Optimal green ammonia system design for minimum levelized costs in Southern Argentina

Abstract

This paper presents a mathematical model for the optimal design of green ammonia production systems in Argentina, specifically in Patagonia and Buenos Aires Province. The objective is to minimize the levelized cost of ammonia (LCOA) while meeting delivery constraints. The location of the renewable energy farm has a significant impact on the optimal system sizing and the LCOA. For the locations under analysis, the optimal farm-toelectrolyzer peak power ratio varies between 1.3 and 2.3, with the LCOA ranging from 562 to 696 USD/t NH3. Comparative analysis of constant nominal efficiencies and variable real efficiencies in the electrolyzer and Haber-Bosch (HB) processes reveals the emergence of different design configurations, with a potential discrepancy of up to 15 % in power ratio, 80 % in H2 storage capacity, and 10 % in LCOA. An increase in the HB turndown ratio from 40 % to 80 % has a significant impact on optimal design, influencing the power ratio, storage of hydrogen, nitrogen, and ammonia, as well as the LCOA, by 11 %, 760 %, 180 %, 14 %, and 7 %, respectively. Systems designed for constant nominal efficiency may experience frequent HB shutdowns when operating at real variable efficiencies. Delivery constraints showed limited impacts.