Spain

Deploying renewable hydrogen presents a significant challenge in accessing off-takers who are willing to make long-term investments. To address this challenge current projects focus on large-scale deployment to replace the demand for non-renewable hydrogen particularly in ammonia synthesis for fertiliser production plants. The traditional process involving Steam Methane Reformers (SMR) connected to Haber-Bosch synthesis could potentially transition towards decarbonisation by gradually integrating water electrolysis. However the coexistence of these processes poses limitations in accommodating the integration of renewable hydrogen thereby creating operational challenges for industrial hubs. To tackle this issue this paper proposes an optimal dispatch model for producing green hydrogen and ammonia while considering the coexistence of different processes. Furthermore the objective is to analyse external factors that could determine the appropriate regulatory and pricing framework to facilitate the phase-out of SMR in favour of renewable hydrogen production. The paper presents a case study based in Spain utilising data from 2018 2022 and 2030 perspectives on the country's renewable resources gas and electricity wholesale markets pricing ranges and regulatory constraints to validate the model. The findings indicate that carbon emissions taxation and the availability and pricing of Power Purchase Agreements (PPAs) will play crucial roles in this transition - the carbon emission price required for total phasing out SMR with water electrolysis would be around 550 EUR/ton CO2.

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.

The article examines the feasibility of implementing standalone hydrogen-based renewable energy systems in Spanish residential buildings specifically analyzing the optimization of a solar-battery and solar-hydrogen system for a building with 20 dwellings in Spain. The study initially assesses two standalone setups: solarbattery and solar-hydrogen. Subsequently it explores scenarios where these systems are connected to the grid to only generate and sell surplus energy. A scenario involving grid connection for self-consumption without storage serves as a benchmark for comparison. All system optimizations are designed to meet energy demands without interruptions while minimizing costs as determined by a techno-economic analysis. The systems are sized using custom software that incorporates an energy management system and employs the Jaya algorithm for optimization. The findings indicate that selling surplus energy can be economically competitive and enhance the efficiency of grid-connected self-consumption systems representing the study’s main innovation. The conclusion highlights the economic and technical potential of an autonomous hybrid energy system that includes hydrogen with the significant remaining challenge being the development of a regulatory framework to support its technical feasibility in Spain.

While the effects of ongoing cost reductions in renewables batteries and electrolyzers on future energy systems have been extensively investigated the effects of significant advances in CO2 capture and storage (CCS) technologies have received much less attention. This research gap is addressed via a long-term (2050) energy system model loosely based on Germany yielding four main findings. First CCS-enabled pathways offer the greatest benefits in the hydrogen sector where hydrogen prices can be reduced by two-thirds relative to a scenario without CCS. Second advanced blue hydrogen technologies can reduce total system costs by 12% and enable negative CO2 emissions due to higher efficiencies and CO2 capture ratios. Third co-gasification of coal and biomass emerged as an important enabler of these promising results allowing efficient exploitation of limited biomass resources to achieve negative emissions and limit the dependence on imported natural gas. Finally CCS decarbonization pathways can practically and economically incorporate substantial shares of renewable energy to reduce fossil fuel dependence. Such diversification of primary energy inputs increases system resilience to the broad range of socio-techno-economic challenges facing the energy transition. In conclusion balanced blue-green pathways offer many benefits and deserve serious consideration in the global decarbonization effort.

Gaseous hydrogen for fuel cell electric vehicles must meet quality standards such as ISO 14687:2019 which contains maximal control thresholds for several impurities which could damage the fuel cells or the infrastructure. A review of analytical techniques for impurities analysis has already been carried out by Murugan et al. in 2014. Similarly this document intends to review the sampling of hydrogen and the available analytical methods together with a survey of laboratories performing the analysis of hydrogen about the techniques being used. Most impurities are addressed however some of them are challenging especially the halogenated compounds since only some halogenated compounds are covered not all of them. The analysis of impurities following ISO 14687:2019 remains expensive and complex enhancing the need for further research in this area. Novel and promising analyzers have been developed which need to be validated according to ISO 21087:2019 requirements.

Green hydrogen produced by water electrolysis with renewable energy plays a crucial role in the revolution towards energy sustainability and it is considered a key source of clean energy and efficient storage. Its ability to address the intermittency of renewable sources and its potential to decarbonize sectors that are difficult to electrify make it a strategic component in climate change mitigation. By using a method based on a bibliometric review of scientific publications this paper represents a significant contribution to the emerging field of research on green hydrogen and provides a detailed review of electrolyzer technologies identifying key areas for future research and technology development. The results reflect the immaturity of a technology which advances with different technical advancements waiting to find the optimal technical solution that allows for its massive implementation as a source of green hydrogen generation. According to the results found in this article alkaline (ALK) and proton exchange membrane (PEM) electrolyzers seem to be the ones that interest the scientific community the most. Similarly in terms of regional analysis Europe is clearly committed to green hydrogen in view of the analysis of its scientific results on materials and electrolyzer capacity forecasts for 2030.

This paper addresses the energy management of a standalone renewable energy system. The system is configured as a microgrid including photovoltaic generation a lead-acid battery as a short term energy storage system hydrogen production and several loads. In this microgrid an energy management strategy has been incorporated that pursues several objectives. On the one hand it aims to minimize the amount of energy cycled in the battery in order to reduce the associated losses and battery size. On the other hand it seeks to take advantage of the long-term surplus energy producing hydrogen and extracting it from the system to be used in a fuel cell hybrid electric vehicle. A crucial factor in this approach is to accommodate the energy consumption to the energy demand and to achieve this a model predictive control (MPC) scheme is proposed. In this context proper models for solar estimation hydrogen production and battery energy storage will be presented. Moreover the controller is capable of advancing or delaying the deferrable loads from its prescheduled time. As a result a stable and efficient supply with a relatively small battery is obtained. Finally the proposed control scheme has been validated on a real case scenario.

Like hydrogen Chile is small by nature and accordingly contributes just 0.3% to global greenhouse gas emissions. However we too have an outsized role to play in turning the tide on rising emissions and pursuing a low carbon path to growth and development.<br/>What we lack in size we more than make up for in potential. In the desert in the North with the highest solar irradiance on the planet and in the Patagonia in the South with strong and consistent winds we have the renewable energy potential to install 70 times the electricity generation capacity we have today. This abundant renewable energy will enable us to become the cheapest producer of green hydrogen on Earth. Our National Green Hydrogen Strategy is aimed at turning this promise into reality.<br/>The Strategy is the result of collaborative work between industry academia civil society and the public sector and is an essential piece of our carbon neutrality plan and commitment to sustainable development. It will allow us to produce and export products that are created using zero carbon fuels distinguishing our exports as clean products for end users. It will also enable us to export our renewable energy to the world in the form of green liquid hydrogen green ammonia and clean synthetic fuels.<br/>Traditionally Chile lacked fossil fuels and was forced to import the energy it required. Now the coming of age of the tiniest atom will allow us to drive deep decarbonization in our own country and throughout the world. This Strategy is the first step for Chile in embracing this promise and fulfilling its new potential.

The transport sector is difficult to decarbonize due to its high reliance on fossil fuels accounting for 37% of global end-use sectors emissions in 2021. Therefore this work proposes an energy model to replace the Spanish vehicle fleet by hydrogen-fueled vehicles by 2050. Thus six regions are defined according to their proximity to regasification plants where hydrogen generation hubs are implemented. Likewise renewables deployment is subject to their land availability. Hydrogen is transported through an overhauled primary natural gas transport network while two distribution methods are compared for levelized cost of hydrogen minimization: gaseous pipeline vs liquid hydrogen supply in trucks. Hence a capacity of 443.1 GW of renewables 214 GW of electrolyzers and 3.45 TWh of hydrogen storage is required nationwide. Additionally gaseous hydrogen distribution is on average 17% cheaper than liquid hydrogen delivery. Finally all the regions present lower prices per km traveled than gasoline or diesel.

The distributed integration of renewable energy sources plays a central role in the decarbonization of economies. In this regard energy communities arise as a promising entity to coordinate groups of proactive consumers (prosumers) and incentivize investment on clean technologies. However the uncertain nature of renewable energy generation residential loads and trading tariffs pose important challenges both at the operational and economic levels. We study how this management can be directly undertaken by an arbitrageur that making use of an adequate price-based demand response (real-time pricing) system serves as an intermediary with the central electricity market to coordinate different types of prosumers under risk aversion. In particular we consider a sequential futures and spot market where the aggregated shortage or excess of energy within the community can be traded. We aim to study the impact of new hydrogen production and storage technologies on community operation and risk management. These interactions are modeled as a game theoretical setting in the form of a stochastic two-stage bilevel optimization problem which is later reformulated without approximation as a single-level mixed-integer linear problem (MILP). An extensive set of numerical experiments based on real data is performed to study the operation of the energy community under different technical and economical conditions. Results indicate that the optimal involvement in futures and spot markets is highly conditioned by the community’s risk aversion and self-sufficiency levels. Moreover the external hydrogen market has a direct effect on the community’s internal price-tariff system and depending on the market conditions may worsen the utility of individual prosumers.

Green hydrogen is gaining increasing attention as a key component of the global energy transition towards a more sustainable industry. Chile with its vast renewable energy potential is well positioned to become a major producer and exporter of green hydrogen. In this context this paper explores the prospects for green hydrogen production and use in Chile. The perspectives presented in this study are primarily based on a compilation of government reports and data from the scientific literature which primarily offer a theoretical perspective on the efficiency and cost of hydrogen production. To address the need for experimental data an ongoing experimental project was initiated in March 2023. This project aims to assess the efficiency of hydrogen production and consumption in the Atacama Desert through the deployment of a mobile on-site laboratory for hydrogen generation. The facility is mainly composed by solar panels electrolyzers fuel cells and a battery bank and it moves through the Atacama Desert in Chile at different altitudes from the sea level to measure the efficiency of hydrogen generation through the energy approach. The challenges and opportunities in Chile for developing a robust green hydrogen economy are also analyzed. According to the results Chile has remarkable renewable energy resources particularly in solar and wind power that could be harnessed to produce green hydrogen. Chile has also established a supportive policy framework that promotes the development of renewable energy and the adoption of green hydrogen technologies. However there are challenges that need to be addressed such as the high capital costs of green hydrogen production and the need for supportive infrastructure. Despite these challenges we argue that Chile has the potential to become a leading producer and exporter of green hydrogen or derivatives such as ammonia or methanol. The country’s strategic location political stability and strong commitment to renewable energy provide a favorable environment for the development of a green hydrogen industry. The growing demand for clean energy and the increasing interest in decarbonization present significant opportunities for Chile to capitalize on its renewable energy resources and become a major player in the global green hydrogen market.

In this review we want to explain how the burning of fossil fuels is pushing us towards green energy. Actually for a long time we have believed that everything is profitable that resources are unlimited and there are no consequences. However the reality is often disappointing. The use of non-renewable resources the excessive waste production and the abandonment of the task of recycling has created a fragile thread that once broken may never restore itself. Metaphors aside we are talking about our planet the Earth and its unique ability to host life including ourselves. Our world has its balance; when the wind erodes a mountain a beach appears or when a fire devastates an area eventually new life emerges from the ashes. However humans have been distorting this balance for decades. Our evolving way of living has increased the number of resources that each person consumes whether food shelter or energy; we have overworked everything to exhaustion. Scientists worldwide have already said actively and passively that we are facing one of the biggest problems ever: climate change. This is unsustainable and we must try to revert it or if we are too late slow it down as much as possible. To make this happen there are many possible methods. In this review we investigate catalysts for using water as an energy source or instead of water alcohols. On the other hand the recycling of gases such as CO2 and N2O is also addressed but we also observe non-catalytic means of generating energy through solar cell production.

The absence of contaminants in the hydrogen delivered at the hydrogen refuelling station is critical to ensure the length life of FCEV. Hydrogen quality has to be ensured according to the two international standards ISO 14687–2:2012 and ISO/DIS 19880-8. Amount fraction of contaminants from the two hydrogen production processes steam methane reforming and PEM water electrolyser is not clearly documented. Twenty five different hydrogen samples were taken and analysed for all contaminants listed in ISO 14687-2. The first results of hydrogen quality from production processes: PEM water electrolysis with TSA and SMR with PSA are presented. The results on more than 16 different plants or occasions demonstrated that in all cases the 13 compounds listed in ISO 14687 were below the threshold of the international standards. Several contaminated hydrogen samples demonstrated the needs for validated and standardised sampling system and procedure. The results validated the probability of contaminants presence proposed in ISO/DIS 19880-8. It will support the implementation of ISO/ DIS 19880-8 and the development of hydrogen quality control monitoring plan. It is recommended to extend the study to other production method (i.e. alkaline electrolysis) the HRS supply chain (i.e. compressor) to support the technology growth.

In this paper we present the first systematic review of Power to X processes applied to the iron and steel industry. These processes convert renewable electricity into valuable chemicals through an electrolysis stage that produces the final product or a necessary intermediate. We have classified them in five categories (Power to Iron Power to Hydrogen Power to Syngas Power to Methane and Power to Methanol) to compare the results of the different studies published so far gathering specific energy consumption electrolysis power capacity CO2 emissions and technology readiness level. We also present for the first time novel concepts that integrate oxy-fuel ironmaking and Power to Gas. Lastly we round the review off with a summary of the most important research projects on the topic including relevant data on the largest pilot facilities (2–6 MW).

In Spain the institutional framework for photovoltaic energy production has experienced distinct stages. From 2007 to 2012 the feed-in-tariff system led to high annual growth rates of this renewable energy but after the suppression of the policy of public subsidies the sector stagnated. In recent years green hydrogen an innocuous gas in the atmosphere has become a driving force that stimulates photovoltaic energy production. Since 2020 encouraged by the European energy strategies and corresponding funds Spain has established a regulation to promote green hydrogen as a form of energy resource. Adopting the new institutional economics (NIE) approach this article investigates the process of changing incentives for the energy business sector and its impact on photovoltaic energy production. The results show an increase in the number of both projects approved or on approval and companies involved in green hydrogen that are planning to use photovoltaic energy in Spain thus engendering the creation of a new photovoltaic business environment based on innovation and sustainability.

Alkaline electrolysis is already a proven technology on land with a high maturity level and good economic performance. However at sea little is known about its economic performance toward hydrogen production. Alkaline electrolysis units operate with purified water to split its molecules into hydrogen and oxygen. Purified water and especially that sourced from the sea has a variable cost that ultimately depends on its quality. However the impurities present in that purified water have a deleterious effect on the electrolyte of alkaline electrolysis units that cause them to drop their energy efficiency. This in turn implies a source of economic losses resulting from the cost of electricity. In addition at sea there are various options regarding the electrolyte management of which the cost depends on various factors. All these factors ultimately impact on the levelized cost of the produced hydrogen. This article aims to shed some light on the economic performance of alkaline electrolysis units operating under sea conditions highlighting the knowledge gaps in the literature and initiating a debate in the field.

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.

The optimisation of green hydrogen production systems is challenging. Moreover an accurate simulation of the system is required for effective optimisation. This study presents a novel method for optimising utility-scale hybrid photovoltaice-wind systems for hydrogen production using accurate simulation models. The optimisation objective is to minimise the levelised cost of hydrogen (LCOH) using genetic algorithms. Different types of systems (such as islanded systems grid-connected systems with or without the possibility of purchasing electricity from the grid and grid-connected systems considering power curtailment) are evaluated and optimised. Each combination of components and control strategy is simulated during the system lifetime (20 yrs) in time steps of 5 min considering the degradation of renewable generators during the system lifetime and different real-time pricing curves and renewable resource curves for each year of the system lifetime. Accurate models are used in the simulations including electrolyser efficiency dependent on the input power and cold-start extra ageing. An application example located in Zaragoza (Spain) is shown obtaining LCOH from 4.74 to 16.06 V/kg depending on the type of project and electrolyser.

Hydrogen (H2) production combined with carbon capture and storage (CCS) is anticipated to be an important technology contributing to reduce the carbon footprint of current fossil-based H2 production systems. This work addresses for the first time the techno-environmental assessment of a CCS process based on the ionic liquid [Bmim][Acetate] for H2 production by steam methane reforming (SMR) and the comparison to conventional amine-based systems. Two different SMR plants using MDEA or [Bmim][Acetate] for CO2 capture were rigorously modelled using Aspen Plus to compute material and energy needs and emissions. Literature and simulation results were then used to perform a life cycle impact assessment (LCIA) of these processes based on the ReCiPe model. Solvent synthesis CCS process and hydrogen production stages were considered for the cradle-to-gate analysis. Results showed that although [Bmim][Acetate] is a priori more harmful to the environment than amines (in a kg-to-kg comparison) LCIAs carried out for both CCS processes showed from 5 to 17 % lower environmental impacts values for all estimated categories when using [Bmim][Acetate] due to a 9.4 % more energy-efficient performance than MDEA which also reduced a 17.4 % the total utility cost. Indeed if a typical amine loss rate of 1.6 kg/tCO2 is assumed the values of the environmental impacts increase up to 14 % for the IL-based CCS plant but still maintaining its favorable results over MDEA. As consequence the SMR plant with the IL-based CCS system exhibited 3–20 % lower values for most of the studied impact categories. These results contribute to shed some light on evaluating the sustainability of ILs with respect to conventional solvents for CO2 capture and to guide the synthesis of new more sustainable ILs but also they would be used to compare the environmental burdens from the synthesis and process performance of other promising ILs for CO2 capture that are not environmentally assed yet.

Water electrolysis to obtain hydrogen in combination with intermittent renewable energy resources is an emerging sustainable alternative to fossil fuels. Among the available electrolyzer technologies anion exchange membrane water electrolysis (AEMWE) has been paid much attention because of its advantageous behavior compared to other more traditional approaches such as solid oxide electrolyzer cells and alkaline or proton exchange membrane water electrolyzers. Recently very promising results have been obtained in the AEMWE technology. This review paper is focused on recent advances in membrane electrode assembly components paying particular attention to the preparation methods for catalyst coated on gas diffusion layers which has not been previously reported in the literature for this type of electrolyzers. The most successful methodologies utilized for the preparation of catalysts including co-precipitation electrodeposition sol–gel hydrothermal chemical vapor deposition atomic layer deposition ion beam sputtering and magnetron sputtering deposition techniques have been detailed. Besides a description of these procedures in this review we also present a critical appraisal of the efficiency of the water electrolysis carried out with cells fitted with electrodes prepared with these procedures. Based on this analysis a critical comparison of cell performance is carried out and future prospects and expected developments of the AEMWE are discussed.

Biogas and hydrogen (H2 ) are breaking through as alternative energy sources in road transport specifically for heavy-duty vehicles. Until a public network of service stations is deployed for such vehicles the owners of large fleets will need to build and manage their own refueling facilities. Fleet refueling management and remote monitoring at these sites will become key business needs. This article describes the construction of a prototype system capable of solving those needs. During the design and development process of the prototype the standard industry protocols involved in these installations have been considered and the latest expertise in information technology systems has been applied. This prototype has been essential to determine the Strengths Challenges Opportunities and Risks (SCOR) of such a system which is the first step of a more ambitious project. A second stage will involve setting up a pilot study and developing a commercial system that can be widely installed to provide a real solution for the industry.

Urban population and the trend towards online commerce leads to an increase in delivery solution in cities. The growth of the transport sector is very harmful to the environment being responsible for approximately 40% of greenhouse gas emissions in the European Union. The problem is aggravated when transporting perishable foodstuffs as the vehicle propulsion engine (VPE) must power not only the vehicle but also the refrigeration unit. This means that the VPE must be running continuously both on the road and stationary (during delivery) as the cold chain must be preserved. The result is costly (high fuel consumption) and harmful to the environment. At present refrigerated transport does not support full-electric solutions due to the high energy consumption required which motivates the work presented in this article. It presents a turnkey solution of a hydrogen-powered refrigeration system (HPRS) to be integrated into standard light trucks and vans for short-distance food transport and delivery. The proposed solution combines an air-cooled polymer electrolyte membrane fuel cell (PEMFC) a lithium-ion battery and low-weight pressurised hydrogen cylinders to minimise cost and increase autonomy and energy density. In addition for its implementation and integration all the acquisition power and control electronics necessary for its correct management have been developed. Similarly an energy management system (EMS) has been developed to ensure continuity and safety in the operation of the electrical system during the working day while maximizing both the available output power and lifetime of the PEMFC. Experimental results on a real refrigerated light truck provide more than 4 h of autonomy in intensive intercity driving profiles which can be increased if necessary by simply increasing the pressure of the stored hydrogen from the current 200 bar to whatever is required. The correct operation of the entire HPRS has been experimentally validated in terms of functionality autonomy and safety; with fuel savings of more than 10% and more than 3650 kg of CO2/ year avoided.

The need to drastically reduce greenhouse gas emissions is driving the development of existing and new technologies to produce and use hydrogen. Anion exchange membrane electrolysis is one of these rapidly developing technologies and presents promising characteristics for efficient hydrogen production. However the environmental performance and the material criticality of anion exchange membrane electrolysis must be assessed. In this work prospective life cycle assessment and criticality assessment are applied first to identify environmental and material criticality hotspots within the production of anion exchange membrane electrolysis units and second to benchmark hydrogen production against proton exchange membrane electrolysis. From an environmental point of view the catalyst spraying process heavily dominates the ozone depletion impact category while the production of the membrane represents a hotspot in terms of the photochemical ozone formation potential. For the other categories the environmental impacts are distributed across different components. The comparison of hydrogen production via anion exchange membrane electrolysis and proton exchange membrane electrolysis shows that both technologies involve a similar life-cycle environmental profile due to similar efficiencies and the leading role of electricity generation for the operation of electrolysis. Despite the fact that for proton exchange membrane electrolysis much less material is required due to a higher lifetime anion exchange membrane electrolysis shows significantly lower raw material criticality since it does not rely on platinum-group metals. Overall a promising environmental and material criticality performance of anion exchange membrane electrolysis for hydrogen production is concluded subject to the expected technical progress for this technology.

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

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

Although alkaline water electrolysis (AWE) is the most widespread technology for hydrogen production by electrolysis its electrochemical and fluid dynamic optimization has rarely been addressed simultaneously using Computational Fluid Dynamics (CFD) simulation. In this regard a two-dimensional (2D) CFD model of an AWE cell has been developed using COMSOL® software and then experimentally validated. The model involves transport equations for both liquid and gas phases as well as equations for the electric current conservation. This multiphysics approach allows the model to simultaneously analyze the fluid dynamic and electrochemical phenomena involved in an electrolysis cell. The electrical response was evaluated in terms of polarization curve (voltage vs. current density) at different operating conditions: temperature electrolyte conductivity and electrode-diaphragm distance. For all cases the model fits very well with the experimental data with an error of less than 1% for the polarization curves. Moreover the model successfully simulates the changes on gas profiles along the cell according to current density electrolyte flow rate and electrode-diaphragm distance. The combination of electrochemical and fluid dynamics studies provides comprehensive information and makes the model a promising tool for electrolysis cell design.

The current political scenario and the concerns for global warming have pushed very harsh regulations on conventional propulsion systems based on the use of fossil fuels. New technologies are being promoted but their current technological status needs further research and development for them to become a competitive substitute for the ever-present internal combustion engine. Hydrogen-fueled internal combustion engines have demonstrated the potential of being a fast way to reach full decarbonization of the transport sector but they still have to face some limitations in terms of the operating range of the engine. For this reason the present work evaluates the potential of reaching full load operation on a conventional diesel engine assuming the minimum modifications required to make it work under H2 combustion. This study shows the methodology through which the combustion model was developed and then used to evaluate a multi-cylinder engine representative of the medium to high duty transport sector. The evaluation included different strategies of dilution to control the combustion performance and the results show that the utilization of EGR brings different benefits to engine operation in terms of efficiency improvement and emissions reduction. Nonetheless the requisites defined for the needed turbocharging system are harsher than expected and result in a potential non-conventional technical solution.

The hydrogen sector is envisaged as one of the key enablers of the energy transition that the European Union is facing to accomplish its decarbonization targets. However regarding the technologies that enable the deployment of a hydrogen economy a growing concern exists about potential burden-shifting across sustainability dimensions. In this sense social life cycle assessment arises as a promising methodology to evaluate the social implications of hydrogen technologies along their supply chains. In the context of the European projects eGHOST and SH2E this study seeks to advance on key methodological aspects of social life cycle assessment when it comes to guiding the ecodesign of two relevant hydrogen-related products: a 5 kW solid oxide electrolysis cell stack for hydrogen production and a 48 kW proton-exchange membrane fuel cell stack for mobility applications. Based on the social life cycle assessment results for both case studies under alternative approaches the definition of a product-specific supply chain making use of appropriate cut-off criteria was found to be the preferable choice when addressing system boundaries definition. Moreover performing calculations according to the activity variable approach was found to provide valuable results in terms of social hotspots identification to support subsequent decision-making processes on ecodesign while the direct calculation approach is foreseen as a complement to ease the interpretation of social scores. It is concluded that advancements in the formalization of such suitable practices could foster the integration of social metrics into the sustainable-by-design framework of hydrogen-related products.

The production of biohydrogen with negative CO2 emissions through the steam methane reforming of biomethane coupled with carbon capture and storage represents a promising technology particularly for industries that are difficult to electrify. In spite of the maturity of this technology which is currently employed in the production of grey and blue hydrogen a detailed cost model that considers the entire supply chain is lacking in the literature. This study addresses this gap by applying correlations derived from actual facilities producing grey and blue hydrogen to calculate the CAPEX while exploring various feedstock combinations for biogas generation to assess the OPEX. The analysis also includes logistic aspects such as decentralised biogas production and the transportation and storage of CO2 . The levelized cost of golden hydrogen is estimated to range from EUR 1.84 to 2.88/kg compared to EUR 1.47/kg for grey hydrogen and EUR 1.93/kg for blue hydrogen assuming a natural gas cost of EUR 25/MWh and excluding the CO2 tax. This range increases to between 3.84 and 2.92 with a natural gas cost of EUR 40/MWh with the inclusion of the CO2 tax. A comparison with conventional green hydrogen is performed highlighting both prices and potential thereby offering valuable information for decision-making.

Energy Intensive Industries (EII) are high users of energy and some of these facilities are extremely dependent on Natural Gas for processing heat production. In European countries where Natural Gas is mostly imported from external producers the increase in international Natural Gas prices is making it difficult for some industries to deliver the required financial results. Therefore they are facing complex challenges that could cause their delocalization in regions with lower energy costs. European countries lack on-site Natural Gas resources and the plans to reduce greenhouse gas emissions in the industrial sector make it necessary to find an alternative. Many different processes cannot be electrified and in these cases synthetic methane is one of the solutions and also represents an opportunity to reduce external energy supply dependency. This study analyzes the current development of power-to-gas technological solutions that could be implemented in large industrial consumers to produce Synthetic Methane using Green Hydrogen as a raw source and using Renewable Energy electricity mainly produced with photovoltaic or wind energy. The study also reviews the triple bottom line impact and the current development status and associated costs for each key component of a power-to-gas plant and the requirements to be fulfilled in the coming years to develop a cost-competitive solution available for commercial use.

Industrial applications of hydrogen are key to the transition towards a sustainable lowcarbon economy. Hydrogen has the potential to decarbonize industrial sectors that currently rely heavily on fossil fuels. Hydrogen with its unique and versatile properties has several in-industrial applications that are fundamental for sustainability and energy efficiency such as the following: (i) chemical industry; (ii) metallurgical sector; (iii) transport; (iv) energy sector; and (v) agrifood sector. The development of a bibliometric analysis of industrial hydrogen applications in Europe is crucial to understand and guide developments in this emerging field. Such an analysis can identify research trends collaborations between institutions and countries and the areas of greatest impact and growth. By examining the scientific literature and comparing it with final hydrogen consumption in different regions of Europe the main actors and technologies that are driving innovation in industrial hydrogen use on the continent can be identified. The results obtained allow for an assessment of the knowledge gaps and technological challenges that need to be addressed to accelerate the uptake of hydrogen in various industrial sectors. This is essential to guide future investments and public policies towards strategic areas that maximize the economic and environmental impact of industrial hydrogen applications in Europe.

Nowadays there is an intense debate in the European Union (EU) regarding the limits to achieve the European Green Deal to make Europe the first climate-neutral continent in the world. In this context there are also different opinions about the role that thermal engines should play. Furhermore there is no clear proposal regarding the possibilities of the use of green hydrogen in the transport decarbonization process even though it should be a key element. Thus there are still no precise guidelines regarding the role of green hydrogen with it being exclusively used as a raw material to produce E-fuels. This review aims to evaluate the possibilities of applying the different alternative technologies available to successfully complete the process already underway to achieve Climate Neutrality by about 2050 depending on the maturity of the technologies currently available and those anticipated to be available in the coming decades.

With renewable energy sources projected to become the dominant source of electricity hydrogen has emerged as a crucial energy carrier to mitigate their intermittency issues. Water electrolysis is the most developed alternative to generate green hydrogen so far. However in the past two decades steam electrolysis has attracted increasing interest and aims to become a key player in the portfolio of electrolytic hydrogen. In practice steam electrolysis follows two distinct operational approaches: Solid Oxide Electrolysis Cell (SOEC) and Proton Exchange Membrane (PEM) at high temperature. For both technologies this work analyses critical cell components outlining material characteristics and degradation issues. The influence of operational conditions on the performance and cell durability of both technologies is thoroughly reviewed. The analytical comparison of the two electrolysis alternatives underscores their distinct advantages and drawbacks highlighting their niche of applications: SOECs thrive in high temperature industries like steel production and nuclear power plants whereas PEM steam electrolysis suits lower temperature applications such as textile and paper. Being PEM steam electrolysis less explored this work ends up by suggesting research lines in the domain of i) cell components (membranes catalysts and gas diffusion layers) to optimize and scale the technology ii) integration strategies with renewable energies and iii) use of seawater as feedstock for green hydrogen production.

In recent years there has been a significant increase in the adoption of autonomous vehicles for marine and submarine missions. The advancement of emerging imaging navigation and communication technologies has greatly expanded the range of operational capabilities and opportunities available. The ENDURUNS project is a European research endeavor focused on identifying strategies for achieving minimal environmental impact. To measure these facts this article evaluates the product impacts employing the Life Cycle Assessment methodology for the first time following the ISO 14040 standard. In this analysis the quantitative values of Damage and Environmental Impact using the Eco-Indicator 99 methodology in SimaPro software are presented. The results report that the main contributors in environmental impact terms have been placed during the manufacturing phase. Thus one of the challenges is accomplished avoiding the use phase emissions that are the focus to reduce nowadays in the marine industry.

The use of aluminum-based products is widespread and growing particularly in industries such as automotive food packaging and construction. Obtaining aluminum is expensive and energy-intensive making the recycling of existing products essential for economic and environmental viability. This work explores the potential of using green hydrogen as a replacement for natural gas in the smelting and refining furnaces in aluminum recycling facilities. The adoption of green hydrogen has the potential to curtail approximately 4.54 Ktons/year of CO2 emissions rendering it a sustainable and economically advantageous solution. The work evaluates the economic viability of a case study through assessing the Net Present Value (NPV) and the Internal Rate of Return (IRR). Furthermore it is employed single- and multi-parameter sensitivity analyses to obtain insight on the most relevant conditions to achieve economic viability. Results demonstrate that integrating on-site green hydrogen generation yields a favorable NPV of €57370 an IRR of 9.83% and a 19.63-year payback period. The primary factors influencing NPV are the initial electricity consumption stack and the H2 price.

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.

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.

Future power systems in which generation will come almost entirely from variable Renewable Energy Sources (vRES) will be characterized by weather-driven supply and flexible demand. In a simulation of the future Dutch power system we analyze whether there are sufficient incentives for market-driven investors to provide a sufficient level of security of supply considering the profit-seeking and myopic behavior of investors. We cosimulate two agent-based models (ABM) one for generation expansion and one for the operational time scale. The results suggest that in a system with a high share of vRES and flexibility prices will be set predominantly by the demand’s willingness to pay particularly by the opportunity cost of flexible hydrogen electrolyzers. The demand for electric heating could double the price of electricity in winter compared to summer and in years with low vRES could cause shortages. Simulations with stochastic weather profiles increase the year-to-year variability of cost recovery by more than threefold and the year-to-year price variability by more than tenfold compared to a scenario with no weather uncertainty. Dispatchable technologies have the most volatile annual returns due to high scarcity rents during years of low vRES production and diminished returns during years with high vRES production. We conclude that in a highly renewable EOM investors would not have sufficient incentives to ensure the reliability of the system. If they invested in such a way to ensure that demand could be met in a year with the lowest vRES yield they would not recover their fixed costs in the majority of years.

: The global demand for energy and the need to mitigate climate change require a shift from traditional fossil fuels to sustainable and renewable energy alternatives. Hydrogen is recognized as a significant component for achieving a carbon-neutral economy. This comprehensive review examines the underground hydrogen storage and particularly laboratory-scale studies related to rock– hydrogen interaction exploring current knowledge. Using bibliometric analysis of data from the Scopus and Web of Science databases this study reveals an exponential increase in scientific publications post-2015 which accounts for approximately 85.26% of total research output in this field and the relevance of laboratory experiments to understand the physicochemical interactions of hydrogen with geological formations. Processes in underground hydrogen storage are controlled by a set of multi-scale parameters including solid properties (permeability porosity composition and geomechanical properties) and fluid properties (liquid and gas density viscosity etc.) together with fluid–fluid and solid–fluid interactions (controlled by solubility wettability chemical reactions etc.). Laboratory experiments aim to characterize these parameters and their evolution simulating real-world storage conditions to enhance the reliability and applicability of findings. The review emphasizes the need to expand research efforts globally to comprehensively address the currently existing issues and knowledge gaps.

The current work presents the electro-oxidation of olive mill and biodiesel wastewaters in an alkaline medium with the aim of hydrogen production and simultaneous reduction in the organic pollution content. The process is performed at laboratory scale in an own-design single cavity electrolyzer with graphite electrodes and no membrane. The system and the procedures to generate hydrogen under ambient conditions are described. The gas flow generated is analyzed through gas chromatography. The wastewater balance in the liquid electrolyte shows a reduction in the chemical oxygen demand (COD) pointing to a decrease in the organic content. The experimental results confirm the production of hydrogen with different purity levels and the simultaneous reduction in organic contaminants. This wastewater treatment appears as a feasible process to obtain hydrogen at ambient conditions powered with renewable energy sources resulting in a more competitive hydrogen cost.

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.

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.

Hydrogen technologies are evolving to decarbonise the transport sector. The present work focuses on the technical design of a Hydrogen Refueling Station to supply hydrogen to five buses in the city of Valencia Spain. The study deals with the technical selection of the components from production to consumption setting an efficient standardisation method. Different calculation are used to size the storage systems for 70.8 kg of hydrogen produced by the elecrolyser daily. For the high-pressure storage system massive and cascade methods are proposed being the last one more efficient (1577.53 Nm3 non usable volume compared to 9948.95 Nm3 of the massive method).

In the automotive sector hydrogen is being increasingly explored as an alternative fuel to replace conventional carbon-based fuels. Its combustion characteristics make it well-suited for adaptation to internal combustion engines. The wide flammability range of hydrogen allows for higher dilution conditions resulting in enhanced combustion efficiency. When combined with lean combustion strategies hydrogen significantly reduces environmental impact virtually eliminating carbon dioxide and nitrogen oxide emissions while maintaining high thermal efficiency. This paper aims to assess the potential of using an outwardly opening poppet valve hydrogen direct injection (DI) system in a small engine for light-duty applications. To achieve this a comparison of performance emission levels and combustion parameters is conducted on a single-cylinder spark-ignition (SI) research engine fueled by hydrogen using both port fuel injection (PFI) and this new direct injection system. Two different engine loads are measured at multiple air dilution and injection timing conditions. The results demonstrate notable efficiency improvements ranging from 0.6% to 1.1% when transitioning from PFI to DI. Accurate control of injection timing is essential for achieving optimal performance and low emissions. Delaying the start of injection results in a 7.6% reduction in compression work at low load and a 3.9% reduction at high load. This results in a 3.1-3.2% improvement in ISFC in both load conditions considered.

Hydrogen will become a key player in transitioning toward a net-zero energy system. However a clear pathway toward a unified European hydrogen infrastructure to support the rapid scale-up of hydrogen production is still under discussion. This study explores plausible pathways using a fully sector-coupled energy system model. Here we assess the emergence of hydrogen infrastructure build-outs connecting neighboring European nations through hydrogen import and domestic production centers with Western and Central European demands via four distinct hydrogen corridors. We identify a potential lock-in effect of blue hydrogen in the medium term highlighting the risk of longterm dependence on methane. In contrast we show that a self-sufficient Europe relying on domestic green hydrogen by 2050 would increase yearly expenses by around 3% and require 518 gigawatts of electrolysis capacity. This study emphasizes the importance of rapidly scaling up electrolysis capacity building hydrogen networks and storage facilities deploying renewable electricity generation and ensuring coherent coordination across European nations.

Renewable hydrogen is emerging as the key to a sustainable energy transition with multiple applications and uses. In the field of transport in addition to fuel cell vehicles it is necessary to develop an extensive network of hydrogen refueling stations (hereafter HRSs). The characteristics and properties of hydrogen make ensuring the safe operation of these facilities a crucial element for their successful deployment and implementation. This paper shows the outcomes of an analysis of hydrogen incidents and accidents considering their potential application to HRSs. For this purpose the HIAD 2.0 was reviewed and a total of 224 events that could be repeated in any of the major industrial processes related to hydrogen refueling stations were analyzed. This analysis was carried out using a mixed methodology of quantitative and qualitative techniques considering the following hydrogen value chain: production storage delivery and industrial use. The results provide general information segmented by event frequency damage classes and failure typology. The analysis shows the main processes of the value chain allow the identification of key aspects for the safety management of refueling facilities.

LNG carriers play a crucial role in the shipping industry meeting the global demand for natural gas (NG). However the energy losses resulting from the propulsion system and the excess boil-off gas (BOG) cannot be overlooked. The present article investigates the H2 production on board LNG carriers employing both the engine's waste heat (WH) and the excess BOG. Conventional (ORC) and dual-pressure (2P-ORC) organic Rankine cycles coupled separately with a solid oxide electrolysis (SOEC) have been simulated and compared. The hydrogen (H2) produced is then compressed at 150 bar for subsequent use as required. According to the results the 2P-ORC generates 14.79 % more power compared to ORC allowing for an increased energy supply to the SOEC; hence producing more H2 (34.47 kg/h compared to 31.14 kg/h). Including the 2P-ORC in the H2 production plant results in a cheaper H2 cost by 0.04 $/kgH2 compared to ORC a 1.13 %LHV higher system efficiency when leveraging all the available waste heat. The plant including 2P-ORC exploits more than 86 % of the of the available waste compared to 70 % when using ORC. Excluding the compression system decreases the capital cost by almost the half regardless of the WH recovery system used yet it plays in favour of the plant with ORC making the cost of H2 cheaper by 0.29 $/kgH2 in this case. Onboard H2 production is a versatile process independent from the propulsion system ensuring the ship's safety and availability throughout a sea journey.