4E Assessment of waste plastic valorization for ammonia production using process integration approach

Ammonia is an important chemical with vast industrial applications and being recognized as a potential renewable energy carrier. On other hand, plastic waste poses significant environmental challenges and its valorization is crucial to minimize its effects and promoting sustainable resource management. This study is aimed at solving two problems, reducing the plastic waste using thermochemical valorization, and reducing the overall production cost of ammonia using multiple feedstocks. Two process models are developed in study including a standalone plastics gasification system (Case 1) and a hybrid gasification and SMR setup (Case 2) for ammonia production. By analyzing energy, exergy and economic aspects, it has been found that Case 2 produced more hydrogen and ammonia and emitted less CO₂ than Case 1. Analyses were also carried out to determine the optimum process conditions for gasification temperature and various ratios of steam, plastic and natural gas. The integrated process (Case 2) achieved 5–6 % higher hydrogen and ammonia yields than standalone plastic gasification (Case 1), while reducing CO₂ emissions by 22 %. Economic analysis showed a 6 % reduction in total investment cost per ton of ammonia and a 16.4 % decrease in levelized production cost, making Case 2 comparable to conventional SMR-based plants. Cash flow analysis indicated a shorter payback period of 9 years for Case 2 versus 10 years for Case 1, with a higher net present value (36.87 M$ vs. 21.19 M$). These results demonstrate that integrating natural gas reforming with plastic gasification enhances both economic viability and environmental performance for sustainable ammonia production.