Energy-efficient and cost-effective ammonia electrolysis for converting ammonia to green hydrogen

Highlights•A technoeconomic analysis of H2-NH3-H2 conversion system is demonstrated•The ammonia electrolyzer uses a low energy consumption of 0.84 kWh Nm−3 H2•Ammonia-based hydrogen production tandem cell with no electrical input is developedSummaryAmmonia (NH3), touted as a promising hydrogen carrier, has received increasing attention. However, the technoeconomic prospects of comprehensive conversion of hydrogen to ammonia and ammonia to hydrogen (H2-NH3-H2) are unclear, and the approach to ammonia-to-hydrogen conversion has not yet reached the full commercialization stage. In this work, we perform a technoeconomic analysis of a H2-NH3-H2 conversion system, including synthesis, storage and transportation, and ammonia-to-hydrogen conversion, where we particularly compared thermal ammonia cracking with ammonia electrolysis. We find that ammonia electrolysis has a significant economic advantage thanks to its low energy consumption and capital cost. With this as motivation, we develop an energy-efficient and durable ammonia electrolyzer with an energy consumption of 0.84 kWh Nm−3 H2 and a continuous operation for 317 h at 100 mA cm−2. In addition, we also innovate a tandem cell to produce hydrogen without any electric power supply by coupling fuel-cell and electrolysis technologies.