Assessment of chemical looping technologies for ammonia synthesis integrated with biomass pyrolysis and char valorization.

Ammonia is increasingly recognized as a viable hydrogen energy carrier due to its established global infrastructure, high hydrogen density, and broad industrial applicability. This study performed an integrated techno-economic analysis (TEA) and life cycle assessment (LCA) to evaluate five ammonia production pathways spanning conventional and emerging configurations: Pathway 0 (HB-SMR), Pathway 1 (HB-SE-SMR), Pathway 2 (PY-H2O-CLAG), Pathway 3 (BM-H2-CLAG), and Pathway 4 (BM-H2O-CLAG). Although Pathway 1 achieved the strongest environmental performance among fossil-based routes and Pathway 4 demonstrated the highest economic return with an IRR of 62.1% and an NPV of 418.6 million USD, both pathways exhibited critical limitations: Pathway 1 remained economically unviable below the 20% IRR threshold, while Pathway 4 incurred the heaviest environmental penalties with a GWP of 11.2 kg CO2 eq/kg NH3. Pathway 3 was identified as the most balanced alternative, uniquely satisfying superior performance across economic viability, environmental impact, and energy efficiency simultaneously, as evidenced by an IRR of 55.2%, a payback period of 3 years, a GWP of 4.1 kg CO2 eq/kg NH3 comparable to the conventional baseline, and reductions of 56% in water consumption and 31% in fossil resource scarcity relative to Pathway 0. These findings suggest that biomass-integrated H2-CLAG systems offer the most scalable and economically pragmatic near-term route toward low-carbon ammonia production, while the integration of green utilities in Pathway 4 defined the long-term environmental frontier under renewable energy conditions.