and the decarbonizing future. Among various electrolysis technologies the emerging anion-exchange membrane water electrolysis (AEMWE) shows the most potential for producing green hydrogen at a competitive price. In this review we demonstrate a comprehensive introduction to AEMWE including the advanced electrode design the lab-scaled testing system establishment and the electrochemical performance evaluation. Specifically recent progress in developing high activity transition metal-based powder electrocatalysts and self-supporting electrodes for AEMWE is summarized. To improve the synergistic transfer behaviors between electron charge water and gas inside the gas diffusion electrode (GDE) two optimizing strategies are concluded by regulating the pore structure and interfacial chemistry. Moreover we provide a detailed guideline for establishing the AEMWE testing system and selecting the electrolyzer components. The influences of the membrane electrode assembly (MEA) technologies and operation conditions on cell performance are also discussed. Besides diverse electrochemical methods to evaluate the activity and stability implement the failure analyses and realize the in-situ characterizations are elaborated. In end some perspectives about the optimization of interfacial environment and cost assessments have been proposed for the development of advanced and durable AEMWE.

Hydrogen is a new promising energy source. Three operating parameters including inlet gas flow rate pH and impeller speed mainly determine the biohydrogen production from membrane bioreactor. The work aims to boost biohydrogen production by determining the optimal values of the control parameters. The proposed methodology contains two parts: modeling and parameter estimation. A robust ANIFS model to simulate a membrane bioreactor has been constructed for the modeling stage. Compared with RMS thanks to ANFIS the RMSE decreased from 2.89 using ANOVA to 0.0183 using ANFIS. Capturing the proper correlation between the inputs and output of the membrane bioreactor process system encourages the constructed ANFIS model to predict the output performance exactly. Then the optimal operating parameters were identified using the honey badger algorithm. During the optimization process inlet gas flow rate pH and impeller speed are used as decision variables whereas the biohydrogen production is the objective function required to be maximum. The integration between ANFIS and HBA boosted the hydrogen production yield from 23.8 L to 25.52 L increasing by 7.22%.

The majority penetration of Variable Renewable Energy (VRE) will challenge the stability of electrical transmission grids due to unpredictable peaks and troughs of VRE generation. With renewable generation located further from high demand urban cores there will be a need to develop new transmission pathways to deliver the power. This paper compares the transport and storage of VRE through a hydrogen pipeline to the transport of VRE through a High Voltage Direct Current (HVDC) transmission line. The analysis found a hydrogen pipeline can offer a cost-competitive method for VRE transmission compared to a HVDC transmission line on a life-cycle cost basis normalized by energy flows for distances at 1000 miles with 2030 technology. This finding has implications for policy makers project developers and system operators for the future development of transmission infrastructure projects given the additionality which hydrogen pipelines can provide in terms of energy storage.

This study presents a novel framework for improving the resilience of microgrids based on the power-to-hydrogen concept and the ability of microgrids to operate independently (i.e. islanded mode). For this purpose a model is being developed for the resilient operation of microgrids in which the compressed hydrogen produced by power-to-hydrogen systems can either be used to generate electricity through fuel cells or sold to other industries. The model is a bi-objective optimization problem which minimizes the cost of operation and resilience by (i) reducing the active power exchange with the main grid (ii) reducing the ohmic power losses and (iii) increasing the amount of hydrogen stored in the tanks. A solution approach is also developed to deal with the complexity of the bi-objective model combining a goal programming approach and Generalized Benders Decomposition due to the mixed-integer nonlinear nature of the optimization problem. The results indicate that the resilience approach although increasing the operation cost does not lead to load shedding in the event of main grid failures. The study concludes that integrating distributed power-to-hydrogen systems results in significant benefits including emission reductions of up to 20 % and cost savings of up to 30 %. Additionally the integration of the decomposition method improves computational performance by 54 % compared to using commercial solvers within the GAMS software.

The article presents a new carbon-free heat production technology for district heating which consists of a combined heat and power generation fuel cell (FC CHP) with CO2 capture and a two-stage cascade high-temperature heat pump (TCHHP). The FC generates heat and electricity the latter being used to drive the compressors of the TCHHP. During the winter period the water temperature achieved can occasionally be too low so it would be heated up with hydrogen gas boilers. The hydrogen would be produced by reforming natural gas synthetic methane or biogas. The results are presented with natural gas utilization—the ratio between the obtained heat flow transferred directly to the water for district heating and the input heat flow of natural gas. In the case of a return water temperature of 60 ◦C and district heating temperature of 85 ◦C the TCHHP whose heat source is groundwater achieves plant efficiency of 270.04% in relation to the higher heating value (HHV) and 241.74% in relation to the lower heating value (LHV) of natural gas. A case with a TCHHP whose heat source is low-temperature geothermal water achieves a plant efficiency of 361.36% in relation to the HHV and 323.49% in relation to the LHV

The demand for fossil fuels is rising rapidly leading to increased greenhouse gas emissions. Hydrogen has emerged as a promising clean energy alternative that could help meet future demands way sustainably especially if produced using renewable methods. For hydrogen to meaningfully contribute to energy transitions it needs more integration into sectors like transportation buildings and power that currently have minimal hydrogen usage. This requires developing extensive cross-sector hydrogen infrastructure. This review examines hydrogen combustion as a fuel by exploring and comparing production techniques enriching ammonia with hydrogen as a CO2-free option and hydrogen applications in engines. Additionally a techno-economic environmental risk analysis is discussed. Results showed steam methane reforming is the most established and cost-effective production method at $1.3–1.5/kg H2 and 70–85% efficiency but generates CO2. Biomass gasification costs $1.25–2.20/kg H2 and pyrolysis $1.77–2.05/kg H2 offering renewable options. However bio-photolysis currently has high costs of $1.42–2.13/kg H2 due to low conversion rates requiring large reactors. Blending H2/NH3 could enable carbon-free combustion aiding carbon neutrality pursuits but minimizing resultant NOx is crucial. Hydrogen’s wide uses from transportation to power underline its potential as a transformational energy carrier.

To facilitate the rapid and large-scale developments of offshore wind energy scholars policymakers and infrastructure developers must start considering its integration into the larger onshore energy system. Such offshore system integration is defined as the coordinated approach to planning and operation of energy generation transport and storage in the offshore energy system across multiple energy carriers and sectors. This article conducts a systematic literature review to identify infrastructure components of offshore energy system integration (including alternative cable connections offshore energy storage and power-to-hydrogen applications) and barriers to their development. An interdisciplinary perspective is provided where current offshore developments require not only mature and economically feasible technologies but equally strong legal and governance frameworks. The findings demonstrate that current literature lacks a holistic perspective on the offshore energy system. To date techno-economic assessments solving challenges of specific infrastructure components prevail over an integrated approach. Nevertheless permitting issues gaps in legal frameworks strict safety and environmental regulations and spatial competition also emerge as important barriers. Overall this literature review emphasizes the necessity of aligning various disciplines to provide a fundamental approach for the development of an integrated offshore energy system. More specifically timely policy and legal developments are key to incentivize technical development and enable economic feasibility of novel components of offshore system integration. Accordingly to maximize real-world application and policy learning future research will benefit from an interdisciplinary perspective.

Geological structures in deep aquifers and salt caverns can play an important role in large-scale hydrogen storage. However more work needs to be done to address the hydrogen storage demand for zero-emission energy systems. Thus the aim of the article is to present the demand for hydrogen storage expressed in the number of salt caverns in bedded rock salt deposits and salt domes or the number of structures in deep aquifers. The analysis considers minimum and maximum hydrogen demand cases depending on future energy system configurations in 2050. The method used included the estimation of the storage capacity of salt caverns in bedded rock salt deposits and salt domes and selected structures in deep aquifers. An estimation showed a large hydrogen storage potential of geological structures. In the case of analyzed bedded rock salt deposits and salt domes the average storage capacity per cavern is 0.05–0.09 TWhH2 and 0.06–0.20 TWhH2 respectively. Hydrogen storage capacity in analyzed deep aquifers ranges from 0.016 to 4.46 TWhH2. These values indicate that in the case of the upper bound for storage demand there is a need for the 62 to 514 caverns depending on considered bedded rock salt deposits and salt domes or the 9 largest analyzed structures in deep aquifers. The results obtained are relevant to the discussion on the global hydrogen economy and the methodology can be used for similar considerations in other countries.

The importance of the energy transition and the role of green hydrogen in facilitating this transition cannot be denied. Therefore it is crucial to pay close attention to and thoroughly understand hydrogen storage which is a critical aspect of the hydrogen supply chain. In this comprehensive review paper we have undertaken the task of categorising and evaluating various hydrogen storage technologies across three different scales. These scales include small-scale and laboratory-based methods such as metal-based hydrides physical adsorbents and liquid organic hydrogen carriers. Also we explore medium and large-scale approaches like compressed gaseous hydrogen liquid cryogenic hydrogen and cryocompressed hydrogen. Lastly we delve into very large-scale options such as salt caverns aquifers depleted gas/oil reservoirs abandoned mines and hard rock caverns. We have thoroughly examined each storage technology from technical and maturity perspectives as well as considering its techno-economic viability. It is worth noting that development has been ongoing for each storage mechanism; however numerous technical and economic challenges persist in most areas. Particularly the cost per kilogramme of hydrogen for most current technologies demands careful consideration. It is recommended that small-scale hydrogen storage technologies such as metal hydrides (e.g. MgH2 LiBH4) need ongoing research to enhance their performance. Physical adsorbents have limited capacity except for activated carbon. Some liquid organic hydrogen carriers (LCOHs) are suitable for medium-scale storage in the near term. Ammonia-borane (AB) with its high gravimetric and volumetric properties is a promising choice for medium-scale storage pending effective dehydrogenation. It shows potential as a hydrogen carrier due to its high storage capacity stability and solubility surpassing DOE targets for storage capabilities. Medium-scale storage utilising compressed gas cylinders and advancements in liquefied and cryocompressed hydrogen storage requires cost reduction measures and a strategic supply chain. Large-scale storage options include salt caverns aquifers and depleted gas/oil reservoirs with salt caverns offering pure hydrogen need further technoeconomic analysis and deployment projects to mature but storage costs are reasonable ranging mostly from €0.25/kg to €1.5/kg for location specific large-scale options.

The intermittency of renewable energy technologies requires adequate storage technologies. Hydrogen systems consisting of electrolysers storage tanks and fuel cells can be implemented as well as batteries. The requirements of the hydrogen purification unit is missing from literature. We measured the same for a 4.5 kW PEM electrolyser to be 0.8 kW for 10 min. A simulation to hybridize the hydrogen system including its purification unit with lithium-ion batteries for energy storage is presented; the batteries also support the electrolyser. We simulated a scenario for operating a Dutch household off-electric-grid using solar and wind electricity to find the capacities and costs of the components of the system. Although the energy use of the purification unit is small it influences the operation of the system affecting the sizing of the components. The battery as a fast response efficient secondary storage system increases the ability of the electrolyser to start up.

Energy and environmental issues are of great importance in the present era. The transition to renewable energy sources necessitates technological political and behavioral transformations. Hydrogen is a promising solution and many countries are investing in the hydrogen economy. Global demand for hydrogen is expected to reach 120 million tonnes by 2024. The incorporation of hydrogen for efficient energy transport and storage and its integration into the transport sector are crucial measures. However to fully develop a hydrogen-based economy the sustainability and safety of hydrogen in all its applications must be ensured. This work describes and compares different technologies for hydrogen production storage and utilization (especially in fuel cell applications) with focus on the research activities under study at SaRAH group of the University of Naples Federico II. More precisely the focus is on the production of hydrogen from bio-alcohols and its storage in formate solutions produced from renewable sources such as biomass or carbon dioxide. In addition the use of materials inspired by nature including biowaste as feedstock to produce porous electrodes for fuel cell applications is presented. We hope that this review can be useful to stimulate more focused and fruitful research in this area and that it can open new avenues for the development of sustainable hydrogen technologies.