Performance of a Small-Scale Haber Process: A Techno-Economic Analysis

In this work, the techno-economic analysis of a 20,000 metric ton (MT) green ammonia production facility is presented. This facility is 30 times smaller than a large-scale conventional process, producing ammonia from totally renewable resources: hydrogen from water electrolysis and nitrogen from pressure swing adsorption. Two different configurations of the Haber–Bosch (HB) process are investigated: high-pressure reaction-condensation (RXN-CON) and low-pressure reaction-absorption (RXN-ABS). Process simulation was implemented using ASPEN Plus, where the reactor and absorber columns were designed as a custom model. The results obtained were then used to estimate the total capital and operating costs. The high-pressure processing improves the single-pass conversion and loop efficiency but relies on costly compression, whereas the low-pressure processing is more favorable for both capital and operating costs. The performance analysis of the HB process indicates that the operating pressure affects ammonia production costs. The levelized cost of ammonia (LCOA) from our small-scale Haber process was found to be about twice more expensive than the conventional commodity ammonia prices. Our sensitivity analysis suggests that inherently safer low-pressure RXN-ABS can be utilized for thermochemical energy storage of renewable resources—for scenarios that numerous small ammonia plants can be implemented in areas with local ammonia demand, with access to excess renewable electricity at the time of high penetration of renewable resources. Under such conditions, the LCOA from this plant can be comparable with the ammonia commodity prices. When the revenue from selling oxygen is considered into economics, small-scale all-electric ammonia can be profitable with an after-tax rate of return of 27.50% for RXN-ABS.