Alkaline electrolysers typically operate above 2 V per cell, consuming over 54 kWh/kg, to reach commercial current densities. This is due to limited electrode activity, high diaphragm gas permeability improving hydrogen purity at high currents, simple flow fields not optimised for low currents, and the need for high currents to lower capital costs per kW. However, green hydrogen costs are now driven mainly by operational expenditure, which depends on efficiency. Therefore, prioritising efficiency over current density is essential to reduce the levelised cost of hydrogen.
EXSOTHyC will optimise electrolyser operation towards lower voltages and higher efficiencies. Within the project, a breakthrough concept for catalyst materials, processes and sub-components for an alkaline electrolyser stack is being proposed. This results in a novel stack design including disruptive components like Zirfon membranes with reduced HTO, catalyst coated diaphragm (CCD), and novel materials, which remarkably improve the voltage efficiency. The scientific innovation is three-fold and addresses all listed reasons for today’s used higher voltages:
• Alternative pathways to the O2 and H2 evolution reactions by new anode and cathode approaches
• Novel concepts of membranes and membrane electrode assemblies with integrated components
• Novel cell design to enhance overall cell efficiency by integrating disruptive concepts
Target KPIs by end of 2026
• Electricity consumption @ nominal capacity 48 kWh/kg
• CAPEX (€/(kg/d) and €/kW) values will be provided by M24
• O&M cost N/A €/(kg/d)/y
• Current density 1.0 A/cm2
• Use of critical raw materials as catalysts <0.3 for alkaline cells and 0.0 for novel materials
Pathway to Impact
EXSOTHyC will lower the levelised cost of hydrogen by reducing electricity use, enabling cost-competitive green hydrogen production, supporting industrial decarbonisation, and reducing dependence on critical raw materials. Large-scale adoption could save over 500 GWh/year per GW of capacity compared to current norms, directly contributing to the EU’s 10 Mt/year renewable hydrogen target by 2030.
