A wave of geothermal projects across the UK is being hailed as a potential game-changer for the nation's net-zero ambitions. But a familiar spectre looms: cost. As the Earth's internal heat offers a steady, low-carbon energy source, the question of economic viability remains the principal barrier to widespread adoption.
According to a new analysis from the British Geological Survey, the UK sits on a geothermal resource capable of meeting up to 20% of current electricity demand. Unlike wind or solar, geothermal provides baseload power, unaffected by weather or time of day. This dispatchability is its greatest asset in a grid increasingly reliant on intermittent renewables.
Dr. Helena Vance, Science & Climate Correspondent, reports from London: 'Geothermal is the quiet workhorse of the energy transition. It runs 24/7, with a capacity factor exceeding 90%. Compare that to coal, or even nuclear, and you see the appeal. The problem is the upfront cost.'
Drilling deep into the Earth's crust to access hot rocks or aquifers is expensive. A single well can cost millions, and the risk of dry holes or insufficient temperature gradients can deter investors. Early projects in Cornwall and the East Midlands have faced delays and budget overruns.
However, recent technological advances are shifting the calculus. Enhanced Geothermal Systems (EGS) allow developers to engineer reservoirs in hot, dry rock by fracturing it and circulating water. Pilots in the United States and Australia have shown promise, and the UK's own United Downs deep geothermal project in Cornwall is testing similar techniques.
The government has pledged £90 million for geothermal research, but that is a fraction of the £1.5 billion committed to carbon capture and storage or the billions for offshore wind. Critics argue that the policy framework is still too weak to attract private capital.
Professor Rebecca Lunn, an expert in geomechanics at the University of Strathclyde, told our correspondent: 'Geothermal heat could decarbonise entire cities through district heating networks. But for that to happen, we need a price on carbon that reflects the true cost of fossil fuels, and a clear regulatory pathway for drilling and heat extraction.'
The UK's net-zero target by 2050 requires a massive expansion of low-carbon energy. Solar and wind are growing rapidly, but they create a demand for storage and backup. Geothermal offers a complementary solution, particularly for heating, which accounts for half of the UK's energy consumption.
In Iceland, geothermal powers nearly all electricity and heating. But the geology is exceptionally favourable. The UK relies on deeper, more expensive resources. Yet as drilling technology improves and costs fall, experts believe a tipping point is within reach.
'We are not talking about a silver bullet,' Dr. Vance added. 'But in the portfolio of solutions we desperately need, geothermal is a powerful, proven tool. The question is whether we have the collective will to invest now for a stable climate later.'
The urgency is palpable. Each year of delay means more carbon locked into the atmosphere. Geothermal’s long lifespan – often 30 years or more – means early projects will pay decarbonisation dividends for decades.
The costs today may be high, but the cost of inaction is far higher. As the planet warms, the heat beneath our feet may prove to be not just a resource, but a lifeline.
