A geothermal power plant, using hot rocks below the surface to generate heat and energy, has been given the go-ahead in Cornwall.
A 51m (167ft) high rig at a St Day industrial estate will drill 5,000m (16,400ft) into the earth's crust where the rocks sit at about 170C.
Water pumped down will return as hot water and steam to generate power.
The £40m plant could produce enough energy to heat 20 schools and produce power for 20,000 homes.
Drilling is due to start in 2011, with power production starting in 2013.
Ryan Law, managing director of Geothermal Engineering, said: "Cornwall has very hot granites and we believe it has significant potential.
"It could generate 1GW of electricity, about the same as one big coal-fired power station."
Each plant has a 25-year lifespan before the rocks cool.
The company was awarded £1.5m in funding by the Department of Energy and Climate Change in 2009.