Written by: Leila Khalid
Edited by: Ada Collins
Approximately 50% of global food production is dependent on the use of fertilizers, whose use is on a significant upward trajectory as the world population continues to grow (Fig. 1). Ammonia, a naturally occurring gas, is used in all nitrogen-based fertilizers to restore soil nitrogen levels, which naturally deplete during crop production (Maygar, 2023). Although extremely effective, the traditional methods used to produce this key ingredient are highly emissions-intensive, and ultimately account for about 1.3% of all energy-related carbon emissions (Edmond, 2023). As the world focuses on transitioning to clean energy, the redevelopment of ammonia remains a critical barrier to achieving a carbon-neutral food production system. This fact is accentuated by the Russia-Ukraine conflict, where sanctions against Russia’s export of ammonia has led to a surge in fertilizer prices and increased ammonia shortages (Edmond, 2023). These barriers provide an opportunity for countries to shift towards ‘green ammonia’ – a renewable energy alternative that has the potential to transform the fertilizer sector.
Ammonia Production
Fundamentally, ammonia is made by combining nitrogen and hydrogen, resulting in a colorless and acrid gas (Serpell et al., 2023). The current method used to make so-called ‘brown ammonia’ was developed in 1909 by German chemist Fritz Haber and was later industrialized using the techniques of fellow chemist Carl Bosch (Service, 2018). The Haber-Bosch method requires splitting the chemical bonds within nitrogen molecules and combining these atoms with hydrogen. The hydrogen gas is supplied by separating it from coal or natural gas using pressurized steam (Service, 2018). This reaction, along with the pressure used to combine the hydrogen and nitrogen, consumes and emits immense amounts of fossil fuels.
Although relatively efficient, as about 60% of the energy used is stored in the ammonia bonds, the Haber-Bosch method remains an energy-intensive process (Service, 2018). It is estimated that for the production of every tonne of brown ammonia, there are two tonnes of greenhouse gasses emitted (Edmond, 2023). For a world currently producing 175 million tonnes of ammonia each year, it is a major source of environmental degradation (Jones, 2022). Large ammonia-producing companies are attempting to mitigate these carbon emissions by sequestering the resulting carbon deep underground (Dvorak, 2023). More prominently, companies have begun investing in green ammonia technologies and infrastructure, hoping to reduce emissions by altering the Haber-Bosch method at its core.
So how can this industrial and emissions-intensive process be transformed for a future of sustainable fertilizers? The key difference from the Haber-Bosch method is the use of an electrolyzer to extract hydrogen from water, rather than from fossil fuels (Maygar, 2023). Airborne nitrogen is then combined with this hydrogen using the same Haber-Bosch method, but runs on completely renewable energy systems (Fig. 2). The result is a ‘green ammonia’ which can be used for existing sectors such as fertilizers, but can also contribute to transport fuel – another sector heavily dependent on greenhouse gasses. In fact, compared to liquid hydrogen, a commonly used green alternative fuel, ammonia has nearly double the energy density and is far easier to package and ship (Serpell et al., 2023). Douglas MacFarlane, a prominent chemist and researcher at Monash University, claims that “liquid ammonia is liquid energy… It’s the sustainable technology we need” (Service, 2018).
Rolling Out Green Ammonia
The benefits of using green ammonia have spurred numerous companies to incorporate it into their own technologies and facilities. Yara, a Norwegian company responsible for producing the largest amount of nitrogen fertilizers world-wide, has created an entire business unit solely for the development of green ammonia (Frangoul, 2021). In Saudi Arabia, a $5 billion plant called Helios is planning to produce 1.2 million tonnes of green ammonia per year by 2025 (Jones, 2022). Although this trend is encouraging, many countries are just now expanding into the clean fertilizer realm, relying on the pressure and subsidy relief from government mandates. The United States developed subsidies specifically for the increase of clean hydrogen production and carbon capture technologies. Additionally, in 2024 the United States Department of Agriculture (USDA) provided $50 million through the Fertilizer Production Expansion Program to improve and increase domestic fertilizers (Huffstutter, 2024). The European Union has also put pressure on major companies to disclose their Scope 3 emissions, which are the total emissions produced from a company’s supply chain. This has led worldwide conglomerates such as PepsiCo and Nestlé to invest in green fertilizer technologies and start-ups (Savage, 2023).
In addition to the benefits for the fertilizer sector, the production of green ammonia has also been critical for reaching other sustainability goals. In 2018, the United Nations pledged to cut 50% of the greenhouse gas emissions from international shipping by 2050 (Dvorak, 2023). These lofty objectives have forced shipping manufacturers to consider green ammonia as a zero-carbon fuel. Furthermore, companies such as JERA, the largest Japanese power generation company, have proposed mixing ammonia into their coal-consuming power plants to reduce emissions (Dvorak, 2023). Although the expected benefits of all these projects are promising, the introduction of green ammonia is not a simple or cheap alternative.
Due to the relatively new nature of green ammonia, the logistics of its manufacturing remain a notable barrier to implementation. Creating the needed infrastructure to replace the Haber-Bosch process and produce green ammonia may not be possible without a head start. That’s why companies like CF Industries, the largest producer of ammonia, and Yara have a significant advantage in this race. According to Svein Tore Holsether, the CEO of Yara, “The technology is there, but it’s also about turning it into a product… and the nice thing about ammonia production and fertilizer production is that you have an existing infrastructure already” (Frangoul, 2021). The same is true for CF, where the shift to producing low-carbon ammonia is much easier considering the vast ammonia-producing infrastructure already in place (Dvorak, 2023). However, even for established companies, green ammonia is not being produced at the volumes necessary for replacing brown ammonia, and is currently far more expensive. In the U.S. it is estimated that it is 73% cheaper to make ammonia using fossil fuels than with renewable energy systems (Jones, 2022). There are also additional concerns with the development of ammonia, as it is a toxic molecule that has the potential to produce harmful nitrogen oxides if it combusts (Serpell et al., 2023).
The Future of Fertilizers
Making green ammonia production up-to-scale and an economical choice for all players remains the main obstacle in the clean fertilizer game. Chemical engineer and ammonia researcher Jimmy Faria believes that, similar to renewable energy systems from wind and solar, “green hydrogen will be as cheap or cheaper than the dirty stuff — the question is when” (Jones, 2022). Similarly, the CEO of the International Fertilizer Association, Alzbeta Klein stated that, “none of these new technologies have been scaled up yet… The door is open to each and every solution” (Savage, 2023). It’s evident that the potential of green ammonia technologies and implementation have not yet been realized, but it may be only a matter of time before green ammonia becomes the future of fertilizers worldwide.
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References:
Ammonia: Zero-carbon fertiliser, fuel and energy store. The Royal Society. (2020). https://royalsociety.org/-/media/policy/projects/green-ammonia/green-ammonia-policy-briefing.pdf
Dvorak, P. (2023). Fertilizer companies are betting on ammonia as a low-carbon fuel. The Wall Street Journal. https://www.wsj.com/business/energy-oil/fertilizer-ammonia-low-carbon-fuel-a287902b
Edmond, C. (2023). From fuel to fertilizer, how green ammonia could help curb emissions. World Economic Forum. https://www.weforum.org/agenda/2023/11/green-ammonia-climate-change-energy-transition/#:~:text=Green%20ammonia%20is%20produced%20without,carbon%20emissions%20in%20intensive%20sectors.
Frangoul, A. (2021). Firms line up “green” ammonia for fertilizer and future fuel. CNBC. https://www.cnbc.com/2021/08/16/firms-line-up-green-ammonia-for-fertilizer-and-future-fuel.html
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Savage, S. (2023). Food producers turn to greener fertilisers to reduce carbon footprints. Financial Times. https://www.ft.com/content/a3288fe8-a8f6-4f7a-8c9b-3c680b8f6cad
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Serpell, O., Hsain, Z., Chu, A., & Johnsen, W. (2023). Ammonia’s role in a net-zero hydrogen economy. Kleinman Center for Energy Policy. https://kleinmanenergy.upenn.edu/research/publications/ammonias-role-in-a-net-zero-hydrogen-economy/
Service, R. (2018). Ammonia—a renewable fuel made from sun, air, and water—could power the globe without carbon. Science. https://www.sciencemag.org/news/2018/07/ammonia-renewable-fuel-made-sun-air-and-water-could-power-globe-without-carbon