Is ammonia the answer to wasted wind?
Wind-powered green ammonia could have a key role to play in energy security and grid resilience in the UK. In the second part of our series on emerging technologies, we uncover the potential of the ASPIRE project.
Lucinda Dann, features editor
Is ammonia the answer to wasted wind?
Wind-powered green ammonia could have a key role to play in energy security and grid resilience in the UK. In the second part of our series on emerging technologies, we uncover the potential of the ASPIRE project.
Lucinda Dann, features editor
Ammonia is the second most produced chemical worldwide due to its plethora of uses, not least of all being as a fertiliser for agriculture. Traditionally it is produced by converting natural gas into hydrogen through steam methane reformation before being combined with nitrogen from the air to create ammonia.
As well as being reliant on fossil fuels, the process contributes between 1.3% and 1.8% of global carbon emissions annually, while the economic viability of production is highly dependent on gas prices. But there could be another way. In theory ‘green’ ammonia could be produced from nothing more than air and water if excess wind generation could be harnessed to power hydrogen electrolysis.
However, for both technical and economic reasons, chemical plants have not traditionally lent themselves to being run flexibly, making them incompatible with renewable generation.
A team of UK scientists believes they have turned the theory of green ammonia into reality. The Ammonia Synthesis Platform using Intermittent Renewable Energy (ASPIRE) demonstration facility can successfully switch between 10-100% production to match wind output. Meanwhile, policy updates have improved the economic case for green ammonia, opening the door to better renewable utilisation and the potential to restart domestic production.
While reigniting a dying industry would bring a myriad of benefits for the UK, from an energy perspective it would also allow hydrogen for industrial use to be stored above ground in tanks, and ammonia could be used in place of both hydrogen and natural gas in peaking plants.
Proportion of global carbon emissions accounted for by the use of fossil fuels to make ammonia
Proportion of UK's ammonia demand met by imports
Proportion of UK wind power curtailed in 2024-25
A new direction
The UK can be seen to be at a crossroads for its ammonia needs with the last major ammonia plant in the UK having been idled due to high natural gas prices since August 2022 and closed completely in July 2023.
Now 80% of the UK’s ammonia use is imported from abroad, which means the UK is still subject to the high-cost volatility of grey ammonia. While it could keep doing this, the volatility of a renewables-based electricity system presents the opportunity to pivot to an alternative approach of using smaller decentralised plants that are in line with net zero.
Around 13% of all the wind generation in Great Britain that was produced in 2024-25 was not used. Keen to see this percentage reduced, the Department for Energy Security and Net Zero (DESNZ) funded the ASPIRE project through its £1 billion net zero innovation portfolio.
The Science and Technology Facilities Council’s (STFC) Energy Research Unit received £4.28 million in 2023 from the fund to build a prototype plant at its Rutherford Appleton Laboratory in Oxfordshire.
The plant officially powered up and came online in December last year, with the first decanting of e-ammonia from the plant taking place in June 2026.
“We’ve built a very flexible ammonia plant” says Tristan Davenne, head of the STFC energy research unit. “Traditionally chemical plants have not been flexible. There has not been a driver for them to be flexible because they are run off a plentiful supply of natural gas, but they tend to run 24 hours a day for a whole year or more.
“We took the stance that if you want to generate green ammonia you have to use green electrons, and renewable energy is intermittent. In order to work with that we need a chemical plant that is flexible. That’s why we got the funding to build the plant to really demonstrate that chemical plants can be more flexible than they have been traditionally. That way they can take advantage of renewable energy when its cheap and available.”
The plant can be run at a generation rate of between 10-100%, but it can also switch between modes at a rate of around two seconds in response to signals from the electricity grid about power availability, thanks to its automated control system.
“We can modulate power in the order of seconds, so we could drop our power in two seconds, but ammonia production rate is a minute or two-minute process so we have small hydrogen buffer stores to accommodate that difference,” says Davenne.
While its ability to run on variable excess wind energy is novel, the ASPIRE plant uses established technology in the form of an electrolyser to split water to make hydrogen and a pressure swing absorption system to separate nitrogen from air.
In other countries scientists are testing more novel approaches to the challenge, according to Davenne.
“The challenge of flexible e-ammonia synthesis has pricked the interest of quite a lot of academics globally in recent years. There are various new e-ammonia plants at pilot stage around the world, but I think ASPIRE may end up being the first to publish performance data with a particular focus on flexibility.
“There have been some more radical approaches to flexible synthesis proposed such as using plasmas or temperature swing reactors, but a lot of these are much lower down the TRL [technical readiness level] scale than our approach. ASPIRE is more of a new twist on an old classic rather than completely reinventing the wheel but I don't think anyone has yet proven or published results from an alternative design to ASPIRE that can deliver flexibility efficiency and reliability in the same way that ASPIRE is now doing,” he adds.
“We took the stance that if you want to generate green ammonia you have to use green electrons, and renewable energy is intermittent. In order to work with that we need a chemical plant that is flexible.”
Tristan Davenne, head of the STFC energy research unit
Carbon taxes
The technical approach of running a chemical plant has only been part of the challenge, as Davenne says it has been hard for green ammonia to compete with fossil fuel-derived ammonia on cost.
“But we are getting closer to cost parity with grey ammonia,” he says. “There have been times when the grey ammonia price has been higher than we think we could achieve because the gas price has gone so high. What we can offer is a secure supply rather than one where it’s at a point where we can’t afford to make it in our own country.”
For certain applications that require very pure ammonia, Davenne believes green ammonia will be cost competitive. “When you make it from natural gas you get lots of nasties which have to be purified out, so for pure ammonia applications we are more competitive we think.”
Davenne believes the first offtakers of green ammonia will be those industries who want very pure ammonia, such as the semiconductor industry and the Ministry of Defence.
There is also the potential for green ammonia plants to financially capitalise on the benefits to the grid that they would provide, in addition to mopping up cheap wind energy. “We’ve been talking to Float energy and Gridbeyond who are companies which are developing AI computer-based systems to control large energy users and the idea is you can extract revenue by backing off your plant when the grid really needs you to do it, so there are multiple electricity market approaches to making it financially viable,” says Davenne.
The economic case for green ammonia is set to improve further because the chemical has been included in the Carbon Border Adjustment Mechanism since the start of the year, adding a significant extra cost on to ammonia imports to offset the associated carbon emissions. The industry is also set to benefit from the Hydrogen Allocation Round (HAR) subsidy scheme due to the fact that ammonia can act as a hydrogen carrier. Around 85% of the energy used to make ammonia is used to create the initial hydrogen.
The first HAR saw 11 projects allocated over £2 billion in funding, including the HyMarnham Power project.
The HyMarnham Power project is being developed on the site of the former High Marnham coal power plant. As well as the deployment of renewable energy and electrolysis capacity, an ammonia-to-power project will see ammonia gas recovered from agricultural waste, cracked and fed into GeoPura’s Hydrogen Power Unit technology – a self-charging battery system powered by green hydrogen.
“I think HAR is what is going to facilitate the first decentralised ammonia plants in the UK, and not only that but reshoring ammonia production because it effectively pays for a large proportion of the electricity that you need to make hydrogen, and that makes us really competitive with grey hydrogen,” says Davenne.
“I think we have got a point with the CBAM and the HAR and the fact that we know that there is a premium for pure ammonia where there is an economic business case for doing this and people are working as fast as they can to make sure that some of the HAR sites have ammonia on them.”
Multitude of benefits
While converting hydrogen into ammonia requires an additional step, there are a multitude of benefits for doing so, not least of all for storage purposes. Although hydrogen is highly energy dense by mass, it is very light and must be compressed and stored at high pressures, which makes the process expensive.
“Ground-level hydrogen storage is expensive, so the only economic way that has been proposed to store it is in large underground caverns at a mid-pressure. But it hasn’t really been done much, and it’s geographically dependent,” says Davenne.
In contrast, ammonia can be stored as a liquid under mild pressure, making it more similar to Liquid Natural Gas. Ammonia is already stored in large cylindrical tanks at ports in a similar way to how town gas was stored. While its production would need to be decentralised to make use of renewable energy, the resulting ammonia could be stored anywhere in the country.
“It’s much cheaper to store energy in the form of ammonia than it is in the form of hydrogen,” says Davenne. “It has had a good safety record from the point of view of storage for many years. In America they are very relaxed about transporting and storing it. In the UK and Europe we are a little more careful but still you’ll see it go up and down the motorway on trucks, it’s quite easy to move around. There’s no reason why you can’t make it somewhere and then move it somewhere else.
“I have heard people say that it gives us a way to trade in renewable energy because you can store the renewable energy in the form of an energetic liquid, and there’s already a network for distribution because we’ve been using it as a fertiliser for the last hundred years.”
Although ammonia can be completely cracked back into hydrogen, Davenne questions the logic of undertaking such an expensive process when ammonia can be burnt in place of hydrogen in many instances. While applications such as hydrogen fuel cells would require ammonia to be completely cracked, the gas could supersede hydrogen in some use cases such as peaking plants. “It’s a good standby fuel for peaking power plants, where when we have a shortage of renewable energy you can run gas turbines on ammonia,” he says.
It is an idea which has been explored in Ireland, he adds: “Ireland are really dedicated to the renewable route but they know they need storage to make that work. They’ve looked at hydrogen and thought 'this is way too difficult; we can’t store enough hydrogen to give us the resilience that we need', so they’ve fallen on ammonia as the way to go.”
In 2023 Centrica and Mitsubishi Power Europe signed a Memorandum of Understanding to explore the development, construction, and operation of Europe's first-ever ammonia-fired power generation facility at Bord Gáis Energy's Whitegate Combined Cycle Gas Turbine (CCGT) power station in Cork, Ireland.
While Bord Gáis Energy would not comment on the outcome of the project, it did confirm that the gas turbine is not currently operating on ammonia.
Despite this potential setback, a future for green ammonia in the UK looks promising, with far fewer obstacles to overcome compared to hydrogen and a ready-made transportation and storage industry to tap into.
This is the second in a series of articles on emerging energy technologies. Read the first one here.
