Ammonia: the invisible petrochemical that fuels industrial agriculture

In short: Ammonia is unique among petrochemicals – its molecule contains no carbon, yet more than 99% of ammonia is produced using fossil fuels. It is the foundation of industrial agriculture but also generates enormous greenhouse gas emissions and locks food production into fossil fuel supply chains.

Instead of decreasing our reliance on ammonia, the industry is seeking new markets by promoting ammonia as a "green" fuel for shipping and power generation. This article explores how ammonia became central to modern agriculture, why its production is so carbon-intensive and why expanding ammonia infrastructure risks prolonging our dependence on fossil fuels rather than accelerating the transition away from them.

In our previous article, We can’t quit fossil fuels without tackling petrochemicals, we discussed why petrochemicals keep us tied to the fossil industry independently of fossil fuel use. We also promised to bring you a separate article on ammonia, since it occupies a unique place among petrochemicals.

Many might be surprised to know that ammonia is a petrochemical. Although ammonia itself contains no carbon (its chemical formula is NH₃), almost all ammonia produced today is made using fossil fuels. Natural gas, coal or oil are used to produce hydrogen, which is then combined with nitrogen from the air through the Haber–Bosch process.

Why is ammonia so important? Historical context

Ammonia is deeply entrenched in our economy. It is a primary source of active nitrogen (meaning nitrogen that can be incorporated into other molecules through chemical reactions) and almost every synthetic molecule that contains nitrogen atoms is synthesised using ammonia. Most ammonia is used to produce fertilisers and about 50% of global food production relies on ammonia-derived fertilisers.

But this has obviously not always been the case. Centuries before the development of industrial agriculture, farmers from different parts of the world used organic waste to fertilise the fields. In the 19th century, industrialising Europe and the United States transformed agriculture through global fertiliser markets, relying heavily on nitrogen resources extracted from South America. First, by exploiting Peruvian deposits of guano, the nitrogen- and phosphorus-rich excrement of seabirds accumulated over centuries. Then, by extracting Chilean deposits of sodium nitrate, which became the main industrial nitrogen fertiliser in the late 19^th century.

At the time, Western Europe and the United States had become increasingly dependent on imported nitrates. Control over these deposits became a matter of geopolitical and imperial competition, as agricultural productivity and military power both depended on access to nitrogen. However, the reserves were being depleted at an alarming rate, and by the end of the 19^th century it was evident that demand for nitrogen compounds would soon exceed the available supply. This boosted research efforts to develop a method that could capture nitrogen from the air and convert it into a reactive form. Fritz Haber, later known for his central role in the development of chemical weapons, developed a method for synthesising ammonia from nitrogen and hydrogen under high pressure. Recognising its industrial potential, the German chemical company BASF acquired the rights to the invention and employed Carl Bosch to scale up the process for industrial production. In 1913, BASF commissioned the first commercial ammonia plant based on the Haber-Bosch process in Oppau, Germany.

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Synthetic ammonia production expanded rapidly during the First World War as the British naval blockade restricted Germany’s access to overseas nitrate supplies, while military demand for nitrogen compounds increased dramatically. After the war, Germany emerged as the leading centre of synthetic ammonia technology. Since then, ammonia production has expanded worldwide, especially from the 1960s onward, when natural gas replaced coal-based processes as the main source of hydrogen, making ammonia production much cheaper.

Ammonia production now

Ammonia production currently sits at 200 million tonnes per year. According to data from 2020, when global ammonia production was 182 million tonnes, direct CO₂ emissions from the global production amounted to 450 million tonnes, with an additional 170 million tonnes from indirect emissions (electricity generation and emissions from reactions that take place when ammonia-derived fertilisers are applied to soils). This means that ammonia production is responsible for around 1.7% of the global CO₂ emissions.

Ammonia is also one of the most emission-intensive materials produced by heavy industry – on a per-tonne basis, emissions from ammonia production are almost twice as intensive as those from steel production and four times as intensive as those from cement production. Ammonia’s per tonne emissions are comparable to plastic production (e.g polyethylene production emits around two tonnes of CO₂ per one tonne of plastic).

There are alternatives to the regular, carbon-intensive ammonia production process. The industry differentiates between various approaches by assigning colours to them.

- Grey ammonia is produced using the conventional fossil-based Haber–Bosch process (and brown is sometimes used to differentiate the coal-based process).

- Blue ammonia is made using fossil-based processes but combined with CO₂ capture.

- Green ammonia is made using hydrogen coming from water hydrolysis (i.e. non-fossil-based).

However, the blue and green alternatives still represent only a tiny fraction of global production – the combined share of net-zero production methods for ammonia is negligible at less than 1% of global production. Alternative methods are also more expensive – green ammonia costs two to four times more than conventional ammonia.

The future of ammonia

Ammonia is a solid link that connects our food systems with petrochemicals. Moreover, its production is extremely unsustainable. It would be logical to choose a development path that reduces our dependence on ammonia, eventually eliminating its use completely. Obviously, such a path is not acceptable for petrochemical companies or the ammonia industry.

The production of ammonia for fertilisers is constantly increasing, yet the industry is still looking for new applications. Tony Will, CEO of the world’s largest ammonia producer, CF Industries, recently said, “Up to this point, we have made a business by selling the nitrogen value of the molecule. What’s really exciting [...] is now there is an opportunity and a market that values the hydrogen portion of the molecule.” The nitrogen portion is used to produce fertilisers, explosives and other synthetic materials containing nitrogen. The hydrogen portion can provide energy, which means that ammonia can also be used as fuel. This illustrates a major strategic shift. Instead of viewing ammonia primarily as a source of nitrogen for fertilisers, producers increasingly present it as a carrier of hydrogen for the energy sector.

Ammonia is now presented as the “green” fuel of the future, mostly for ships and as co-fuel for gas-powered power plants. The reality is that ammonia is far from green. First of all, basically all ammonia produced nowadays is fossil-based grey ammonia. There are many new projects promising blue ammonia, but the carbon capture projects have often failed to achieve their promised capture rates and captured CO₂ is sometimes used for enhanced oil recovery rather than permanent storage. Moreover, blue ammonia does not address the main issue, which is the dependence on fossils. This could be solved by green ammonia, but the electrolysis-based process is not efficient enough at this point to produce ammonia at large enough scale.

Additionally, ammonia production poses environmental concerns related to methane and nitrous oxide emissions which occur during production. These could become of a major concern if the production increases since methane and nitrous oxide are much more potent greenhouse gases than CO₂.

Don't fall for the ammonia hype

It is important to understand that the narrative presented by the fossil companies and the ammonia industry, in which expanding the ammonia infrastructure will soon enable a transition towards green shipping fuel, is just a greenwashing strategy for fossils. Ammonia is not a viable fuel solution on a large scale and it is essentially oil or gas in disguise. Expanding ammonia infrastructure risks locking in decades of additional fossil fuel dependence. Public investment would be better directed towards solutions that reduce energy demand and fossil fuel use rather than creating new markets for fossil-derived ammonia.

Instead of relying on strategies that simply maintain business as usual, we need a change in approach to both shipping (where ammonia could be used as a fuel) and agriculture (where ammonia is already used to produce fertilisers). More sustainable alternatives include, for example, wind propulsion and organic fertilisers, which can bring real environmental benefits, provided that they are combined with a general scale-down of the shipping industry and industrial agriculture.

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For more information contact: info@scarabtrust.org.uk

Image: Photo by Wolfgang Weiser on Unsplash