Techno-economic and environmental analysis of sustainable ammonia process developed through integrated low-carbon technologies for maritime sector

초록

Ammonia is anticipated to play a pivotal role as a carbon-free fuel in the future maritime industry. Moreover, with the increasing capacity of renewable energy sources, ammonia production methods must align with the evolving energy mix. In this study, we harnessed renewable energy while integrating the existing natural gas reforming process with chemical looping reforming (CLR) and electrolysis cell (EC) to simultaneously reduce carbon emissions and capital expenditures (CAPEX). The proposed ammonia process demonstrated a levelized cost of ammonia (LCOA) of $264.8/ton, which is over 10 % lower than the existing commercial ammonia processes. Furthermore, by optimizing the existing carbon capture and storage (CCS) process through blend amine and physical regeneration, and integrating it with CLR, the proposed process achieved over 98 % reduction in direct emissions compared to Kellogg Brown & Root (KBR) and Linde ammonia process. Notably, even in energy mix scenarios with upstream emissions exceeding 18 gCO2e/kWh, the proposed process emitted less carbon than green ammonia. To assess the value of ammonia produced by the proposed process as marine fuel, we applied three scenarios (tanker, oil tanker, and container ship) and compared it with the conventional liquefied natural gas with onboard carbon capture system (LNG + OCCS) method. The results demonstrate that the proposed process not only serves as a straightforward ammonia production method but also proves its economic and environmental viability as a marine fuel production process, with a simple payback period of just 2 years. Considering the lifecycle of ammonia value chain, the proposed process exhibits approximately 77 % lower carbon emissions compared to 82 % carbon capture in shipping. This comprehensive study validates the proposed process not only for ammonia production but also as a sustainable solution for the marine industry.

키워드