A new report from the British Geological Survey (BGS) and the UK government confirms what geothermal advocates have long argued: the Earth's heat is an immense, largely untapped resource capable of supplying a significant fraction of Britain's energy needs. However, the study also delivers a stark reality check. To unlock this potential, deep drilling and upfront capital costs remain formidable. The message is one of Calm Urgency. We are not running out of time; we are running out of cheap carbon budgets. The inertia of the energy transition can feel like the slow creep of a glacier. But with emissions accumulating in the atmosphere at a rate of roughly 2 parts per million per year, the physical reality is that every gigawatt of fossil fuel generation we replace with a firm, low-carbon alternative like geothermal is a net gain for the planetary energy balance.
The geology is cooperative. The UK sits on a variety of geothermal resources, from shallow ground source heat pumps suitable for individual homes to deep, hot aquifer systems in sedimentary basins like the Cheshire or Wessex basins. Even deeper, engineered geothermal systems (EGS) could tap the hot, dry rocks beneath Cornwall and Weardale. Temperatures of 60 to 90 degrees Celsius are accessible at depths of 1 to 2 kilometres in several regions, ideal for district heating networks. Go deeper, around 4 to 5 kilometres, and temperatures exceed 150 degrees Celsius, sufficient for electricity generation. The total recoverable heat is estimated to be roughly 100 times the UK's annual heat demand. The resource is physically there.
Yet the cost picture is challenging. Drilling a single 5 km exploration well is a multi-million pound gamble with no guarantee of commercial flow. The UK currently has no operational geothermal power plants and only a handful of district heating schemes. Compare that to Iceland or Kenya, where geothermal provides a significant share of baseload power. The difference is geology but also policy. In those countries, geothermal development has been supported by risk mitigation schemes and long-term tariffs. The UK's Contracts for Difference scheme, successful for offshore wind, does not currently make provision for geothermal’s unique cost profile. The BGS report estimates levelised costs of electricity from deep geothermal at 15 to 25 pence per kilowatt-hour, versus roughly 5 pence for offshore wind today. That gap is a reflection of the technology's early stage.
But the analogy should be drawn to the early days of wind and solar. In 2010, offshore wind cost £140/MWh. Now it is below £50. As the report argues, the cost of geothermal will fall with deployment, learning by doing, and standardisation of drilling techniques. There are crossovers with the oil and gas sector. The skills, supply chains, and geophysical expertise exist in Aberdeen and the North Sea. That is a resource we should not leave stranded. The report's key recommendation is the creation of a Geothermal Development Corporation, a public body to de-risk early projects, acquire seismic data, and drill stratigraphic wells. It is a sensible, evidence-based proposal. The cost of not acting is the continued leakage of heat from our buildings at an efficiency that would be unacceptable in any other industrial process.
The climate does not care about our economic models. It only responds to the concentration of CO2 in the atmosphere. Geothermal offers firm, baseload power and heat with a minimal land footprint and no intermittency. It is a hedge against future gas price spikes and a tool for energy security. The study provides a roadmap. The path is clear. The physical reality is that the heat is there. The policy reality must now catch up.
