The UK's First Geothermal Power Plant: All You Need to Know

The UK has activated its first deep geothermal power facility in Cornwall after an 18-year development period that cost £50m (US$63m), representing a modest yet noteworthy addition to the nation's renewable energy portfolio.

Located near Redruth, the United Downs plant is managed by Geothermal Engineering Ltd (GEL) and has taken nearly two decades to bring online.

Ryan Law, CEO of GEL, says, "To finally reach this point is exciting – and a bit of a relief."

Water is circulated through fractures in granite rock approximately 5 km underground, where temperatures approach 200 C. These geological characteristics are relatively uncommon across the UK.

Typically, descending 1 km below ground level results in temperatures increasing by around 20 C.

The granite beneath Cornwall retains heat more effectively, however, producing temperature increases of roughly 40 C per kilometre of depth.

After drilling, superheated water from the deepest point is pumped upward, generating steam that powers a turbine before the cooled water, reduced to approximately 50 C, is returned underground through the fault line for reheating.

Octopus Energy has purchased the electricity produced, which will be distributed through the National Grid to power more than 10,000 households.

Continuous generation and market potential

Geothermal energy differs from wind and solar power through its continuous operation, a characteristic Ryan emphasises as fundamental to its commercial case.

"Unlike other renewable sources like wind and solar we are constantly on, 24/7 electricity," he says, noting that the elimination of fuel costs removes the price volatility associated with gas.

Between 2018 and 2024, worldwide investment in deep geothermal electricity has increased by 80% year on year, partly driven by data centre energy requirements from companies including Google, Meta and Microsoft.

This market trend could warrant greater governmental attention, according to Geothermal UK, the industry's representative body.

Anne Murrell, who is Head of Geothermal UK, suggests the sector lacks adequate policy support.

"The challenges we have include investment and to unlock investment and increase investor confidence, we need a supportive government policy framework – geothermal needs to be recognised by government as a key part of our energy strategy," she explains.

Lithium extraction capabilities expand

The plant's ability to extract lithium could prove equally important to its power generation function.

Mineral-rich water extracted from the Porthtowan Fault Zone contains lithium carbonate, an essential component in rechargeable battery manufacturing.

The facility will initially produce approximately 100 tonnes of lithium each year, sufficient for 1,400 electric vehicles, though GEL indicates it intends to increase output to 18,000 tonnes annually within ten years, potentially supplying around 250,000 EVs per year.

The UK government provided £1.8m (US$2.27m) – half the total cost – towards the initial lithium extraction infrastructure.

China currently handles more than 60% of global lithium processing, meaning any substantial domestic production could represent a significant change in supply chain dependency for British battery producers.

Future development challenges

The British Geological Survey has characterised the plant as a "major step forward" for geothermal technology, whilst acknowledging that elevated drilling costs present barriers to widespread adoption.

Deep geothermal projects are also technically viable in Scotland and north-east England, although no approved schemes currently exist in either location.

GEL is developing two additional Cornwall sites, though one has received an initial planning refusal based on environmental concerns – a determination the company is contesting.

The £50m (US$63m) expenditure to date was financed through private investment and £15m (US$18.9m) from the European Development Fund, a funding source unavailable to UK projects since Brexit.

Whether the government's recent appointment of Lord Whitehead as the nation's first geothermal minister will deliver the policy infrastructure the sector requires remains uncertain.