Capacity Configuration of Offshore Wind-Hydrogen System with Coupled AWE/PEM for Improving Power Resilience under Extreme Weather

Membraneless Electrolyzers for Low-Cost Hydrogen Production in a Renewable Energy Future

Water electrolyzers and fuel cells can be used to create a closed loop system for space exploration. Electrolyzers allow for reliable self-sustainable generation of hydrogen and oxygen for energy storage, followed by conversion into electrical energy in a fuel cell. A first-order safety concern for water electrolyzer operation is hydrogen crossover. Transport of hydrogen to the oxygen rich anode in proton exchange membrane (PEM) water electrolyzers poses safety concerns when the hydrogen concentration in the anode flow field approaches the hydrogen lower flammability limit (LFL). Hydrogen storage efficiency relies on high hydrogen pressure, leading to pressure-driven hydrogen crossover. Mitigation of hydrogen crossover through research and development of a platinum metal recombination layer has been demonstrated in high performing, durable PEMWEs.1-4 Ouimet4 explored the use of a novel dual recombination layer configuration to mitigate PEM water electrolyzer hydrogen crossover. In addition, the current state of the art for PEM fuel cells and water electrolyzers rely on perfluoro-sulfonated acid (PSFA) based membranes. There are significant challenges facing the use of PSFA-based membranes; namely, environmental contamination and performance limitations. The use of a hydrocarbon membrane allows for the development of a PSFA-free system that shows higher efficiency and durability. Investigation of hydrocarbon membranes pave way for developing a PEM water electrolyzer that will demonstrate improved gas permeability resistance, mechanical strength, and thermal stability.5-8 There is a need for both hydrogen crossover mitigation strategies and durability testing with hydrocarbon membranes.The research outlined in this work is focused on the development of PSFA-free PEM water electrolyzers with low hydrogen crossover. In this work, the dual recombination layer configuration will be incorporated into a hydrocarbon membrane for PEM water electrolysis. Polarization, electrochemical impedance spectroscopy, electrochemical equivalent circuits, distribution of relaxation times, and materials characterization will be used to investigate the cell performance and durability. References G. Mirshekari, R. Ouimet, Z. Zeng, H. Yu, S. Bliznakov, L. Bonville, A. Niedzwiecki, C. Capuano, K. Ayers, and R. Maric, “High-performance and cost-effective membrane electrode assemblies for advanced proton exchange membrane water electrolyzers: Long-term durability assessment,” international journal of hydrogen energy, vol. 46, no. 2, pp. 1526–1539, 2021.Z. Zeng, R. Ouimet, L. Bonville, A. Niedzwiecki, C. Capuano, K. Ayers, A. P. Soleymani, J. Jankovic, H. Yu, G. Mirshekari, et al., “Degradation mechanisms in advanced meas for pem water electrolyzers fabricated by reactive spray deposition technology,” Journal of The Electrochemical Society, vol. 169, no. 5, p. 054536, 2022.A. Martin, D. Abbas, P. Trinke, T. Böhm, M. Bierling, B. Bensmann, S. Thiele, and R. Hanke-Rauschenbach, “Communication—proving the importance of ptinterlayer position in pemwe membranes for the effective reduction of the anodic hydrogen content,” Journal of The Electrochemical Society, vol. 168, no. 9, p. 094509, 2021.R. J. Ouimet, “Catalyst development by a novel fabrication process for energy applications,” University of Connecticut Doctoral Dissertation, 2021.P. Trinke, P. Haug, J. Brauns, B. Bensmann, R. Hanke-Rauschenbach, and T. Turek, “Hydrogen crossover in pem and alkaline water electrolysis: mechanisms, direct comparison and mitigation strategies,” Journal of The Electrochemical Society, vol. 165, no. 7, p. F502, 2018.P. Trinke, B. Bensmann, and R. Hanke-Rauschenbach, “Current density effect on hydrogen permeation in pem water electrolyzers,” International Journal of Hydrogen Energy, vol. 42, no. 21, pp. 14355–14366, 2017.H. Q. Nguyen and B. Shabani, “Proton exchange membrane fuel cells heat recovery opportunities for combined heating/cooling and power applications,” Energy Conversion and Management, vol. 204, p. 112328, 2020.C. Klose, T. Saatkamp, A. Münchinger, L. Bohn, G. Titvinidze, M. Breitwieser, K. D. Kreuer, and S. Vierrath, “All-hydrocarbon mea for pem water electrolysis combining low hydrogen crossover and high efficiency,” Advanced Energy Materials, vol. 10, no. 14, p. 1903995, 2020.

This study evaluates the techno-economic feasibility of solar-based green hydrogen potential for off-grid and utility-scale systems in Niger. The geospatial approach is first employed to identify the area available for green hydrogen production based on environmental and socio-technical constraints. Second, we evaluate the potential of green hydrogen production using a geographic information system (GIS) tool, followed by an economic analysis of the levelized cost of hydrogen (LCOH) for alkaline and proton exchange membrane (PEM) water electrolyzers using fresh and desalinated water. The results show that the electricity generation potential is 311,617 TWh/year and 353,166 TWh/year for off-grid and utility-scale systems. The hydrogen potential using PEM (alkaline) water electrolyzers is calculated to be 5932 Mt/year and 6723 Mt/year (5694 Mt/year and 6454 Mt/year) for off-grid and utility-scale systems, respectively. The LCOH production potential decreases for PEM and alkaline water electrolyzers by 2030, ranging between 4.72–5.99 EUR/kgH2 and 5.05–6.37 EUR/kgH2 for off-grid and 4.09–5.21 EUR/kgH2 and 4.22–5.4 EUR/kgH2 for utility-scale systems.

Introducción The yearly increase in energy demand has encouraged the scientific community to find new sources of energy production without affecting the environment. Renewable technologies have become extremely popular due to the low greenhouse emissions and availability of natural energy sources (wind, sun, water, earth, tides, etc.), However, because of the intermittent energy generation from renewable sources, it is complex to rely on these technologies to guarantee the energy supply. Therefore, over the last decade, hydrogen has become increasingly studied as an energy carrier to replace current energy production technologies based on fossil fuels. Hydrogen can be easily coupled with other energy sources, increasing the efficiency of the systems. Nevertheless, hydrogen cannot be found in nature on its own and needs to be produced, currently, the most efficient method for green hydrogen generation is based on the electrolysis of water, this electrochemical process relies on the availability of water and the efficiency and correct selection of the electrolyser. Thus, this research evaluates the Alkaline and Proton Exchange Membrane (PEM) electrolysers for green hydrogen generation using water from hydroelectric power plants in Ecuador. Objetivos Evaluate Alkaline and PEM electrolysers for green hydrogen generation from hydroelectric power in Ecuador Método The methodology consists of a literature review of different brands of alkaline and PEM electrolysers selecting the ones with the highest efficiencies. For the analysis of data and information processing, quantitative methods were used. Finally, a sample of 9 hydroelectric plants was obtained for the study (Molino, Mazar, Agoyán, San Francisco, Pucará, La Península, Illuchi N 1, Illuchi N 2, Marcel Laniado). Principales resultados Different electrolyser manufacturers were analysed: Nel ASA producer of alkaline as well as PEM electrolysers, among them several models were evaluated NEL A 300, NEL A 485, NEL A 1000, NEL A 3880 with alkaline technology, and NEL MC 250, NEL M 5000 with PEM technology. H-TECH Electronic Co.Ltd with its model H-TEC HCS 10 using PEM technology. SIEMENS Energy, with its electrolyser technology PEM Silyzer 300 and McPhy with Mclyzer alkaline technology. All models were evaluated with the data from the 9 hydroelectric plants. Using technical data from the selected electrolysers and availability factor (90 %) from the hydroelectric plants, the potential of hydrogen production per year was calculated. The NEL A 3880 model with a system factor of 94% and a power of 14.7 MW displays the highest hydrogen production for alkaline technology, while the NEL MC 250, with an efficiency of 79% and 1 MW of power using PEM technology shows the highest hydrogen generation, these results are achieved for the Agoyan hydroelectric plant. Conclusiones The alkaline electrolysers show a better hydrogen generation capacity, achieving a total of 300 x 10e6 Kg of H2 per year with the NEL A 3880 model, in comparison with the PEM electrolyser technology that accounts for a maximum hydrogen production of 214 x 10e6 Kg of H2 per year. These results from the evaluation of the electrolysers show that it is feasible to establish a system for green hydrogen production based on hydroelectric power plants in Ecuador. The authors acknowledge the financial support received from the Universidad Técnica de Ambato and Dirección de Investigación y Desarrollo (DIDE) through the research project number PFICM28 “ANÁLISIS DE FACTIBILIDAD DE GENERACIÓN DE HIDRÓGENO VERDE MEDIANTE FUENTES DE ENERGÍA HIDROELÉCTRICA EN EL ECUADOR”.

Hydrogen, as a clean energy carrier, is of great potential to be an alternative fuel in the future. Proton exchange membrane (PEM) water electrolysis is hailed as the most desired technology for high purity hydrogen production and self-consistent with volatility of renewable energies, has ignited much attention in the past decades based on the high current density, greater energy efficiency, small mass-volume characteristic, easy handling and maintenance. To date, substantial efforts have been devoted to the development of advanced electrocatalysts to improve electrolytic efficiency and reduce the cost of PEM electrolyser. In this review, we firstly compare the alkaline water electrolysis (AWE), solid oxide electrolysis (SOE), and PEM water electrolysis and highlight the advantages of PEM water electrolysis. Furthermore, we summarize the recent progress in PEM water electrolysis including hydrogen evolution reaction (HER) and oxygen evolution reaction (OER) electrocatalysts in the acidic electrolyte. We also introduce other PEM cell components (including membrane electrode assembly, current collector, and bipolar plate). Finally, the current challenges and an outlook for the future development of PEM water electrolysis technology for application in future hydrogen production are provided.

Green ammonia and hydrogen from renewable energy sources have emerged as crucial players during the transition of the chemical industry from a fossil energy‐dominated economy to one that is environmentally friendly. This work proposes a green ammonia synthesis system driven by synergistic hydrogen generation using alkaline water electrolyzers (AWE) and proton exchange membrane electrolyzers (PEMEC). The effects of hydrogen‐production ratios of PEMEC and AWE on the thermodynamic and economic performance of the system are compared and analyzed via multi‐objective optimization. The findings showed that an increase in the amount of hydrogen produced by PEMEC improves the system's energy efficiency, but the payback period is delayed because of the PEMEC high initial investment cost. The techno‐economic performance of the system at a 1:1 ratio of PEMEC to AWE hydrogen production are investigated considering the system level heat integration based on the pinch point analysis method to maximize the heat recovery. The results show that increasing the operational temperature, the pressure of the electrolyzer, and the ammonia synthesis pressure will enhance the system's thermal performance. Economic analysis shows that reducing electricity prices and electrolyzer investment costs will be the key to achieving the economic feasibility of the green ammonia system.

Despite only accounting for a fraction of the annual global hydrogen production, commercial application of water electrolysis is expected to grow significantly in line with global climate action goals1. Furthermore, water electrolysis driven by renewable energy is expected to aid in nullifying the intermittency of renewable energy sources such as wind and solar photovoltaics2.Two main types of water electrolysis have found widespread commercial application – alkaline water electrolysis (AWEs) and polymer electrolyte membrane electrolysis (PEMEs). While PEMEs operate at higher current densities and higher efficiencies, they require expensive precious metal catalysts such as Ir-based cathodes and Pt-based anodes3. In addition, PEMEs generally have a shorter lifespan than AWEs4. Therefore, AWEs are better suited for gigawatt-scale deployment5. Furthermore, it has been shown that AWEs with Ni-based catalysts can compete with Ir and Pt-based PEMEs if a dramatic reduction in the thickness of the separator can be achieved6.A key development in AWEs is the adoption of a zero-gap electrode (ZGE) configuration in which the electrodes are pressed directly on the surface of the separator. It is possible to leverage silicon-based lithographic techniques to produce separators with well-defined pore sizes and porosities, which are significantly thinner than commercially available AWE separators. This has been previously demonstrated for photoelectrochemical devices7. Such porous silicon devices typically suffer from the high gas crossover. One method to limit gas crossover is infilling the pores with ionomers. However, due to volumetric expansion in electrolytes, ionomers – such as the commonly used PEME membrane material, Nafion – are not suitable for microfabricated devices8.In this work, we report the fabrication of stable porous silicon separators with metal electrodes in a zero-gap configuration. These porous silicon separators exhibit ionic resistance comparable to Zirfon (the most commonly used AWE separator9) but at an order of magnitude lower porosity. The ordered and well-defined pore structure of the microfabricated separators allows us to study the influence of separator properties such as pore size and porosity on ionic conductivity and gas crossover in cylindrical pores with no interconnections. References International Energy Agency, The Future of Hydrogen, IEA, IEA, Paris, (2021), p. 203 https://www.iea.org/reports/hydrogen.L. M. Pierpoint, Energy Policy, 96, 751–757 (2016).A. S. Gago et al., ECS Trans., 85, 3 (2018).M. David, C. Ocampo-Martínez, and R. Sánchez-Peña, Journal of Energy Storage, 23, 392–403 (2019).M. Schalenbach, Aleksandar R. Zeradjanin, Olga Kasian, Serhiy Cherevko, and Karl J.J. Mayrhofer, Int. J. Electrochem. Sci., 1173–1226 (2018).M. Schalenbach et al., J. Electrochem. Soc., 163, F3197 (2016).W. J. C. Vijselaar et al., Advanced Energy Materials, 9, 1803548 (2019).T. Pichonat and B. Gauthier-Manuel, Fuel Cells, 6, 323–325 (2006).R. Phillips and C. W. Dunnill, RSC Adv., 6, 100643–100651 (2016).

The production of hydrogen by the water electrolysis technique to provide a fossil fuel alternative energy source has attracted a plethora of attention among the other different methods in the context of sustainability, renewable energy source utilization and green technology.[1] Conventional alkaline water electrolyzer (AWE) offers many advantages compared with other systems. One of the major advantages of AWE over proton exchange membrane water electrolyser (PEMWE) is the replacement of conventional noble metal electrocatalysts with active, stable and relatively low-cost transition metal catalysts. However, AWE electrolyzers suffer from lower operational current density compared with their PEMWE counterpart. Like AWE, anion exchange membrane (AEM) electrolyzer does not require noble metal catalysts, which makes this technology much less expensive than PEMWE, while possessing the advantage of PEMWE. However, the electrochemical water splitting performance of AEM water electrolysis is still much lower than that of PEMWE. Focusing on this issue, the presented work aims at improving the performance of AWE and AEM electrolysers by developing cost effective non-noble electrodes on macro-porous transport layer (MPL) using the air plasma spray deposition method.[2] MPLs were fabricated by depositing Ni-graphite on porous substrates. Graphite was removed during particle in-flight forming a controlled porous layer. Electrodes were developed by plasma spraying of NiMoAl for cathode and NiAl for anode on top of the MPL followed by activation in which Al was partially leached out from layers of both electrodes using an alkaline solution. Electrochemical tests were conducted on half-cell in 6M KOH solution and then in the full cells for AWE and AEM in 6M and 0.3M KOH, respectively. The electrochemical performance is recorded via over-potential measurements, electrochemical impedance spectroscopy (EIS), cyclic voltammetery and polarization curve. With optimal combination of MPL and electrodes, current density of 0.5 Acm-2 at 1.80 V was recorded as the initial performance in 6M solutions for AWE using Zirfon separator and the current density of 0.31 Acm-2 at 1.80 V was recorded for AEM electrolyzer with more dilute KOH solution (0.3M) using an anion exchange membrane. 64 days of abusive testing was conducted for the AWE without measurable degradation in the performance in 6M KOH. The catalysts developed in this work will be promising in supporting the pursuit of cheap, affordable and ideal eco-friendly hydrogen fuel. [1] F. Razmjooei, K.P. Singh, D.S. Yang, et al., Acs Catalysis, 2017, 7, 2381-2391. [2] A.S. Gago, S.A. Ansar, B. Saruhan, et al., J Power Sources, 2016, 307, 815-825.

To achieve optimal performance of renewable hydrogen production systems (RHPS), this study proposes a novel optimization framework for synergistically integrating wind–solar resources with diversified electrolyzers. A comprehensive techno-economic model is developed, incorporating both alkaline electrolyzers (AEL) and proton exchange membrane electrolyzers (PEMEL), and enabling the determination of the optimal wind–solar configuration ratio, electrolyzer types and capacities, and system-level economic performance. The results reveal that the nature of the renewable energy source predominantly influences the selection of electrolyzers. Specifically, pure photovoltaic (PV) systems tend to favor PEMEL, with an optimal PEMEL:AEL capacity ratio of 2:1, whereas pure wind turbine (WT) systems and PV–WT hybrid systems are more suited to AEL, with corresponding AEL:PEMEL ratios of 8:3 and 7:3, respectively. The combined operation of wind–solar complementarity and diversified electrolyzers reduces the levelized cost of hydrogen (LCOH) to USD 4.52/kg, representing a 41.1% reduction compared to standalone PV systems, with a renewable energy utilization rate of 92.26%. Case studies confirm that collaborative AEL–PEMEL operation enhances system stability and efficiency, with PEMEL mitigating power fluctuations and AEL supplying baseload hydrogen production. This synergy improves hydrogen production efficiency, extends equipment lifespan, and provides a viable and theoretically sound solution for RHPS optimization.

The increasing global demand for energy paired with carbon neutrality targets have been motivating factors in the development of water electrolysis (WE) technology to produce green hydrogen. The traditional WE methods are alkaline water electrolysis (AWE) and proton exchange membrane water electrolysis (PEMWE), however there are limitations associated with both AWE (e.g., low efficiency, high operating costs) and PEMWE (e.g., high capital costs of noble catalysts (Pt, Ir)). Anion exchange membrane water electrolysis (AEMWE) is a recent development that addresses the limitations of AWE and PEMWE, including the use of non-noble catalysts and a higher efficiency than AWE. AEMWE still has many challenges to overcome, including short operational lifetime and hydrogen crossover through the membrane. The focus of this project is to study how characteristic of the cathode catalyst layer (CL), including thickness and catalyst loading, impact hydrogen crossover in AEMWE. The aim is to better understand where the reaction zone of the hydrogen evolution reaction (HER) is located within the CL, which provides insight on how to better design the CL to reduce hydrogen crossover. A better understanding of hydrogen crossover in AEMWE will improve the safety, efficiency, and will help contribute to further development and commercialization of AEMWE technology.

<p indent="0mm">Green hydrogen has gained much interest due to its low cost, sustainability, and environmental friendliness, especially when combined with water electrolysis technology powered by renewable energy resources. It has been recognized as one of the perfect solutions to achieve the goal of near-zero carbon emissions. According to the type of materials used to separate the anode and cathode and the ionic species it conduct, the electrolyzers can be divided into several categories, i.e., alkaline water electrolyzer (AWE) that involve the use of liquid electrolyte, proton exchange membrane water electrolyzer (PEMWE), solid oxide electrolyzer (SOE), and anion exchange membrane water electrolyzer (AEMWE). As the key component in different water electrolysis technologies, polymeric membrane materials, including proton exchange membrane (PEM), anion exchange membrane (AEM), and ion-solvating membranes (ISM), are of great importance, which serve as the ionic conductor and gas separator. Thus, the efficiency and durability of water electrolyzers are mainly determined by the properties of membranes, such as ionic conductivity, chemical stability, and mechanical properties. However, these unfavorable performance parameters of membranes still limited the worldwide commercialization of water electrolysis for the production of green hydrogen. In a typical AWE, a porous diaphragm made of asbestos or composite ceramic (or asbestos)/polymer materials (Zirfon, a state-of-the-art diaphragm) is used to separate the gas product and transport hydroxide ions. Although the mature AWE technology shows higher durability, low capital cost, and high compatibility with non-noble metal catalysts, they operate at low current densities lying between <sc>0.3−0.4 A cm⁻²,</sc> owning to the high ionic resistance and high gas permeation of the non-ionic separator membranes. The replacement of porous diaphragm with ionic polymeric membranes, such as PEM, AEM, and ISM based on polybenzimidazoles have attracted increasing attention in water electrolysers, due to their effectiveness of ion transport and gas tightness of the dense membrane. The acidic PEM allow the operation of water splitting with higher efficiency and current densities <sc>(500−2000 A cm⁻²).</sc> However, large-scale implementation of PEMWE technology is limited by the expensive PEM and precious platinum group metal (PGM) catalysts. When working under basic environment, the AWE using solid AEM and ISM combines the merits of traditional AWE and PEMWE, i.e., an alkaline working environment allows for the use of PGM-free catalysis and the solid hydroxide ion conducting membrane reduce the ionic resistance of the cells. Thus, the design of AEM and ISM materials plays a crucial role in the overall performance and durability of electrolytic cells. Currently, compared with PEMWE, the AEMs and ISMs with sufficient conductivity and satisfactory stability are still highly needed, due to the well-recognized vulnerable functional cations and polymer backbones in hot and alkali aqueous solutions. Thus, numerous chemical designs on AEMs are carried out. In this review, we summarized the research progress of polymeric membranes in water electrolysis for hydrogen production. We first compared the properties of membranes and electrolyzer device performance using different types of membranes, and analyzed the relationship between polymer structure and device performance; then, after analyzing the development and the technical advantages and disadvantages of PEM, AEM, and ISMs, the technical limitations and future developing trends of these technical routes were discussed. Finally, we also give a brief prospect on how to guide and encourage the future development of various technical pathways through the policy guidance, so as to realize the large-scale market penetration of water electrolysis technology for green hydrogen production.

An electrolysis system uses electricity to split water molecules into hydrogen and oxygen. In this process, the electrolysis system produces hydrogen, and the remaining oxygen escapes to the atmosphere or is captured or stored for use in industrial processes, or for other purposes. This study provides a detailed assessment of four major electrolysis technologies (alkaline water electrolysis, proton exchange membrane electrolysis, solid oxide electrolysis, and anion exchange membrane electrolysis), their characteristics, key players in the global electrolyser market, and recent trends that define electrolysis technology and market development. The scope of this study extends not only to the analysis of electrolysis technologies, but also to an overview of the availability of critical materials, shortages or disruptions in supply of which can prove challenging or even harmful for those markets/regions with limited excess platinum group metals (platinum, palladium, rhodium, ruthenium, iridium, and osmium) and rare earth metals. Also, for two electrolysis technologies: alkaline water electrolysis and proton exchange membrane electrolysis, a comparison of efficiency and initial calculation of CAPEX for installations with medium and large installed capacities (5 and 100 MW) was presented.

Hydrogen is an ideal alternative energy carrier to generate power for all of society's energy demands including grid, industrial, and transportation sectors. Among the hydrogen production methods, water electrolysis is a promising method because of its zero greenhouse gas emission and its compatibility with all types of electricity sources. Alkaline electrolyzers (AELs) and proton exchange membrane electrolyzers (PEMELs) are currently used to produce hydrogen. AELs are commercially mature and are used in a variety of industrial applications, while PEMELs are still being developed and find limited application. In comparison with AELs, PEMELs have more compact structure and can achieve higher current densities. Recently, however, an alternative technology to PEMELs, hydroxide exchange membrane electrolyzers (HEMELs), has gained considerable attention due to the possibility to use platinum group metal (PGM)-free electrocatalysts and cheaper membranes, ionomers, and construction materials and its potential to achieve performance parity with PEMELs. Here, the state-of-the-art AELs and PEMELs along with the current status of HEMELs are discussed in terms of their positive and negative aspects. Additionally discussed are electrocatalyst, membrane, and ionomer development needs for HEMELs and benchmark electrocatalysts in terms of the cost-performance tradeoff.

The investment costs of water electrolysis represent one key challenge for the realisation of renewable hydrogen-based energy systems. This work presents a technology cost assessment and outlook towards 2030 for alkaline electrolysers (AEL) and PEM electrolysers (PEMEL) in the MW to GW range taking into consideration the effects of plant size and expected technology developments. Critical selected data was fitted to a modified power law to describe the cost of an electrolyser plant based on the overall capacity and a learning/technology development rate to derive cost estimations for different PEMEL and AEL plant capacities towards 2030. The analysis predicts that the CAPEX gap between AEL and PEMEL technologies will decrease significantly towards 2030 with plant size until 1–10 MW range. Beyond this, only marginal cost reductions can be expected with CAPEX values approaching 320–400 $/kW for large scale (greater than 100 MW) plants by 2030 with subsequent cost reductions possible. Learning rates for electrolysers were estimated at 25–30% for both AEL and PEMEL, which are significantly higher than the learning rates reported in previous literature.

This prospective life cycle assessment (LCA) compares the environmental impacts of alkaline electrolyser (AE) and proton exchange membrane (PEM) electrolyser systems for green hydrogen production with a special focus on the stack components. The study evaluates both baseline and near-future advanced designs, considering cradle-to-gate life cycle from material production to operation. The electricity source followed by the stacks are identified as major contributors to environmental impacts. No clear winner emerges between AE and PEM in relation to environmental impacts. The advanced designs show a reduced impact in most categories compared to baseline designs which can mainly be attributed to the increased current density. Advanced green hydrogen production technologies outperform grey and blue hydrogen production technologies in all impact categories, except for minerals and metals resource use due to rare earth metals in the stacks. Next to increasing current density, decreasing minimal load requirements. improving sustainable mining practices (including waste treatment) and low carbon intensity steel production routes can enhance the environmental performance of electrolyser systems, aiding the transition to sustainable hydrogen production.