We evaluated the cost of the ammonia synthesis loops embedded with Ru/Ca(NH2)2 and Ru/Pr2O3, newly developed and very active catalysts under mild conditions. The results elucidated that the cost for ruthenium is dominant, and the lifetime of catalysts is one of the critical parameters. Moreover, the new catalysts are advantageous for green ammonia synthesis: the case that the electricity price is high and the production scale is small. Finally, as the directions for further research, the results suggest reducing catalysts cost, such as the extension of catalyst lifetime, recycling or reactivation of the catalysts, and substituting ruthenium with cheap metal.