Drilling rigs are appearing across the British countryside, not for oil or gas, but for heat. Geothermal energy, the heat trapped within the Earth's crust, is moving from fringe project to national priority. The UK government this week announced an additional £31 million in funding for deep geothermal exploration, part of a broader push to decarbonise heating, which accounts for roughly a third of the nation's emissions.
The principle is simple: drill two to five kilometres down, circulate water through hot rocks, and bring the heat back up. Unlike solar or wind, geothermal provides continuous, baseload power and heat, independent of weather. But the engineering is brutal. Temperatures at those depths can exceed 200°C, and the granite and sandstone layers are abrasive. A single well can cost £10 million to £20 million, with no guarantee of adequate flow rate or temperature.
Geothermal’s potential in the UK is significant but geologically constrained. The hottest rocks lie beneath Cornwall, where granite bodies radiate heat from radioactive decay. The Cornwall Geothermal District Heat Network, supported by new funding, aims to supply heat to thousands of homes by 2028. Further north, the Cheshire Basin and East Yorkshire hold promising sedimentary aquifers. Yet only a handful of deep geothermal projects have been built since the 1980s, when a plant near Camborne was abandoned after technical failures.
Why now? The energy crisis and net zero deadlines have shifted the economics. Electricity prices are high, and the government’s Contracts for Difference scheme now includes geothermal power. Dr. Alice Bunn, director of the UK Geoenergy Observatory, told me: “We know the heat is there. The challenge is proving we can extract it reliably and cost-effectively. This is infrastructure, not a magic bullet.”
Geothermal also faces competition from heat pumps, which are cheaper and quicker to deploy. But heat pumps require electricity, which geothermal could supply. A combined system: geothermal power for the grid, geothermal heat for district networks, could displace gas in cities. The Eden Project in Cornwall already runs partly on geothermal heat from a 5 km well, cutting its gas use by 80%.
The environmental impact is low: minimal land use, no combustion, and small carbon footprint. But the upfront cost is immense. A 50 MW geothermal plant costs around £200 million, comparable to offshore wind but with longer construction times. Investors want government guarantees against dry holes. The new funding covers exploration risks, but commercialisation remains years away.
Even so, the logic is compelling. The UK has enough geothermal heat beneath its feet to supply the country’s heating needs for centuries, if we can tap it. The Earth’s core is as hot as the Sun’s surface, and that heat is slowly migrating upward. We just need to reach it. The question is whether we have the patience and capital to do so before the climate clock runs out.
As I write this, the drilling rigs are turning. Raw energy, waiting. And costing a fortune.
