Hydrogen is often cited as the energy source of the future, because of its capabilities in providing low-carbon energy, essential to reaching net-zero emissions. Besides hydrogen, green ammonia has also appeared on the scene and is mentioned as the workhorse for reaching the EU climate goals. But what is green ammonia and what benefits does it have compared to green hydrogen? And will green ammonia overtake green hydrogen in the energy transition?

Ammonia, the nitrogen- and hydrogen-composed compound, with the formula NH3, is mainly used in the production of fertilisers. Nowadays, approximately 80 per cent of the annual global ammonia production is used for this purpose. What is more, the need for fertilisers is expected to grow in the future, pushed by the increasing food demand. However, Europe’s fertiliser supply has recently been put at stake by the Russian-Ukrainian war. In 2021, Russia stood as the world’s top exporter of fertilisers.

How is ammonia produced?

Ammonia is produced most often by the so-called Haber-Bosch process, in which nitrogen gained from the atmosphere is entered in reaction with hydrogen using a metal catalyst under high temperatures and pressures. Producing nitrogen is relatively less challenging as it can be found in the atmosphere, however, it is hydrogen production that is laborious, as it requires a huge amount of energy, including electricity. Furthermore, most of the energy currently comes from the combustion of fossil fuels, in general methane or natural gas which results in high CO2 emissions.

Ammonia production accounts for around 420 million tonnes of carbon dioxide emissions per year (MtCO2/yr), which together with hydrogen production, which accounts for 830 MtCO2 /yr, create around 2 per cent of the annual global greenhouse gas (GHG) emissions.

However, ammonia can now be produced in a more climate-friendly way, without emissions, by supplying hydrogen from water electrolysis and using electricity coming from renewable energy sources. This emission-free output is called green ammonia.

What can it be used for?

Although green ammonia could make a significant contribution to the decarbonisation of agriculture through more sustainable production of fertilisers, it cannot be reduced only to that use. It can also serve for power generation or as a clean fuel for transportation, mainly to power ships.

Using ammonia to power ships may be quite novel, as Kriti Future, the world’s first ammonia-fuelled vessel, was taken over by its Greek owner Avin International earlier last year. Although it has not been specified whether it runs on green, grey or blue ammonia, it is considered more eco-friendly compared to traditional vessels.

In addition, green ammonia has also several benefits in terms of energy storage or as a hydrogen carrier. However, it is to be noted that green ammonia technology is still in the initial phase. Europe’s first commercial-scale green ammonia production plant, a joint-venture project of Iberdrola and Fertiberia started operations in mid-May 2022. But, interestingly, even if it is called a green-ammonia plant, the aim of the partners with the Spanish-located plant is said to produce green hydrogen. More precisely, it is expected to produce 40,000 million tonnes of green hydrogen per year.

Is green ammonia better than green hydrogen?

So will green ammonia overtake green hydrogen in the energy transition? So far great attention was placed on hydrogen, which is the most abundant element in the universe and has a range of uses. It can serve as fuel for light-and heavy-duty road vehicles and fuel for aviation and trains. It is also applied for power generation and to provide heat to residential buildings. According to the EU strategy, hydrogen will meet about a quarter of energy demand by 2050.

But what is green ammonia and what benefits does it have compared to green hydrogen? And will green ammonia overtake green hydrogen in the energy transition? Hydrogen can be also an energy carrier, but in this field, green ammonia’s benefits might outweigh those of hydrogen. This may be because ammonia is denser than hydrogen and needs to be compressed only to 10 times atmospheric pressure or cooled to -33°C to store energy. On the other hand, hydrogen, for storage, must be compressed to 350-700 times atmospheric pressure as a gas, or cryogenically cooled to -253°C as a liquid. The fact that it can be stored at lower temperatures makes it an ideal energy carrier. It is also suitable for storing and transporting energy from renewable energy sources. As ammonia is already widely used for fertilisers, there is already an existing distribution network where ammonia is stored in large, refrigerated tanks and then transported by various means, such as pipelines and water which is also an advantage and could be used for green ammonia in the fertilisers sector, or if extended also in other ways.

In a 2020 study by the Royal Society of London experts also say that ammonia is easier and cheaper to store and transport. However, ammonia and hydrogen could be considered as friends supporting each other rather than competitors. This is also possible because ammonia can serve as an outstanding carrier of hydrogen that can be reconverted to hydrogen after transportation.

Green ammonia corridors

Due to favourable climate conditions, the most efficient sources of wind and solar energy are often found outside Europe. Since the vast majority of the costs of green ammonia production is the price of energy, ammonia plants are being located in close proximity to the green energy sources. Most recently, projects are announced with ammonia production in Brazil, Chili, Australia, UAE, Namibia and South Africa.

The country to country traded ammonia market is expected to grow from 18-20 MTon in 2021 to 250-300 Mton by 2050. Since ammonia is a highly toxic gas, the need to provide safe and efficient supply chain solutions into Europe for this fuel of the future is growing quickly. But capabilities in this area are limited primarily to the needs of the fertiliser industry and this will therefore drive demand for large scale investments in independent storage, shipping and infrastructure in Europe and abroad.

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This post is based on a publication by CEEnergy News