Low‐Temperature Electrochemical Ammonia Synthesis: Measurement Reliability and Comparison to Haber–Bosch in Terms of Energy Efficiency

Abstract

Recently, several studies have paved a way to nearly 100% selectivity of the electrochemical ammonia synthesis (EAS), which had been identified earlier as a main challenge. These results motivate us to benchmark the energy efficiency (EE) of EAS against the Haber–Bosch process for EAS works published in 2020, 2021, and 2022. A method is presented to estimate EE of EAS, which can be used by a broader audience. EAS studies historically suffered from reliability issues, and to avoid benchmarking of false‐positive results, a method is established to calculate a reliability indicator to assess the measurement reliability of a published work. The EE of EAS is calculated for works that are assessed as reliable with the indicator. Several promising systems and strategies enabling higher selectivity and EE are identified and discussed. The EE of some aqueous EAS reports is up to 55%, and nonaqueous is below 15%. However, while nonaqueous media reports suffer from low energy efficiency, they demonstrate much higher technology readiness levels (TRL) and total ammonium produced. Aqueous media reports have a great potential for higher energy efficiency, but they are at much lower TRL and total ammonia quantities produced are low.