The United Kingdom is doubling down on geothermal energy, a resource long overshadowed by wind and solar. A new government initiative will allocate £100 million to deep geothermal projects across Cornwall, Yorkshire, and the Midlands. The goal: to tap into the Earth's internal heat, a near-limitless power source that runs 24/7, unlike its intermittent renewable cousins.
Dr. Helena Vance, climate correspondant: Geothermal energy exploits the temperature gradient between the surface and the deep crust. For every kilometre drilled, the rock gets about 30 degrees Celsius hotter. At depths of 4 to 5 kilometres, we can reach 150 to 200 degrees Celsius – hot enough to drive turbines or heat entire districts.
The UK sits on moderate geothermal potential. The granite batholiths of Cornwall, for example, contain natural radioactive decay that warms the surrounding rock. Enhanced geothermal systems, which crack hot rock and circulate water, could extract this heat. However, the upfront costs are brutal: drilling a single well can exceed £10 million. The new funding aims to de-risk exploration and attract private capital.
Proponents argue that geothermal provides baseload power without the intermittency of wind or solar. A single deep geothermal plant can run for decades with minimal fuel cost. Moreover, the technology has a remarkably small land footprint. A 50-megawatt plant occupies roughly the same area as a football pitch, compared to hundreds of acres for a solar farm of equal capacity.
But challenges remain. Drilling failure rates are high, and the best spots are often in protected landscapes. There is also the risk of induced seismicity – small earthquakes caused by fracturing rock. And the energy output per well is modest; to match a single nuclear reactor, you would need dozens of geothermal plants.
Still, the logic of geothermal is compelling. The Earth's crust contains 50,000 times more energy than all the world's oil and gas reserves. In places like Iceland, geothermal provides 25% of national electricity and 90% of heating. The UK could cover at least 10% of its heating demand with shallow ground-source heat pumps alone, but deep geothermal remains a longer shot.
Technological solutions are advancing. Horizontal drilling and hydraulic fracturing, borrowed from oil and gas, can boost well productivity. Closed-loop systems that circulate a working fluid through deep fractures avoid water depletion. And new materials like high-temperature alloys allow drilling deeper and hotter.
The government's plan includes a 'Geothermal Ready' certification for housing developments, ensuring new builds can easily connect to future district heating networks. This is a piece of the puzzle: even if deep geothermal electricity is slow to scale, ground-source heat pumps for individual homes can cut gas use by 70%.
But there is a sobering fact. Heat pumps, whether ground-source or air-source, require electricity to run. If that electricity comes from gas or coal, the carbon savings diminish. The UK's grid is decarbonising fast, but not fast enough. A ground-source heat pump installed today might be only 60% cleaner than a gas boiler by 2030, depending on grid mix.
This is where the 'calm urgency' must guide policy. Geothermal is not a silver bullet. It is an expensive, complex tool in a toolbox that must also include efficiency, solar, wind, nuclear, and storage. But every joule from the Earth's core avoids a joule from fossil fuels. And the time for half-measures is over.
As I write this, the ground beneath our feet is warming. The radioactive decay of uranium, thorium, and potassium in the crust adds a steady 40 terawatts of heat flow to the surface. That is larger than global energy demand. We just have to get to it.
The revolution will be drilled, not born.
