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

Abstract

Ammonia (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.