Conceptual process design and technoeconomic analysis of an e-ammonia plant: Green H2 and cryogenic air separation coupled with Haber-Bosch process

Abstract

Manufacturing low-carbon ammonia (NH3) is paramount for the green transition of the chemical industry and society at large. The conventional Haber-Bosch (HB) process based on steam methane reforming (SMR) entails whopping CO2 emissions (i.e., 400 Mt y−1), therefore we propose a sustainable plant design comprising water electrolysis and cryogenic distillation for H2 and N2 production, respectively. This electrified configuration powered by wind energy affords 80% lower carbon emissions than the conventional SMR-based process. However, the electrolyser unit can represent between 36 and 61% of the total capital cost, depending on its energy efficiency, and its high energy demand drives the electricity cost which accounts for more than 68% of the plant operational costs. Thus, even with anticipated improvements in efficiency of the electrolyser unit, the Levelized Cost of Production (LCOP) of e-NH3 in a 2050 scenario is 65% higher than the current benchmark; nonetheless, the two processes could be equally viable with a 135.8 $ tCO2−1 carbon penalty on the average conventional process. Notably, the cost of electricity is the most prominent cost driver in the e-process, which could be more economically viable than the fossil counterpart with electricity prices below 12.5 $ MWh−1. These findings provide evidence that the proposed e-process can replace the commercial benchmark in small-scale, standalone applications.