Pressurised alkaline electrolyser with high efficiency and wide operating range - The Project „RESelyser“

The project RESelyser develops high pressure, highly efficient, low cost alkaline water electrolysers that can be integrated with renewable energy power sources (RES) using an advanced membrane concept, highly efficient electrodes and a new cell design. A new separator membrane with internal electrolyte circulation and an adapted design of the cell to improve mass transfer, especially gas evacuation is investigated and demonstrated. Intermittent and varying load operation with RES is addressed by improved electrode stability and a cell concept for increasing the gas purity of hydrogen and oxygen especially at part load and high pressure operation. Some recent results will be presented: high performance electrodes with a plasma sprayed coating layer give an overpotential reduction of 330 mV compared to uncoated electrodes thus showing high performance and stability. Detailed investigation of the electrode pore structure and microstructure at beginning of life and after operation shows possible degradation mechanisms. A double layer diaphragm with internal KOH supply improves the gas purity and high current density performance of the cell. The cell concept was realizes in single cells of 300 cm2 area and a 10 kW stack. The research leading to these results has received funding from the European Union’s Seventh Framework Programme (FP7/2007-2013) for the Fuel Cells and Hydrogen Joint Technology Initiative under grant agreement n° [278732] 10