More than half of the UK’s electrical power was supplied by renewable energy on February 25 2026.
That consisted mainly of solar, wind and hydroelectric sources. The next day, a new source of electricity started feeding into the grid for the first time – geothermal power.
At a site near Redruth called United Downs, in Cornwall, a company called Geothermal Engineering Ltd has started producing geothermal electricity.
To generate power (electricity), this project is using two of the deepest wells ever drilled in the UK – down to three miles beneath the surface. A considerable feat of engineering.
To understand why the Cornish landscape is so suitable for geothermal power, imagine life on Earth roughly 300 million years ago, when magma from deep beneath the Earth’s surface cooled to formed large bodies of granite. This igneous rock with a crystalline structure contains small amounts of naturally radioactive elements, such as uranium, thorium and potassium.
Over a long geological timescale, these give off heat. Geologists call this a “granite‑hosted geothermal system”. Fractures throughout this granite provide pathways for fluids to flow. This is key to harnessing the thermal energy (heat) from within these rocks.
What the UK’s first geothermal power plant means for the nation’s electricity supply
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