Enabling low-carbon/low-cost electrified ammonia decomposition reaction for hydrogen supply applications: A multi-step assessment approach

Abstract

Process electrification is a viable solution for reducing reliance on non-renewable fuels, with green ammonia considered as a promising hydrogen carrier with a gravimetric storage capacity of 17.6 wt%. The incorporation of these two direct CO_X-free energy systems inevitably facilitates enhanced environmental performance; however, extensive improvements are required to achieve cost-effectiveness. Therefore, this study proposed and optimized the concept of electrified ammonia decomposition (AD) and evaluated it in terms of the technological, environmental, and economic feasibilities. To mitigate indirect CO₂ emissions, a novel electrification process was proposed wherein a multi-concentric porous heater (MCPHs-AD) configuration was developed and compared to the natural gas heated (NGH-AD) process and the conventional electrically heated wall-adjacent heated reaction (WAH-AD.) A multi-step analysis approach was implemented, involving various scenarios of electricity sources (gray, blue, and green energy), to thoroughly assess the economic and environmental feasibility of the heat supply routes for the hydrogen refueling station. The non-feasibility of electrification was highlighted when using gray electricity owing to increased cost and CO₂ emissions of 12.8 USD/kg-H₂ and 10.5 kg-CO₂/kg-H₂, respectively. The application of CCS-integrated electricity reduced the carbon intensity by 14.3 % and 11.6 % for WAH-AD and MCPHs-AD, respectively, compared to NGH-AD with up to 14.7 % increase in cost. For the 2050 scenario, green electricity implementation reduced the carbon emissions and cost to 10.7 USD/kg-H₂ and 3.5 kg-CO₂/kg-H₂ when using MCPHs-AD with up to 8.2 % decrease in carbon intensity compared to WAH-AD. This achievement is attributable to the high energy efficiency because of the high surface area of the MCPHs-AD.