N2 Fixation by Plasma-Activated Processes

Summary Sustainable nitrogen fixation could offset the significant environmental and societal costs associated with the energy-intensive conventional Haber-Bosch process (HB). This perspective compares the energy requirements, CO2 emissions, and commodity prices associated with alternative plasma-activated ammonia synthesis to those for HB. The threshold efficiency required for a plasma process to become competitive is established for various scenarios of H2 sources, energy sources from natural gas to CO2-free renewable energy, and carbon pricing policies. Economic positive externalities are evaluated for renewable energy-powered modular ammonia production, which is projected to become competitive upon achieving a 6-fold improvement in plasma process efficiency. The technological prospects for achieving the thresholds are discussed, including advancements in plasma-catalyst synergy, direct reactions of N2 with plasma-activated water, and plasma N2 oxidation. A comparison of theoretical energy minima reveals that the energy required for plasma-activated nitrogen fixation might be lower than that for HB.