Never mind the gas crisis – beneath our feet lies enough free heat to keep the UK warm not just this winter, but every winter for decades to come.
That is according to UK members of parliament on the Environmental Audit Committee (EAC) on 19 October claiming that there is enough geothermal energy in the UK to meet the country’s annual heating demand for at least a century.
“The evidence received by the Committee was clear and consistent: the UK has significant geothermal resources which can contribute to both the UK’s energy security and its transition to net zero,” wrote EAC chair Philip Dunne. “The quantity of heat potentially accessible has been estimated between 100% and 200% of the UK’s annual heating demand.”
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Given such huge resources, the EAC argues that the government should be doing much more to bring geothermal projects to fruition – particularly in the face of spiralling gas prices. But can the UK really ditch gas boilers completely and heat all its homes with warmth from underground?
Geothermal energy, which involves extracting the heat from Earth and using it for heating and electricity, currently delivers less than 0.3 per cent of the UK’s annual heat demand.
Huge potential
. But figuring out exactly how much of the UK could run on geothermal energy is less straightforward.
The most comprehensive study to date on the UK’s geothermal resources is more than 40 years old. The paper, paid for by the Department for Energy and the European Union, concluded that there is at least 200 years’ worth of heating and hot water in sedimentary basins around the UK.
Later studies have made slightly more conservative estimates. A by at Durham University, UK, and his colleagues, , suggests that geothermal energy resources in the UK are sufficient to deliver about 100 years of heat supply for the entire UK.
They could also provide the equivalent of 85 per cent of Scotland’s and 9 per cent of England’s current electricity demand, it added.
“If we simply abstracted water and didn’t put more back in the ground to warm up again, we nominally could supply the heating demand to the UK for 100 years,” says Gluyas. “That is just eye-watering.”
So the EAC is in the right ball park when it talks about the potential heat under the feet of those in the UK. But translating that potential into warm homes over winter is less straightforward, says Gluyas.
“The next question is could you get at it and could you supply it to where people live and work,” he says. “That’s when it gets a little more difficult.”
Geologists know very little about the deep geology of the UK, particularly when it comes to predicting temperature and water flow, essential details for scoping out potential geothermal projects.
This means there is huge uncertainty around the amount of heat available from the UK’s deep geothermal resources, which extract heat from up to 6.5 kilometres underground, says at the British Geological Survey.
“We don’t have any wells that go to that depth and have explored what the actual temperatures are and what the water flow rate is,” she says. “So it’s a theoretical value.”
Expensive process
In many cases, developers need to drill new boreholes to test the geothermal potential of a site, a very expensive process, particularly when there is no gold rush of oil waiting at the bottom of the well.
The other part of the problem is geography. Across the UK – particularly in Cornwall, north-east England and southern England – there are hotspots of heat. Geothermal developers need to match these hotspots with demand for heating, says Abesser. “Heat doesn’t travel that well, so you can only use that resource when you have cities or a big heat demand nearby.”
Against the odds, some developers are making it work. When it opens in Cornwall next year, the . The site will generate power for the national grid as well as low-carbon heating for a local rum distillery and a new housing estate.
But getting the scheme off the ground took more than a decade, including five years to secure funding, says Ryan Law, founder of Geothermal Engineering Ltd, the firm behind the project.
He agrees with MPs that the UK government needs to step in to incentivise investment in geothermal. That could include the government setting long-term deployment targets, sharing the financial risk of drilling exploratory wells or guaranteeing that geothermal schemes could win government power supply contracts.
Heating all of the UK’s homes with geothermal would be a stretch, but it is clear that the country’s resources are considerable. Spiralling gas prices might just be the push politicians need to finally tap these reserves, Law hopes.
“In the UK particularly, we’ve been a bit lazy because our cost of gas has been very low, and it’s only now that there has started to be an economic driver to do this, instead of just a carbon driver,” he says. “It’s just starting to gain momentum.”
