The Earth's internal heat represents a virtually limitless source of clean energy, yet tapping it remains prohibitively costly. New research led by UK scientists aims to change that, developing technologies to make geothermal power a mainstream option in the global energy mix.
Geothermal energy harnesses heat from the Earth's crust, typically by drilling wells into hot rock formations and using the resulting steam to drive turbines. Unlike solar or wind, it provides a constant baseload power, unaffected by weather or time of day. However, high upfront costs for drilling and exploration have limited its deployment to regions with naturally high geothermal gradients, such as Iceland, Kenya, and Indonesia.
The UK, despite lacking such favourable conditions, is now at the forefront of research into enhanced geothermal systems (EGS). These involve injecting water into hot, dry rock deep underground to create artificial reservoirs. This process requires advanced drilling techniques and precise engineering, but could unlock geothermal potential in many parts of the world. The British Geological Survey estimates that UK geothermal resources could meet the country's heating demand for over a century.
A new government-backed initiative, the UK Geothermal Energy Research Programme, has been awarded a coalition of universities and industry partners. The programme will focus on three key areas: reducing drilling costs through automation and better materials, improving reservoir creation with advanced imaging and modelling, and developing novel heat extraction methods that use supercritical carbon dioxide instead of water. The latter could double efficiency while also providing a use for captured CO2.
Dr Sarah Mitchell, lead researcher at the University of Bristol, says that making geothermal economically viable is a matter of physics and engineering, not discovery. We know the heat is there. The challenge is accessing it without breaking the bank. Our goal is to reduce the levelised cost of geothermal electricity to below $50 per MWh by 2030, making it competitive with fossil fuels.
The potential impact is enormous. A 2023 study from the International Renewable Energy Agency found that geothermal could provide up to 8% of global electricity by 2050, up from less than 1% today. But only if costs fall. The UK programme is one of several worldwide, including the US Department of Energy's Enhanced Geothermal Shot which aims to cut costs by 90% by 2035.
This is not about wishful thinking. The thermal gradient in the Earth's crust is a constant source of flux. Every kilometre you go down, the temperature rises. At a depth of 10km, you can easily reach 200°C, suitable for power generation. The question is whether we can drill that deep cheaply enough and manage the induced seismicity that sometimes accompanies EGS.
Advanced drilling technologies borrowed from oil and gas are already helping. For example, polycrystalline diamond compact bits can chew through hard granite faster than ever. Meanwhile, directional drilling allows multiple wells from a single pad, reducing surface footprint.
There is also progress in reservoir engineering. By cooling the rock with water, you create fractures where fluid flows. But if not managed carefully, this can cause small earthquakes, as seen in Basel, Switzerland and Pohang, South Korea. The UK programme includes a workstream on subsurface risk assessment, using machine learning to predict optimal injection rates.
The environmental calculus is compelling. Geothermal plants emit negligible greenhouse gases, have a small land footprint and can operate for decades with minimal maintenance. Unlike nuclear, they produce no long-lived waste. Unlike hydro, they do not displace communities or ecosystems.
But the energy transition is not a smorgasbord. There is a physics constraint. We cannot afford to ignore any carbon-free source that is abundant and reliable. As Dr Mitchell puts it: The cheapest form of power is often the one you do not build, but that is not always possible. Geothermal may be expensive now, but with research it could become a backbone of our future grid.
The UK government has committed to reducing greenhouse gas emissions to net zero by 2050. Achieving this will require a tripling of clean electricity generation. Geothermal could provide around 15% of the required capacity. That is a substantial slice of the pie.
This is not a pipe dream. It is a hard rock reality. The funding is there. The science is sound. The only missing piece is the determination to see it through.
