Spatial Variation in Cost of Electricity-Driven Continuous Ammonia Production in the United States

Abstract

Cost-effective, low-carbon ammonia production is necessary for decarbonizing its existing uses but could also enable decarbonization of other difficult to electrify end uses such as shipping, where the energy density is a key criterion. Here, we assess the levelized cost of ammonia production (95% availability) at industrial-scale quantities (250 tonnes/day) in 2030 from integrating commercial technologies for renewable electricity generation, electrolysis, ammonia synthesis, and energy storage. Our analysis accounts for the spatial and temporal variability in cost and emissions attributes of the electricity supply from variable renewable energy (VRE) sources and the grid and its implications on plant design, operations, cost, and emissions. On the basis of 2030 technology cost and grid projections, we find that grid-connected ammonia in midcontinental U.S. costs 0.54–0.64 $/kg, in comparison to 0.3–0.4 $/kg for natural-gas-based ammonia and, depending on the generation mix of the grid, may have higher or lower CO₂ emissions. Fully VRE based ammonia production, even with simultaneous wind and PV utilization, is more expensive than grid-connected outcomes, due to the need for storage to manage VRE intermittency and continuous ammonia production. Using a combination of VRE and grid electricity at locations of existing ammonia facilities in the midcontinental U.S. can achieve 2–80% CO₂ emissions reduction per tonne of ammonia in comparison to natural gas routes and corresponds to a levelized cost range of 0.57–0.85 $/kg NH₃. Further cost reductions are shown to be possible if the ammonia synthesis loop can be made more flexible, which reduces the need for a round-the-clock electricity supply and substitutes use of battery storage with ammonia storage.