Scaling up of cells and stacks for large electrolysers The application of electrolysers to industrial clusters and hydrogen hubs in order to achieve substantial CO2 savings is inhibited by the present capacities of electrolyser stacks. Hydrogen production could be achieved more cost effectively if larger electrolyser cells and stacks were available. When compared with the current SoA, the development of an electrolyser module of about 10MW, if feasible, would be a considerable step-forward (where a module comprises the least number of stacks and preferably only one stack). However, there are several R&I challenges which first need to be overcome to realise this. Proposals are expected to address the following:Scale-up of cell active areas by a factor of at least two, operating at higher current densities and increasing the number of cells per stack, while ensuring durability and performance (mechanically, electrically and in terms of heat and mass transfer) for the envisaged balanced pressure or differential pressure stack;Ensure the catalyst and electrode production techniques achieve uniform performance for the required cell areas;Develop appropriate production methods and supply chains for larger cell plates and electrodes;Establish any technical limits that may restrict the achievable cell size, current density or stack size for a large electrolyser;Establish the extent of cost reductions, relative to a SoA stack, when innovating larger cells and stack;Ensure a good match between the design of the stack assembly and the power supply unit to minimise energy losses and the overall cost of the electrolyser module;Appropriately scale-up of the balance-of-plant while ensuring a compact design for the electrolyser module;Minimise weight and footprint to ensure ease of handling and shipping;Maximise the overall cost reduction potential by minimising parts count and value engineering;Build and test several short stacks, based on large cells, in order to establish the feasibility of subsequently building an electrolyser module of 10MW capacity comprising preferably a single stack;Identifying any optimal sizes for larger cells and stacks from scientific, engineering, logistics and economic perspectives. Activities developing test protocols and procedures for the performance and durability assessment of electrolysers and fuel cell components proposals should foresee a collaboration mechanism with JRC (see section 22.214.171.124 ""Collaboration with JRC""), in order to support EU-wide harmonisation. Test activities should adopt the already published EU harmonised testing protocols[[https://www.clean-hydrogen.europa.eu/knowledge-management/collaboration-jrc-0_en]] to benchmark performance and quantify progress at programme level.Activities are expected to start at TRL 3 and achieve TRL 5 by the end of the project.The conditions related to this topic are provided in the chapter 126.96.36.199 of the Clean Hydrogen JU 2022 Annual Work Plan and in the General Annexes to the Horizon Europe Work Programme 2021–2022 which apply mutatis mutandis.