"Green" Ammonia: Impact of Renewable Energy Intermittency on Plant Sizing and Levelized Cost of Ammonia

Ammonia production currently contributesalmost 11% of global industrial carbon dioxide emissions, or1.3% of global emissions. In the context of global emissiontargets and growing demand, decarbonization of this processis highly desirable. We present a method to calculate a firstestimate for the optimum size of an ammonia productionplant (at the process level), the required renewable energy(RE) supply, and the levelized cost of ammonia (LCOA) forislanded operation with a hydrogen buffer. A model wasdeveloped to quantitatively identify the key variables thatimpact the LCOA (relative to a ±10 GBP/tonne change inLCOA): levelized cost of electricity (±0.89 GBP/MWh), electrolyzer capital expenditure (±65 GBP/kW), minimum Haber−Bosch (HB) load (±12% of rated power), maximum rate of HB load ramping, and RE supply mix. Using 2025/2030 estimatesresults in a LCOA of 588 GBP/tonne for Lerwick, Scotland. The application of the model will facilitate and improve theproduction of carbon-free ammonia in the future.