Spain

The increase in the overall global temperature and its subsequent impact on extreme weather events are the most critical consequences of human activity. In this scenario transportation plays a significant role in greenhouse gas (GHG) emissions which are the main drivers of climate change. The decline of non-renewable energy sources coupled with the aim of reducing GHG emissions from fossil fuels has forced a shift towards a net-zero emissions economy. As an example of this transition the European Union has set 2050 as the target for achieving carbon neutrality. Hydrogen (H2 ) is gaining increasing relevance as one of the most promising carbon-free energy vectors. If produced from renewable sources it facilitates the integration of various alternative energy sources for achieving a carbon-neutral economy. Recently interest in its application to the transportation sector has grown including different power plant concepts such as fuel cells or internal combustion engines. Despite exhibiting significant drawbacks such as low density combustion instabilities and incompatibilities with certain materials hydrogen is destined to become one of the future fuels. In this publication experimental activities are reported that were conducted on a sparkignition engine fueled with hydrogen at different operating points. The primary objective of this research is to gain a better understanding of the thermodynamic processes that control combustion and their effects on engine performance and pollutant emissions. The results show the emission levels performance and combustion characteristics under different conditions of dilution load and injection strategy and timing.

Turquoise hydrogen from natural gas pyrolysis has recently emerged as a promising alternative for low-carbon hydrogen production with a high-value pure carbon by-product. However the implications of this technology on the broader energy system are not well understood at present. To close this literature gap this study presents an assessment of the integration of natural gas pyrolysis into a simplified European energy system. The energy system model minimizes the cost by optimizing investment and hourly dispatch of a broad range of electricity and fuel production transmission and storage technologies as well as imports/exports on the global market. Norway is included as a major natural gas producer and Germany as a major energy importer. Results reveal that pyrolysis is economically attractive at modest market shares where the carbon by-product can be sold into highvalue markets for 400 €/ton. However pyrolysis-dominated scenarios that employ methane as a hydrogen carrier also hold promise as they facilitate deep decarbonization without the need for vast expansions of international electricity hydrogen and CO2 transmission networks. The simplicity and security benefits of such pyrolysis-led decarbonization pathways justify the modest 11 % cost premium involved for an energy system where natural gas is the only energy trade vector. In conclusion there is a strong case for turquoise hydrogen in future energy systems and further efforts for commercialization of natural gas pyrolysis are recommended.

Hydrogen due to its high energy density stands out as an energy storage method for the car industry in order to reduce the impact of the automotive sector on air pollution and global warming. The fuel cell electric vehicle (FCEV) emerges as a modification of the electric car by adding a proton exchange membrane fuel cell (PEMFC) to the battery pack and electric motor that is capable of converting hydrogen into electric energy. In order to control the energy flow of so many elements an optimal energy management system (EMS) is needed where rule-based strategies represent the smallest computational burden and are the most widely used in the industry. In this work a rulebased operation mode control strategy for the EMS of an FCEV validated by different driving cycles and several tests at the strategic points of the battery state of charge (SOC) is proposed. The results obtained in the new European driving cycle (NEDC) show the 12 kW battery variation of 2% and a hydrogen consumption of 1.2 kg/100 km compared to the variation of 1.42% and a consumption of 1.08 kg/100 km obtained in the worldwide harmonized light-duty test cycle (WLTC). Moreover battery tests have demonstrated the optimal performance of the proposed EMS strategy

Smart energy networks provide an effective means to accommodate high penetrations of variable renewable energy sources like solar and wind which are key for the deep decarbonisation of energy production. However given the variability of the renewables as well as the energy demand it is imperative to develop effective control and energy storage schemes to manage the variable energy generation and achieve desired system economics and environmental goals. In this paper we introduce a hybrid energy storage system composed of battery and hydrogen energy storage to handle the uncertainties related to electricity prices renewable energy production and consumption. We aim to improve renewable energy utilisation and minimise energy costs and carbon emissions while ensuring energy reliability and stability within the network. To achieve this we propose a multi-agent deep deterministic policy gradient approach which is a deep reinforcement learning-based control strategy to optimise the scheduling of the hybrid energy storage system and energy demand in real time. The proposed approach is model-free and does not require explicit knowledge and rigorous mathematical models of the smart energy network environment. Simulation results based on real-world data show that (i) integration and optimised operation of the hybrid energy storage system and energy demand reduce carbon emissions by 78.69% improve cost savings by 23.5% and improve renewable energy utilisation by over 13.2% compared to other baseline models; and (ii) the proposed algorithm outperforms the state-of-the-art self-learning algorithms like the deep-Q network.

Sustainable aviation fuels (SAFs) represent the short-term solution to reduce fossil carbon emissions from aviation. The Carbon Offsetting and Reduction Scheme for International Aviation (CORSIA) was globally adopted to foster and make SAFs production economically competitive. Fischer-Tropsch synthetic paraffinic kerosene (FTSPK) produced from forest residue is a promising CORSIA-eligible fuel. FT conversion pathway permits the integration of carbon capture and storage (CCS) technology which provides additional carbon offsetting ca pacities. The FT-SPK with CCS process was modelled to conduct a comprehensive analysis of the conversion pathway. Life-cycle assessment (LCA) with a well-to-wake approach was performed to quantify the SAF’s carbon footprint considering both biogenic and fossil carbon dynamics. Results showed that 0.09 kg FT-SPK per kg of dry biomass could be produced together with other hydrocarbon products. Well-to-wake fossil emissions scored 21.6 gCO2e per MJ of FT-SPK utilised. When considering fossil and biogenic carbon dynamics a negative carbon flux (-20.0 gCO2eMJ− 1 ) from the atmosphere to permanent storage was generated. However FT-SPK is limited to a 50 %mass blend with conventional Jet A/A1 fuel. Using the certified blend reduced Jet A/A1 fossil emissions in a 37 % and the net carbon flux resulted positive (30.9 gCO2eMJ− 1 ). Sensitivity to variations in process as sumptions was investigated. The lifecycle fossil-emissions reported in this study resulted 49 % higher than the CORSIA default value for FT-SPK. In a UK framework only 0.7 % of aviation fuel demand could be covered using national resources but the emission reduction goal in aviation targeted for 2037 could be satisfied when considering CCS.

The present study investigates the design and scale-up of a pure hydrogen oxy-fuel combustion burner for industrial applications. In recent years this technology has garnered attention as an effective approach to the decarbonisation of high-temperature industrial processes. Replacing air with oxygen in combustion processes significantly reduces nitrogen oxides emissions and leads to sustainable energy use. A laboratory-scale burner was designed with inlet nozzle dimensions adapted to the specific properties of hydrogen and oxygen as fuel and oxidant respectively. Implementing oxy-fuel combustion requires addressing several technical issues to prevent the burner wall from overheating and to ensure a stable flame. An infrared camera was used to characterise the performance and operating conditions of the laboratory-scale burner in the range of 2.5–30 kW. The 10 kW baseline case was analysed numerically and validated experimentally using thermocouples. This revealed stable lifted flames with maximum temperatures of 2800 K and a flame length of 0.15 m. A key challenge in engineering is transferring results from laboratory-scale to large-scale industrial applications. Once validated the prototype design was scaled up numerically from 10 kW to 1 MW investigating the feasibility of different scaling criteria. The impact of these criteria on flame characteristics mixing patterns and the volumetric distribution of the reaction zone was then assessed. The constant velocity criterion yielded the lowest pressure drops although it also resulted in longer flame lengths. In contrast the constant residence time criterion generated the highest pressure drops. The increased velocities associated with this criterion enhanced mixing leading to shorter flame lengths as noted in the cases of 200 kW decreasing from 0.98 m under constant velocity criterion to 0.46 m. The intermediate criteria demonstrated a feasible alternative for scaling up the burner by effectively balancing flame length mixing rate and pressure losses. Nevertheless all criteria enabled the burner to sustain high combustion efficiency. Overall this investigation provides valuable insight into the potential of hydrogen oxy-fuel combustion technology to reduce carbon emissions in high-temperature processes.

Hydrogen is a key energy carrier for decarbonizing multiple sectors particularly when produced via water electrolysis powered by renewable energy. Proton exchange membrane (PEM) electrolyzers are well suited for this application due to their ability to rapidly adjust to fluctuating power inputs. Despite being conventionally operated at high temperatures and pressures to reduce heating and compression needs recent studies suggest that under partial loads lower operating conditions may enhance efficiency. This study introduces a novel optimization framework for dynamically adjusting pressure and temperature in PEM electrolyzers. The model integrates an efficiency map within a Mixed-Integer Linear Programming (MILP) formulation and applies McCormick tightening to address nonlinearities. A one-week case study demonstrates operational cost reductions of up to 12.5 % through optimal control favoring lower temperatures and pressures at low current densities and higher temperatures near rated load while maintaining moderate pressures. The results show improved efficiency and reduced hydrogen crossover enhancing safety and enabling scalable application over extended time horizons. These insights are valuable for long-term planning and evaluation of hydrogen production and storage systems.

Buildings are major energy consumers accounting for a significant portion of global energy consumption. Integrating hydrogen systems electrolyzers accumulation and fuel cells is proposed as a clean and efficient energy alternative to mitigate this impact and move toward a more sustainable future. This paper presents a systematic procedure for incorporating these technologies into buildings considering building engineers and stakeholders. First an in-depth analysis of buildings’ main energy consumption parameters is conducted identifying areas of energy need with the most significant optimization potential. Next a detailed review of the various opportunities for hydrogen applications in buildings is conducted evaluating their advantages and limitations. Performing a scientific review to find and understand the requirements of building engineers and the stakeholders has given notions of integration that emphasize the needs. As a result of the review process and identifying the needs to integrate hydrogen into buildings a flowchart is proposed to facilitate decision-making regarding integrating hydrogen systems into buildings. This flowchart is accompanied by a matrix of variables that considers the defined requirements allowing for combining the most suitable solution for each case. The results of this research contribute to advancing the adoption of hydrogen technologies in buildings thus promoting the transition to a more sustainable and resilient energy model.

Hydrogen production via water electrolysis and renewable electricity is expected to play a pivotal role as an energy carrier in the energy transition. This fuel emerges as the most environmentally sustainable energy vector for non-electric applications and is devoid of CO2 emissions. However an electrolyzer´s infrastructure relies on scarce and energyintensive metals such as platinum palladium iridium (PGM) silicon rare earth elements and silver. Under this context this paper explores the exergy cost i.e. the exergy destroyed to obtain one kW of hydrogen. We disaggregated it into non-renewable and renewable contributions to assess its renewability. We analyzed four types of electrolyzers alkaline water electrolysis (AWE) proton exchange membrane (PEM) solid oxide electrolysis cells (SOEC) and anion exchange membrane (AEM) in several exergy cost electricity scenarios based on different technologies namely hydro (HYD) wind (WIND) and solar photovoltaic (PV) as well as the different International Energy Agency projections up to 2050. Electricity sources account for the largest share of the exergy cost. Between 2025 and 2050 for each kW of hydrogen generated between 1.38 and 1.22 kW will be required for the SOEC-hydro combination while between 2.9 and 1.4 kW will be required for the PV-PEM combination. A Grassmann diagram describes how non-renewable and renewable exergy costs are split up between all processes. Although the hybridization between renewables and the electricity grid allows for stable hydrogen production there are higher non-renewable exergy costs from fossil fuel contributions to the grid. This paper highlights the importance of nonrenewable exergy cost in infrastructure which is required for hydrogen production via electrolysis and the necessity for cleaner production methods and material recycling to increase the renewability of this crucial fuel in the energy transition.

Brazil has emerged as one of the global leaders in adopting renewable energy standing out in the implementation of onshore wind energy and more recently in the development of future offshore wind energy projects. Onshore wind energy has experienced exponential growth in the last decade positioning Brazil as one of the countries with the largest installed capacity in the world by 2023 with 30 GW. Wind farms are mainly concentrated in the northeast region where winds are constant and powerful enabling efficient and cost-competitive generation. Although in its early stages offshore wind energy presents significant potential of 1228 GW due to Brazil’s extensive coastline which exceeds 7000 km. Offshore wind projects promise greater generating capacity and stability as offshore winds are more constant than onshore winds. However their development faces challenges such as high initial costs environmental impacts on marine ecosystems and the need for specialized infrastructure. From a sustainability perspective this article discusses that both types of wind energy are key to Brazil’s energy transition. They reduce dependence on fossil fuels generate green jobs and foster technological innovation. However it is crucial to implement policies that foster synergy with green hydrogen production and minimize socio-environmental impacts such as impacts on local communities and biodiversity. Finally the article concludes that by 2050 Brazil is expected to consolidate its leadership in renewable energy by integrating advanced technologies such as larger more efficient turbines energy storage systems and green hydrogen production. The combination of onshore and offshore wind energy and other renewable sources could position the country as a global model for a clean sustainable and resilient energy mix.

Dark fermentation (DF) has gained increasing interest over the past two decades as a sustainable route for biohydrogen production; however understanding how reproducible the process can be both from macro- and microbiological perspectives remains limited. This study assessed the reproducibility of a parallel continuous DF system using fruit-vegetable waste as a substrate under strictly controlled operational conditions. Three stirred-tank reactors were operated in parallel for 90 days monitoring key process performance indicators. In addition to baseline operation different process enhancement strategies were tested including bioaugmentation supplementation with nutrients and/or additional fermentable carbohydrates and modification of key operational parameters such as pH and hydraulic retention time all widely used in the field to improve DF performance. Microbial community structure was also analyzed to evaluate its reproducibility and potential relationship with process performance and metabolic patterns. Under these conditions key performance indicators and core microbial features were reproducible to a large extent yet full consistency across reactors was not achieved. During operation unforeseen operational issues such as feed line clogging pH control failures and mixing interruptions were encountered. Despite these disturbances the system maintained an average hydrogen productivity of 3.2 NL H2/L-d with peak values exceeding 6 NL H2/L-d under optimal conditions. The dominant microbial core included Bacteroides Lactobacillus Veillonella Enterococcus Eubacterium and Clostridium though their relative abundances varied notably over time and between reactors. An inverse correlation was observed between lactate concentration in the fermentation broth and the amount of hydrogen produced suggesting it can serve as a precursor for hydrogen. Overall the findings presented here demonstrate that DF processes can be resilient and broadly reproducible. However they also emphasize the sensitivity of these processes to operational disturbances and microbial shifts. This underscores the necessity for refined control strategies and further systematic research to translate these insights into stable high-performance real-world systems.

The transition towards a low-carbon energy system remains a critical challenge for regions heavily dependent on fossil fuels such as Andalusia. This study proposes an energy planning framework based on the Low Emissions Analysis Platform (LEAP) to model alternative scenarios and assess the feasibility of meeting the 2030 and 2050 decarbonisation targets. Three scenarios are evaluated the Tendential Scenario (TS01) the Efficient Scenario (ES01) and the Efficient UJA (EEUJA) Scenario with this last being specifically designed to ensure full compliance with regional energy goals. The results indicate that while the Tendential Scenario falls short in reducing primary energy consumption and greenhouse gas (GHG) emissions the Efficient Scenario achieves significant progress though it is still insufficient to meet renewable energy integration targets. The proposed EEUJA Scenario introduces more ambitious measures including large-scale electrification smart grids energy storage and green hydrogen deployment resulting in a 39.5% reduction in primary energy demand by 2030 and 97% renewable energy penetration by 2050. Furthermore by implementing sector-specific decarbonisation strategies for the industry transport residential and services sectors Andalusia could position itself as a frontrunner in the energy transition while minimising economic and environmental risks. These findings underscore the importance of policy enforcement technological innovation and financial incentives in securing a sustainable energy future. The methodology developed in this study is replicable for other regions aiming for carbon neutrality and energy resilience through strategic planning and scenario analysis.

This article presents an innovative approach to address the optimization and planning of hydrogen network transmission focusing on minimizing computational and operational costs including capital operational and maintenance expenses. The mathematical models developed for gas flow rate pipelines junctions and storage form the basis for the optimization problem which aims to reduce costs while satisfying equality inequality and binary constraints. To achieve this we implement a dynamic algorithm incorporating 100 scenarios to account for uncertainty. Unlike conventional successive linear programming methods our approach solves successive piecewise problems and allows comparisons with other techniques including stochastic and deterministic methods. Our method significantly reduces computational time (56 iterations) compared to deterministic (92 iterations) and stochastic (77 iterations) methods. The non-convex nature of the model necessitates careful selection of starting points to avoid local optimal solutions which is addressed by transforming the primal problem into a linear program by fixing the integer variable. The LP problem is then efficiently solved using the Complex Linear Programming Expert (CPLEX) solver enhanced by Monte Carlo simulations for 100 scenarios achieving a 39.13% reduction in computational time. In addition to computational efficiency this approach leads to operational cost savings of 25.02% by optimizing the selection of compressors (42.8571% decreased) and storage facilities. The model’s practicality is validated through realworld simulations on the Belgian gas network demonstrating its potential in solving large-scale hydrogen network transmission planning and optimization challenges.

Hydrogen internal combustion engines (ICEs) have gained significant attention as a promising solution for achieving zero-carbon emissions in the transportation sector. This study investigates the conversion of a 2 L Diesel ICE into a lean hydrogen-powered ICE focusing on key challenges such as hydrogen mixing pre-ignition combustion flame development and NOx emissions. The novelty of this research lies in the specific modifications made to optimize engine performance and reduce emissions while utilizing the existing Diesel engine infrastructure. The study identifies several important design changes for the successful conversion of a Diesel engine to hydrogen including the following: Intake port design: transitioning from a swirl to a tumble design to enhance hydrogen mixing; Injection and spark plug configuration: using a lateral injection system combined with a central spark plug to improve combustion; Piston design: employing a lenticular piston shape with adaptable depth to enhance mixing; Mitigating Coanda effect: preventing hydrogen issues at the spark plug using deflectors or caps; and Head design: maintaining a flat head design for efficient mixing while ensuring adequate cooling to avoid pre-ignition. These findings highlight the importance of specific modifications for converting Diesel engines to hydrogen providing a solid foundation for further research in hydrogen-powered ICEs which could contribute to carbon emission reduction and a more sustainable energy transition.

The study of the electrochemical catalyst conversion of renewable electricity and carbon oxides into chemical fuels attracts a great deal of attention by different researchers. The main role of this process is in mitigating the worldwide energy crisis through a closed technological carbon cycle where chemical fuels such as hydrogen are stored and reconverted to electricity via electrochemical reaction processes in fuel cells. The scientific community focuses its efforts on the development of high-performance polymeric membranes together with nanomaterials with high catalytic activity and stability in order to reduce the platinum group metal applied as a cathode to build stacks of proton exchange membrane fuel cells (PEMFCs) to work at low and moderate temperatures. The design of new conductive membranes and nanoparticles (NPs) whose morphology directly affects their catalytic properties is of utmost importance. Nanoparticle morphologies like cubes octahedrons icosahedrons bipyramids plates and polyhedrons among others are widely studied for catalysis applications. The recent progress around the high catalytic activity has focused on the stabilizing agents and their potential impact on nanomaterial synthesis to induce changes in the morphology of NPs.

In the search of low-carbon hydrogen production routes this study evaluates four biomass gasification processes: conventional steam gasification (CSG) sorption-enhanced gasification (SEG) and their solar-assisted variants (SSG and SSEG). The comparison focuses on three key aspects: hydrogen production overall energy efficiency (to H2 and power) and carbon capture potential (generation of a pure CO2 process stream for storage or utilization). For a realistic comparison a pseudo-equilibrium model of a double-bed gasifier was developed based on experimental correlations of char conversion under conventional and SEG conditions. The solar processes were designed for stable year-round operation considering seasonal weather variations by appropriately dimensioning the heliostat field and the thermal and chemical energy storage systems whose inventory dynamics were modelled. Both the gasifier and central solar tower models were rigorously validated with published data enhancing the reliability of the results. Solar-assisted configurations significantly outperform non-solar ones in hydrogen production with SSEG yielding 128 kg H2/ton biomassdaf compared to 90–95 kg for non-solar options. SEG demonstrates superior carbon capture potential (76 %) while solar-assisted systems achieve higher energy efficiency (67–73 % vs. 60–63 % for non-solar). These results underscore the potential of solar-assisted gasification for sustainable hydrogen production offering enhanced yields improved efficiency and substantial carbon capture capabilities. Future work will involve economic and environmental analysis to determine the best overall configuration.

The recovery of energy and valuable compounds from exhaust gases in the iron and steel industry deserves specialattention due to the large power consumption and CO 2 emissions of the sector. In this sense the hydrogen content of coke oven gas(COG) has positioned it as a promising source toward a hydrogen-based economy which could lead to economic and environmentalbenefits in the iron and steel industry. COG is presently used for heating purposes in coke batteries or furnaces while in highproduction rate periods surplus COG is burnt in flares and discharged into the atmosphere. Thus the recovery of the valuablecompounds of surplus COG with a special focus on hydrogen will increase the efficiency in the iron and steel industry compared tothe conventional thermal use of COG. Different routes have been explored for the recovery of hydrogen from COG so far: i)separation/purification processes with pressure swing adsorption or membrane technology ii) conversion routes that provideadditional hydrogen from the chemical transformation of the methane contained in COG and iii) direct use of COG as fuel forinternal combustion engines or gas turbines with the aim of power generation. In this study the strengths and bottlenecks of themain hydrogen recovery routes from COG are reviewed and discussed.

The growing penetration of renewable energy sources requires resilient microgrids capable of providing stable and continuous operation. Hybrid energy storage systems (HESS) which integrate hydrogen-based storage systems (HBSS) battery storage systems (BSS) and supercapacitor banks (SCB) are essential to ensuring the flexibility and robustness of these microgrids. Accurate modelling of these microgrids is crucial for analysis controller design and performance optimization but the complexity of HESS poses a significant challenge: simplified linear models fail to capture the inherent nonlinear dynamics while nonlinear approaches often require excessive computational effort for real-time control applications. To address this challenge this study presents a novel state space model with linear variable parameters (LPV) which effectively balances accuracy in capturing the nonlinear dynamics of the microgrid and computational efficiency. The research focuses on a high-voltage DC bus microgrid architecture in which the BSS and SCB are connected directly in parallel to provide passive DC bus stabilization a configuration that improves system resilience but has received limited attention in the existing literature. The proposed LPV framework employs recursive linearisation around variable operating points generating a time-varying linear representation that accurately captures the nonlinear behaviour of the system. By relying exclusively on directly measurable state variables the model eliminates the need for observers facilitating its practical implementation. The developed model has been compared with a reference model validated in the literature and the results have been excellent with average errors MAE RAE and RMSE values remaining below 1.2% for all critical variables including state-of-charge DC bus voltage and hydrogen level. At the same time the model maintains remarkable computational efficiency completing a 24-h simulation in just 1.49 s more than twice as fast as its benchmark counterpart. This optimal combination of precision and efficiency makes the developed LPV model particularly suitable for advanced model-based control strategies including real-time energy management systems (EMS) that use model predictive control (MPC). The developed model represents a significant advance in microgrid modelling as it provides a general control-oriented approach that enables the design and operation of more resilient efficient and scalable renewable energy microgrids.

Hydrogen is a critical enabler of CO2 valorization essential for the synthesis of carbon-neutral fuels such as efuels and advanced biofuels. Biohydrogen produced from renewable biomass is a stable and dispatchable source of low-carbon hydrogen helping to address supply fluctuations caused by the intermittency of renewable electricity and the limited availability of electrolytic hydrogen. This study experimentally demonstrates that sorption-enhanced steam reforming (SESR) is a robust and adaptable process for hydrogen production from biomass-derived syngas-like gas streams. By incorporating in situ CO2 capture SESR overcomes the thermodynamic limits of conventional reforming achieving high hydrogen yields (>96 %) and purities (up to 99.8 vol%) across a wide range of syngas compositions. The process maintains high conversion efficiency despite variations in CO CH4 and CO2 concentrations and sustains performance even with H2-rich feeds conditions that typically inhibit reforming reactions. Among the operating parameters temperature has the greatest influence on performance followed by the steam-to-carbon ratio and space velocity. Multi-objective optimization shows that SESR can maintain high hydrogen yield (>96 %) selectivity (>99 %) and purity (>99.5 vol%) within a moderately flexible operating window. Methane reforming is identified as the main performance-limiting step with a stronger constraint on H2 yield and purity than CO conversion through the water–gas shift reaction. In addition to hydrogen SESR produces a concentrated CO2 stream suitable for downstream utilization or storage. These results support the potential of SESR as a flexible and efficient approach for hydrogen production from heterogeneous renewable feedstocks.

The impact of the HyResponder project on the training of responders in 10 European countries is described. An overview is presented of training activities undertaken within the project in Austria Belgium Czech Republic France Germany Italy Norway Spain Switzerland and the United Kingdom. National leads with training expertise are given and the longer-term plans in each region are mentioned. Responders from each region took part in a specially tailored “train the trainer” programme and then delivered training within their regions. A flexible approach to training within the HyResponder network has enabled fit for purpose region appropriate activities to be delivered impacting over 1250 individuals during the project and many more beyond. Teaching and learning materials in hydrogen safety for responders have been made available in 8 languages: English Czech Dutch French German Italian Norwegian Spanish. They are being used to inform training within each of the partner countries. Dedicated national working groups focused on hydrogen safety training for responders have been established in Belgium the Czech Republic Italy and Switzerland.

Hydrogen threatens the structural integrity of metals and thus predicting hydrogen-material interactions is key to unlocking the role of hydrogen in the energy transition. Quantifying the interplay between material deformation and hydrogen diffusion ahead of cracks and other stress concentrators is key to the prediction and prevention of hydrogen-assisted failures. In this work a generalised theoretical and computational framework is presented that for the first time encompasses: (i) stress-assisted diffusion (ii) hydrogen trapping due to multiple trap types rigorously accounting for the rate of creation of dislocation trap sites (iii) hydrogen transport through dislocations (iv) equilibrium (Oriani) and non-equilibrium (McNabb-Foster) trapping kinetics (v) hydrogen-induced softening and (vi) hydrogen uptake considering the role of hydrostatic stresses and local electrochemistry. Particular emphasis is placed on the numerical implementation in COMSOL Multiphysics releasing the relevant models and discussing stability discretisation and solver details. Each of the elements of the framework is independently benchmarked against results from the literature and implications for the prediction of hydrogen-assisted fractures are discussed. The second part of this work (Part II) shows how these crack tip predictions can be combined with crack growth simulations.

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.

Innovative green vehicle concepts have become increasingly prevailing in consumer purchasing habits as technology evolves. The global transition towards sustainable transportation indicates an increase in new-generation vehicles including both fuel-cell electric vehicles (FCEVs) and plug-in electric vehicles (PEVs) that will take on roads in the future. This change requires new-generation stations to support electrification. This study introduced a prominent multi-energy system concept with a hydrogen refueling station. The proposed multi-energy system (MES) consists of green hydrogen production a hydrogen refueling station for FCEVs hydrogen injection into natural gas (NG) and a charging station for PEVs. An on-site renewable system projected at the station and a polymer electrolyte membrane electrolyzer (PEM) to produce hydrogen for two significant consumers support MES. In addition the MES offers the ability to conduct two-way trade with the grid if renewable energy systems are insufficient. This study develops a comprehensive multi-energy system with an economically optimized energy management model using a mixed-integer linear programming (MILP) approach. The determinative datasets of vehicles are generated in a Python environment using Gauss distribution. The fleet of FCEVs and PEVs are currently available on the market. The study includes fleets of the most common models from well-known brands. The results indicate that profits increase when the storage capacity of the hydrogen tank is higher and natural gas injections are limitless. Optimization results for all cases tend to choose higher-priced natural gas injections over hydrogen refueling because of the difference in costs of refueling and injection expenses. The analyses reveal the highest hydrogen sales to the natural gas (NG) grid by consuming 2214.31 kg generating a revenue of $6966 and in contrast the lowest hydrogen sales to the natural gas grid at 1045.38 kg resulting in a revenue of $3286. Regarding electricity the highest sales represent revenue of $7701 and $2375 for distribution system consumption and electric vehicles (EV) respectively. Conversely Cases 1 and 2 have achieved sales to EV of $2286 and $2349 respectively but do not have any sales to distribution system consumption regarding the constraints. Overall the optimization results show that the solution is optimal for a multi-energy system operator to achieve higher profits and that all end-user parties are satisfied.

The importance of new alternative fuels has assumed great relevance in the last decades to face the issues of global warming and pollutant emissions from energy production. The scientific community is responsible for developing solutions to achieve the necessary environmental restriction policies. In this context ammonia appears as a potential fuel candidate and energy vector that may solve the technological difficulties of using hydrogen (H2 ) directly in internal combustion engines. Its high hydrogen content per unit mass higher energy density than liquid hydrogen well-developed infrastructure and experience in handling and storage make it suitable to be implemented as a long-term solution. In this work a virtual engine model was developed to perform prospective simulations of different operating conditions using ammonia and H2 -enriched ammonia as fuel in a spark-ignition (SI) engine integrating a chemical kinetics model and empirical correlations for combustion prediction. In addition specific conditions were evaluated to consider and to understand the governing parameters of ammonia combustion using computational fluid dynamics (CFD) simulations. Results revealed similar thermal efficiency than methane fuel with considerable improvements after appropriate H2 - enrichment. Moreover increasing the intake temperature and the turbulence intensity inside the cylinder evinced significant reductions in combustion duration. Finally higher compression ratios ensure efficiency gains with no evidence of abnormal combustion (knocking) even at high compression ratios (above 16:1) and low engine speeds (800 rpm). Numerical simulations showed the direct influence of the flame front surface area and the turbulent combustion velocity on efficiency reflecting the need for optimizing the SI engines design paradigm for ammonia applications.

The number of Fuel Cell Electric Vehicles (FCEVs) in circulation has undergone a significant increase in recent years. This trend is foreseen to be stronger in the near future. In correlation with the FCEVs market increase the hydrogen delivery infrastructure must be developed. With this aim many countries have announced ambitious projects. For example Spain has the objective of increasing the number of Hydrogen Refuelling Stations (HRS) with public access from three units in operation currently to about 150 by 2030. HRSs are complex systems with high variability in terms of layout design size of components operational strategy hydrogen generation method or hydrogen generation location. This paper is focused on on-site HRS with electrolysis-based hydrogen production which provides interesting advantages when renewable energy is utilized compared to off-site hydrogen production despite their complexity. To optimize HRS design and operation a simulation model must be implemented. This paper describes a generic on-site HRS with electrolysis-based hydrogen production a cascaded multi-tank storage system with multiple compressors renewable energy sources and multiple types of dispensing formats. A modelling approach of the layout is presented and tested with real-based parameters of an HRS currently under development which is capable of producing 11.34 kg/h of green H2 with irradiation at 1000 W/m2. For the operation an operational strategy is proposed. The modelled system is tested through several simulations. A sensitivity analysis of the effects of hydrogen demand and day-ahead hydrogen production objective on emissions demand satisfaction and variable costs is performed. Simulation results show how the operational strategy has achieved service up to 310 FCEVs refuelling events of heavy duty and light duty FCEVs bringing the total H2 sold up to almost 7200 H2kg in one month of winter. Additionally considering variable costs of the energy from the utility grid the model shows a profit in the range of 21–50 k€ for a daily demand of 60 H2kg/day and 100 H2kg/day respectively. In terms of emissions a year simulation with 60 H2kg/day of demand shows specific emissions in the production of H2 in Spain of 6.26 kgCO2eq/H2kg which represents a greenhouse gas emission intensity of 52.26 kgCO2eq/H2MJ.