Spatial variation in cost of electricity-driven continuous ammonia production in the United States

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 like shipping where 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 electricity supply from variable renewable energy (VRE) sources and the grid, and its implications on plant design, operations, cost and emissions. Based on 2030 technology cost and grid projections, we find that grid-connected ammonia in the midcontinental U.S. costs 0.54-0.64 $/kg, as compared to 0.3-0.4 $/kg for natural gas-based ammonia and depending on the generation mix of the grid, may have higher or lower CO2 emissions. Fully VRE-based ammonia production, even with simultaneous wind and PV utilization, is more expensive than grid connected outcomes, due to the need for storage to manage VRE intermittency and continuous ammonia production. Instead, using VRE and grid electricity for ammonia production under moderate carbon policy (50$/tonne CO2 price) in the midcontinental U.S. can achieve 55-100% CO2 emissions reduction per tonne of ammonia compared to natural gas routes and corresponds to levelized cost range of 0.54-0.63 $/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 round- the-clock electricity supply and the substitute use of battery storage with ammonia storage.