According to research, global ammonia production annually emits approximately 1.8% of overall global carbon dioxide emissions, equating to 176 million tonnes of ammonia per year. To achieve net-zero targets, it is essential to create and implement an urgent plan for decarbonizing ammonia production, which would create opportunities to replace fossil fuels with ammonia in other applications.

The majority of the carbon dioxide released during ammonia production comes from the steam methane reforming (SMR) process used to produce hydrogen. To manage the transition to net-zero carbon systems, blue hydrogen can be produced in the short term by combining carbon capture and storage with the SMR process. However, this is not a viable long-term solution in a zero-carbon economy. Electrolyzing water to produce green hydrogen presents a pathway to zero-carbon ammonia production. However, it depends on low-cost sustainable electricity and a continued decrease in electrolyzer costs. Currently, renewable energy electricity costs are close to a tipping point for the affordable production of zero-carbon green ammonia in regions rich in wind and solar energy. A green ammonia market would significantly enhance economic opportunities to extend renewable penetration into the energy economy. Nonetheless, given the poor overall efficiency, the energy system must be considered to ensure that ammonia production is relevant to the local situation.

Further research could lead to the development of various processes to produce green ammonia, such as new production catalysts, electrochemical ammonia production, and chemical looping processes. Some of these technologies may address the challenge of directly coupling ammonia production to intermittent renewable power. Ammonia is a convenient energy storage medium that can be stored in large quantities as a liquid at modest pressures (10-15 bar) or refrigerated to -33°C, with an energy density of approximately 40% of petroleum.

As a zero-carbon fuel, ammonia can be utilized in fuel cells or through combustion in internal combustion engines, industrial burners, and gas turbines. The maritime industry is likely to adopt ammonia as a fuel early on, and it has the potential to decarbonize heavy road transport, rail, and aviation.

Ammonia can also be utilized to generate electricity via fuel cells, gas turbines, or internal combustion engines, which can then provide power to the grid or remote areas. Furthermore, as an efficient energy carrier, it has the potential to be a key player in nascent international sustainable energy supply chains. It is more affordable and easier to transport and store than pure hydrogen, has existing international infrastructure, can be cracked to produce hydrogen when needed, and is itself a zero-carbon fuel. Ammonia also has potential use in district heating systems. Despite the established global manufacturing and distribution system and the safe transportation and use of ammonia, new applications will require a careful risk assessment, and additional control measures may be necessary to reduce risks to health and the environment.