Publications

In the realm of renewable energy the integration of wind power and hydrogen energy systems represents a promising avenue towards environmental sustainability. However the development of cost-effective hydrogen energy storage solutions is crucial to fully realize the potential of hydrogen as a renewable energy source. By combining wind power generation with hydrogen storage a comprehensive hydrogen energy system can be established. This study aims to devise a physiologically inspired optimization approach for designing a standalone wind power producer that incorporates a hydrogen energy system on a global scale. The optimization process considers both total cost and capacity loss to determine the optimal configuration for the system. The optimal setup for an off-grid solution involves the utilization of eight distinct types of compact horizontal-axis wind turbines. Additionally a sensitivity analysis is conducted by varying component capital costs to assess their impact on overall cost and load loss. Simulation results indicate that at a 15% loss the cost of energy (COE) is $1.3772 while at 0% loss it stands at $1.6908. Capital expenses associated with wind turbines and hydrogen storage systems significantly contribute to the overall cost. Consequently the wind turbine-hydrogen storage system emerges as the most cost-effective and reliable option due to its low cost of energy.

Sustainable aviation fuel (SAF) production is one of the strategies to guarantee an environmental-friendly development of the aviation sector. This work evaluates the technical economic and environmental feasibility of obtaining SAFs by hydrogenation of vegetable oils thanks to in-situ hydrogen production via aqueous phase reforming (APR) of glycerol by-product. The novel implementation of APR would avoid the environmental burden of conventional fossil-derived hydrogen production as well as intermittency and storage issues related to the use of RES-based (renewable energy sources) electrolysers. The conceptual design of a conventional and advanced (APR-aided) biorefinery was performed considering a standard plant capacity equal to 180 ktonne/y of palm oil. For the advanced scenario the feed underwent hydrolysis into glycerol and fatty acids; hence the former was subjected to APR to provide hydrogen which was further used in the hydrotreatment reactor where the fatty acids were deoxygenated. The techno-economic results showed that APR implementation led to a slight increase of the fixed capital investment by 6.6% compared to the conventional one while direct manufacturing costs decreased by 22%. In order to get a 10% internal rate of return the minimum fuel selling price was found equal to 1.84 $/kg which is 17% lower than the one derived from conventional configurations (2.20 $/kg). The life-cycle GHG emission assessment showed that the carbon footprint of the advanced scenario was equal to ca. 12 g CO2/MJSAF i.e. 54% lower than the conventional one (considering an energy-based allocation). The sensitivity analysis pointed out that the cost of the feedstock SAF yield and the chosen plant size are keys parameters for the marketability of this biorefinery while the energy price has a negligible impact; moreover the source of hydrogen has significant consequences on the environmental footprint of the plant. Finally possible uncertainties for both scenarios were undertaken via Monte Carlo simulations.

The development of hydrogen production technologies as well as new uses represents an opportunity both to accelerate the ecological transition and to create an industrial sector. However the risks associated with the use of hydrogen must not be overlooked. The mitigation of a hydrogen explosion in an enclosure is partly based on prevention strategies such as detection and ventilation but also on protection strategies such as explosion venting. However in several situations such as in highly constrained urban environments the discharge of the explosion through blast walls could generate significant overpressure effects outside the containment which are unacceptable. Thus having alternative mitigation solutions can make the effects of the explosion acceptable by reducing the flame speed and the overpressure loading or suppressing the secondary explosion. The objective of this paper is to present the experimental study of the mitigation of hydrogen-air deflagration in a 4 m3 vented enclosure by injection of aqueous foam. After a description of the experimental set-up the main experimental results are presented showing the influence of aqueous foam on flame propagation (Fig. 1). Different foam expansion ratios were investigated. An interpretation of the mitigating effect of foam on the explosion effects is proposed based on the work of Kichatov [5] and Zamashchikov [2].

Green hydrogen is often promoted as a key facilitator for the clean energy transition but its implementation raises concerns around energy justice. This paper examines the socio-political and techno-economic challenges that green hydrogen projects may pose to the three tenets of energy justice: distributive procedural and recognition justice. From a socio-political perspective the risk of neocolonial resource extraction uneven distribution of benefits exclusion of local communities from decision-making and disregard for indigenous rights and cultures threaten all three justice tenets. Techno-economic factors such as water scarcity land disputes and resource-related conflicts in potential production hotspots further jeopardise distributive and recognition justice. The analysis framed by an adapted PEST model reveals that while green hydrogen holds promise for sustainable development its implementation must proactively address these justice challenges. Failure to do so could perpetuate injustices exploitation and marginalisation of vulnerable communities undermining the sustainability goals it aims to achieve. The paper highlights the need for inclusive and equitable approaches that respect local sovereignty integrate diverse stakeholders and ensure fair access and benefit-sharing. Only by centring justice considerations can the transition to green hydrogen catalyse positive social change and realise its full potential as a driver of sustainable energy systems.

High-pressure hydrogen tanks which are composed of an aluminum alloy liner and a carbon fiber wound layer are currently the most popular means to store hydrogen on vehicles. Nevertheless the aluminum alloy is easily affected by high-pressure hydrogen which leads to the appearance of hydrogen embrittlement (HE). Serious HE of hydrogen tank represents a huge dangers to the safety of vehicles and passengers. It is critical and timely to outline the mainstream approach and point out potential avenues for further investigation of HE. An analysis including the mechanism (including hydrogen-enhanced local plasticity model hydrogen-enhanced decohesion mechanism and hydrogen pressure theory) the detection (including slow strain rate test linearly increasing stress test and so on) and methods for the prevention of HE on aluminum alloys of hydrogen vehicles (such as coating) are systematically presented in this work. Moreover the entire experimental detection procedures for HE are expounded. Ultimately the prevention measures are discussed in detail. It is believed that further prevention measures will rely on the integration of multiple prevention methods. Successfully solving this problem is of great significance to reduce the risk of failure of hydrogen storage tanks and improve the reliability of aluminum alloys for engineering applications in various industries including automotive and aerospace.

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

In the last few decades the problem of pollution resulting from human activities has pushed research toward zero or net-zero carbon solutions for transportation. The main objective of this paper is to perform a preliminary performance assessment of the use of hydrogen in conventional turbine engines for aeronautical applications. A 0-D dynamic model of the Allison 250 C-18 turboshaft engine was designed and validated using conventional aviation fuel (kerosene Jet A-1). A dedicated experimental campaign covering the whole engine operating range was conducted to obtain the thermodynamic data for the main engine components: the compressor lateral ducts combustion chamber high- and low-pressure turbines and exhaust nozzle. A theoretical chemical combustion model based on the NASA-CEA database was used to account for the energy conversion process in the combustor and to obtain quantitative feedback from the model in terms of fuel consumption. Once the engine and the turbomachinery of the engine were characterized the work focused on designing a 0-D dynamic engine model based on the engine’s characteristics and the experimental data using the MATLAB/Simulink environment which is capable of replicating the real engine behavior. Then the 0-D dynamic model was validated by the acquired data and used to predict the engine’s performance with a different throttle profile (close to realistic request profiles during flight). Finally the 0-D dynamic engine model was used to predict the performance of the engine using hydrogen as the input of the theoretical combustion model. The outputs of simulations running conventional kerosene Jet A-1 and hydrogen using different throttle profiles were compared showing up to a 64% reduction in fuel mass flow rate and a 3% increase in thermal efficiency using hydrogen in flight-like conditions. The results confirm the potential of hydrogen as a suitable alternative fuel for small turbine engines and aircraft.

The chemical industry serves as a global economic backbone and it is an intensive consumer of conventional energy. Due to the depletion of fossil fuels and the emission of greenhouse gases it is necessary to analyze energy supply solutions based on renewable energy sources in this industrial sector. Unlike other sectors such as residential or service industries which have been thoroughly analyzed by the scientific community the use of renewable energies in the chemical industry remains comparatively less examined by the scientific community. This article studies the use of an energy supply system based on photovoltaic technology or a PEM fuel cell for a styrene production industry analyzing the integration of energy storage systems such as batteries as well as different uses for the surplus hydrogen produced by the facility. The most interesting conclusions of the article are: (1) the renewable microgrid considered is viable both technically and economically with a discounted payback period between 5.4 and 6.5 years using batteries as an energy storage system; and (2) the use of hydrogen as energy storage system for a styrene industry is not yet a viable option from an economic point of view.

The iron and steel industry is a major emitter of carbon dioxide globally. To reduce their carbon footprint the iron and steel industry pursue different decarbonization strategies including deploying bio-based materials and energy carriers for reduction carburisation and/or energy purposes along their value-chains. In this study two potential roles for biomass were analysed: (a) substituting for fossil fuels in iron-ore pellets induration and (b) carburisation of DRI (direct reduced iron) produced via fully hydrogen-based reduction. The purpose of the study was to analyse the regional demand-driven price and allocative effects of biomass assortments under different biomass demand scenarios for the Swedish iron and steel industry. Economic modelling was used in combination with spatial biomass supply assessments to predict the changes on relevant biomass markets. The results showed that the estimated demand increases for forest biomass will have significant regional price effects. Depending on scenario the biomass demand will increase up to 25 percent causing regional prices to more than doubling. In general the magnitude of the price effects was driven by the volumes and types of biomasses needed in the different scenarios with larger price effects for harvesting residues and industrial by-products compared to those of roundwood. A small price effect of roundwood means that the incentives for forest-owners to increase their harvests and thus also the availability of harvest residues are small. Flexibility in the feedstock sourcing (both regarding quality and geographic origin) will thus be important if forest biomass is to satisfy demands in iron and steel industry.

In case of accidental conditions involving high-speed hydrogen combustion the considerable pressure and thermal loads could result in substantial deformation and/or destruction of the industrial appliances. Accounting of such effects in the safety analysis with CFD tools can provide critical information on the design and construction of the sensitive appliances’ elements. The current paper presents the development and the implementation of a new 3D-technique which makes possible to perform simulations of the gas-dynamic processes simultaneously with adaptation of the geometry of complex configurations. Using the data obtained in the experiments on the flame acceleration and DDT in the tubes of industrial arrangements performed in MPA and KIT the authors performed a series of the combustion simulations corresponding to the experimental conditions. The combustion gas-dynamics was simulated using COM3D code and the tube wall material behavior was modelled using finite-element code ABAQUS - © Dassault Systèmes with real-time data exchange between the codes. Obtained numerical results demonstrated good agreement with the observed experimental data on both pressure dynamics and tube deformation history.

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

With the adjustment of energy structure the utilization of hydrogen energy has been widely attended. China’s carbon neutrality targets make it urgent to change traditional coal-fired power generation. The paper investigates the combustion of pulverized coal blended with hydrogen to reduce carbon emissions. In terms of calorific value the pulverized coal combustion with hydrogen at 1% 5% and 10% blending ratios is investigated. The results show that there is a significant reduction in CO2 concentration after hydrogen blending. The CO2 concentration (mole fraction) decreased from 15.6% to 13.6% for the 10% hydrogen blending condition compared to the non-hydrogen blending condition. The rapid combustion of hydrogen produces large amounts of heat in a short period which helps the ignition of pulverized coal. However as the proportion of hydrogen blending increases the production of large amounts of H2O gives an overall lower temperature. On the other hand the temperature distribution is more uniform. The concentrations of O2 and CO in the upper part of the furnace increased. The current air distribution pattern cannot satisfy the adequate combustion of the fuel after hydrogen blending.

This work investigated hydrogen production from biomass feedstocks (i.e. glucose starch lignin and cellulose) using a 100 mL h-type proton exchange membrane electrolysis cell. Biomass electrolysis is a promising process for hydrogen production although low in technology readiness level but with a series of recognised advantages: (i) lower-temperature conditions (compared to thermochemical processes) (ii) minimal energy consumption and low-cost post-production (iii) potential to synthesise high-volume H2 and (iv) smaller carbon footprint compared to thermochemical processes. A Lewis acid (FeCl3 ) was employed as a charge carrier and redox medium to aid in the depolymerisation/oxidation of biomass components. A comprehensive analysis was conducted measuring the H2 and CO2 emission volume and performing electrochemical analysis (i.e. linear sweep voltammetry and chronoamperometry) to better understand the process. For the first time the influence of temperature on current density and H2 evolution was studied at temperatures ranging from ambient temperature (i.e. 19 ◦C) to 80 ◦C. The highest H2 volume was 12.1 mL which was produced by FeCl3 -mediated electrolysis of glucose at ambient temperature which was up to two times higher than starch lignin and cellulose at 1.20 V. Of the substrates examined glucose also showed a maximum power-to-H2 -yield ratio of 30.99 kWh/kg. The results showed that hydrogen can be produced from biomass feedstock at ambient temperature when a Lewis acid (FeCl3 ) is employed and with a higher yield rate and a lower electricity consumption compared to water electrolysis.

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

The need to reduce the carbon footprint of conventional energy sources has made green hydrogen a promising solution for the energy transition. The most environmentally friendly way to produce hydrogen is through water-based production using renewable energy. However the availability of fresh water is limited so switching to wastewater instead of fresh water is the key solution to this problem. In response to this issue the present review reports the main findings of the research studies dealing with the feasibility of hydrogen production from wastewater using various technologies including biological electrochemical and advanced oxidation routes. These methods have been studied in a large number of experiments with the aim of investigating and improving the potential of each method. On the other hand the maturity of solar energy technologies has led researchers to focus on the possibility of harnessing this source and combining it with wastewater treatment techniques for the production of green hydrogen. Therefore the present review pays special attention to solar driven hydrogen production from wastewater by highlighting the potential of several technologies for simultaneous water treatment and green hydrogen production from wastewater. Recent results limitations challenges possible improvements and techno-economic assessments reported by several authors as well as future directions of research and industrial implementation in this field are reported.

Currently there is a growing interest in increasing the power range of air-cooled fuel cells (ACFCs) as they are cheaper easier to use and maintain than water-cooled fuel cells (WCFCs). However air-cooled stacks are only available up to medium power (<10 kW). Therefore a good solution may be the development of ACFCs consisting of several stacks until the required power output is reached. This is the concept of air-cooled multi-stack fuel cell (AC-MSFC). The objective of this work is to develop a turnkey solution for the integration of AC-MSFCs in renewable microgrids specifically those with high-voltage DC (HVDC) bus. This is challenging because the AC-MSFCs must operate in the microgrid as a single ACFC with adjustable power depending on the number of stacks in operation. To achieve this the necessary power converter (ACFCs operate at low voltages so high conversion rates are required) and control loops must be developed. Unlike most designs in the literature the proposed solution is compact forming a system (AC-MSFCS) with a single input (hydrogen) and a single output (high voltage regulated power or voltage) that can be easily integrated into any microgrid and easily scalable depending on the power required. The developed AC-MSFCS integrates stacks balance of plant data acquisition and instrumentation power converters and local controllers. In addition a virtual instrument (VI)has been developed which connected to the energy management system (EMS) of the microgrid allows monitoring of the entire AC-MSFCS (operating temperature purging cell voltage monitoring for degradation evaluation stacks operating point control and alarm and event management) as well as serving as a user interface. This allows the EMS to know the degradation of each stack and to carry out energy distribution strategies or specific maintenance actions which improves efficiency lifespan and of course saves costs. The experimental results have been excellent in terms of the correct operation of the developed AC-MSFCS. Likewise the accumulated degradation of the stacks was quantified showing cells with a degradation of >80%. The excellent electrical and thermal performance of the developed power converter was also validated which allowed the correct and efficient supply of regulated power (average efficiency above 90%) to the HVDC bus according to the power setpoint defined by the EMS of the microgrid.

Legislation regulating the sustainability requirements for hydrogen technologies relies more and more on life cycle assessments (LCAs). Due to different scopes and development processes different pieces of EU legislation refer to different LCA methodologies with differences in the way multifunctional processes (i.e. co-productions recycling and energy recovery) are treated. These inconsistencies arise because incentive mechanisms are not standardized across sectors even though the end product hydrogen remains the same. The goal of this paper is to compare the life-cycle greenhouse gas (GHG) emissions of hydrogen from four production pathways depending on the multifunctional approach prescribed by the different EU policies (e.g. using substitution or allocation). The study reveals a large variation in the LCA results. For instance the life-cycle GHG emissions of hydrogen co-produced with methanol is found to vary from 1 kg CO2-equivalent/kg H2 (when mass allocation is considered) to 11 kg CO2-equivalent/kg H2 (when economic allocation is used). These inconsistencies could affect the market (e.g. hydrogen from a certain pathway could be considered sustainable or unsustainable depending on the approach) and the environment (e.g. pathways that do not lead to a global emission reduction could be promoted). To mitigate these potential negative effects we urge for harmonized and strict guidelines to assess the life-cycle GHG emissions of hydrogen technologies in an EU policy context. Harmonization should cover international policies too to avoid the same risks when hydrogen will be traded based on its GHG emissions. The appropriate methodological approach for each production pathway should be chosen by policymakers in collaboration with the LCA community and stakeholders from the industry based on the potential market and environmental consequences of such choice.

Following the introduction of the EU’s Hydrogen Strategy in 2020 as part of the European Green Deal some EU member states have deployed a very active hydrogen diplomacy. Germany The Netherlands and Belgium have been the most active ones establishing no less than 40 bilateral hydrogen trade partnerships with 30 potential export countries in the last three years. However concerns have been voiced about whether such hydrogen trade relationships can be economically feasible geopolitically wise environmentally sustainable and socially just. This article therefore evaluates these partnerships considering three risk dimensions: economic political and sustainability (covering both environmental and justice) risks. The analysis reveals that the selection of partner countries entails significant trade-offs. Four groups of partner countries can be identified based on their respective risk profile: “Last Resorts” “Volatile Ventures” “Strategic Gambits” and “Trusted Friends”. Strikingly less than one-third of the agreements are concluded with countries that fall within the “Trusted Friends” category which have the lowest overall risk profile. These findings show the need for policy makers to think much more strategically about which partnerships to pursue and to confront tough choices about which risks and trade-offs they are willing to accept.

Proton Exchange Membrane (PEM) electrolysis an advanced technique for producing hydrogen with efficiency and environmental friendliness signifies the forefront of progress in this domain. Compared to alkaline cells these electrolytic cells offer numerous advantages such as lower operating temperatures enhanced hydrogen production efficiency and eliminating the need for an aqueous solution. However PEM electrolysis still faces limitations due to the high cost of materials used for the membrane and catalysts resulting in elevated expenses for implementing large-scale systems. The pivotal factor in improving PEM electrolysis lies in the Platinum catalyst present on the membrane surface. Enhancing catalytic efficiency through various methods and advancements holds immense significance for the progress of this technology. This study investigates the use of patterned membranes to improve the performance of PEM electrolytic cells toward green hydrogen production. By increasing the Platinum loading across the membrane surface and enhancing catalytic performance these patterned membranes overcome challenges faced by conventionally fabricated counterparts. The findings of this research indicate that membranes with modified surfaces not only exhibit higher current draw but also achieve elevated rates of hydrogen production.

Hydrogen is a promising energy carrier for a low-carbon future energy system as it can be stored on a megaton scale (equivalent to TWh of energy) in subsurface reservoirs. However safe and efficient underground hydrogen storage requires a thorough understanding of the geomechanics of the host rock under fluid pressure fluctuations. In this context we summarize the current state of knowledge regarding geomechanics relevant to carbon dioxide and natural gas storage in salt caverns and depleted reservoirs. We further elaborate on how this knowledge can be applied to underground hydrogen storage. The primary focus lies on the mechanical response of rocks under cyclic hydrogen injection and production fault reactivation the impact of hydrogen on rock properties and other associated risks and challenges. In addition we discuss wellbore integrity from the perspective of underground hydrogen storage. The paper provides insights into the history of energy storage laboratory scale experiments and analytical and simulation studies at the field scale. We also emphasize the current knowledge gaps and the necessity to enhance our understanding of the geomechanical aspects of hydrogen storage. This involves developing predictive models coupled with laboratory scale and field-scale testing along with benchmarking methodologies.

In this review we compare hydrogen production from waste by pyrolysis and bioprocesses. In contrast the pyrolysis feed was limited to plastic and tire waste unlikely to be utilized by biological decomposition methods. Recent risks of pyrolysis such as pollutant emissions during the heat decomposition of polymers and high energy demands were described and compared to thresholds of bioprocesses such as dark fermentation. Many pyrolysis reactors have been adapted for plastic pyrolysis after successful investigation experiences involving waste tires. Pyrolysis can transform these wastes into other petroleum products for reuse or for energy carriers such as hydrogen. Plastic and tire pyrolysis is part of an alternative synthesis method for smart polymers including semi-conductive polymers. Pyrolysis is less expensive than gasification and requires a lower energy demand with lower emissions of hazardous pollutants. Short-time utilization of these wastes without the emission of metals into the environment can be solved using pyrolysis. Plastic wastes after pyrolysis produce up to 20 times more hydrogen than dark fermentation from 1 kg of waste. The research summarizes recent achievements in plastic and tire waste pyrolysis development.

n the pursuit of sustainable energy solutions the integration of renewable energy sources and hydrogen technologies has emerged as a promising avenue. This paper introduces the Integrated Renewable Energy-Driven Hydrogen System as a holistic approach to achieve energy independence and self-sufficiency. Seamlessly integrating renewable energy sources hydrogen production storage and utilization this system enables diverse applications across various sectors. By harnessing solar and/or wind energy the Integrated Renewable EnergyDriven Hydrogen System optimizes energy generation distribution and storage. Employing a systematic methodology the paper thoroughly examines the advantages of this integrated system over other alternatives emphasizing its zero greenhouse gas emissions versatility energy resilience and potential for large-scale hydrogen production. Thus the proposed system sets our study apart offering a distinct and efficient alternative compared to conventional approaches. Recent advancements and challenges in hydrogen energy are also discussed highlighting increasing public awareness and technological progress. Findings reveal a payback period ranging from 2.8 to 6.7 years depending on the renewable energy configuration emphasizing the economic attractiveness and potential return on investment. This research significantly contributes to the ongoing discourse on renewable energy integration and underscores the viability of the Integrated Renewable EnergyDriven Hydrogen System as a transformative solution for achieving energy independence. The employed model is innovative and transferable to other contexts.

In the context of the increasingly strict pollutant emission regulations and carbon emission reduction targets proposed by the International Maritime Organization the shipping industry is seeking new types of marine power plants with the advantages of high efficiency and low emissions. Among the possible alternatives the fuel cell is considered to be the most practical technology as it provides an efficient means to generate electricity with low pollutant emissions and carbon emissions. Very few comprehensive reviews focus on the maritime applications of the fuel cell. Thus news reports and literature on the maritime applications of the fuel cell in the past sixty years were collected and the industrial development status and prospects of the marine fuel cell were summarized as follows. Some countries in Europe North America and Asia have invested heavily in researching and developing the marine fuel cell and a series of research projects have achieved concrete results such as the industrialized marine fuel cell system or practical demonstration applications. At present the worldwide research of the marine fuel cell focuses more on the proton exchange membrane fuel cell (PEMFC). However the power demand of the marine fuel cell in the future will show steady growth and thus the solid oxide fuel cell (SOFC) with the advantages of higher power and fuel diversity will be the mainstream in the next research stage. Although some challenges exist the SOFC can certainly lead the upgrading and updating of the marine power system with the cooperative efforts of the whole world.

The production of hydrogen-based dense energy carriers (DECs) has been proposed as a combined solution for the storage and dispatch of power generated through intermittent renewables. Frameworks that model and optimize the production storage and dispatch of generated energy are important for data-driven decision making in the energy systems space. The proposed multiperiod framework considers the evolution of technology costs under different levels of promotion through research and targeted policies using the year 2021 as a baseline. Furthermore carbon credits are included as proposed by the 45Q tax amendment for the capture sequestration and utilization of carbon. The implementation of the mixed-integer linear programming (MILP) framework is illustrated through computational case studies to meet set hydrogen demands. The trade-offs between different technology pathways and contributions to system expenditure are elucidated and promising configurations and technology niches are identified. It is found that while carbon credits can subsidize carbon capture utilization and sequestration (CCUS) pathways substantial reductions in the cost of novel processes are needed to compete with extant technology pathways. Further research and policy push can reduce the levelized cost of hydrogen (LCOH) by upwards of 2 USD/kg.

Electrification using renewable energy sources represents a clear path toward solving the current global energy crisis. In Colombia this challenge also involves the diversification of the electrical energy sources to overcome the historical dependence on hydropower. In this context green hydrogen represents a key energy carrier enabling the storage of renewable energy as well as directly powering industrial and transportation sectors. This work explores the realistic potential of the main renewable energy sources including solar photovoltaics (8172 GW) hydropower (56 GW) wind (68 GW) and biomass (14 GW). In addition a case study from abroad is presented demonstrating the feasibility of using each type of renewable energy to generate green hydrogen in the country. At the end an analysis of the most likely regions in the country and paths to deploy green hydrogen projects are presented favoring hydropower in the short term and solar in the long run. By 2050 this energy potential will enable reaching a levelized cost of hydrogen (LCOH) of 1.7 1.5 3.1 and 1.4 USD/kg-H2 for solar photovoltaic wind hydropower and biomass respectively.

In the framework of the “Multidisciplinary Optimization and Regulations for Low-boom and Environmentally Sustainable Supersonic aviation” project pursued by a consortium of European government and academic institutions coordinated by Politecnico di Torino under the European Commission Horizon 2020 financial support the Italian Aerospace Research Centre is computationally investigating the high-pressure hydrogen/air kinetic combustion in the operative conditions typically encountered in supersonic aeronautic ramjet engines. This task is being carried out starting from the zero-dimensional and one-dimensional chemical kinetic assessment of the complex and strongly pressure-sensitive ignition behavior and flame propagation characteristics of hydrogen combustion through the validation against experimental shock tube and laminar flame speed measurements. The 0D results indicate that the kinetic mechanism by Politecnico di Milano and the scheme formulated by Kéromnès et al. provide the best matching with the experimental ignition delay time measurements carried out in high-pressure shock tube strongly argon-diluted reaction conditions. Otherwise the best behavior in terms of laminar flame propagation is achieved by the Mueller scheme while the other investigated kinetic mechanisms fail to predict the flame speeds at elevated pressures. This confirms the non-linear and intensive pressure-sensitive behavior of hydrogen combustion especially in the critical high-pressure and low-temperature region which is hard to be described by a single all-encompassing chemical model.

As a clean and renewable energy carrier hydrogen is one of the most promising alternative fuels. Cryogenic compressed hydrogen can achieve high storage density without liquefying hydrogen which has good application prospects. Investigation of the safety problems of cryogenic compressed hydrogen is necessary before massive commercialization. The present study modeled the instantaneous flow field using the Large Eddy Simulation (LES) for cryogenic (50 and 100 K) underexpanded hydrogen jets released from a round nozzle of 1.5 mm diameter at pressures of 0.5-5.0 MPa. The simulation results were compared with the experimental data for validation. The axial and radial concentration and velocity distributions were normalized to show the self-similar characteristics of underexpanded cryogenic jets. The shock structures near the nozzle were quantified to correlate the shock structure sizes to the source pressure and nozzle diameter. The present study on the concentration and velocity distributions of underexpanded cryogenic hydrogen jets is useful for developing safety codes and standards.

Hydrogen is an important raw material in chemical industries and the steam reforming of light hydrocarbons (such as methane) is the most used process for its production. In this process the use of a catalyst is mandatory and if compared to precious metal-based catalysts Ni-based catalysts assure an acceptable high activity and a lower cost. The aim of a distributed hydrogen production for example through an on-site type hydrogen station is only reachable if a novel reforming system is developed with some unique properties that are not present in the large-scale reforming system. These properties include among the others (i) daily startup and shutdown (DSS) operation ability (ii) rapid response to load fluctuation (iii) compactness of device and (iv) excellent thermal exchange. In this sense the catalyst has an important role. There is vast amount of information in the literature regarding the performance of catalysts in methane steam reforming. In this short review an overview on the most recent advances in Ni based catalysts for methane steam reforming is given also regarding the use of innovative structured catalysts.

Environmental emissions global warming and energy-related concerns have accelerated the advancements in conventional vehicles that primarily use internal combustion engines. Among the existing technologies hydrogen fuel cell electric vehicles and fuel cell hybrid electric vehicles may have minimal contributions to greenhouse gas emissions and thus are the prime choices for environmental concerns. However energy management in fuel cell electric vehicles and fuel cell hybrid electric vehicles is a major challenge. Appropriate control strategies should be used for effective energy management in these vehicles. On the other hand there has been significant progress in artificial intelligence machine learning and designing data-driven intelligent controllers. These techniques have found much attention within the community and state-of-the-art energy management technologies have been developed based on them. This manuscript reviews the application of machine learning and intelligent controllers for prediction control energy management and vehicle to everything (V2X) in hydrogen fuel cell vehicles. The effectiveness of data-driven control and optimization systems are investigated to evolve classify and compare and future trends and directions for sustainability are discussed.

Due to the large quantities of carbon emissions generated by the transportation sector cleaner automotive technologies are needed aiming at a green energy transition. In this scenario hydrogen is pointed out as a promising fuel that can be employed as the fuel of either a fuel cell or an internal combustion engine vehicle. Therefore in this work we propose the design and modeling of a fuel cell versus an internal combustion engine passenger car for a driving cycle. The simulation was carried out using the quasistatic simulation toolbox tool in Simulink considering the main powertrain components for each vehicle. Furthermore a brief analysis of the carbon emissions associated with the hydrogen production method is addressed to assess the clean potential of hydrogen-powered vehicles compared to conventional fossil fuel-fueled cars. The resulting analysis has shown that the hydrogen fuel cell vehicle is almost twice as efficient compared to internal combustion engines resulting in a lower fuel consumption of 1.05 kg-H2/100 km in the WLTP driving cycle for the fuel cell vehicle while the combustion vehicle consumed about 1.79 kg-H2/100 km. Regarding using different hydrogen colors to fuel the vehicle hydrogen-powered vehicles fueled with blue and grey hydrogen presented higher carbon emissions compared to petrol-powered vehicles reaching up to 2–3 times higher in the case of grey hydrogen. Thus green hydrogen is needed as fuel to keep carbon emissions lower than conventional petrol-powered vehicles.

This article presents a comprehensive description of the safety system of a real installation that comprises PV panels lithium-ion batteries an electrolyzer H2 storage a fuel cell and a barium chloride/ammonia thermochemical prototype for heat recovery and cooling production. Such a system allows for the increase of the overall efficiency of the H2 chain by exploiting the waste heat and transforming it into a cooling effect particularly useful in tropical regions like French Polynesia. The study provides a great deal of detail regarding practical aspects of the system implementation and a consistent reference to the relevant standards and regulations applicable to the subject matter. More specifically the study covers the ATEX classification of the site the safety features of each component the electrical power distribution the main safety instrumented system fire safety and the force ventilation system. The study also includes safety assessment and a section on lessons learned that could serve as guidance for future installations. In addition an extensive amount of technical data is readily available to the reader in repository (P&ID electrical diagrams etc.).

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

Hydrogen is anticipated to play a key role in global decarbonization and within the UK’s pathway to achieving net zero targets. However as the production of hydrogen expands in line with government strategies a key concern is where this hydrogen will be stored for later use. This study assesses the different large-scale storage options in geological structures available to the UK and addresses the surrounding uncertainties moving towards establishing a hydrogen economy. Currently salt caverns look to be the most favourable option considering their proven experience in the storage of hydrogen especially high purity hydrogen natural sealing properties low cushion gas requirement and high charge and discharge rates. However their geographical availability within the UK can act as a major constraint. Additionally a substantial increase in the number of new caverns will be necessary to meet the UK’s storage demand. Salt caverns have greater applicability as a good short-term storage solution however storage in porous media such as depleted hydrocarbon reservoirs and saline aquifers can be seen as a long-term and strategic solution to meet energy demand and achieve energy security. Porous media storage solutions are estimated to have capacities which far exceed projected storage demand. Depleted fields have generally been well explored prior to hydrocarbon extraction. Although many saline aquifers are available offshore UK geological characterizations are still required to identify the right candidates for hydrogen storage. Currently the advantages of depleted gas reservoirs over saline aquifers make them the favoured option after salt caverns.

In the frame of hydrogen-powered aircraft Airbus wants to understand all the H2 physics and explore every scenario in order to develop and manufacture safe products operated in a safe environment. Within the framework of a Large Eddy Simulation (LES) methodology for modeling turbulence a comparative numerical study of free under-expanded jet H2/AIR flame is conducted. The investigated geometry consists of straight nozzles with a millimetric diameter fed with pure H2 at upstream pressures ranging from 2 to 10 bar. Numerical results are compared with available experimental measurements such as; temperature signals using thermocouples. LES confirms its prediction capability in terms of shock jet structure and flame length. A particular attention is paid for capturing experimental unstable flame when upstream pressure decreases. Furthermore flame stabilization and flame anchoring are analyzed. Mechanisms of flame stabilization are highlighted for case 1 and stabilization criteria are tested. Finally an ignition map to reach flame stabilization is proposed for each case regarding the literature.

Electrification of the transportation sector is one of the main drivers in the decarbonization of energy and mobility systems and it is a way to ensure security of energy supply. Public bus fleets can assist in achieving fast reduction of CO2 emissions. This article provides an analysis of a unique real-world dataset to support decision makers in the decarbonization of public fleets and interlink it with the social acceptance of drivers. Data was collected from 21 fuel cell and electric buses. The tank-to-wheel efficiency results of fuel cell electric buses (FCEB) are much lower than that of battery electric buses (BEB) and there is a higher variation in consumption for BEBs compared to FCEBs. Both technologies permit a strong reduction in CO2 emissions compared to conventional buses. There is a high level of acceptance of drivers which are likely to support the transition towards zero-emission buses introduced by the management.

In light of the Italian Hydrogen Roadmap goals the 2030 national RES installation targets need to be redefined. This work aims to propose a more appropriate RES installation deployment on national scale by matching the electrolysers capacity and the green hydrogen production goals. The adopted approach envisages the power-to-gas value chain priority for the green hydrogen production as a means of balancing system. Thus the 2030 Italian energy system has been modelled and several RES installation scenarios have been simulated via EnergyPLAN software. The simulation outputs have been integrated with a breakdown model for the overgeneration RES share detection in compliance with the PV dispatching priority of the Italian system. Therefore the best installation solutions have been detected via multi-objective optimization model based on the green hydrogen production additional installation cost critical energy excess along with the Levelized Cost of Hydrogen (LCOH). Higher wind technology installations provide more competitive energy and hydrogen costs. The most suitable scenarios show that the optimal LCOH and hydrogen production values respectively equal to 3.6 €/kg and 223 ktonH2 arise from additional PV/wind installations of 35 GW on top of the national targets.

The road-transport is one of the major contributors to greenhouse global gas (GHG) emissions where hydrogen (H2) combustion engines can play a crucial role in the path towards the sector’s decarbonization goal. This study focuses on comparing the performance and emissions of port-fuel injection (PFI) and direct injection (DI) in a spark ignited combustion engine when is fuelled by hydrogen and other noteworthy fuels like methane and coke oven gas (COG). Computational fluid dynamic simulations are performed at optimal spark advance and air-fuel ratio (λ) for engine speeds between 2000 and 5000 rpm. Analysis reveals that brake power increases by 40% for DI attributed to 30.6% enhanced volumetric efficiency while the sNOx are reduced by 36% compared to PFI at optimal λ = 1.5 for hydrogen. Additionally H2 results in 71.8% and 67.2% reduction in fuel consumption compared to methane and COG respectively since the H2 lower heating value per unit of mass is higher.

Fuel cell-battery electric drivetrains are attractive alternatives to reduce the shipping emissions. This research focuses on emission-free cargo vessels and provides insight on the design lifetime operation and costs of hydrogen-hybrid systems which require further research for increased utilization. A representative round trip is created by analysing one-year operational data based on load ramps and power frequency. A low-pass filter controller is employed for power distribution. For the lifetime cost analysis 14 scenarios with varying capital and operational expenses were considered. The Net Present Value of the retrofitted fuel cell-battery propulsion system can be up to $ 2.2 million lower or up to $ 18.8 million higher than the original diesel mechanical configuration highly dependent on the costs of green hydrogen and carbon taxes. The main propulsion system weights and volumes of the two versions are comparable but the hydrogen tank (68 tons 193 m3 ) poses significant design and safety challenges.

To reduce the impact of the agricultural sector on the environment human health and resource depletion several steps should be taken to develop innovative powertrain systems. The agricultural sector must be involved in this innovation since diesel-powered tractors are an important source in terms of pollution. In this context fuel-cell systems have gained importance making them one of the possible substitutes due to their characteristics featuring almost zero local emissions low refueling time and high efficiency. However to effectively assess the sustainability of a fuel-cell tractor a cradle-to-grave life cycle assessment comprising production use phase and end of life must be performed. This article presents a comparative analysis according to different impact categories of the life cycle impacts of a traditional diesel-powered tractor and a fuel-cell hybrid tractor designed considering operative requirements and functional constraints. The study was conducted according to the LCA technique (defined by ISO 14040 and ISO 14044 standards) combining secondary data mainly derived from studies and reports available in the literature with the use of the Ecoinvent 3.0 database. The results are presented according to ten different impact categories defined by ReCiPe 2016 v 1.03 at the midpoint level. The findings obtained showed that the fuel-cell tractor allows for a relevant reduction in all the considered categories. The highest-impact reduction more than 92% was obtained in the human toxicity non-carcinogenic category while the lowest reduction around 4.55% was observed for the fossil fuel scarcity category mainly due to the adoption of gray hydrogen which is produced from fossil fuels. As for the climate change category the fuel-cell tractor showed a reduction of more than 34% in the life cycle impact. Finally the authors also considered the case of green hydrogen produced using solar energy. In this case further reductions in the impact on climate change and fossil fuel resource depletion were obtained. However for the other impact categories the results were worse compared to using gray hydrogen.

This paper presents work undertaken by the HSE as part of the Hytunnel-CS project a consortium investigating safety considerations for fuel cell hydrogen (FCH) vehicles in tunnels and similar confined spaces.<br/>Hydrogen vehicles typically have a Thermally activated Pressure Release Device (TPRD) providing protection to the on-board storage of the vehicle. Upon activation the content of the vessel is released in a blowdown. The release of this hydrogen gas poses a significant hazard of ignition. The consequences of such an ignition could also be compounded by confinement or congestion.<br/>HSE undertook a series of experiments investigating the consequences of these events by releasing hydrogen into a tunnel and causing ignitions. A sub-section of these tests involved steel structures providing congestion in the tunnel. The mass of hydrogen released into the tunnel prior to ignition was varied by storage pressure (up to 59 MPa) release diameter and ignition delay. The ignition delays were set based on the expected worst-case predicted by pre-simulation models. To assess the consequences overpressure measurements were made down the tunnel walls and for the tests with congestion at the face and rear of the congestion structures. The flame arrival time was also measured using exposed-tip thermocouples resulting in an estimate for flame speed down the tunnel. The measured overpressure and flame extent results are presented and compared against overpressure levels of concern.

This review comprehensively evaluates the integration of solar-powered electrolytic hydrogen (H2) production and captured carbon dioxide (CO2) management for clean fuel production considering all potential steps from H2 production methods to CO2 capture and separation processes. It is expected that the near future will cover CO2-capturing technologies integrated with solar-based H2 production at a commercially viable level and over 5 billion tons of CO2 are expected to be utilized potentially for clean fuel production worldwide in 2050 to achieve carbon-neutral levels. The H2 production out of hydrocarbon-based processes using fossil fuels emits greenhouse gas emissions of 17-38 kg CO2/kg H2. On the other hand . renewable energy based green hydrogen production emits less than 2 kg CO2/kg H2 which makes it really clean and appealing for implementation. In addition capturing CO2 and using for synthesizing alternative fuels with green hydrogen will help generate clean fuels for smart cities. In this regard the most sustainable and promising CO2 capturing method is post-combustion with an adsorption-separation-desorption processes using monoethanolamine adsorbent with high CO2 removal efficiencies from flue gases. Consequently this review article provides perspectives on the potential of integrating CO2-capturing technologies and renewable energy-based H2 production systems for clean production to create sustainable cities and communities.

Green hydrogen is becoming increasingly popular with academics institutions and governments concentrating on its development efficiency improvement and cost reduction. The objective of the Ministry of Petroleum Mines and Energy is to achieve a 35% proportion of renewable energy in the overall energy composition by the year 2030 followed by a 50% commitment by 2050. This goal will be achieved through the implementation of feed-in tariffs and the integration of independent power generators. The present study focused on the economic feasibility of green hydrogen and its production process utilizing renewable energy resources on the northern coast of Mauritania. The current investigation also explored the wind potential along the northern coast of Mauritania spanning over 600 km between Nouakchott and Nouadhibou. Wind data from masts Lidar stations and satellites at 10 and 80 m heights from 2022 to 2023 were used to assess wind characteristics and evaluate five turbine types for local conditions. A comprehensive techno-economic analysis was carried out at five specific sites encompassing the measures of levelized cost of electricity (LCOE) and levelized cost of green hydrogen (LCOGH) as well as sensitivity analysis and economic performance indicators. The results showed an annual average wind speed of 7.6 m/s in Nouakchott to 9.8 m/s in Nouadhibou at 80 m. The GOLDWIND 3.0 MW model showed the highest capacity factor of 50.81% due to its low cut-in speed of 2.5 m/s and its rated wind speed of 10.5 to 11 m/s. The NORDEX 4 MW model forecasted an annual production of 21.97 GWh in Nouadhibou and 19.23 GWh in Boulanoir with the LCOE ranging from USD 5.69 to 6.51 cents/kWh below the local electricity tariff and an LCOGH of USD 1.85 to 2.11 US/kg H2 . Multiple economic indicators confirmed the feasibility of wind energy and green hydrogen projects in assessed sites. These results boosted the confidence of the techno-economic model highlighting the resilience of future investments in these sustainable energy infrastructures. Mauritania’s north coast has potential for wind energy aiding green hydrogen production for energy goals.

A new dimensionless number (DN) is proposed in order to evaluate the performance of a high-pressure vessel composite structure. It shows that very few composite part is used at its maximum loading potential during bursting. Today for 70 MPa on-board type IV composite tanks DN values close to 20%. The suggested DN will be a useful indicator for an industrial application. By maximizing the DN at the design phase it is possible to minimize the mass of the composite structure of a CPV to reduce the manufacturing time and cost. To increase the DN as close as possible to 100% it is necessary to succeed in increasing the overall loading of the composite structure to have better oriented fibre. For this it seems necessary to find new processes which make it possible to better orient the fibre.

In recent years there has been a significant increase in research on hydrogen due to the urgent need to move away from carbon-intensive energy sources. This transition highlights the critical role of hydrogen storage technology where hydrogen tanks are crucial for achieving cleaner energy solutions. This paper aims to provide a general overview of hydrogen treatment from a mechanical viewpoint and to create a comprehensive review that integrates the concepts of hydrogen safety and storage. This study explores the potential of hydrogen applications as a clean energy alternative and their role in various sectors including industry automotive aerospace and marine fields. The review also discusses design technologies safety measures material improvements social impacts and the regulatory landscape of hydrogen storage tanks and safety technology. This work provides a historical literature review up to 2014 and a systematic literature review from 2014 to the present to fill the gap between hydrogen storage and safety. In particular a fundamental feature of this work is leveraging systematic procedural techniques for performing an unbiased review study to offer a detailed analysis of contemporary advancements. This innovative approach differs significantly from conventional review methods since it involves a replicable scientific and transparent process which culminates in minimizing bias and allows for highlighting the fundamental issues about the topics of interest and the main conclusions of the experts in the field of reference. The systematic approach employed in the paper was used to analyze 55 scientific articles resulting in the identification of six primary categories. The key findings of this review work underline the need for improved materials enhanced safety protocols and robust infrastructure to support hydrogen adoption. More importantly one of the fundamental results of the present review analysis is pinpointing the central role that composite materials will play during the transition toward hydrogen applications based on thin-walled industrial vessels. Future research directions are also proposed in the paper thereby emphasizing the importance of interdisciplinary collaboration to overcome existing challenges and facilitate the safe and efficient use of hydrogen.

Healthcare facilities in isolated rural areas of sub-Saharan Africa face challenges in providing essential health services due to unreliable energy access. This study examines the use of hybrid renewable energy systems consisting of solar PV wind turbines batteries and hydrogen storage for the electrification of rural healthcare facilities in Nigeria and South Africa. The study deployed the efficacy of Hybrid Optimization of Multiple Energy Resources software for techno-economic analysis and the Evaluation based on the Distance from Average Solution method for multicriteria decision-making for sizing optimizing and selecting the optimal energy system. Results show that the optimal configurations achieve cost-effective levelized energy costs ranging from $0.336 to $0.410/kWh for both countries. For the Nigeria case study the optimal energy system includes 5 kW PV 10 kW fuel cell 10 kW inverter 10 kW electrolyzer and 16 kg hydrogen tank. South Africa's optimal configuration has 5 kW PV 10 kW battery 10 kW inverter and 7.5 kW rectifier. Solar PV provides more than 90% of energy with dual axis tracking yielding the highest output: 8889kWh/yr for Nigeria and 10470kWh/yr for South Africa. The multi-criteria decisionmaking analysis reveals that Nigeria's preferred option is the hybrid system without tracking. In contrast the horizontal axis weekly adjustment tracking configuration is optimal for South Africa considering technical economic and environmental criteria. The findings highlight the importance of context-specific optimization for hybrid renewable energy systems in rural healthcare facilities to accelerate Sustainable Development Goals 3 and 7.

The production of hydrogen from photovoltaics (PV) has gained attention due to its potential as an energy vector. In this context there are two basic configurations for electrically coupling PV to hydrogen electrolyzers: direct and indirect. The direct configuration operates variably based on meteorological conditions but has simplicity as an advantage. The indirect configuration involves a power stage (PS) with a maximum power point tracker and a DC-DC converter maintaining an optimal power transfer from PV to electrolyzers but incurs losses at the PS. The direct configuration avoids these losses but requires a specific design of the PV generator to achieve high electrical transfer. The comparative analysis of hydrogen production between these two approaches indicates that the indirect paradigm yields a 37.5% higher hydrogen output throughout a typical meteorological year compared to the optimized direct configuration. This increase enhances the overall sunlight-to-hydrogen efficiency elevating it from 5.0% in the direct case to 6.9% in the indirect one. Furthermore the direct setup sensitive to PV power fluctuations suffers an 18% reduction in hydrogen production with just a 5% reduction in photogenerated power. Under optimal performance the direct coupling produces less hydrogen unless the DCDC converter efficiency drops 17% below commercial standards.

Given China’s ambition to realize carbon peak by 2030 and carbon neutralization by 2060 hydrogen is gradually becoming the pivotal energy source for the needs of energy structure optimization and energy system transformation. Thus hydrogen combined with renewable energy has received more and more attention. Nowadays power-to-hydrogen power-to-methanol and power-to-ammonia are regarded as the most promising three hydrogen-driven power-to-X technologies due to the many commercial or demonstration projects in China. In this paper these three hydrogen-driven power-to-X technologies and their application status in China are introduced and discussed. First a general introduction of hydrogen energy policies in China is summarized and then the basic principles technical characteristics trends and challenges of the three hydrogen-driven power-to-X technologies are reviewed. Finally several typical commercial or demonstration projects are selected and discussed in detail to illustrate the development of the power-to-X technologies in China.

The global green hydrogen rush is prone to repeat extractivist patterns at the expense of economies ecologies and communities in the production zones in the Global South. With a socio-ecological risk analysis grounded in energy water and environmental justice scholarship we systematically assess the risks of the ‘green’ hydrogen transition and related injustices arising in 28 countries in the Global South with regard to energy water land and global justice dimensions. Our findings show that risks materialize through the exclusion of affected communities and civil society the enclosure of land and resources for extractivist purposes and through the externalization of socio-ecological costs and conflicts. We further demonstrate that socio-ecological risks are enhanced through country-specific conditions such as water scarcity historical continuities such as post-colonial land tenure systems as well as repercussions of a persistently uneven global politico-economic order. Contributing to debates on power inequality and justice in the global green hydrogen transition we argue that addressing hydrogen risks requires a framework of environmental justice and a transformative perspective that encompasses structural shifts in the global economy including degrowth and a decentering of industrial hegemonies in the Global North.

The import of hydrogen and derivatives forms part of many national strategies and is fundamental to achieving climate protection targets. This paper provides an overview and technical comparison of import pathways for hydrogen and derivatives in terms of efficiency technological maturity and development and construction times with a focus on the period up to 2030. The import of hydrogen via pipeline has the highest system efficiency at 57–67 % and the highest technological maturity with a technology readiness level (TRL) of 8–9. The import of ammonia and methanol via ship and of SNG via pipeline shows efficiencies in the range of 39–64 % and a technological maturity of TRL 7 to 9 when using point sources. Liquid hydrogen LOHC and Fischer-Tropsch products have the lowest efficiency and TRL in comparison. The use of direct air capture (DAC) reduces efficiency and TRL considerably. Reconversion of the derivatives to hydrogen is also associated with high losses and is not achievable for all technologies on an industrial scale up to 2030. In the short to medium term import routes for derivatives that can utilise existing infrastructures and mature technologies are the most promising for imports. In the long term the most promising option is hydrogen via pipelines.

Air transportation contributes significantly to harmful and greenhouse gas emissions. To combat these issues there has been a recent emergence of aircraft electrification as a potential solution to mitigate environmental concerns and address fuel shortages. However current technologies related to batteries electric machinery and power systems are still in the developmental phase to meet the requirements for power and energy density weight safety and reliability. In the interim there is a focus on the more electric and hybrid electric propulsion systems for aircraft. Hydrogen with its high specific energy and carbon-free characteristics stands out as a promising alternative fuel for aviation. This paper is centred on the application of hydrogen in aircraft propulsion mainly fuel cell hybrid electric (FCHE) propulsion systems. Furthermore application of hydrogen as a fuel for the aircraft propulsion systems is considered. A comprehensive overview of the hydrogen propulsion systems in aviation is presented with an emphasis on the technical aspects crucial for creating a more sustainable and efficient air transportation sector. Additionally the paper acknowledges the technical and regulatory challenges that must be addressed to attain these goals.