Cornwall 'hot rocks' firm claims breakthrough deal

Two wells have been drilled into granite below the United Downs site

A geothermal power plant will supply the National Grid with electricity in what is thought to be the first deal of its type in the UK.

The deal between Geothermal Engineering Limited (GEL) and Ecotricity will power 10,000 homes, said GEL.

The £20m United Downs project, near Redruth in Cornwall, powers turbines with steam created from hot water found deep under the earth's surface.

There are also plans to power a rum distillery on the site.

Drilling began two years ago with two wells 2.8 miles (4.5km) and 1.5 miles (2.5km) into the granite below where the temperature is up to 200C (390F).

Just over three megawatts will be supplied to the grid next year said GEL, with an aim to get planning permission for future sites in Cornwall and raise the output to 20 megawatts.

A drill bit which has been used to find heated water below the surface

Michael Liebreich, visiting professor at Imperial College London and advisor to the Board of Trade, said that the "extremely rare geology" of the site meant that "this particular approach is not scaleable in the UK".

He said: "I congratulate them, but it can never be more than a local solution."

Ryan Law, GEL's managing director, said United Downs "was always a demonstration to prove the concept for other sites".

And he insisted that geothermal heat and power was "available right the way across the UK" and "just depends how deep the wells are and what techniques are used".

Dale Vince, chief executive of Ecotricity, said geothermal was a "really exciting form of energy that is, as yet untapped in the UK" and "has a big role to play in our plans to decarbonise the country".