Enhanced ammonia-cracking process via induction heating for green hydrogen: A comprehensive energy, exergy, economic, and environmental (4E) analysis

Abstract

Ammonia (NH3) is gaining attention as a hydrogen carrier due to its high H2 storage capacity and ease of liquefaction at ambient temperatures. The conventional method of ammonia decomposition is thermal cracking through fossil fuel combustion, resulting in significant carbon dioxide (CO2) emissions. Therefore, developing an eco-friendly and highly efficient ammonia decomposition process is important. This study proposed four high-efficiency processes without carbon emissions by improving the induction-heating-based ammonia decomposition process designed in a previous study. The four proposed processes were designed to utilize the H2 discarded as off-gas of the PSA unit in the existing induction-heating-based ammonia decomposition process. The proposed processes incorporate various unit components, including a proton exchange membrane fuel cell (PEMFC), solid oxide fuel cell (SOFC), burner, and palladium (Pd) membrane. These units were integrated with the PSA outlet to achieve enhanced thermodynamic efficiency compared with the conventional process without carbon emissions. Energy, exergy, economic, and environmental analyses were conducted to assess the feasibility of each case. Thermodynamic analysis revealed that integrating the Pd membrane yields the highest thermal (78.29 %) and exergy (64.02 %) efficiencies. Integrating a PEMFC exhibits the lowest levelized cost of H2 (6.93 USD/kg H2). Finally, When the four proposed processes are operated with renewable energy, clean hydrogen can be produced at 2.45 to 3.21 kgCO2/kgH2 emission levels. The enhanced processes presented in this study can serve as a blueprint for achieving carbon-free green H2 production at on-site H2 refueling stations.