The long–awaited solution to Britain’s climate crisis could finally be here.
Scientists have identified eight potential sites for the ‘direct air capture machines’ (DAC), which would extract CO2 from the air and turn it to stone.
The eight promising locations include Antrim in Northern Ireland, Borrowdale in the Lake District and the Isle of Mull in Scotland.
According to the experts, the sites have a wealth of volcanic rock underground that would react with CO2 and turn the greenhouse gas into a solid form.
Combined, the eight sites could safely store more than three billion tonnes of CO2 – equivalent to around 45 years’ worth of the UK’s industrial emissions.
Researchers think the UK offers ‘significant CO2 storage potential’ as one weapon against climate change.
Study leader Professor Gilfillan, geochemist at the University of Edinburgh, said ‘we urgently need carbon storage’ solutions like this to reduce CO2 in the atmosphere.
‘We would suggest that these potential storage site should be part of the consideration for the siting of any future DAC sites in the UK, especially for the early trials,’ he told the Daily Mail.
‘CO2 mineralisation offers the UK more room to store CO2, adding to the huge resource offered by the rocks beneath the North Sea.’
The researchers analysed the geology, chemistry and volume of reactive rocks from 21 sites around the UK, mostly in the north.
They calculated how much CO2 each rock group could hold by combining the surface area and thickness of the rocks with details of their chemistry.
In all, eight made the final selection due to their suitability, with Antrim Plateau basalts in Northern Ireland at the very top of the list.
Mid–range estimates found that the Antrim Plateau offered the largest storage potential of 1,400 million tonnes of CO2.
Next were Borrowdale in the Lake District and Skye Lava Group in Scotland’s Inner Hebrides, estimated to offer 700 million tonnes and 600 million tonnes of storage, respectively.
Rounding out the top eight were Shetland Ophiolite Suite (Shetland Islands), the Isle of Mull (eastern Scotland), Isle of Rum intrusives (Inner Hebrides), Ballentrae Ophiolite Complex (southwest Scotland) and Lizard ophiolite (Cornwall, England).
At these sites, companies could potentially be licensed to build ‘carbon–sucking’ machines similar to those from Zurich–based firm Climeworks, which has already installed machines in Switzerland and Iceland.
These machines comprise a stack of huge steel fans that draw in CO2, dissolve the gas in water, and pump it deep underground.
The researchers analysed the geology, chemistry and volume of reactive rocks from 21 sites around the UK, but eight were deemed suitable
Carbon–sucking machines comprise a stack of huge steel fans that draw in CO2, dissolve the gas in water, and pump it deep underground. Over a few years, the CO2 turns into solid form
Over a few years, the CO2 turns into a solid mineral called carbonate when it touches certain rocks that are rich in metals like iron, calcium and magnesium – a process known as carbon mineralisation.
In essence, the method stores CO2 safely as a solid underground, reducing the amount of the greenhouse gas that reaches the atmosphere.
According to the study authors, rocks in these eight areas are rich in calcium and magnesium that readily bind with CO2 to form the solid carbonate – suggesting they’d be ideal locations.
‘Mineralisation of CO2 in reactive formations has the potential to enable safe, scalable, permanent CO2 storage at an attainable cost,’ they write in their paper, published in Earth Science, Systems and Society.
‘Safe and permanent storage of CO2 will be required to limit global warming to 1.5–2°C above pre–industrial levels.’
According to Professor Gilfillan, the next steps are to assess ‘effective porosity and rock reactivity’ in detail at each site.
‘This will tell us how efficiently each formation can mineralise CO2 in practice,’ he said.
Pilot projects in Iceland and the US have already shown that CO2 mineralises rapidly and securely and now the UK government is eyeing the technology.
It has already begun negotiations with Climeworks to set up an equivalent machine, called Silver Birch, which would be constructed in Stanlow near Liverpool.
Capturing CO2 and storing it underground reduces the amount of the greenhouse gas in the atmosphere and potentially offers one solution to global warming
However, critics warn that carbon capture and storage does not tackle the root cause of global warming – the release of CO2 from burning of fossil fuels.
Environmental organisation Greenpeace has called carbon capture a ‘scam’ that relies on money from ‘the public purse’.
Stuart Haszeldine, a professor of carbon capture and storage at the University of Edinburgh who was not involved in this new study, has called CCS projects ‘a deal with the devil’.
‘Storage of two or five million tons of CO2 per year should not become a policy excuse to release additional tens or hundreds of million tons of CO2 from development of new oil and gas extraction through many tens of new licences,’ Professor Haszeldine said.
Other concerns are that the process itself is very energy intensive and so could drive up energy prices.
The technology also has safety concerns – after being stored underground, some experts fear that CO2 could leak and taint nearby water supplies or create tremors caused by the build–up of pressure underground.
