British homes could soon be heated with geothermal energy found thousands of metres underground

Apr 11, 2023

Much is made of the debate over whether heat pumps or hydrogen are the future of home heating, yet by 2050 more than one in five homes could get their warmth and hot water from an entirely different technology – geothermal energy.

"I’ll stick my neck out and say that by 2050 I’d hope we’d be well above 20 per cent of homes heated by geothermal," Professor Jon Gluyas, an expert in geo-energy at Durham University, told i.

Deriving energy from geothermal is a relatively straightforward idea. In many parts of Britain, around two to four kilometres below the ground, there is hot water flowing through rocks. If pipes are drilled deep enough, the heat from this water can be harnessed.

The concept has been around for more than a century but was traditionally associated with highly volcanic countries such as Iceland. In the past two decades, however, several European countries have proved that it can be done even in the least volcanic of places.

In October last year, Parliament's Environmental Audit Committee heard that the UK had enough geothermal potential to support all of its heating needs. Nevertheless, the UK barely has any installed geothermal.

"We’re absolutely miles behind Europe," said Professor Gluyas.

A new report by the MP Kiaran Mullan, commissioned by Boris Johnson when he was prime minister and published on Friday argues that given the right incentives the UK could readily tap into its geothermal potential to provide heat and hot water to millions of homes.

The report has been welcomed by Rishi Sunak, and the Energy Secretary, Grant Shapps, while the technology has the backing of environmental groups including Greenpeace.

Doug Parr, Greenpeace UK's policy director, told i: If there's the capability to harness the earth's heat here in the UK, it absolutely should become part of our clean and renewable energy system – providing jobs, energy security and zero emission power.

"We need to emulate the successes we’ve seen in off-shore wind, and a similar guaranteed tariff-based system could help accelerate its roll-out."

The Government announced that it was giving £22m to the Langarth Garden Village geothermal project in Cornwall. This, however, was part of an ad hoc grants system.

Dr Mullan is calling for the Government to put in place a guaranteed price system, similar to that which was put in place for the wind and solar sectors to help them get established.

His report estimates a guaranteed price of £50 to £55 per megawatt hour would be needed for the industry to take off. That's around £10 less than the average price of energy over the last decade.

While it's more expensive than solar and wind, geothermal provides stable and continuous power meaning it could command a premium. The tariff agreed for Hinkley Point C nuclear reactor is more than £90 per megawatt hour.

"There are lots of plans where people just need a bit of security to put the money on the line. So I think the second there was any kind of tariff guarantee, I think you’d very quickly see plans moving forward all over the place," Dr Mullan told i.

Dr Mullan's report also found that the areas with the best potential for geothermal energy, such as around his own constituency in Crewe and Nantwich, often overlapped with areas targetted by the Government's levelling up agenda.

The initial focus for geothermal would likely be on large institutions and businesses, such as hospitals, followed by new housing developments, according to Dr Mullan. Professor Gluyas said, however, that it would eventually be feasible to bring it to existing developments, as was done with the gas network.

"When it comes to new build development, the costs are trivial because it's like putting in your sewage pipes or your sewage or your freshwater," he said.

Historically, very high-grade geothermal energy has been used in power plants to generate electricity. In the UK, however, it's likely to take the form of district heating systems where a centralised heat exchange taps into warmth from deep below the ground and pumps hot water around the neighbourhood.

Each home would then have its own small heat exchanger, similar in size and shape to a boiler, which would heat water for radiators, underfloor heating and hot water.

Unlike fracking, the process does not involve pumping chemicals into the wells or fracturing the rock which can lead to seismic activity, but resembles conventional oil drilling.

In some cases, rather than drill deep for the water, the heat can be extracted from flooded former coal mines. These could also be used to store solar energy for use overnight. Such a project is already underway at Seaham Garden Village near Sunderland.

Since the UK has not already embraced the technology, scaling it up could prove difficult due to a lack of existing expertise and supply chains. Professor Gluyas, however, told i that Britain's North Sea oil and gas workers and business would be well suited to the job, given some retraining.

That sentiment was echoed by Dr Parr, who called it "an opportunity to re-use the skills the workers possess, and so help create a fair transition to cleaner energy."