The case for high-pressure PEM water electrolysis

Hydrogen compression is a key part of the green hydrogen supply chain, but mechanical compressors are prone to failure and add system complexity and cost. High-pressure water electrolysis can alleviate this problem through electrochemical compression of the gas internally in the electrolyzer and thereby eliminating the need for an external hydrogen compressor. In this work, a detailed techno-economic assessment of high-pressure proton exchange membrane-based water electrolysis (PEMEL) systems was carried out. Electrolyzers operating at 80, 200, 350, and 700 bar were compared to state-of-the-art systems operating at 30 bar in combination with a mechanical compressor. The results show that it is possible to achieve economically viable solutions with high-pressure PEMEL-systems operating up to 200 bar. These pressure levels fit well with the requirements in existing and future industrial applications, such as e-fuel production (30–120 bar), injection of hydrogen into natural gas grids (70 bar), hydrogen gas storage (≥200 bar), and ammonia production (200–300 bar). A sensitivity analysis also showed that if the cost of electricity is sufficiently low (<0.1 € kWh−1), it may even be economical to operate PEMEL systems with hydrogen outlet pressures up to 350 bar.