Publications

New hypotheses for reusing platforms reaching their end-of-life have been investigated in several works discussing the potential conversions of these infrastructures from recreational tourism to fish farming. In this perspective paper we discuss the conversion options that could be of interest in the context of the current energy transition with reference to the off-shore Italian scenario. The study was developed in support of the development of a national strategy aimed at favoring a circular economy and the reuse of existing infrastructure for the implementation of the energy transition. Thus the investigated options include the onboard production of renewable energy hydrogen production from seawater through electrolyzers CO2 capture and valorization and platform reuse for underground fluid storage in depleted reservoirs once produced through platforms. Case histories are developed with reference to a typical fictitious platform in the Adriatic Sea Italy to provide an engineering-based approach to these different conversion options. The coupling of the platform with the underground storage to set the optimal operational conditions is managed through the forecast of the reservoir performance with advanced numerical models able to simulate the complexity of the phenomena occurring in the presence of coupled hydrodynamic geomechanical geochemical thermal and biological processes. The results of our study are very encouraging because they reveal that no technical environmental or safety issues prevent the conversion of offshore platforms into valuable infrastructure contributing to achieving the energy transition targets as long as the selection of the conversion option to deploy is designed taking into account the system specificity and including the depleted reservoir to which it is connected when relevant. Socio-economic issues were not investigated as they were out of the scope of the project.

The overuse of fossil fuels has caused a serious energy crisis and environmental pollution. Due to these challenges the search for alternative energy sources that can replace fossil fuels is necessary. Hydrogen is a widely acknowledged future energy carrier because of its nonpolluting properties and high energy density. To realize a hydrogen economy in the future it is essential to construct a comprehensive hydrogen supply chain that can make hydrogen a key energy carrier. This paper reviews the various technologies involved in the hydrogen supply chain encompassing hydrogen production storage transportation and utilization technologies. Then the challenges of constructing a hydrogen supply chain are discussed from techno-economic social and policy perspectives and prospects for the future development of a hydrogen supply chain are presented in light of these challenges.

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. The sudden failure of a pressurised hydrogen vessel was identified as a scenario of concern due to the severity of the consequences associated with such an event. In order to investigate this scenario experimentally HSE designed a bespoke and reusable ‘sudden release’ vessel. This paper presents an overview of the vessel and the results of a series of 13 tests whereby hydrogen was released from the bespoke vessel into a tunnel at pressures up to 65 MPa. The starting pressure and the volume of hydrogen in the vessel were altered throughout the campaign. Four of the tests also included congestion in the tunnel. The tests reliably autoignited. Overpressure measurements and flame arrival times measured with exposed-tip thermocouples enabled analysis of the severity of the events. A high-pressure fast-acting pressure transducer in the body of the vessel showed the pressure decay in the vessel which shows that 90% of the hydrogen was evacuated in between 1.8 and 3.2 ms (depending on the hydrogen inventory). Schlieren flow imagery was also used at the release point of the hydrogen showing the progression of the shock front following initiation of the tests. An assessment of the footage shows an estimated initial velocity of Mach 3.9 at 0.4 m from the release point. Based on this an ignition mechanism is proposed based upon the temperature behind the initial shock front.

Trains have been a crucial part of modern transport and their high energy efficiency and low greenhouse gas emissions make them ideal candidates for the future transport system. Transitioning from diesel trains to hydrogen fuel cell electric trains is a promising way to decarbonize rail transport. That’s because the fuel cell electric trains have several advantages over other electric trains such as lower life-cycle emissions and shorter refueling time than battery ones and less requirements for wayside infrastructure than the ones with overhead electric wires. However hydrogen fuel technology still needs to be advanced in areas including hydrogen production storage refueling and on-board energy management. Currently there are several pilot projects of hydrogen fuel cell electric trains across the globe especially in developed countries including one commercialized and permanent route in Germany. The experiences from the pilot projects will promote the technological and economic feasibility of hydrogen fuel in rail transport.

The seasonally varying potential to produce electricity from renewable sources such as wind PV and hydropower is a challenge for the continuous supply of hydrogen for transport and mobility. Seasonal storage of energy allows to avoid the use of grid electricity when it is scarce; storage systems can thus increase the resilience of the energy system. For grid-neutral and renewable hydrogen production an electrolyser is considered together with a Power-to-Gas seasonal storage system which consists of a methanation the gas grid as intermediate storage and a steam reformer. As feed stream electricity from an own photovoltaic (PV) system is considered and for some cases additional electricity from the grid or from a wind turbine. The dynamic operation of the plant during a year is simulated. It is possible to safely supply fuel cell vehicles with hydrogen from the grid-neutral plant without using electricity when it is scarce and expensive. To supply 135 kgH2/day unit sizes of 1 MW–2.9 MW for the PV system and 0.9 MW–2.6 MW for the electrolysis are required depending on the amount of available grid-electricity. The usage of grid-electricity increases the capacity factor of the electrolysis which results in decreased unit sizes and in a better economic performance. Seasonal storage of energy is required which results in an increased hydrogen production in summer of approximately 50% more than directly needed by the fuel cell vehicles. The overall efficiency from electricity to hydrogen is decreased due to the storage path by 10%-points to 56% based on the higher heating value. Assuming a cost-equivalent hydrogen price per driven kilometre in comparison to the actual diesel price and electricity costs of 10 Ct/kWhel from the grid the revenues of the system are higher than the operating costs.

Logistics is becoming more cost competitive while customers and regulatory bodies pressure businesses to disclose their carbon footprints creating interest in alternative fuels as a decarbonization strategy. This paper provides a thematic review of the role of alternative fuels in sustainable air land and sea logistics their challenges and potential mitigations. Through an extensive literature survey we determined that biofuels synthetic kerosene natural gas ammonia alcohols hydrogen and electricity are the primary alternative fuels of interest in terms of environmental sustainability and techno-economic feasibility. In air logistics synthetic kerosene from hydrogenated esters and fatty acids is the most promising route due to its high technical maturity although it is limited by biomass sourcing. Electrical vehicles are favorable in road logistics due to cheaper green power and efficient vehicle designs although they are constrained by recharging infrastructure deployment. In sea logistics liquified natural gas is advantageous owing to its supply chain maturity but it is limited by methane slip control and storage requirements. Overall our examination indicates that alternative fuels will play a pivotal role in the logistics networks of the future.

The article presents the application of the metalog family of probability distributions to predict the energy production of photovoltaic systems for the purpose of generating small amounts of green hydrogen in distributed systems. It can be used for transport purposes as well as to generate energy and heat for housing purposes. The monthly and daily amounts of energy produced by a photovoltaic system with a peak power of 6.15 kWp were analyzed using traditional statistical methods and the metalog probability distribution family. On this basis it is possible to calculate daily and monthly amounts of hydrogen produced with accuracy from the probability distribution. Probabilistic analysis of the instantaneous power generated by the photovoltaic system was used to determine the nominal power of the hydrogen electrolyzer. In order to use all the energy produced by the photovoltaic system to produce green hydrogen the use of a stationary energy storage device was proposed and its energy capacity was determined. The calculations contained in the article can be used to design home green hydrogen production systems and support the climate and energy transformation of small companies with a hydrogen demand of up to ¾ kg/day.

Chemical looping dry reforming of methane (CLDRM) using perovskites as a catalyst is considered a promising option for producing hydrogen from biogas. In this work the life-cycle performance of a system compiling a CLDRM unit paired with a water gas shift unit a pressure swing adsorption unit and a combined cycle scheme to provide steam and electricity was assessed. The main data needed to reflect the behavior of the reforming reaction was obtained experimentally and implemented in an Aspen Plus® simulation. Inventory data was obtained through process simulation and used to assess the environmental performance of the process in terms of carbon footprint acidification freshwater eutrophication ozone depletion photochemical ozone formation and depletion of minerals and metals. Overall the environmental viability of the production of green hydrogen from biogas was found to be heavily dependent on the biogas leakage in anaerobic digestion plants. The CLDRM system was benchmarked against a conventional DRM implementation for the same feedstock. While the conventional DRM plant environmentally outperformed the perovskite-based CLDRM the latter might present advantages from an implementation point of view.

The refining industry is shifting from decarbonization to hydrogenation for processing heavy fractions to reduce pollution and improve efficiency. However the carbon footprint of hydrogen production presents significant environmental challenges. This study couples refinery linear programming models with life cycle assessment to evaluate from a long-term perspective the role of low-carbon hydrogen in promoting sustainable and profitable hydrogenation refining practices. Eight hydrogen-production pathways were examined including those based on fossil fuels and renewable energy providing hydrogen for three representative refineries adopting hydrogenation decarbonization and co-processing routes. Learning curves were used to predict future hydrogen cost trends. Currently hydrogenation refineries using fossil fuels benefit from significant cost advantages in hydrogen production demonstrating optimal economic performance. However in the long term with increasing carbon taxes hydrogenation routes will be affected by the high carbon emissions associated with fossil-based hydrogen losing economic advantages compared to decarbonization pathways. With increasing installed capacity and technological advancements low-carbon hydrogen is anticipated to reach cost parity with fossil-based hydrogen before 2060. Coupling renewable hydrogen is expected to yield the most significant economic advantages for hydrogenation refineries in the long term. Renewable hydrogen drives the transition of refining processing routes from a decarbonization-oriented approach to a hydrogenation-oriented paradigm resulting in cleaner refining processes and enhanced competitiveness under emission-reduction pressures.

Hydrogen has gained tremendous momentum worldwide as an energy carrier to transit to a net zero emission energy sector. It has been widely adopted as a promising large-scale renewable energy (RE) storage solution to overcome RE resources’ variability and intermittency nature. The fuel cell (FC) technology became in focus within the hydrogen energy landscape as a cost-effective pathway to utilize hydrogen for power generation. Therefore FC technologies’ research and development (R&D) expanded into many pathways such as cost reduction efficiency improvement fixed and mobile applications lifetime safety and regulations etc. Many publications and industrial reports about FC technologies and applications are available. This raised the necessity for a holistic review study to summarize the state-of-the-art range of FC stacks such as manufacturing the balance of plant types technologies applications and R&D opportunities. At the beginning the principal technologies to compare the well known types followed by the FC operating parameters are presented. Then the FC balance of the plant i.e. building components and materials with its functionality and purpose types and applications are critically reviewed with their limitations and improvement opportunities. Subsequently the electrical properties of FCs with their key features including advantages and disadvantages were investigated. Applications of FCs in different sectors are elaborated with their key characteristics current status and future R&D opportunities. Economic attributes of fuel cells with a pathway towards low cost are also presented. Finally this study identifies the research gaps and future avenues to guide researchers and the hydrogen industry.

Hydrogen offers the UK a unique opportunity to deliver on our Net Zero ambitions enabling deep decarbonisation of the parts of the energy system that are challenging to electrify balancing the energy system by providing large scale long duration energy storage and reducing pressure on electricity infrastructure. The UK Government in recognition of the centrality of hydrogen to the future energy system has set a 10GW hydrogen production ambition to be achieved by 2030. This ambition and its supporting policies such as the Hydrogen Business Model the Low Carbon Hydrogen Standard and the Hydrogen Transport and Storage Business Models will unlock private sector investment and kick-start the UK’s hydrogen activity. Encouragingly the UK has a positive track record of deploying low carbon technologies. The  combination of the UK’s world leading policies and incentive schemes alongside a vibrant  Research Development and Innovation (RD&I)  and engineering environment has enabled rapid  deployment of technologies such as offshore wind  and electric vehicles. Yet despite being world leaders  in deployment early opportunities for regional  supply chain growth and job creation were not fully  realised and taken advantage of from inception. The  hydrogen sector is therefore at a tipping point. To  capitalise on the economic opportunity hydrogen  offers the UK must learn from prior technology  deployments and build a strong domestic hydrogen  supply chain in parallel to championing deployment.

Hydrogen is unique amongst low carbon  technologies. It represents a significant economic  opportunity with future hydrogen markets estimated  by the Hydrogen Innovation Initiative to be worth  $8tn and hydrogen technology markets estimated to reach $1tn by 20501 but crucially it is also still a nascent market. Unlike many other low carbon technologies where supply chains are already well established hydrogen supply chains are embryonic meaning that the UK has an opportunity to anchor these supply chains here and establish itself as a global leader.

The UK is well placed to capitalise on this opportunity with favourable geography and geology  that enables us to produce and store hydrogen cost effectively coupled with a strong pipeline of hydrogen projects a stable policy environment that is attractive to investors and a wealth of transferable skills and expertise from the oil and gas industry.

We must ensure that alongside our focus on deployment we are also investing in technology and supply chains. Not only will this deliver exponential economic benefits from the projects supported by Government but it will also enable us to tackle increasing global supply chain constraints. Hydrogen UK estimated in its Economic Impact Assessment that hydrogen could deliver 30000 jobs annually and £7bn of GVA by 2030

It is important to be targeted and strategic in our investment and activities and recognise that hydrogen represents a wide range of technologies and the UK should not expect to lead in every area. Hydrogen UK with the support of the Hydrogen Delivery Council has undertaken analysis of the hydrogen value chain building on UK strengths and identifying the high value items that can deliver significant impact and benefit to the UK. We have also conducted widespread engagement with project developers to identify the barriers to utilising UK technology in projects and with technology developers to identify the challenges and barriers to investing and siting development and manufacturing in the UK.

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

Salt caverns have great potential to store relevant amounts of hydrogen as part of the energy transition. However the durability and suitability of commonly used steels for piping in hydrogen salt caverns is still under research. In this work aging effects focusing on corrosion and cracking patterns of casing steel API 5CT J55 and “H2ready” pipeline steel API 5L X56 were investigated with scanning electron microscopy and energy dispersive X-ray spectroscopy after accelerated stress tests with pressure/temperature cycling under hydrogen salt cavern-like conditions. Compared to dry conditions significant more corrosion by presence of salt ions was detected. However compared to X56 only for J55 an intensification of corrosion and cracking at the surface due to hydrogen atmosphere was revealed. Pronounced surface cracks were observed for J55 over the entire samples. Overall the results strongly suggest that X56 is more resistant than J55 under the conditions of a hydrogen salt cavern.

Hydrogen is one of the key solutions to decarbonising the UK economy along with other carbon abatement solutions such as electrification CCUS biofuels and energy efficiency. It provides a low carbon alternative to fossil fuels that has many of the same desirable features such as burning with a high temperature flame without producing carbon emissions during combustion. Hydrogen will be particularly valuable in hard-to-decarbonise sectors that have few cost-effective alternatives including elements of industry heavy transport and dispatchable power generation. However it’s use could be much more widespread depending on how costs preferences and policy for different low carbon solutions develop. The Government’s Hydrogen Strategy estimates that based on analysis from the Climate Change Committee (CCC) in 2050 between 20% and 35% of the UK’s final energy demand could be met with low carbon hydrogen1 . While hydrogen provides a promising solution to reducing emissions current deployment of low carbon hydrogen is low with almost all hydrogen in the UK produced from unabated fossil fuels resulting in high emissions. In the UK hydrogen production must meet the Low Carbon Hydrogen Standard (LCHS) to access government support. This is currently set at 20g CO2 e/MJ(LHV) and will ensure that future deployment will deliver significant emissions reductions when switching from fossil fuels2. The period to 2030 will be a critical time for the UK to seize the economic opportunity presented by low carbon hydrogen sector. Internationally increasing attention has been placed on hydrogen as a solution to global emissions. In the USA the Inflation Reduction Act (IRA) has provided fixed rate tax credits of up to $3/kg (£2.4/kgII) for clean hydrogen production3. Closer to home the EU is targeting 10 million tonnes of domestic electrolytic production and an additional 10 million tonnes of electrolytic hydrogen imports by 20304. This will be achieved through a variety of policy levers including an auction for fixed price subsidy support for electrolytic production with a ceiling of €4.5/kg5 (£3.84/kgIII). In the UK Government have set an ambitious target of up to 10 GW of low carbon hydrogen production by 2030 with at least half of this from electrolytic sources6. This will be supported by the Hydrogen Production Business Model (HPBM) a two-way variable CfD which could potentially provide hydrogen for a price as low as the natural gas price7 . As global supply chains investment and skills are in international competition the UK must continue its ambitious hydrogen aspirations to ensure the decarbonisation and economic opportunity presented by low carbon hydrogen is captured. This study estimates the economic impact of the low carbon hydrogen sector in the UK by 2030. The impact is assessed by estimating the costs of hydrogen deployment and applying employment and GVA multipliers to these costs based on historic economic activity. These estimates are broken down by different forms of low carbon hydrogen production and end use as well as the enabling infrastructure required to connect production and demand namely hydrogen networks and storage. Both the employment and GVA are estimated for each of these value chain elements for every year between 2024 and 2030. Employment and economic growth from the hydrogen sector will be created across the UK with many benefits arising in regions that have faced historic underinvestment such as the industrial clusters and Scotland. Beyond the high-level economic benefits estimated in this study the hydrogen sector creates an opportunity for the hundreds of thousands oil and gas sector jobs in the UK to transition to a low carbon alternative.

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

The transformation of fossil fuel-based power generation systems towards greenhouse gas-neutral ones based on renewable energy sources is one of the key challenges facing contemporary society. The temporal volatility that accompanies the integration of renewable energy (e.g. solar radiation and wind) must be compensated to ensure that at any given time a sufficient supply of electrical energy for the demands of different sectors is available. Green hydrogen which is produced using renewable energy sources via electrolysis can be used to chemically store electrical energy on a seasonal basis. Reconversion technologies are needed to generate electricity from stored hydrogen during periods of low renewable electricity generation. This study presents a detailed technoeconomic assessment of hydrogen gas turbines. These technologies are also superior to fuel cells due to their comparatively low investment costs especially when it comes to covering the residual loads. As of today hydrogen gas turbines are only available in laboratory or small-scale settings and have no market penetration or high technology readiness level. The primary focus of this study is to analyze the effects on gas turbine component costs when hydrogen is used instead of natural gas. Based on these findings an economic analysis addressing the current state of these turbine components is conducted. A literature review on the subsystems is performed considering statements from leading manufactures and researchers to derive the cost deviations and total cost per installed capacity (€/kWel). The results reveal that a hydrogen gas turbine power plant has an expected cost increase of 8.5% compared to a conventional gas turbine one. This leads to an average cost of 542.5 €/kWel for hydrogen gas turbines. For hydrogen combined cycle power plants the expected cost increase corresponds to the cost of the gas turbine system as the steam turbine subsystem remains unaffected by fuel switching. Additionally power plant retrofit potentials were calculated and the respective costs in the case of an upgrade were estimated. For Germany as a case study for an industrialized country the potential of a possible retrofit is between 2.7 and 11.4 GW resulting to a total investment between 0.3 and 1.1 billion €.

Acting in accordance with the requirements of the 2015 Paris Agreement Poland as well as other European Union countries have committed to achieving climate neutrality by 2050. One of the solutions to reduce emissions of harmful substances into the environment is the implementation of large-scale hydrogen technologies. This article presents the cost of producing green hydrogen produced using an alkaline electrolyzer with electricity supplied from a photovoltaic farm. The analysis was performed using the Monte Carlo method and for baseline assumptions including an electricity price of 0.053 EUR/kWh the cost of producing green hydrogen was 5.321 EUR/kgH2 . In addition this article presents a sensitivity analysis showing the impact of the electricity price before and after the energy crisis and other variables on the cost of green hydrogen production. The large change occurring in electricity prices (from 0.035 EUR/kWh to 0.24 EUR/kWh) significantly affected the levelized cost of green hydrogen (LCOH) which could change by up to 14 EUR/kgH2 in recent years. The results of the analysis showed that the parameters that successively have the greatest impact on the cost of green hydrogen production are the operating time of the plant and the unit capital expenditure. The development of green hydrogen production facilities along with the scaling of technology in the future can reduce the cost of its production.

In the present work we present the results of numerical simulations involving the dispersion and combustion of a hydrogen cloud released in an empty tunnel. The simulations were conducted with the use of ADREA-HF CFD code and the results are compared with measurements from experiments conducted by HSE in a tunnel with the exact same geometry. The length of the tunnel is equal to 70 m and the maximum height from the floor is equal to 3.25 m. Hydrogen release is considered to occur from a train containing pressurized hydrogen stored at 580 bars. The release diameter is equal to 4.7 mm and the release direction is upwards. Initially dispersion simulation was performed in order to define the initial conditions for the deflagration simulations. The effect of the initial wind speed and the effect of the ignition delay time were investigated. An extensive grid sensitivity study was conducted in order to achieve grid independent results. The CFD model takes into account the flame instabilities that are developed as the flame propagates inside the tunnel and turbulence that exists in front of the flame front. Pressure predictions are compared against experimental measurements revealing a very good performance of the CFD model.

A growing share of renewable energy production in the energy supply systems is key to reaching the European political goal of zero CO2 emission in 2050 highlighted in the green deal. Linked to the irregular production of solar and wind energies which have the highest potential for development in Europe massive energy storage solutions are needed as energy buffers. The European project HyPSTER [1] (Hydrogen Pilot STorage for large Ecosystem Replication) granted by the Clean Hydrogen Partnership addresses this topic by demonstrating a cyclic test in an experimental salt cavern filled with hydrogen up to 3 tons using hydrogen that is produced onsite by a 1 MW electrolyser. One specific objective of the project is the assessment of the risks and environmental impacts of cyclic hydrogen storage in salt caverns and providing guidelines for safety regulations and standards. This paper highlights the first outcome of the task WP5.5 of the HyPSTER project addressing the regulatory and normative frameworks for the safety of hydrogen storage in salt caverns from some selected European Countries which is dedicated to defining recommendations for promoting the safe development of this industry within Europe.

Hydrogen refueling stations rely on pressure vessels capable of withstanding pressures up to 90 MPa while mitigating concerns related to hydrogen embrittlement. However a gap exists in understanding the long-term fatigue behavior of these vessels under real operational conditions. This study focuses on evaluating the safety of SA372 pressure vessels using operational data from a hydrogen refueling station in Pyeongtaek South Korea. A predictive reinspection methodology is proposed based on this evaluation. Parameters including hydrogen-induced stress intensity factor (KIH) initial crack size (a0 c0) and pressure vessel specifications are considered to assess critical crack depth (ac) critical usage cycles (Nc) and allowable usage cycles (Nallowed). Leveraging operational data collected between August and November 2023 fatigue analysis and Rainflow counting inform reinspection schedules. Results indicate a need for mid-bank vessel reinspection within the second year high-bank vessel reinspection every 20 years and low-bank vessel reinspection every 143 years in accordance with safety regulations. Additionally a revised refueling logic is proposed to optimize vehicle charging methods and pressure ranges enhancing operational safety. This study serves as a preliminary investigation highlighting the need for broader data collection and analysis to generalize findings across multiple stations.

Hydrogen and carbon capture and storage are pivotal to decarbonize the European energy system in a broad range of pathway scenarios. Yet their timely uptake in different sectors and distribution across countries are affected by supply options of renewable and fossil energy sources. Here we analyze the decarbonization of the European energy system towards 2060 covering the power heat and industry sectors and the change in use of hydrogen and carbon capture and storage in these sectors upon Europe’s decoupling from Russian gas. The results indicate that the use of gas is significantly reduced in the power sector instead being replaced by coal with carbon capture and storage and with a further expansion of renewable generators. Coal coupled with carbon capture and storage is also used in the steel sector as an intermediary step when Russian gas is neglected before being fully decarbonized with hydrogen. Hydrogen production mostly relies on natural gas with carbon capture and storage until natural gas is scarce and costly at which time green hydrogen production increases sharply. The disruption of Russian gas imports has significant consequences on the decarbonization pathways for Europe with local energy sources and carbon capture and storage becoming even more important. Given the highlighted importance of carbon capture and storage in reaching the climate targets it is essential that policymakers ameliorate regulatory challenges related to these value chains.

H2 production via membrane-assisted steam methane reforming (MA-SMR) can ensure higher energy efficiency and lower emissions compared to conventional reforming processes (SMR). Ceramic-supported Pd–Ag membranes have been extensively investigated for membrane-assisted steam methane reforming applications with outstanding performance. However costs sealings for integration in the reactor structure and resistance to solicitations remain challenging issues. In this work the surface quality of a low-cost porous Hastelloy-X filter is improved by asymmetric filling with α-Al2O3 of decreasing size and deposition of γ-Al2O3 as an interdiffusion barrier. On the modified support a thin Pd–Ag layer was deposited via electroless plating (ELP) resulting in a membrane with H2/N2 selectivity >10000. The permeation characteristics of the membrane were studied followed by testing for membrane-assisted methane steam reforming. The results showed the ability of the membrane reactor to overcome thermodynamic conversion of the conventional process for all explored operating conditions as well as ensuring 99.3% H2 purity in the permeate stream at 500 ◦C and 4 bar.

Research on proton exchange membrane water electrolysis for renewable hydrogen production is rapidly advancing worldwide driven by the imperative to reduce costs and enhance efficiency through development of novel materials. However to effectively evaluate and validate these advancements standardized testing methods are essential extending beyond single-cell analysis to encompass stack-level characterization. This paper proposes comprehensive characterization methods tailored for analysis of electrolysis stacks and their performance characteristics. Each method is introduced with a focus on its practical applicability accompanied by detailed procedural guidelines for implementation. Furthermore variations within each method are discussed offering possibilities for gathering additional insights. Presenting a portfolio of different methods ranging from standard to advanced techniques applicable at the stack level the paper showcases results obtained through their application. These results normalized to cell area demonstrate the significance of each method in obtaining stack characteristics crucial for informed design de cisions on material selection and subsequent integration into electrolysis systems. By illustrating results derived from various stacks this study contributes valuable insights for evaluating design material suitability and operational performance thereby advancing the development and deployment of proton exchange membrane water electrolysis technology for sustainable hydrogen production.

Direct solar hydrogen generation via a combination of photovoltaics (PV) andwater electrolysis can potentially ensure a sustainable energy supply whileminimizing greenhouse emissions. The PECSYS project aims at demonstrating asolar-driven electrochemical hydrogen generation system with an area >10 m 2with high efficiency and at reasonable cost. Thermally integrated PV electrolyzers(ECs) using thin-film silicon undoped and silver-doped Cu(InGa)Se 2 and siliconheterojunction PV combined with alkaline electrolysis to form one unit aredeveloped on a prototype level with solar collection areas in the range from 64 to2600 cm 2 with the solar-to-hydrogen (StH) efficiency ranging from 4 to 13%.Electrical direct coupling of PV modules to a proton exchange membrane EC totest the effects of bifaciality (730 cm 2 solar collection area) and to study the long-term operation under outdoor conditions (10 m 2 collection area) is also inves-tigated. In both cases StH efficiencies exceeding 10% can be maintained over thetest periods used. All the StH efficiencies reported are based on measured gasoutflow using mass flow meters.

Biomass gasification produces syngas composed mainly of hydrogen carbon monoxide carbon dioxide methane water and higher hydrocarbons till C4 mainly ethane. The hydrocarbon content can be upgraded into richer hydrogen streams through the steam reforming reaction. This study assessed the steam reforming process at the thermodynamic equilibrium of five streams with different compositions from the gasification of three different biomass sources (Lignin Miscanthus and Eucalyptus). The simulations were performed on Aspen Plus V12 software using the Gibbs energy minimization method. The influence of the operating conditions on the hydrogen yield was assessed: temperature in the range of 200 to 1100 ◦C pressures of 1 to 20 bar and steamto‑carbon (S/C) molar ratios from 0 (only dry reforming) to 10. It was observed that operating conditions of 725 to 850 ◦C 1 bar and an S/C ratio of 3 enhanced the streams’ hydrogen content and led to nearly complete hydrocarbon conversion (>99%). Regarding hydrogen purity the stream obtained from the gasification of Lignin and followed by a conditioning phase (stream 5) has the highest hydrogen purity 52.7% and an hydrogen yield of 48.7%. In contrast the stream obtained from the gasification of Lignin without any conditioning (stream 1) led to the greatest increase in hydrogen purity from 19% to 51.2% and a hydrogen yield of 61.8%. Concerning coke formation it can be mitigated for S/C molar ratios and temperatures >2 and 700 ◦C respectively. Experimental tests with stream 1 were carried out which show a similar trend to the simulation results particularly at high temperatures (700–800 ◦C).

Anion exchange membrane water electrolysis (AEMWE) is a potentially low-cost and sustainable technology for hydrogen production that combines the advantages of proton exchange membrane water electrolysis and traditional alkaline water electrolysis systems. Despite considerable research efforts in recent years the medium-term (100 h) stability of Aemion™ membranes needs further investigation. This work explores the chemical and electrochemical durability (>100 h) of Aemion™ anion exchange membranes in a flow cell using nickel felt as the electrode material on the anode and cathode sides. Remixing the electrolytes between the AEMWE galvanostatic tests was very important to enhance electrolyte refreshment and the voltage stability of the system. The membranes were analyzed by NMR spectroscopy after the AEMWE tests and the results showed no sign of severe chemical degradation. In a separate experiment the chemical stability and mechanical integrity of the membranes were studied by soaking them in a strongly alkaline electrolyte for a month (>700 h) at 90 C followed by NMR analysis. A certain extent of ionic loss was observed due to chemical degradation and the membranes disintegrated into small pieces.

Climate change necessitates urgent action to decarbonize the transport sector. Sustainable vehicles represent crucial alternatives to traditional combustion engines. This study comprehensively compares four prominent sustainable vehicle technologies: biofuel-powered vehicles (BPVs) fuel cell vehicles (FCVs) electric vehicles (EVs) and solar vehicles. We examine each technology’s history development classification key components and operational principles. Furthermore we assess their sustainability through technical factors environmental impacts cost considerations and policy dimensions. Moreover the discussion section addresses the challenges and opportunities associated with each technology and assesses their social impact including public perception and adoption. Each technology offers promise for sustainable transportation but faces unique challenges. Policymakers industry stakeholders and researchers must collaborate to address these challenges and accelerate the transition toward a decarbonized transport future. Potential future research areas are identified to guide advancements in sustainable vehicle technologies.