Production & Supply Chain

Green hydrogen produced by water electrolysis using renewable energy sources (RES) is an emerging technology that aligns with sustainable development goals and efforts to address climate change. In addition to energy electrolyzers require ultrapure water to operate. Although seawater is abundant on the Earth it must be desalinated and further purified to meet the electrolyzer’s feeding water quality requirements. This paper reviews seawater purification processes for electrolysis. Three mature and commercially available desalination technologies (reverse osmosis multiple-effect distillation and multi-stage flash) were examined in terms of working principles performance parameters produced water quality footprint and capital and operating expenditures. Additionally pretreatment and post-treatment techniques were explored and the brine management methods were investigated. The findings of this study can help guide the selection and design of water treatment systems for electrolysis.

Hydrogen is expected to play a critical role in future energy systems projected to have an annual demand of 401–660 Mt by 2050. With large-scale green hydrogen projects advancing in water-scarce regions like Australia Chile and the Middle East and North Africa understanding water requirements for large-scale green hydrogen production is crucial. Meeting this future hydrogen demand will necessitate 4010 to 6600 GL of demineralised water annually for electrolyser feedwater if dry cooling is employed or an additional 6015 to 19800 GL for cooling water per year if evaporative cooling is employed. Using International Panel of Climate Change 2050 climate projections this work evaluated the techno-economic implications of dry vs. evaporative cooling for large-scale electrolyser facilities under anticipated higher ambient temperatures. The study quantifies water demands costs and potential operational constraints showing that evaporative cooling is up to 8 times cheaper to implement than dry cooling meaning that evaporative cooling can be oversized to accommodate increased cooling demand of high temperature events at a lower cost. Furthermore of the nations analysed herein Chile emerged as having the lowest cost of hydrogen owing to the lower projected ambient temperatures and frequency of high temperature events.

The global push for sustainable energy has heightened the demand for green hydrogen which is crucial for decarbonizing heavy industry. However current electrolysis plant capacities are insufficient. This research addresses the challenge through optimizing large-scale electrolysis construction via standardization modularization process optimization and automation. This paper introduces H2Giga a project for mass-producing electrolyzers and HyPLANT100 investigating largescale electrolysis plant structure and construction processes. Modularizing electrolyzers enhances production efficiency and scalability. The integration of AutomationML facilitates seamless information exchange. A digital twin concept enables simulations optimizations and error identification before assembly. While construction site automation provides advantages tasks like connection technologies and handling cables tubes and hoses require pre-assembly. This study identifies key tasks suitable for automation and estimating required components. The Enapter Multicore electrolyzer serves as a case study showcasing robotic technology for tube fittings. In conclusion this research underscores the significance of standardization modularization and automation in boosting the electrolysis production capacity for green hydrogen contributing to ongoing efforts in decarbonizing the industrial sector and advancing the global energy transition.

Hydrogen energy the cleanest fuel presents extensive applications in renewable energy technologies such as fuel cells. However the transition process from carbon-based (fossil fuel) energy to desired hydrogen energy is usually hindered by inevitable scientific technological and economic obstacles which mainly involves complex hydrocarbon reforming reactions. Hence this paper provides a systematic and comprehensive analysis focusing on the hydrocarbon reforming mechanism. Accordingly recent related studies are summarized to clarify the intrinsic difference among the reforming mechanism. Aiming to objectively assess the activated catalyst and deactivation mechanism the rate-determining steps of reforming process have been emphasized summarized and analyzed. Specifically the effect of metals and supports on individual reaction processes is discussed followed by the metalsupport interaction. Current tendency and research map could be established to promote the technology development and expansion of hydrocarbon reforming field. This review could be considered as the guideline for academics and industry designing appropriate catalysts.

Green hydrogen is gaining prominence as a sustainable fuel to decarbonize hard-to-electrify industries and complement renewable energy growth. Among clean hydrogen production technologies seawater-based PEM electrolysis systems hold substantial promise. However implementing offshore PEM electrolysis systems faces significant challenges in ensuring long-term availability due to technological infancy and harsh environmental conditions. Ensuring safe and reliable operation is therefore critical to advancing global sustainability goals. While existing research has primarily focused on component-level techno-economic feasibility limited attention has been given to system-level safety and availability analysis particularly for offshore renewable-powered seawater-based PEM electrolysis systems. This study addresses this gap by conducting a comprehensive availability analysis of containerized plug-and-play PEM systems in offshore environments. A Bayesian Network model is employed incorporating Fault Tree Analysis and Reliability Block Diagram approaches for failure and availability analysis at the system level. A maintenance decision support tool using Influence diagram is developed to analyse different maintenance planning strategies impact on system availability improvement. A case study incorporating industrial modular PEM model is utilised to analyse the developed model effectiveness. The study identifies 81 availability states with the hydrogen generation subsystem being the most critical to system performance. Comparative analysis shows that applying redundancy across all subsystems improves availability by 18.54% but reduces Expected Utility by 4.94%. The optimal strategy involves redundancy for seawater purification cooling and monitoring subsystems with preventive maintenance for hydrogen generation achieving a maximum EU of 5.29 × 106. This framework supports decision-makers in evaluating system availability under uncertain offshore conditions optimizing maintenance strategies and ensuring resilience for large-scale H2 production.

Anaerobic digestion (AD) is a biotechnological process in which the microorganisms degrade complex organic matter to simpler components under anaerobic conditions to produce biogas and fertilizer. This process has many environmental benefits such as green energy production organic waste treatment environmental protection and greenhouse gas emissions reduction. It has long been known that the two main species (acidogenic bacteria and methanogenic archaea) in the community of microorganisms in AD differ in many aspects and the optimal conditions for their growth and development are different. Therefore if AD is performed in a single bioreactor (single-phase process) the optimal conditions are selected taking into account the slow-growing methanogens at the expense of fast-growing acidogens affecting the efficiency of the whole process. This has led to the development of two-stage AD (TSAD) in recent years where the processes are divided into a cascade of two separate bioreactors (BRs). It is known that such division of the processes into two consecutive BRs leads to significantly higher energy yields for the two-phase system (H2 + CH4) compared to the traditional single-stage CH4 production process. This review presents the state of the art advantages and disadvantages and some perspectives (based on more than 210 references from 2002 to 2024 and our own studies) including all aspects of TSAD—different parameters’ influences types of bioreactors microbiology mathematical modeling automatic control and energetical considerations on TSAD processes.

Hydrogen has been receiving a lot of attention in the last few years since it is seen as a viable yet not thoroughly dissected alternative for addressing climate change issues namely in terms of energy storage and therefore great investments have been made towards research and development in this area. In this context a study about the main options for hydrogen production along with the analysis of a variety of the main power electronics converter topologies for such applications is presented as the purpose of this paper. Much of the analyzed available literature only discusses a few types of hydrogen production methods so it becomes crucial to include an analysis of all known types of methods for producing hydrogen according to their production type along with the color code associated with each type and highlighting the respective contextualization as well as advantages and disadvantages. Regarding the topologies of power electronics converters most suitable for hydrogen production and more specifically for green hydrogen production a list of them was analyzed through the available literature and a discussion of their advantages and disadvantages is presented. These topologies present the advantage of having a low ripple current output which is a requirement for the production of hydrogen.

Water electrolysis is considered as an important technology for an increased renewable energy penetration. This perspective on low-temperature water electrolysis joins the dots between the interdisciplinary fields of fundamental science describing physicochemical processes engineering for the targeted design of cell components and the development of operation strategies. Within this aim the mechanisms of ion conduction gas diffusion corrosion and electrocatalysis are reviewed and their influence on the optimum design of separators electrocatalysts electrodes and other cell components are discussed. Electrocatalysts for the water splitting reactions and metals for system components are critically accessed towards their stability and functionality. On the basis of the broad scientific analysis provided challenges for the design of water electrolyzers are elucidated with special regard to the alkaline or acidic media of the electrolyte.

Combining electrolytic hydrogen production with wind–photovoltaic power can effectively smooth the fluctuation of power and enhance the schedulable wind–photovoltaic power which provides an effective solution to solve the problem of wind–photovoltaic power accommodation. In this paper the optimization operation strategy is studied for the wind–photovoltaic power-based hydrogen production system. Firstly to make up for the deficiency of the existing research on the multi-state and nonlinear characteristics of electrolyzers the three-state and power-current nonlinear characteristics of the electrolyzer cell are modeled. The model reflects the difference between the cold and hot starting time of the electrolyzer and the linear decoupling model is easy to apply in the optimization model. On this basis considering the operation constraints of the electrolyzer hydrogen storage tank battery and other equipment the optimization operation model of the wind–photovoltaic power-based hydrogen production system is developed based on the typical scenario approach. It also considers the cold and hot starting time of the electrolyzer with the daily operation cost as the goal. The results show that the operational benefits of the system can be improved through the proposed strategy. The hydrogen storage tank capacity will have an impact on the operation income of the wind–solar hydrogen coupling system and the daily operation income will increase by 0.32% for every 10% (300 kg) increase in the hydrogen storage tank capacity.

The conversion of solar to chemical energy is one of the central processes considered in the emerging renewable energy economy. Hydrogen production from water splitting over particulate semiconductor catalysts has often been proposed as a simple and a cost-effective method for largescale production. In this review we summarize the basic concepts of the overall water splitting (in the absence of sacrificial agents) using particulate photocatalysts with a focus on their synthetic methods and the role of the so-called “co-catalysts”. Then a focus is then given on improving light absorption in which the Z-scheme concept and the overall system efficiency are discussed. A section on reactor design and cost of the overall technology is given where the possibility of the different technologies to be deployed at a commercial scale and the considerable challenges ahead are discussed. To date the highest reported efficiency of any of these systems is at least one order of magnitude lower than that deserving consideration for practical applications.

Switching to renewable resources for hydrogen production is essential. Present hydrogen resources such as coal oil and natural gas are depleted and rapidly moving to a dead state and they possess a high carbon footprint. Wastewater is a promising avenue in searching for a renewable hydrogen production resource. Profuse techniques are preferred for hydrogen production. Among them electrolysis is great with wastewater against biological processes by hydrogen purity. Present obstacles behind the process are conversion efficiency intensive energy and cost. This review starts with hydrogen demand wastewater availability and their H2 potential then illustrates the three main types of electrolysis. The main section highlights renewable energy-assisted electrolysis because of its low carbon footprint and zero emission potential for various water electrolysis. High-temperature steam solid oxide electrolysis is a viable option for future scaling due to the versatile adoption of photo electric and thermal energy. A glance at some effective aspirations to large-scale H2 economics such as co-generation biomass utilization Microbial electrolysis waste to low-cost green electrode Carbon dioxide hydrogenation and minerals recovery. This study gives a broader view of facing challenges via versatile future perspectives to eliminate the obstacles above. renewable green H2 along with a low carbon footprint and cost potential to forward the large-scale wastewater electrolysis H2 production in addition to preserving the environment from wastewater and fossil fuel. Geographical and seasonal availability constraints are unavoidable; therefore energy storage and coupling of power sources is essential to attain consistent supply. The lack of regulations and policies supporting the development and adoption of these technologies did not reduce the gap between research and implementation. Life cycle assessment of this electrolysis process is rarely available so we need to focus on the natural effect of this process on the environment.

Electrolysis of water to generate hydrogen fuel is an attractiverenewable energy storage technology. However grid-scale fresh-water electrolysis would put a heavy strain on vital water re-sources. Developing cheap electrocatalysts and electrodes that cansustain seawater splitting without chloride corrosion could ad-dress the water scarcity issue. Here we present a multilayer anodeconsisting of a nickel–iron hydroxide (NiFe) electrocatalyst layeruniformly coated on a nickel sulfide (NiSx) layer formed on porousNi foam (NiFe/NiSx-Ni) affording superior catalytic activity andcorrosion resistance in solar-driven alkaline seawater electrolysisoperating at industrially required current densities (0.4 to 1 A/cm2)over 1000 h. A continuous highly oxygen evolution reaction-active NiFe electrocatalyst layer drawing anodic currents towardwater oxidation and an in situ-generated polyatomic sulfate andcarbonate-rich passivating layers formed in the anode are respon-sible for chloride repelling and superior corrosion resistance of thesalty-water-splitting anode.

From navigating the rainbow of colours to the lack of consensus in establishing a common taxonomy the labelling and definition of green or renewable hydrogen presents a growing challenge. In this context carbon taxonomy is understood through five critical aspects: carbon intensity temporal and geographical correlation additionality of renewable energy generation and different system boundaries in Life Cycle Assessment (LCA). This study examines the effect of carbon taxonomy on the design and operation of Power-to-Gas (PtG) systems for renewable hydrogen production including the electricity supply portfolio via Power Purchase Agreements (PPA) and grid-connected electrolysis. To this end an optimisation model combining energy system modelling and LCA is developed and then applied to a case study in the Japanese context. The importance of the PPA portfolio in securing cheap and low-carbon electricity to produce hydrogen is addressed. To support this evaluation process an eco-efficiency metric is introduced and proved to be a comprehensive tool for evaluating renewable hydrogen production. Regarding carbon taxonomies the findings emphasize additionality as the key determinant factor followed by temporal correlation and the definition of carbon intensity thresholds. The application of a cradle-togate LCA boundary influenced the cabron intensity accounting playing an unexpected role on the design and optimal PtG dispatch strategy.

The growing challenges of climate change the depletion of fossil fuel reserves and the urgent need for carbon-neutral energy solutions have intensified the focus on renewable energy. In this perspective the generation of green hydrogen from renewable sources like biogas/landfill gas (LFG) offers an intriguing option providing the dual benefits of a sustainable hydrogen supply and enhanced waste management through energy innovation and valorization. Thus this review explores the production of green hydrogen from biogas/LFG through four conventional reforming processes specifically dry methane reforming (DMR) steam methane reforming (SMR) partial oxidation reforming (POX) and autothermal reforming (ATR) focusing on their mechanisms operating parameters and the role of catalysts in hydrogen production. This review further delves into both the environmental aspects specifically GWP (CO2 eq·kg−1 H2) emissions and the economic aspects of these processes examining their efficiency and impact. Additionally this review also explores hydrogen purification in biogas/LFG reforming and its integration into the CO2 capture utilization and storage roadmap for net-negative emissions. Lastly this review highlights future research directions focusing on improving SMR and DMR biogas/LFG reforming technologies through simulation and modeling to enhance hydrogen production efficiency thereby advancing understanding and informing future research and policy initiatives for sustainable energy solutions.

Although hydrogen is increasingly seen as a crucial energy carrier in future zero-carbon energy system a profitable exploitation of electrolysers requires still high amounts of subsidies. To analyze the profitability of electrolysers attention has to be paid not only to the costs but also to the interaction between electricity and hydrogen markets. Using a model of internationally integrated electricity and hydrogen markets this paper analyses the profitability of electrolysers plants in various future market circumstances. We find that in particular the future supply of renewable electricity the demand for electricity as well as the prices of natural gas and carbon strongly affect the profitability of electrolysis. In order to make massive investments in electrolysers profitable with significantly lower subsidy requirements the amount of renewable electricity generation needs to grow strongly and the carbon prices should be higher while the demand for electricity should not increase accordingly. This research underscores the critical role of market conditions in shaping the viability of hydrogen electrolysis providing valuable insights for policymakers and stakeholders in the transition to a zero-carbon energy system.

An equilibrium-based steady-state simulator model that predicts and optimizes hydrogen production from steam gasification ofbiomass is developed using ASPEN Plus software and artificial intelligence techniques. Corn cob’s chemical composition wascharacterized to ensure the biomass used as a gasifier and with potential for production of hydrogen. Artificial intelligence is usedto examine the effects of the significant input variables on response variables such as hydrogen mole fraction and hydrogen energycontent. Optimizing the steam-gasification process using response surface methodology (RSM) considering a variety of biomass-steam ratios was carried out to achieve the best results. Hydrogen yield and the impact of main operating parameters wereconsidered. A maximum hydrogen concentration is found in the gasifier and water-gas shift (WGS) reactor at the highest steam-to-biomass (S/B) ratio and the lowest WGS reaction temperature while the gasification temperature has an optimum value. ANFISwas used to predict hydrogen of mole fraction 0.5045 with the input parameters of S/B ratio of 2.449 and reactor pressure andtemperature of 1 bar and 848°C respectively. With the steam-gasification model operating at temperature (850°C) pressure (1 bar)and S/B ratio of 2.0 an ASPEN simulator achieved a maximum of 0.5862 mole fraction of hydrogen while RSM gave an increaseof 19.0% optimum hydrogen produced over the ANFIS prediction with the input parameters of S/B ratio of 1.053 and reactorpressure and temperature of 1 bar and 850°C respectively. Varying the gasifier temperature and S/B ratio have on the other handa crucial effect on the gasification process with artificial intelligence as a unique tool for process evaluation prediction andoptimization to increase a significant impact on the products especially hydrogen.

Green hydrogen generation technologies are currently the most pressing worldwide issues ofering promising alternatives to existing fossil fuels that endanger the globe with growing global warming. The current research focuses on the creation of green hydrogen in alkaline electrolytes utilizing a Ni-Co-nano-graphene thin flm cathode with a low overvoltage. The recommended conditions for creating the target cathode were studied by electrodepositing a thin Ni-Co-nano-graphene flm in a glycinate bath over an iron surface coated with a thin copper interlayer. Using a scanning electron microscope (SEM) and energy-dispersive X-ray (EDX) mapping analysis the obtained electrode is physically and chemically characterized. These tests confrm that Ni Co and nano-graphene are homogeneously dispersed resulting in a lower electrolysis voltage in green hydrogen generation. Tafel plots obtained to analyze electrode stability revealed that the Ni-Co-nano-graphene cathode was directed to the noble direction with the lowest corrosion rate. The Ni-Co-nano-graphene generated was used to generate green hydrogen in a 25% KOH solution. For the production of 1 kg of green hydrogen utilizing Ni-Co-nano-graphene electrode the electrolysis efciency was 95.6% with a power consumption of 52 kwt h−1 whereas it was 56.212. kwt h−1 for pure nickel thin flm cathode and 54. kwt h−1 for nickel cobalt thin flm cathode respectively.

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

On today’s episode of Everything About Hydrogen we speak with Raffi Garabedian CEO and Co-Founder of Electric Hydrogen (EH2) a deep decarbonization company pioneering new technology for low cost high efficiency fossil free hydrogen systems. By using electrolyzers many times larger than the industry standard EH2 aims to help eliminate more than 30% of global GHG emissions from difficult to electrify sectors like steel ammonia and freight.

We are excited to learn more from Raffi about the EH2 technology lessons learned by scaling First Solar and what we might expect to see next.

The podcast can be found on their website.

Today Everything About Hydrogen had a chance to speak with Paul Barrett the CEO of Hysata and dig into what makes this electrolysis company different.

The podcast can be found on their website.

Rapid industrialization is consuming too much energy and non-renewable energy resources are currently supplying the world’s majority of energy requirements. As a result the global energy mix is being pushed towards renewable and sustainable energy sources by the world’s future energy plan and climate change. Thus hydrogen has been suggested as a potential energy source for sustainable development. Currently the production of hydrogen from fossil fuels is dominant in the world and its utilization is increasing daily. As discussed in the paper a large amount of hydrogen is used in rocket engines oil refining ammonia production and many other processes. This paper also analyzes the environmental impacts of hydrogen utilization in various applications such as iron and steel production rocket engines ammonia production and hydrogenation. It is predicted that all of our fossil fuels will run out soon if we continue to consume them at our current pace of consumption. Hydrogen is only ecologically friendly when it is produced from renewable energy. Therefore a transition towards hydrogen production from renewable energy resources such as solar geothermal and wind is necessary. However many things need to be achieved before we can transition from a fossil-fuel-driven economy to one based on renewable energy

Environmental issues related to greenhouse gas emissions are progressively pushing the transition toward fossil-free energy scenario in which renewable energies such as solar and wind power will unavoidably play a key role. However for this transition to succeed significant issues related to renewable energy storage have to be addressed. Power-to-X (PtX) technologies have gained increased attention since they actually convert renewable electricity to chemicals and fuels that can be more easily stored and transported. H2 production through water electrolysis is a promising approach since it leads to the production of a sustainable fuel that can be used directly in hydrogen fuel cells or to reduce carbon dioxide (CO2) in chemicals and fuels compatible with the existing infrastructure for production and transportation. CO2 electrochemical reduction is also an interesting approach allowing the direct conversion of CO2 into value-added products using renewable electricity. In this review attention will be given to technologies for sustainable H2 production focusing on water electrolysis using renewable energy as well as on its remaining challenges for large scale production and integration with other technologies. Furthermore recent advances on PtX technologies for the production of key chemicals (formic acid formaldehyde methanol and methane) and fuels (gasoline diesel and jet fuel) will also be discussed with focus on two main pathways: CO2 hydrogenation and CO2 electrochemical reduction.

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.

As countries work towards achieving net-zero emissions the need for cleaner fuels has become increasingly urgent. Hydrogen produced from fossil fuels with carbon capture and storage (blue hydrogen) has the potential to play a significant role in the transition to a low-carbon economy. This study examined the technical and economic potential of blue hydrogen produced at 600 MWth(LHV) and scaled up to 1000 MWth(LHV) by benchmarking sorption-enhanced steam reforming process against steam methane reforming (SMR) autothermal gasheated reforming (ATR-GHR) integrated with carbon capture and storage (CCS) and SMR with CCS. Aspen Plus® was used to develop the process model which was validated using literature data. Cost sensitivity analyses were also performed on two key indicators: levelised cost of hydrogen and CO2 avoidance cost by varying natural gas price electricity price CO2 transport and storage cost and carbon price. Results indicate that at a carbon price of 83 £/tCO2e the LCOH for SE-SR of methane is the lowest at 2.85 £/kgH2 which is 12.58% and 22.55% lower than that of ATR-GHR with CCS and SMR plant with CCS respectively. The LCOH of ATR-GHR with CCS and SMR plant with CCS was estimated to be 3.26 and 3.68 £/kgH2 respectively. The CO2 avoidance cost was also observed to be lowest for SE-SR followed by ATR-GHR with CCS then SMR plant with CCS and was observed to reduce as the plant scaled to 1000 MWth(LHV) for these technologies.

This article challenges the view that zero carbon hydrogen from steam methane reforming (SMR) is prohibitively expensive and that the cost of CO2 capture increases exponentially as residual emissions approach zero; a flawed narrative often eliminating SMR produced hydrogen as a route to net zero. We show that the capture and geological storage of 100% of the fossil CO2 produced in a SMR is achievable with commercially available post-combustion capture technology and an open art solvent. The Levelised Cost of Hydrogen (LCOH) of 69£/MWhth HHV (2.7£/kg) for UK production remains competitive to other forms of low carbon hydrogen but retains a hydrogen lifecycle carbon intensity of 5 gCO2e/MJ (LHV) due to natural gas supply chain and embodied greenhouse gas (GHG) emissions. Compensating for the remaining lifecycle GHG emissions via Direct Air Capture with geological CO2 Storage (DACCS) increases the LCOH to 71–86 £/MWhth HHV (+3–25%) for a cost estimate of 100–1000 £/tCO2 for DACCS and the 2022 UK natural gas supply chain methane emission rates. Finally we put in perspective the cost of CO2 avoidance of fuel switching from natural gas to hydrogen with long term price estimates for natural gas use and DACCS and hydrogen produced from electrolysis.

Economical offshore wind developments depend on alternatives for cost-efficient transmission of the generated energy to connecting markets. Distance to shore availability of an offshore power grid and scale of the wind farm may impede export through power cables. Conversion to H2 through offshore electrolysis may for certain offshore wind assets be a future option to enable energy export. Here we analyse the cost sensitivity of offshore electrolysis for harvesting offshore wind in the North Sea using a technology-detailed multi-carrier energy system modelling framework for analysis of energy export. We include multiple investment options for electric power and hydrogen export including HVDC cables new hydrogen pipelines tie-in to existing pipelines and pipelines with linepacking. Existing hydropower is included in the modelling and the effect on offshore electrolysis from increased pumping capacity in the hydropower system is analysed. Considering the lack of empirical cost data on offshore electrolysis as well as the high uncertainty in future electricity and H2 prices we analyse the cost sensitivity of offshore electrolysis in the North Sea by comparing costs relative to onshore electrolysis and energy prices relative to a nominal scenario. Offshore electrolysis is shown to be particularly sensitive to the electricity price and an electricity price of 1.5 times the baseline assumption was needed to provide sufficient offshore energy for any significant offshore electrolysis investments. On the other hand too high electricity prices would have a negative impact on offshore electrolysis because the energy is more valuable as electricity even at the cost of increased wind power curtailment. This shows that there is a window-of-opportunity in terms of onshore electricity where offshore electrolysis can play a significant role in the production of H2 . Pumped hydropower increases the maximum installed offshore electrolysis at the optimal electricity and H2 prices and makes offshore electrolysis more competitive at low electricity prices. Linepacking can make offshore electrolysis investments more robust against low H2 and high electricity prices as it allow for more variable H2 production through storing excess energy from offshore. The increased electrolysis capacity needed for variable electrolyser operation and linepacking is installed onshore due to its lower CAPEX compared to offshore installations.

This study proposes a multitype electrolytic collaborative hydrogen production model for optimizing the capacity configuration of renewable energy off grid hydrogen production systems. The electrolytic hydrogen production process utilizes the synergistic electrolysis of an alkaline electrolyzer (AEL) and proton exchange membrane electrolyzer (PEMEL) fully leveraging the advantages of the low cost of the AEL and strong regulation characteristics of the PEMEL. For the convenience of the optimization solution the article constructs a mixed linear optimization model that considers the constraints during system operation with the objective function of minimizing total costs while meeting industrial production requirements. Gurobi is used for the optimal solution to obtain the optimal configuration of a renewable energy off grid hydrogen production system. By comparing and analyzing the optimal configuration under conventional load and high-load conditions it is concluded that collaborative electrolysis has advantages in improving resource consumption and reducing hydrogen production costs. This is of great significance for optimizing the capacity configuration of off grid hydrogen production systems and improving the overall economic benefits of the system.

Methane reforming is an interesting resource for obtaining hydrogen. DBD plasma-catalysis allows a direct use of electricity for methane reforming reactions such as direct methane reforming (MR) dry methane reforming (DMR) and steam methane reforming (SMR). In this work the first comprehensive comparison of these three routes for hydrogen production is experimentally and systematically investigated using dielectric barrier discharge (DBD) plasma and various catalyst formulations. Among the three routes SMR is the most effective achieving significantly higher methane conversion rates (24 %) and hydrogen content (80 %). DMR produces predominantly syngas mixture whereas MR yields hydrogen along with other light carbon compounds. In SMR route the favorable textural properties of Ni/Al2O3 are responsible for its high methane conversion rates while Ni/CeO2 increases hydrogen content since it favors the water-gas shift reaction especially at high power inputs. Therefore SMR using a suitable catalyst stands out as the most feasible reforming route for hydrogen production.

Hydrogen is gaining prominence in global efforts to combat greenhouse gas emissions and climate change. While steam methane reforming remains the predominant method of hydrogen production alternative approaches such as water electrolysis and methane cracking are gaining attention. The bridging technology – methane cracking – has piqued scientific interest with its lower energy requirement (74.8 kJ/mol compared to steam methane reforming 206.278 kJ/mol) and valuable by-product of filamentous carbon. Nevertheless challenges including coke formation and catalyst deactivation persist. This review focuses on two main reactor types for catalytic methane decomposition – fixed-bed and fluidised bed. Fixed-bed reactors excel in experimental studies due to their operational simplicity and catalyst characterisation capabilities. In contrast fluidised-bed reactors are more suited for industrial applications where efforts are focused on optimising the temperature gas flow rate and particle characterisation. Furthermore investigations into various fluidised bed regimes aim to identify the most suitable for potential industrial deployment providing insights into the sustainable future of hydrogen production. While the bubbling regime shows promise for upscaling fluidised bed reactors experimental studies on turbulent fluidised-bed reactors especially in achieving high hydrogen yield from methane cracking are limited highlighting the technology’s current status not yet reaching commercialisation.

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

Hydrogen (H2) is presented as an important alternative for clean energy and raw material in the modern world. However the environmental benefits are linked to its process of production. Herein the chemical aspects advantages/disadvantages and challenges of the main processes of H2 production from petroleum to water are described. The fossil fuel (FF)-based methods and the state-of-art strategies are outlined to produce hydrogen from water (electrolysis) wastewater and seawater. In addition a discussion based on a color code to classify the cleanliness of hydrogen production is introduced. By the end a summary of the hydrogen value chain addresses topics related to the financial aspects and perspective for 2050: green hydrogen and zero-emission carbon.

Hydrogen production based on a combination of intermittent renewables and grid electricity is a promising approach for reducing emissions in hard-to-decarbonise sectors at lower costs. However for such a configuration to provide climate benefits it is crucial to ensure that the grid electricity consumed in the process is derived from low-carbon sources. This paper examined the use of hourly grid emission factors (EFs) to more accurately determine the short-term climate impact of dynamically operated electrolysers. A model of the interconnected northern European electricity system was developed and used to calculate average grid-mix and marginal EFs for the four bidding zones in Sweden. Operating a 10 MW electrolyser using a combination of onshore wind and grid electricity was found to decrease the levelised cost of hydrogen (LCOH) to 2.40–3.63 €/kgH2 compared with 4.68 €/kgH2 for wind-only operation. A trade-off between LCOH and short-term climate impact was revealed as specific marginal emissions could exceed 20 kgCO2eq/kgH2 at minimum LCOH. Both an emission-minimising operating strategy and an increased wind-to-electrolyser ratio was found to manage this trade-off by enabling simultaneous cost and emission reductions lowering the marginal carbon abatement cost (CAC) from 276.8 €/tCO2eq for wind-only operation to a minimum of 222.7 and 119.3 €/tCO2eq respectively. Both EF and LCOH variations were also identified between the bidding zones but with no notable impact on the marginal CAC. When using average grid-mix emission factors the climate impact was low and the CAC could be reduced to 71.3–200.0 €/tCO2eq. In relation to proposed EU policy it was demonstrated that abiding by hourly renewable temporal matching principles could ensure low marginal emissions at current levels of fossil fuels in the electricity mix.

Based on the concept of sustainable development to promote the development and application of renewable energy and enhance the capacity of renewable energy consumption this paper studies the design and optimization of renewable energy hydrogen production systems. For this paper six different scenarios for grid-connected and off-grid renewable energy hydrogen production systems were designed and analyzed economically and technically and the optimal grid-connected and off-grid systems were selected. Subsequently the optimal system solution was optimized by analyzing the impact of the load data and component capacity on the grid dependency of the grid-connected hydrogen production system and the excess power rate of the off-grid hydrogen production system. Based on the simulation results the most matched load data and component capacity of different systems after optimization were determined. The grid-supplied power of the optimized grid-connected hydrogen production system decreased by 3347 kWh and the excess power rate of the off-grid hydrogen production system decreased from 38.6% to 10.3% resulting in a significant improvement in the technical and economic performance of the system.

A reliable and sustainable energy source is essential for human survival and progress. Hydrogen energy is both clean and environmentally friendly which highlights the need for the development of effective photocatalysts to enhance the efficiency of photocatalytic hydrogen production. Near-infrared (NIR) light makes up a significant part of the solar spectrum and possesses strong penetration capabilities. Therefore it is important to enhance research on photocatalysis that utilizes both NIR and visible light. Metal-organic frameworks (MOFs) possess outstanding photocatalytic characteristics and are utilized in various applications for the photocatalytic generation of hydrogen. Consequently this minireview examines the fundamental characteristics of MOFs focusing on their classification the mechanisms of hydrogen production and the use of MOFs composites in photocatalytic hydrogen production. It discusses MOFs materials that feature type I II III Z and S heterojunctions along with strategies for modifying MOFs through elemental doping and the addition of co-catalysts. The study investigates methods to expand the photo-response range through up-conversion reduce the band gap of photocatalyst materials and utilize plasmon resonance and photothermal effects. This minireview lays the groundwork for achieving photocatalysis that responds to near-infrared and visible light thereby enhancing photocatalytic efficiency for hydrogen production. Finally the guidance and obstacles for upcoming studies on MOFs materials in the context of photocatalytic hydrogen production are examined.

Green hydrogen has become a central topic in discussions about the global energy transition seen as a promising solution for decarbonizing economies and meeting climate goals. As part of the process of decarbonization green hydrogen can replace fossil fuels currently in use helping to reduce emissions in sectors vital to the global economy such as industry and transport as well as in the power and heat sectors. Whilst there is significant potential for green hydrogen there are also challenges. The upfront costs for infrastructure and technology are high and the availability and accessibility of the renewables needed for production varies by region. Green hydrogen production and storage technologies are continuously evolving and being promoted as the demand for hydrogen in many applications grows. Considering this this paper presents the main methods for its production and storage as well as its economic impact. Hence the trend of governments and international organizations is to invest in research and development to make this technology more accessible and efficient given the carbon reduction targets.

The transition from fossil fuels to carbon-neutral energy sources is necessary to reduce greenhouse gas (GHG) emissions and combat climate change. Hydrogen (H2) provides a promising path to harness fossil fuels to reduce emissions in sectors such as transportation. However regional economic analyses of various H2 production techniques are still lacking. We selected a well-known fossil fuel-exporting region the USA’s Intermountain-West (I-WEST) to analyze the carbon intensity of H2 production and demonstrate regional tradeoffs. Currently 78 % of global H2 production comes from natural gas and coal. Therefore we considered steam methane reforming (SMR) surface coal gasification (SCG) and underground coal gasification (UCG) as H2 production methods in this work. We developed the cost estimation frameworks of SMR SCG and UCG with and without carbon capture utilization and sequestration (CCUS). In addition we identified optimal sites for H2 hubs by considering the proximity to energy sources energy markets storage sites and CO2 sequestration sites. We included new production tax credits (PTCs) in the cost estimation to quantify the economic benefit of CCUS. Our results suggest that the UCG has the lowest levelized cost of H2 production due to the elimination of coal production cost. H2 production using the SMR process with 99 % carbon capture is profitable when the PTCs are considered. We also analyzed carbon utilization opportunities where CO2 conversion to formic acid is a promising profitable option. This work quantifies the potential of H2 production from fossil fuels in the I-WEST region a key parameter for designing energy transition pathways.

Green hydrogen (H2 ) has emerged as a promising energy carrier for decarbonizing the industrial building and transportation sectors. However current green H2 production technologies face challenges that limit cost reduction and scaling up. Platinum-group metals (PGMs) including platinum and iridium present exceptional electrocatalytic properties for water splitting but their high cost is a significant barrier. This directly impacts the overall cost of electrolyzers thus increasing green H2 production costs. The present work covers the fundamentals of water electrolysis the currently available technologies focusing on proton-exchange membrane electrolyzers and the critical role of electrocatalysts discussing potential strategies for reducing the PGM content and consequently decreasing green H2 cost.

The International Energy Agency (IEA) established the "H2 Implementing Agreement (HIA)" to promote H2 transition in various economic sectors. Today less than one percent of the world's H2 production is “Green”. Lack of regulations high production costs and inadequate infrastructure are significant impediments. The U.S. Department of Energy set a "111-target" which translates into $1/kg-H2 in the next decade. Many countries in the Middle East and North Africa (MENA) region have announced ambitious plans to produce green H2. Through techno-economic metrics and the impact of economies of scale this study investigates H2@Scale production. H2 Production Analysis and the System Advisor Model developed by the U.S. Department of Energy were used for analysis. The results demonstrate a significant decrease in the levelized cost of H2 (LCOH) when the production volume is scaled up. It was determined that the key cost drivers are capital cost energy installed balance of the plant and mechanical and electrical subsystems. The studied location is found promising for scaled production and developing its commodity status. The findings could serve as a benchmark for key stakeholders investors policymakers and the developer of relevant strategies in the infrastructure and H2 value chain.

This work studies the efficiency and long-term viability of powered hydrogen production. For this purpose a detailed exploration of hydrogen production techniques has been undertaken involving data collection information authentication data organization and analysis. The efficiency trends environmental impact and hydrogen production costs in a landscape marked by limited data availability were investigated. The main contribution of this work is to reduce the existing data gap in the field of hydrogen production by compiling and summarizing dispersed data. The findings are expected to facilitate the decision-making process by considering regional variations energy source availability and the potential for technological advancements that may further enhance the economic viability of electrolysis. The results show that hydrogen production methods can be identified that do not cause significant harm to the environment. Photolysis stands out as the least serious offender producing 0 kg of CO2 per kg of H2 while thermolysis emerges as the major contributor to emissions with 20 kg of CO2 per kg of H2 produced.

Alkaline water electrolysis is a key technology for large-scale hydrogen production. In this process safety and efficiency are among the most essential requirements. Hence optimization strategies must consider both aspects. While experimental optimization studies are the most accurate solution model-based approaches are more cost and time-efficient. However validated process models are needed which consider all important influences and effects of complete alkaline water electrolysis systems. This study presents a dynamic process model for a pressurized alkaline water electrolyzer consisting of four submodels to describe the system behavior regarding gas contamination electrolyte concentration cell potential and temperature. Experimental data from a lab-scale alkaline water electrolysis system was used to validate the model which could then be used to analyze and optimize pressurized alkaline water electrolysis. While steady-state and dynamic solutions were analyzed for typical operating conditions to determine the influence of the process variables a dynamic optimization study was carried out to optimize an electrolyte flow mode switching pattern. Moreover the simulation results could help to understand the impact of each process variable and to develop intelligent concepts for process optimization

Defossilisation of the current fossil fuels dominated global energy system is one of the key goals in the upcoming decades to mitigate climate change. Sharp reduction in the costs of solar photovoltaics wind power and battery technologies enables a rapid transition of the power and some segments of the transport sectors to sustainable energy resources. However renewable electricity-based fuels and chemicals are required for the defossilisation of hard-to-abate segments of transport and industry. The global demand for carbon dioxide as raw material for the production of e-fuels and e-chemicals during a global energy transition to 100% renewable energy is analysed in this research. Carbon dioxide capture and utilisation potentials from key industrial point sources including cement mills pulp and paper mills and waste incinerators are evaluated. According to this study’s estimates the demand for carbon dioxide increases from 0.6 in 2030 to 6.1 gigatonnes in 2050. Key industrial point sources can potentially supply 2.1 gigatonnes of carbon dioxide and thus meet the majority of the demand in the 2030s. By 2050 however direct air capture is expected to supply the majority of the demand contributing 3.8 gigatonnes of carbon dioxide annually. Sustainable and unavoidable industrial point sources and direct air capture are vital technologies which may help the world to achieve ambitious climate goals.

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.

To improve the economic viability of renewable (green) hydrogen production excess renewable energy which cannot be input to the electricity grid (curtailed power) can be utilized. While several models have attempted to optimize hydrogen production using curtailed power several factors must be considered in greater detail including the impacts of future renewable energy capacity weather variability and electricity grid constraints. This study aims to explore these aspects through an integrated model performing a techno-economic assessment and size optimization in order to achieve the minimum levelized cost of hydrogen (LCOH). Based on the Irish case optimizing the production of hydrogen from curtailed power results in a minimum LCOH of 1.20–9.39 €/kg. To maximize variable renewable energy penetration in the grid while allowing for low-cost hydrogen production from curtailed power it is suggested to focus on grid improvements while ensuring rapid commissioning of offshore wind installations leading to a LCOH of 1.26–2.44 €/kg.

Low carbon hydrogen can be produced by a variety of processes that require substantial quantities of water. Several major hydrogen projects are proposed in Scotland; as an energy storage medium allowing new renewable power capacity to operate and as a direct alternative to displace natural gas as a primary fuel source. The additional water consumption associated with these hydrogen projects presents an infrastructure challenge.

The aims of the study are to evaluate the water requirements of new hydrogen production facilities and the associated implications for water infrastructure and to develop a strategic framework for assessing these aspects of hydrogen projects throughout the UK. The initial focus of the study is on Scotland; however the methodology developed in the project will be used throughout the UK

Benefits

Low carbon hydrogen can be produced by a variety of processes all of which require substantial quantities of water. Several major hydrogen projects are proposed in Scotland; both as an energy storage medium allowing new renewable power capacity (particularly wind) to operate and as a direct alternative to displace natural gas as a primary fuel source. The additional water consumption associated with these hydrogen projects presents an infrastructure challenge e.g. the Scottish Environment Protection Agency (SEPA) recently highlighted Scotland’s vulnerability to dry weather and climate-induced changes in the availability and functioning of water resources.

The project in partnership with Ramboll will look to deliver a technical assessment and feasibility study into water requirements for hydrogen production in Scotland. The aims of the study are to evaluate the water requirements of new hydrogen production facilities and the associated implications for water infrastructure and to develop a strategic framework for assessing these aspects of hydrogen projects throughout the UK. The initial focus of the study is on Scotland; however the methodology developed in the project will be used throughout the UK.

The research paper can be found on their website.

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.

Liquid hydrogen carriers will soon play a significant role in transporting energy. The key factors that are considered when assessing the applicability of ammonia cracking in large-scale projects are as follows: high energy density easy storage and distribution the simplicity of the overall process and a low or zero-carbon footprint. Thermal systems used for recovering H2 from ammonia require a reaction unit and catalyst that operates at a high temperature (550–800 ◦C) for the complete conversion of ammonia which has a negative effect on the economics of the process. A non-thermal plasma (NTP) solution is the answer to this problem. Ammonia becomes a reliable hydrogen carrier and in combination with NTP offers the high conversion of the dehydrogenation process at a relatively low temperature so that zero-carbon pure hydrogen can be transported over long distances. This paper provides a critical overview of ammonia decomposition systems that focus on non-thermal methods especially under plasma conditions. The review shows that the process has various positive aspects and is an innovative process that has only been reported to a limited extent.

This paper provides an in-depth examination of critical and strategic raw materials (CRMs) and their crucial role in the development of electrolyzer and fuel cell technologies within the hydrogen economy. It methodically analyses a range of electrolyzer technologies including alkaline proton-exchange membrane solid-oxide anion-exchange membrane and proton-conducting ceramic systems. Each technology is examined for its specific CRM dependencies operational characteristics and the challenges associated with CRM availability and sustainability. The study further extends to hydrogen storage and separation technologies focusing on the materials employed in high-pressure cylinders metal hydrides and hydrogen separation processes and their CRM implications. A key aspect of this paper is its exploration of the supply and demand dynamics of CRMs offering a comprehensive view that encompasses both the present sttate and future projections. The aim is to uncover potential supply risks understand strategies and identify potential bottlenecks for materials involved in electrolyzer and fuel cell technologies addressing both current needs and future demands as well as supply. This approach is essential for the strategic planning and sustainable development of the hydrogen sector emphasizing the importance of CRMs in achieving expanded electrolyzer capacity leading up to 2050.

Green hydrogen is the term used to reflect the fact that hydrogen is generated from renewable energies. This process is commonly performed by means of water electrolysis decomposing water molecules into oxygen and hydrogen in a zero emissions process. Proton exchange membrane (PEM) electrolyzers are applied for such a purpose. These devices are complex systems with nonlinear behavior which impose the measurement and control of several magnitudes for an effective and safe operation. In this context the modern paradigm of Digital Twin (DT) is applied to represent and even predict the electrolyzer behavior under different operating conditions. To build this cyber replica a paramount previous stage consists of characterizing the device by means of the curves that relate current voltage and hydrogen flow. To this aim this paper presents a processes supervision system focused on the characterization of a experimental PEM electrolyzer. This device is integrated in a microgrid for production of green hydrogen using photovoltaic energy. Three main functions must be performed by the supervision system: measurement of the process magnitudes data acquisition and storage and real-time visualization. To accomplish these tasks firstly a set of sensors measure the process variables. In second place a programmable logic controller is responsible of acquiring the signals provided by the sensors. Finally LabVIEW implements the user interface as well as data storage functions. The process evolution is observed in real-time through the user interface composed by graphical charts and numeric indicators. The deployed process supervision system is reported together with experimental results to prove its suitability.

Green hydrogen is expected to play a crucial role in the future energy landscape particularly in the pursuit of deep decarbonisation strategies within hard-to-abate sectors such as the chemical and steel industries and heavy-duty transport. However competitive production costs are vital to unlock the full potential of green hydrogen. In the case of green hydrogen produced via water electrolysis powered by fluctuating renewable energy sources the design of the plant plays a pivotal role in achieving market-competitive production costs. The present work investigates the optimal design of power-to-hydrogen systems powered by renewable sources (solar and wind energy). A detailed model of a power-to-hydrogen system is developed: an energy simulation framework coupled with an economic assessment provides the hydrogen production cost as a function of the component sizes. By spanning a wide range of size ratios namely the ratio between the size of the renewable generator and the size of the electrolyser the cost-optimal design point (minimum hydrogen production cost) is identified. This investigation is carried out for three plant configurations: solar-only wind-only and hybrid. The objective is to extend beyond the analysis of a specific case study and provide broadly applicable considerations for the optimal design of green hydrogen production systems. In particular the rationale behind the cost-optimal size ratio is unveiled and discussed through energy (utilisation factors) and economic (hydrogen production cost) indicators. A sensitivity analysis on investment costs for the power-to-hydrogen technologies is also conducted to explore various technological learning paths from today to 2050. The optimal size ratio is found to be a trade-off between the utilisation factors of the electrolyser and the renewable generator which exhibit opposite trends. Moreover the costs of the power-to-hydrogen technologies are a key factor in determining the optimal size ratio: depending on these costs the optimal solution tends to improve one of the two utilization factors at the expense of the other. Finally the optimal size ratio is foreseen to decrease in the upcoming years primarily due to the reduction in the investment cost of the electrolyser.

The intermittency of renewable energy sources necessitates energy storage to meet the full demand and balancing requirements of the grid. Green hydrogen (H2) is a chemical energy carrier that can be used in a flexible manner and store large amounts of energy for long periods of time. This techno-economic analysis investigates H2 production from wind using commercially available desalination and electrolysis units. Proton exchange membrane and alkaline electrolyser units are utilised and compared. The intermittency of wind is examined with comparison against grid-bought electricity. A model is developed to determine the selling price required to ensure profitability over a 10-year period. Firstly where H2 is produced using energy from the grid with electricity purchased when below a specified price point or between specified hours. In the second scenario a wind turbine is owned by the user and the electricity price is not considered while the turbine capital expenditure is. The price of H2 production from wind is found to be comparable with natural gas derived H2 at a larger scale with a minimum selling price calculated to be 4.85 £/kg at a setpoint of 500 kg of H2/hr. At a setpoint of 50 kg of H2/hr this is significantly higher at 12.10 £/kg. In both cases the alkaline electrolyser produced cheaper H2. This study demonstrates an economy of scale with H2 prices decreasing with increased scale. H2 prices are also closely linked to the capital expenditure with the equipment size space and safety identified as limiting factors.