Toward sustainable ammonia: A techno-economic and environmental assessment of emerging electrochemical ammonia synthesis pathways

This study conducts a comprehensive techno-economic and environmental assessment of three emerging electrochemical ammonia (NH₃) synthesis pathways: nitrogen reduction (N₂RR), lithium-mediated nitrogen reduction (Li-NRR), and nitrate reduction (NO₃RR). Based on experimental system-level data, we quantify the levelized cost of ammonia (LCOA) and global warming impact (GWI) for each pathway under future grid scenarios. Of the assessed routes, NO₃RR demonstrates the most favorable performance (LCOA: $0.84/kg; GWI: ~2 kg CO₂eq/kg NH₃), particularly when using wastewater-derived nitrate. Li-NRR moderate economic feasibility ($1.13/kg), enabled by gas-phase NH₃ separation, although it remains sensitive to the hydrogen source. In contrast, N₂RR represents the most direct route for the production of NH₃ from N₂ but requires major advances in catalyst selectivity and current density to reduce the LCOA (>$1.7/kg). Sensitivity analysis reveals bottlenecks that must be addressed for electrochemical NH₃ synthesis to become a viable alternative to the Haber–Bosch process, including catalytic and system-level limitations for N₂RR, energy efficiency and hydrogen sourcing for Li-NRR, and sustainable nitrate supply chains for NO₃RR. These findings provide insights for the development of research and deployment strategies for economically viable and climate-competitive electrochemical NH₃ production.