Life Cycle Assessment of Selected Ammonia Production Technologies From the Perspective of Ammonia as a Fuel for Heavy-Duty Vehicle

Abstract

One of the promising options for the decarbonization of industry dependent on heavy-duty vehicles is to use alternative fuels such as ammonia. The study investigates the environmental impact of five selected ammonia production technologies and compares them to diesel fuel: ammonia based on hydrogen from steam methane reforming (gray), ammonia based on steam methane reforming with carbon capture and storage (blue), ammonia based on hydrogen from electrolysis with electrical energy supplied by: PV (green PV), wind (green wind), and nuclear plant (pink). Environmental impact is assessed using the ReCiPE method based on three midpoint and two endpoint categories: climate change, fossil depletion, freshwater consumption, human health, and ecosystem quality. The climate change results per 1 MJ (LHV) are as follows: gray ammonia at 0.148 kg CO2 eq., blue ammonia at 0.0701 kg CO2 eq., green ammonia PV at 0.0197 kg CO2 eq., green ammonia wind at 0.01039 kg CO2 eq., pink ammonia at 0.00565 kg CO2 eq., and diesel (including its stoichiometric combustion) at 0.0851 kg CO2 eq. The life cycle assessment (LCA) was performed using the lca for experts (GaBi) software, with Sphera's comprehensive Managed LCA Content as the primary data source for the life cycle inventory. The study indicates nuclear and renewable-based routes to be the best options in terms of the climate change and human health categories; however, their high impact on freshwater consumption and ecosystem quality is revealed. Still, ammonia is proven to be an effective solution toward decarbonization, as compared to diesel, given its blue, green, or pink source.