Hydrogen costs from water electrolysis at high temperature and pressure

Highlights: • A high temperature and pressure water electrolysis techno-economic model was developed. • Hydrogen cost was evaluated under several pressurization and electrochemical schemes. • Trade-offs between improved kinetics at higher temperatures were identified. • High temperature and pressure electrolysis can be cost competitive with PEM and AEL electrolysis. Green hydrogen demand will increase in the coming decades, and water electrolysis can enable low- or zero-carbon production pathways. High-temperature and pressure operation can improve electrode kinetics and reduce compression requirements. In this work, the economics of water electrolysis were analyzed under these conditions by making an electrochemical model. The energy consumption was calculated to obtain the levelized cost of hydrogen under varying temperature, pressure, and catalyst performance. The lowest cost and energy requirements occurred at 270–310 °C and 700 bar. Our results illustrate a trade-off between improved kinetics at higher temperatures and increased operating costs due to high water activities. With performance similar to the best available measurements, operation under high temperature and pressure was competitive if electrolyzer system costs are less than 25% higher than their low-temperature counterparts.