Publications

This study aims to advance the understanding of hydrogen embrittlement (HE) in low-carbon and low-alloy steels by developing a predictive framework for assessing fracture toughness (FT) a critical parameter for mitigating HE in hydrogen infrastructure. A machine learning (ML) model was constructed by analyzing data from relevant literature to evaluate the fracture toughness of steels exposed to hydrogen environments. Seven ML modeling techniques were initially considered with four selected for detailed evaluation based on predictive accuracy. The chosen modeling techniques were k-nearest neighbors (KNN) random forest (RF) gradient boosting (GB) and decision tree regression (DT). The selected models were further evaluated for their predictive accuracy and reliability and the best model was used to perform parametric studies to investigate the impact of relevant parameters on FT. According to the results the KNN model demonstrated reliable predictive performance supported by high R-squared values and low error metrics. Among the variables considered hydrogen pressure and yield strength emerged as the most influential with hydrogen pressure alone accounting for 32% of the variation in FT. The model revealed a distinct trend in FT behavior showing a significant decline at low hydrogen pressures (0–6.9 MPa) and a plateau at higher pressures (>8 MPa) indicating a saturation point. Alloying element contents specifically those of carbon and phosphorus also played a notable role in FT prediction. Additionally the study confirmed that low concentrations of oxygen (

Green hydrogen production is a sustainable energy solution with great potential offering advantages such as adaptability storage capacity and ease of transport. However there are challenges such as high energy consumption production costs demand and regulation which hinder its largescale adoption. This study explores the role of simulation models in optimizing the technical and economic aspects of green hydrogen production. The proposed system which integrates photovoltaic and energy storage technologies significantly reduces the grid dependency of the electrolyzer achieving an energy self-consumption of 64 kWh per kilogram of hydrogen produced. By replacing the high-fidelity model of the electrolyzer with a reduced-order model it is possible to minimize the computational effort and simulation times for different step configurations. These findings offer relevant information to improve the economic viability and energy efficiency in green hydrogen production. This facilitates decision-making at a local level by implementing strategies to achieve a sustainable energy transition.

This study investigates the integration of green hydrogen into building energy systems using local solar power with the electricity grid serving as a backup plan. A comprehensive bottom-up analysis compares six energy system configurations: the natural gas grid boiler system all-electric heat pump system natural gas and hydrogen blended system hydrogen microgrid boiler system cogeneration hydrogen fuel cell system and hybrid hydrogen heat pump system. Energy efficiency evaluations were conducted for 25 homes within one block in a neighborhood across five typological house stocks located in Stoke-on-Trent UK. This research was modeled using a spreadsheet-based approach. The results highlight that while the all-electric heat pump system still demonstrates the highest energy efficiency with the lowest consumption the hybrid hydrogen heat pump system emerges as the most efficient hydrogen-based solution. Further optimization through the implementation of a peak-shaving strategy shows promise in enhancing system performance. In this approach hybrid hydrogen serves as a heating source during peak demand hours (evenings and cold seasons) complemented by a solar energy powered heat pump during summer and daytime. An hourly operational configuration is recommended to ensure consistent performance and sustainability. This study focuses on energy performance excluding cost-effectiveness analysis. Therefore the cost of the energy is not taken into consideration requiring further development for future research in these areas.

In rotating machinery unbalanced mass is one of the most common causes of system vibration. This paper presents an experimental investigation of the unbalance response of a gas foil bearing-rotor system based on a 30 kW-rated commercial hydrogen fuel cell vehicle air compressor. The study examines the response of the system to varying unbalanced masses at different rotational speeds. Experimental results show that after adding unbalanced mass subsynchronous vibration of the rotor is relatively slight while synchronous vibration is the main source of vibration; when unbalanced mass is added to one side of the rotor the synchronous vibration on that side initially decreases and then increases with speed while synchronous vibration on the opposite side continuously increases with speed; when unbalanced mass is added to both sides the synchronous vibration on each side increases with the phase difference of the unbalanced mass at low speed while the opposite trend occurs at high speed. The analysis of the gas foil bearingrotor system dynamics model established based on the dynamic coefficient of the bearing shows that the bending of the rotor offsets the displacement caused by the unbalanced mass which is the primary reason for the nonlinear behavior of the synchronous vibration of the rotor. These findings contribute to an improved understanding of GFB-rotor interactions under unbalanced conditions and provide practical guidance for optimizing dynamic balancing strategies in hydrogen fuel cell vehicle compressors.

Dual fuel combustion has gained attention as a cost-effective solution for reducing the pollutant emissions of internal combustion engines. The typical approach is combining a conventional high-reactivity fossil fuel (diesel fuel) with a sustainable low-reactivity fuel such as bio-methane ethanol or green hydrogen. The last one is particularly interesting as in theory it produces only water and NOx when it burns. However integrating hydrogen into stock diesel engines is far from trivial due to a number of theoretical and practical challenges mainly related to the control of combustion at different loads and speeds. The use of 3D-CFD simulation supported by experimental data appears to be the most effective way to address these issues. This study investigates the hydrogen-diesel dual fuel concept implemented with minimum modifications in a light-duty diesel engine (2.8 L 4-cylinder direct injection with common rail) considering two operating points representing typical partial and full load conditions for a light commercial vehicle or an industrial engine. The numerical analysis explores the effects of progressively replacing diesel fuel with hydrogen up to 80% of the total energy input. The goal is to assess how this substitution affects engine performance and combustion characteristics. The results show that a moderate hydrogen substitution improves brake thermal efficiency while higher substitution rates present quite a severe challenge. To address these issues the diesel fuel injection strategy is optimized under dual fuel operation. The research findings are promising but they also indicate that further investigations are needed at high hydrogen substitution rates in order to exploit the potential of the concept.

Global attention is being given to hydrogen as it is seen as a versatile energy carrier and a flexible energy vector in transitioning to a low-carbon economy. Hydrogen production/storage/conveyance is metal intensive and it is crucial to understand if there is material availability to fulfil the committed plans. Using the material intensity of electrolysers pipelines and desalinators along with the projected Portuguese and European Union roadmaps we are able to identify possible bottlenecks in the supply chains. The availability of the vast majority of raw materials does not represent a threat to hydrogen technologies implementation with electrolysers requiring almost up to 3 Mt of raw materials and pipelines up to 2.5 Mt. The evident exception is iridium although representing less than 0.001 % of the material requirements it may hinder the widespread implementation of proton exchange membrane electrolysers. Desalinators have the least material footprint of the studied infrastructure.

This study focuses on the potential valorization of brewers’ spent grain (BSG) through gasification for ultra-pure green hydrogen production via membrane separation. First a fundamental physicochemical characterization of BSG samples from two different Spanish brewing industries was conducted revealing high energy content and good reproducibility of elemental composition thus providing great potential for hydrogen generation in the context of circular economy for the brewery industry. The syngas composition reached by BSG gasification has been predicted and main operating conditions optimized to maximize the hydrogen yield (25–75 vol% air-steam mixture ratio GR = 0.75 T = 800 ◦C and P = 5 bar). For gas purification two Pd-membranes were fabricated by ELP-PP onto tubular PSS supports with high reproducibility (Pd-thickness in the range 8.22–8.75 μm) exhibiting an almost complete H2-selectivity good fitting to Sieverts’ law and hydrogen permeate fluxes ranging from 175 to 550 mol m− 2 h− 1 under ideal gas feed composition conditions. The mechanical resistance of membranes was maintained at pressure driving forces up to 10 bar thus highlighting their potential for commercialization and industrial application. Furthermore long-term stability tests up to 75 h indicated promising membrane performance for continuous operation offering valuable insights for stakeholders in the brewery industry to enhance economic growth and environmental sustainability through green hydrogen production from BSG.

CO2 emission reduction of sectors such as aviation maritime shipping road haulage and chemical production is challenging but necessary. Although these sectors will most likely continue to rely on carbonaceous energy carriers they are expected to gradually shift away from fossil fuels. In order to do so the prominent option is to utilize alternative carbon sources—like biomass and CO2 originating from carbon capture—for the production of non-fossil carbonaceous vectors (biofuels and e-fuels). However the limited availability of biomass and the varying nature of other carbon sources necessitate a comprehensive evaluation of trade-offs between potential carbon uses and existing sources. Then it is primordial to understand the origin of carbon used in sustainable aviation fuel (SAF) to understand the implications of defossilizing aviation for the energy system. Moreover the production of SAF implies deep changes to the energy system that are quantified in this work. This study utilizes the linear programming cost optimization tool EnergyScope TD to analyze the holistic French energy system encompassing transport industry electricity and heat sectors while ensuring net greenhouse gas neutrality. A novel method to model and quantify carbon flows within the system is introduced enabling a comprehensive assessment of greenhouse gas neutrality. This study highlights the significance of fulfilling clean energy requirements and implementing carbon dioxide removal measures as crucial steps toward achieving climate neutrality. Indeed to reach climate neutrality a production of 1046 TWh of electricity by non-fossil sources is needed. Furthermore the findings underscore the critical role of efficient carbon and energy valorization from biomass providing evidence that producing fuels by combining biomass and hydrogen is optimal. The study also offers valuable insights into the future cost and impact of SAF production for air travel originating from France. That is the European law ReFuelEU would increase the price of plane tickets by +33% and would require 126 TWh of hydrogen and 50 TWh of biomass to produce the necessary 91 TWh of jet fuel. Finally the implications of the assumption behind the production of SAF are discussed.

Addressing the critical need for sustainable high-density hydrogen (H2) carriers to decarbonize the global energy landscape this paper presents a comprehensive critical review of ammonia’s pivotal role in the energy transition with a specific focus on its application in the transportation sector. While H2 is recognized as a future fuel its storage and distribution challenges necessitate alternative vectors. Ammonia (NH3) with its compelling advantages including high volumetric H2 density established global infrastructure and potential for near-zero greenhouse gas emissions emerges as a leading candidate. This review uniquely synthesizes the evolving landscape of sustainable NH3 production pathways (e.g. green NH3 from renewable electricity) with a systematic analysis of technological advancements to investigate its direct utilization as a transportation fuel. The paper critically examines the multifaceted challenges and opportunities associated with NH3-fueled vehicles refueling infrastructure development and comprehensive safety considerations alongside their environmental and economic implications. By providing a consolidated forward-looking perspective on this complex energy vector this paper offers crucial insights for researchers policymakers and industry stakeholders highlighting NH3’s transformative potential to accelerate the decarbonization of hard-to-abate transportation sectors and contribute significantly to a sustainable energy future.

Decarbonizing long-haul heavy-duty transport in Europe focuses on batteryelectric trucks with high-power chargers or electric road systems and fuel-cell-electric vehicles with hydrogen refueling stations. We present a comparative life cycle assessment and total cost of ownership analysis of these technologies for 20% of Germany’s heavy-duty long-haul transport alongside internal combustion engine vehicles. The results show that fuel cell vehicles with on-site hydrogen have the highest life cycle emissions (65 Mt CO2e) followed by internal combustion engine vehicles (55 Mt CO2e). Battery-electric vehicles using electric road systems achieve the lowest emissions (21 Mt CO2e) and the lowest costs (EUR 45 billion). In contrast fuel cell vehicles with on-site hydrogen have the highest costs (EUR 69 billion). Operational costs dominate total expenses making them a compelling target for subsidies. The choice between battery and fuel cell technologies depends on the ratio of vehicles to infrastructure transport performance and range. Fuel cell trucks are better suited for remote areas due to their longer range while integrating electric road systems with high-power charging could offer synergies. Recent advancements in battery and fuel cell durability further highlight the potential of both technologies in heavy-duty transport. This study provides insights for policymakers and industry stakeholders in the shift towards sustainable transport. The greenhouse gas emission savings from adopting battery-electric trucks are 54% in our high-power charging scenario and 62% in the electric road system scenario in comparison to the reference scenario with diesel trucks.

As an efficient and low-carbon renewable energy source hydrogen plays a strategic role in the global energy transition particularly in the transportation sector. However the flammable and explosive nature of hydrogen makes leakage risks in enclosed environments a core challenge for the safe promotion of hydrogen fuel cell vehicles. Catalytic combustion sensors are ideal choices due to their high sensitivity and long lifespan. Nevertheless they face technical bottlenecks under vehicle operational conditions such as high-power consumption caused by elevated working temperatures slow response rates weak anti-interference capabilities and catalyst poisoning. This paper systematically reviews the research status of catalytic combustion hydrogen sensors for vehicle applications summarizes technical difficulties and development strategies from the perspectives of hydrogen-sensitive material design and integration processes and provides theoretical references and technical guidance for the development of catalytic combustion hydrogen sensors suitable for vehicle use.

Deployment of innovative renewable-based energy applications are critical for reducing CO2 emissions and achieving global climate neutrality. This work evaluates the production of decarbonized green H2 based on sorption-enhanced biomass (sawdust) gasification. The calcium-based sorbent was evaluated in a looping cycle configuration as sorption material to enhance both the CO2 capture rate and the energy-efficient hydrogen production. The investigated concept is set to produce 100 MWth high purity hydrogen (>99.95% vol.) with very high decarbonization yield (>98–99%) using woody biomass as a fuel. Conventional biomass (sawdust) gasification systems with and without CO2 capture capability are also assessed for the calculation of energy and economic penalties induced by decarbonization. The results show that the decarbonized green hydrogen manufacture by sorption-enhanced biomass gasification shows attractive performances e.g. high overall energy efficiency (about 50%) reduced energy and economic penalties for almost total decarbonization (down to 8 net efficiency points) low specific carbon emissions at system level (lower than 7 kg/MWh) and negative CO2 emission for whole biomass value chain (about − 518.40 kg/MWh). However significant developments (e.g. improving reactor design and fuel/sorbent conversion yields reducing sorbent make-up etc.) are still needed to advance this innovative concept from present level to industrial sizes.

Hydrogen production by seawater electrolysis is significantly hindered by high energy costs and undesirable detrimental chlorine chemistry in seawater. In this work energy-saving hydrogen production is reported by chlorine-free seawater splitting coupling tip-enhanced electric field promoted electrocatalytic sulfion oxidation reaction. We present a bifunctional needle-like Co3S4 catalyst grown on nickel foam with a unique tip structure that enhances the kinetic rate by improving the current density in the tip region. The assembled hybrid seawater electrolyzer combines thermodynamically favorable sulfion oxidation and cathodic seawater reduction can enable sustainable hydrogen production at a current density of 100 mA cm−2 for up to 504 h. The hybrid seawater electrolyzer has the potential for scale-up industrial implementation of hydrogen production by seawater electrolysis which is promising to achieve high economic efficiency and environmental remediation.

The report provides a detailed examination of the biofuel sector and advanced biofuel sector within the European Union (EU) focusing on its economic environmental and technological dimensions. The report is an update of the CETO 2023 report. The EU is highlighted as the central point of view with specific references to EU Member States showcasing their roles in the sector. The report is essential for understanding the multifaceted role of advanced biofuels in the EU's strategy to reduce greenhouse gas emissions and enhance energy security. The report underscores the EU's commitment through various policies and directives such as the Renewable Energy Directive and its amendment which set sustainability criteria and define advanced biofuels. The report details the EU's leadership in scientific publications and high-value patents in the advanced biofuel sector. It gives insights into the current state of innovation and the areas where the EU is leading. The report delves into technological advancements and challenges in the biofuel sector. It discusses various advanced biofuel technologies currently being developed and commercialised. The report covers the trends in installed capacity and production of biofuels within the EU providing a comparative analysis with other regions. It details the production capacities and operational plants for bioethanol and biodiesel. The report provides comprehensive data on the economic contributions of the advanced biofuel sector to the EU's economy. The report details the sector's impact on GDP and employment highlighting the significant contributions from operation and maintenance feedstock supply construction and equipment manufacturing. The report emphasises the importance of continued investment technological development and international collaboration to ensure the advanced biofuel sector's growth and sustainability.

The current solicitude in hydrogen production and its utilization as a greenhouse-neutral energy vector pushed deep interest in developing new and reliable systems intended for its detection. Most sensors available on the market offer reliable performance; however their limitations such as restricted dynamic range hysteresis reliance on consumables transducer–sample interaction and sample dispersion into the environment are not easily overcome. In this paper a non-dispersive Raman effect-based system is presented and compared with its dispersive alternative. This approach intrinsically guarantees no sample dispersion or preparation as no direct contact is required between the sample and the transducer. Moreover the technique does not suffer from hysteresis and recovering time issues. The results evaluated in terms of sample pressures and camera integration time demonstrate promising signal-to-noise ratio (SNR) and limit of detection (LOD) values indicating strong potential for direct field application.

The decarbonization of the maritime sector represents a priority in the energy policy agendas of the majority of Countries worldwide and the International Maritime Organization (IMO) has recently revised its strategy aiming for an ambitious zero-emissions scenario by 2050. In these regards there is a broad consensus on hydrogen as one of the most promising clean energy vectors for maritime transport and a key towards that goal. However to date an international regulatory framework for the use of hydrogen on-board of ships is absent this posing a severe limitation to the adoption of hydrogen technologies in this sector. To cope with this issue this paper presents a preliminary gap assessment analysis for the International Code of Safety for Ship Using Gases or other Low-flashpoint Fuels (IGF Code) with relation to hydrogen as a fuel. The analysis is structured according to the IGF Code chapters and a bottom-up approach is followed to review the code content and assess its relevance to hydrogen. The risks related to hydrogen are accounted for in assessing the gaps and providing a first level set of recommendations for IGF Code updates. By this means this work settles the basis for further research over the identified gaps towards the identification of a final set of recommendations for the IGF Code update.

Offshore wind power construction has seen significant development due to the high density of offshore wind energy and the minimal terrain restrictions for offshore wind farms. However integrating this energy into the grid remains a challenge. The scientific community is increasingly focusing on hydrogen as a means to enhance the integration of these fluctuating renewable energy sources. This paper reviews the research on renewable energy power generation water electrolysis for hydrogen production and large-scale hydrogen storage. By integrating the latest advancements we propose a system that couples offshore wind power generation seawater electrolysis (SWE) for hydrogen production and salt cavern hydrogen storage. This coupling system aims to address practical issues such as the grid integration of offshore wind power and large-scale hydrogen storage. Regarding the application potential of this coupling system this paper details the advantages of developing renewable energy and hydrogen energy in Jiangsu using this system. While there are still some challenges in the application of this system it undeniably offers a new pathway for coastal cities to advance renewable energy development and sets a new direction for hydrogen energy progress.

This study examines the effects of transitioning to hydrogen production in the National Capital Region (NCR) and Palawan Province Philippines focusing on technology environment and stakeholder impact. This research conducted through a July 2022 survey aimed to assess public awareness knowledge risk perception and acceptance of hydrogen and its environmentally friendly variant green hydrogen infrastructure. Disparities were found between urban NCR and rural Palawan with lower awareness in Palawan. Safety concerns were highlighted with NCR respondents generally considering hydrogen production safe while Palawan respondents had mixed feelings particularly regarding nuclear-based hydrogen generation. This report emphasizes the potential ecological advantages of hydrogen technology but highlights potential issues concerning water usage and land impacts. It suggests targeted public awareness campaigns robust safety assurance programs regional pilot projects and integrated environmental plans to facilitate the seamless integration of hydrogen technology into the Philippines’ energy portfolio. This collective effort aims to help the country meet climate action obligations foster sustainable development and enhance energy resilience.

Renewable hydrogen is a promising energy carrier that facilitates greater renewable energy integration while supporting the decarbonization of the industrial and transportation sectors. This study investigates the optimal design and operation of two hydrogen-based energy systems. The first energy system comprises an electrolyser compressor and hydrogen storage system. It aims to supply hydrogen as a drop-in fuel for a future potential hydrogen fleet. The electrolyser provides excess heat and oxygen for a combined heat and power (CHP) plantand ancillary services to the grid for frequency support. In the second energy system the hydrogen stored in the hydrogen tank is used by a fuel cell or gas turbine to sell electricity to the grid following price signals. The optimisation algorithm developed in this study finds the optimal capacities for the hydrogen production and storage systems and optimizes the hourly dispatch of the electrolyser. The profitability of the first investigated hydrogen-based energy system is closely connected to the hydrogen production cost which fluctuates depending on the average electricity price. The profitability is also affected by the average compensation of the ancillary services and to a lesser extent by the value of excess heat and oxygen produced during the electrolysis. Only 2020 marked out by the lowest average electricity price among the investigated years could lead to a profitable investment for the first studied energy system. The breakeven hydrogen selling price varied between 24.13 SEK/kg in 2020 to 65.63 SEK/kg in 2022 while considering the extra revenues of the grid service compensation and heat and oxygen sale. If only hydrogen sale was considered the breakeven hydrogen selling prices varied between 31.28 SEK/kg in 2020 to 86.08 SEK/kg in 2022. For the second investigated hydrogen-based energy system if the threshold electricity price for activating the hydrogen consumption system is the 90th percentile of the electricity prices every week the profitability is never attained. The fuel cell system leads to lower electrolyser and hydrogen tank capacities to meet the targeted power supply given the higher assumed efficiency as compared to the gas turbine. Nevertheless the fuel cell system shows in all the investigated subcases lower net present values as compared to the gas turbine subcases due to the higher investment and running costs. The fuel cell system shows better performances in terms of net present values than the gas turbine only in an optimistic sub case marked out by higher conversion efficiencies and lower investment and running costs for the fuel cell. The profitability of the second investigated hydrogen-based energy system is guaranteed only at an annual average electricity price above 2.7 SEK/kWh.

To improve the energy utilization rate and realize the low-carbon emission of a park integrated energy system (PIES) this paper proposes an optimal operation strategy for multiple PIESs. Firstly the electrical power cooperative trading framework of multiple PIESs is constructed. Secondly the hydrogen blending mechanism and carbon capture system and power-to-gas system joint operation model are introduced to establish the model of each PIES. Then based on the Nash bargaining game theory a multi-PIES cooperative trading and operation model with electrical power cooperative trading is constructed. Then the alternating direction method of multipliers algorithm is used to solve the two subproblems. Finally case studies analysis based on scene analysis is performed. The results show that the cooperative operation model reduces the total cost of a PIES more effectively compared with independent operation. Meanwhile the efficient utilization and production of hydrogen are the keys to achieve carbon reduction and an efficiency increase in a PIES.

Our energy system is facing major challenges in the course of the unavoidable shift from fossil fuels to fluctuating renewable energy sources. Regional hydrogen production by electrolysis utilizing regional available excess energy can support the expansion of renewable energy by converting surplus energy into hydrogen and sup plying it to the end energy sectors as a secondary energy carrier or process media. We developed a methodology which allows the identification of the regional optimal electrolysis scaling the achievable Levelized Costs of Hydrogen (LCOH) as well as the annually producible amount of hydrogen for Central European regions using renewable surplus energy from PV and wind production. The results show that as best case currently LCOH of 4.5 €/kg can be achieved in regions with wind energy and LCOH of 5.6 €/kg in regions with PV energy at 1485 €/kW initial investment costs for the hydrogen production infrastructure. In these cases regions with wind energy require electrolysis systems with a capacity of 60 % of the wind peak power. Regions with PV energy require a scaling factor of only 45 % of the PV peak power. However we show that the impact of regional electricity demand and grid expansion has a significant influence on the LCOH and the scaling of the electrolysis. These effects were illustrated in clear heatmaps and serve as a guideline for the dimensioning of grid-supporting electrolysis systems by defining the renewable peak power the regional electricity demand as well as the existing grid capacity of the region under consideration.

In this work the wastewater obtained from the hydrothermal liquefaction of black liquor was treated and valorized for hydrogen production by supercritical water gasification (SCWG). The influence of the main process parameters on the conversion yield was studied. The experiments were conducted at three different temperatures (below and above the critical point of water): 350 ◦C 450 ◦C and 600 ◦C. The results showed that by increasing the temperature from 350 ◦C to 600 ◦C the total gas yield was highly improved (from 1.9 mol gas/kg of dried feedstock to 13.1 mol gas/kg of dried feedstock). The H2 composition was higher than that of CH4 and CO2 at 600 ◦C and the HHV of the obtained gas was 61.2 MJ/kg. The total organic carbon (TOC) removal efficiency was also improved by increasing the temperature indicating that the SCWG process could be used for both applications: (i) for wastewater treatment; (ii) for producing a high calorific gas. The experiments with the Raney-nickel catalyst were performed in order to study the catalyst’s influence on the conversion yield. The results indicated that the catalyst enhances carbon conversion and gas production from mild to higher temperatures. The maximum total gas yield obtained with this catalyst was 32.4 mol gas/kg of dried feedstock at 600 ◦C which is 2.5 times higher than that obtained at the same operating conditions without a catalyst. The H2 yield and the HHV of the obtained gas with the catalyst were 20.98 mol gas/kg dried feedstock and 80.2 MJ/kg respectively. However the major contribution of the catalytic SCWG process was the improvement of the total gas yield at mild operating temperatures (450 ◦C) and the obtained performance was even higher than that obtained at 600 ◦C without catalyst (17.81 mol gas/kg dried feedstock and 13.1 mol gas/kg dried feedstock respectively). This is a sustainable approach for treating wastewater at mild temperatures by catalytic SCWG.

The coastal region of Ceará Brazil is expected to host offshore wind farms aimed at producing green hydrogen (GH2) through electrolysis. However the viability and cost of these developments may be affected by the mechanical behaviour of the marine subsoil which is largely composed of carbonate sands. These sediments are known for their complex and variable geotechnical properties which can influence the foundation performance. This study investigates the geotechnical characteristics of carbonate sands in comparison with quartz sands to support the design of offshore wind turbine foundations. Field testing using the Ménard pressuremeter and laboratory analyses including particle size distribution microscopy X-ray fluorescence calcimetry direct shear and triaxial testing were performed to determine the key strength and stiffness parameters. The results show substantial differences between carbonate and quartz sands particularly in terms of the stiffness and friction angle with notable variability even within the same material type. These findings highlight the need for site-specific characterisation in offshore foundation design. This study contributes data that can improve geotechnical risk assessments and assist in selecting appropriate foundation solutions under local conditions supporting the planned offshore wind energy infrastructure essential to Ceará’s green hydrogen strategy.

Hydrogen fuel cells are gaining attention as an eco-friendly propulsion system for ships but the structural safety of storage tanks which store hydrogen at high pressure and supply it to the fuel cell is a critical concern. Marine liquid hydrogen storage tanks typically designed as rotationally symmetric structures face challenges when subjected to asymmetric wave-induced sloshing loads that break geometric symmetry and induce localized stress concentrations. This study conducted a fluid–structure interaction (FSI) analysis of a rotationally symmetric liquid hydrogen storage tank for marine applications to evaluate the impact of asymmetric liquid sloshing induced by wave loads on the tank structure and propose symmetry-guided structural improvement measures to ensure fatigue life. Sensitivity analysis using the finite difference method (FDM) revealed the asymmetric influences of design variables on stress distribution: increasing the thickness of triangular mounts (T1) reduced stress 3.57 times more effectively than circular ring thickness (T2) highlighting a critical symmetry-breaking feature in support geometry. This approach enables rapid and effective design modifications without complex optimization simulations. The study demonstrates that restoring structural symmetry through targeted reinforcement is essential to mitigate fatigue failure caused by asymmetric loading.

Integrating renewable energy requires robust large-scale storage solutions to balance intermittent supply. Underground hydrogen storage (UHS) in geological formations such as salt caverns depleted hydrocarbon reservoirs or aquifers offers a promising way to store large volumes of energy for seasonal periods. This review focuses on the biological aspects of UHS examining the biogeochemical interactions between H2 reservoir minerals and key hydrogenotrophic microorganisms such as sulfate-reducing bacteria methanogens acetogens and iron-reducing bacteria within the gas–liquid–rock–microorganism system. These microbial groups use H2 as an electron donor triggering biogeochemical reactions that can affect storage efficiency through gas loss and mineral dissolution–precipitation cycles. This review discusses their metabolic pathways and the geochemical interactions driven by microbial byproducts such as H2S CH4 acetate and Fe2+ and considers biofilm formation by microbial consortia which can further change the petrophysical reservoir properties. In addition the review maps 76 ongoing European projects focused on UHS showing 71% target salt caverns 22% depleted hydrocarbon reservoirs and 7% aquifers with emphasis on potential biogeochemical interactions. It also identifies key knowledge gaps including the lack of in situ kinetic data limited field-scale monitoring of microbial activity and insufficient understanding of mineral–microbe interactions that may affect gas purity. Finally the review highlights the need to study microbial adaptation over time and the influence of mineralogy on tolerance thresholds. By analyzing these processes across different geological settings and integrating findings from European research initiatives this work evaluates the impact of microbial and geochemical factors on the safety efficiency and long-term performance of UHS.