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Can green ammonia overtake green hydrogen in the energy transition?

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?

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. Indeed, by applying ammonia-based fertilisers the impact of the increasingly extreme weather on crops can also be mitigated.

The impact of the war and LNG prices on fertilisers and ammonia production

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. The conflict, which could lead to an average of 10 per cent inflation in the 11 EU Member States of Central and Eastern Europe, apart from causing supply disruptions, supply shortages and price rises in case of commodities such as oil, gas and metals, has led to supply shortages and price rises of fertilisers as well.

This is what Hungary’s Prime Minister Viktor Orbán and the Czech Minister of Agriculture Zdeněk Nekula were concerned about already in March when they reminded us of how much their countries rely on the imports of raw materials and fertilisers from Russia and Ukraine.

The price increase of ammonia, a rise of nearly 30 per cent since the beginning of 2022, is linked also to the price increase of LNG, as natural gas is currently used as a feedstock for ammonia production. Similarly, fertiliser shortages can also be linked to higher LNG prices. This is affecting CEE manufacturers such as Azomures, the largest fertiliser plant in Romania, located on the outskirts of Târgu Mures, which has suspended its operations several times this year due to high energy prices.

How do we produce ammonia?

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 this 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. 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 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.

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.

Though as time goes on, the often combined use of green hydrogen and ammonia, including the REPowerEU programme’s 20 million tons renewable hydrogen target, as well as the benefits of green ammonia on its own could provide an incentive to see projects of this type in several regions of Europe.

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