Review of ammonia production and utilization: Enabling clean energy transition and net-zero climate targets

In 2015, the Paris agreement was signed by 196 countries in attendance at COP21 that highlighted the need for rapid decarbonization and carbon dioxide removal (CDR) and sets ambitions to reach net zero emissions by mid-century. The production of ammonia can contribute to achieving net-zero emissions in several ways including energy storage, clean fuel, industrial applications and carbon capture and utilization (CCU) processes, if produced using renewable energy (RE) sources with very low greenhouse gas (GHG) emissions during production and utilization. This review study highlights the potential of green ammonia production pathways, utilization, ammonia storage and transport, ammonia infrastructure and economy, to serve various roles and provide potential benefits in decarbonizing industry and clean energy transitions to meet net-zero climate targets. Renewable ammonia cannot only help decarbonize existing ammonia markets by displacing fossil fuels, but can also help greening the industrial sector such as fertilizer and chemical industries and accelerate decarbonization in hard-to-abate industries, including retrofit of existing ammonia plants. Ammonia is also expected to be used in the stationary power sector as renewable fuel as the technology matures. It can also play an imperative role as a promising maritime fuel, owing to its zero-emission properties, high energy density and compliance with ever more stringent environmental regulations, transporting RE, in the shipping industry that is one of the largest GHG emitters. Moreover, as a hydrogen carrier, ammonia can deliver industrial feedstocks and enable lower-cost hydrogen imports as compared with renewable hydrogen. Encouraging green ammonia production technologies and near-zero-emission technology progress can guide desirable future pathways for the ammonia industry, including handling important safety considerations of production, storage and end-use.