The near-infinite energy source that could win Britain’s net zero race
Matt Oliver
6 min read
A geothermal plant started providing energy for the Eden Project this week - Matt Greenwell/PGB
The crumbling pumping stations dotting the landscape of the Gwennap district are a visible reminder of the area’s pivotal role in the long-gone Cornish mining boom.
During the Industrial Revolution, the huge output of the district’s copper and tin mines, not far from Redruth, helped garner it a reputation as “richest square mile on earth”.
Today, businesses are digging deep in search of a different sort of treasure: energy.
It does this by pumping out water warmed to 200 degrees celsius to power a heat exchanger, before being pumped back down again to a shallower well.
From next year, the scheme will provide heat and power to 3,800 homes near Truro, as well as the Royal Cornwall Hospital, local schools and a leisure centre, after receiving £22m in funding from the Government.
Ryan Law, chief executive of Geothermal Engineering, believes it can serve as a template for similar schemes across Britain, at a time when policymakers are exploring what role the technology can play in the race to “net zero”.
It comes as another geothermal plant has also begun generating energy this week for the Eden Project near St Blazey, roughly 20 miles from United Downs.
“Geothermal has really become a hot topic in the last two years,” says Law. “We chose Cornwall because it’s the hottest spot in the UK – and United Downs is sort of the trailblazer.”
Although it can be used to generate power, like wind and solar farms, Law believes geothermal’s real promise lies in heating buildings, providing a viable replacement for gas-fired boilers. About one fifth of the UK’s carbon emissions come from keeping buildings warm, with carbon-free solutions such as electric heat pumps currently too expensive for many households.
The rock underneath Cornwall is hot because it contains small amounts of the radioactive elements uranium, potassium and thorium, Law explains, which over a large area creates “quite a lot of heat”.
This means it can be available all year-round, barring short periods needed for power plant maintenance.
“It is just a massive resource,” adds Law. “It’s like taking buckets out of the ocean. I wouldn’t say it’s infinite, but it is huge.
“And unlike wind and solar, it just keeps going once you switch it on.”
However, he argues geothermal will not compete directly with those renewables, “because it’s a different form of energy”.
“Wind and solar are pretty good at producing large scale electricity, but where geothermal fits into the mix is with this sort of elephant in the room of how we will meet our zero carbon heating targets.
“I see these projects as being installed in areas that need power and heat, for example big swathes of urban areas, because it’s that combination which could see geothermal have a big impact on the UK.”
The company already has two more projects, in Penhallow and Manhay, that have been granted planning permission. They will be even bigger, with Geothermal Engineering aiming to win support for the schemes through the Government’s contracts for difference auction this summer.
The company is seeking about £119 per megawatt hour of electricity generated, although Law says he believes the price for future plants could eventually be two thirds lower based on other projects in operation in the US today.
He also reckons that the cost of drilling the two wells at United Downs – about £24m – can be halved.
At the moment, less than 1pc of the country’s energy is generated through geothermal schemes.
But the technology has been pioneered and proven successful elsewhere, including in Iceland, the US, Italy, France and Germany.
In Iceland, 30pc of electricity is now generated from geothermal sources. The resulting power is so cheap it is used to heat greenhouses growing bananas domestically and the freezing country has become a magnet for energy-intensive aluminium producers.
Munich has also pursued geothermal in a big way. Regional energy company Stadtwerke Munich (SWM) now operates six geothermal plants in and around the German city, providing heat and electricity for hundreds of thousands of residents and facilities.
Law claims the example of Munich is proof that the technology can be deployed in densely populated areas with relatively little disruption, despite the need for rigs to drill the wells initially.
In Britain, the most promising areas for development after Cornwall include parts of the North West such as Manchester and swathes of Yorkshire including Hull.
The UK Government is preparing to publish a white paper in the coming weeks that could set out the potential for geothermal energy and where the best opportunities are.
Geothermal energy has proved highly successful in countries such as Iceland, where 30pc of electricity is now generated from geothermal sources - LANDSVIRKJUN/AFP via Getty Images
However, the UK currently lacks a specific regulatory regime for geothermal, according to a House of Commons Library report, and both planning and grid connection delays pose challenges.
The Eden Project scheme, for example, could potentially export some power to the grid but has been told it cannot be connected until 2036 at the earliest.
“We would love to turn it into electricity. But it’s a nightmare,” Gus Grand, the boss of Eden Geothermal, told the Financial Times.
Geothermal Engineering’s Law says a key test for the industry will be whether his company’s projects - and others - win funding from a government-run energy auction this summer. There is a specific pot of money earmarked for “developing technologies”.
This will underpin “substantial further investment” from private sources, he says.
Another emerging use of geothermal technology, being developed by his company and others including Cornish Lithium, is the extraction of underground minerals using liquid solutions. This allows resources like lithium – a key material used to make batteries – to be extracted with minimal environmental disruption and zero carbon emissions.
At the same time, as in Iceland, the technology could open up new frontiers for British agriculture. Powering greenhouses would allow British farmers to grow produce from hotter climes here without incurring ruinous energy costs.
“We’re at an inflection point now,” says Law. “I really think we’re at the tip of the iceberg and it’s just a question of maturity.
“If you remember with offshore wind, people said it would never work because it was too expensive.
