The Potential Economic Feasibility of Direct Electrochemical Nitrogen Reduction as a Route to Ammonia

Abstract

<div><div><div><p>The Haber-Bosch synthesis produces ammonia from hydrogen and nitrogen gases in a globally important energy-intensive process that uses coal or natural gas as a fuel and as a hydrogen source. Direct electrochemical ammonia synthesis from nitrogen and water using renewable energy sources presents an alternative to the Haber-Bosch process that would be sustainable and environmentally benign. Additionally, the different production structure of direct electrochemical nitrogen reduction technology suggests a supply chain alternative to the ammonia industry, and a method for load-leveling of the electrical grid. This alternative route to ammonia from dinitrogen would not require the same large capital investments as does the Haber-Bosch process, nor would it require access to a fossil fuel supply. We show that under certain scenarios, at feasibly achievable levels of energy efficiency with a future electrocatalyst, direct nitrogen reduction would be economically competitive or advantageous compared with Haber-Bosch-based ammonia production.</p></div></div></div>

Environmental and economic potential of decentralised electrocatalytic ammonia synthesis powered by solar energy

“…44,53,54 In particular, the costs for the electrolyser system were taken from the ones of water electrolysers using a similar PEM technology, under the assumption of a comparable aspirational current density. 89 Such assumption is consistent with the limited influence of current density 34 and electrode material 79 on the CAPEX term. We considered the replacement of active materials for the electrolyser and the fuel cell in the cost calculations.…”

“…48 The system operates at 25°C and 1 bar. We consider a theoretical cell voltage = 1.17 V to ideally operate nitrogen th U electroreduction with the oxygen evolution reaction as the anodic half-reaction; 49 moreover, an overpotential of 0.3 V at each electrode 34,50 and an additional ohmic drop of 0.1 V 51 were assumed to calculate the cell voltage. Accordingly, the total voltage efficiency was determined with Equation 1:…”