Techno-economic comparison of power-to-ammonia and biomass-to-Ammonia plants using electrolyzer, CO₂ capture and water-gas-shift membrane reactor

Conventional ammonia plants currently account for around 1.5% of global greenhouse gas emissions. To effectively address this issue and reduce fossil fuel consumption, green and alternative technologies could play a significant role, despite the challenging economic performance. Ammonia, as a carbon-free synthetic fuel and hydrogen carrier, has the potential to be produced through power-to-ammonia and biomass-to-ammonia concepts. This research article presents three green ammonia configurations: The first one is developed by an alkaline water electrolysis unit (system (I)); the second and third ones are designed by a steam/O₂ gasification unit followed by co-current water-gas-shift membrane reactors (system (II)) and counter-current ones (system (III)). The configurations are investigated from energy efficiency and economic viewpoints at an ammonia production capacity of 2000 tons/day. At the optimal economic point, configuration (I) achieves a levelized cost of $394.01/ton and a payback time of 4.95 years, which is lower than configuration (II) ($468.13/ton and 6.95 years) and configuration (III) ($425.85/ton and 6.35 years). Configuration (III) has an overall energy efficiency of 54.64% at the optimal energy efficiency point, which is higher than configuration (I) (50.19%) and configuration (II) (51.6%). Configuration (I), with its levelized cost of $394.01/ton and payback time of under 5 years, can be techno-economically competitive with conventional ammonia plants.