Achieving the European Green Deal target of becoming the world’s first climate-neutral continent by 2050 will require deep cuts to emissions across all aspects of the economy, including the power generation and heating sector. This, combined with the REPowerEU plans, places hydrogen as a clean energy carrier in a unique position. It can be used in, and thereby couple, all sectors like; power&heat, transport and industry. Hydrogen offers long term storage, it can be transported over large distances and it can be produced and used without, or with very low emissions. A central part of the EU climate strategies is the target of domestic renewable hydrogen production of 10 million tons by 2030, in addition to the same amount imported. Large-scale stationary fuel cells in the MW-range should be able to operate on such industrial quality H2 without repurification. They can offer a low-cost clean alternative for both large scale (peak) power and heat production, as well as for small, medium and large-scale back-up power units for the critical infrastructure, thereby also improving the resilience of the energy system. The aim of CLEANER is to develop and demonstrate for more than 5000 hours a >100 kW PEM fuel cell system operating on industrial quality hydrogen.