New assessments from the British Geological Survey confirm that geothermal energy, a vast and largely untapped resource under the United Kingdom, could power the nation for centuries. But the cost of extraction and infrastructure remains a formidable barrier, raising urgent questions about the path to net zero by 2050.
Deep beneath the surface, the Earth’s core radiates heat a remnant of planetary formation and radioactive decay. In Britain, this heat is accessed through boreholes, typically reaching 2 to 5 kilometres, where rock temperatures can exceed 100°C. The heat is then used to generate electricity or warm homes via district heating networks. The potential is enormous: enough thermal energy to meet the country's heating demands for over 100 years, according to the BGS.
This is not speculative. The technology exists. In Cornwall, the United Downs Deep Geothermal Power project has already demonstrated that electricity can be generated from granite heated by radioactive decay. The site produces around 3 megawatts of power, enough for several thousand homes. But scaling this to national significance is a challenge measured in billions of pounds.
Drilling deep boreholes is expensive. A single geothermal well can cost £20 million. To make a meaningful contribution to the grid, hundreds would be required. The initial capital outlay is high, but the operational costs are low and the energy output is consistent, unlike wind or solar. Geothermal plants run 24/7, providing baseload power without the intermittency that plagues renewables. Furthermore, the land footprint is minimal; a plant can be tucked into a rural landscape with little visual intrusion.
The UK is not alone in this pursuit. Iceland and New Zealand already generate significant shares of their electricity from geothermal sources. The United States leads in installed capacity, with plants in California and Nevada. Britain lags because its geological conditions are less extreme. Most of the country sits on sedimentary basins or older granites, which require deeper drilling and therefore greater expense. Yet the prize is national energy security and a steady supply of low-carbon heat.
Geothermal energy is not a silver bullet. It should be seen as one component of a diverse energy mix. But its role in decarbonising heat is critical. Over 80 per cent of UK homes use gas boilers for heating, a significant source of emissions. Geothermal district heating networks could replace these, using the Earth’s heat to warm water circulated through underground pipes. Cities like Southampton already use this method, drawing hot water from a deep aquifer under the city centre.
The government’s current strategy focuses on offshore wind and nuclear power. These are vital, but they do not address heat directly. Geothermal can fill that gap. What is needed is a coordinated effort to de-risk exploration and fund pilot projects. The cost will be high, but so is the cost of inaction. As the climate clock ticks, every available tool must be deployed.
Let us be clear: the planet is warming because we burn fossil fuels. Geothermal offers a way to replace those fuels with a constant, natural heat flow. It is not a fix for everything, but it is a substantial part of the solution. The calme urgency of this moment demands that we invest in the infrastructure now, so that future generations can live in a stable climate.
The Earth beneath our feet is hot and waiting. The only question is whether we have the will to pay the price of admission.
