Drilling to start at the UK's first deep geothermal electricity plant

  • Geothermal energy refers to heat from below the Earth's surface which can be used to produce energy.
  • At the U.K. site, two "deep geothermal wells" will be drilled into granite rock, with the deepest reaching 4.5 kilometers.
The plant is located in Cornwall and will provide enough energy to power 3,000 homes. 
Geothermal Engineering Limited
The plant is located in Cornwall and will provide enough energy to power 3,000 homes. 

Drilling at the U.K.'s first deep geothermal electricity plant is to start this week. Located at the United Downs Industrial Estate in Cornwall, southwest England, the plant will provide enough energy to power 3,000 homes, according to Geothermal Engineering Ltd (GEL).

Described by the U.S. Department of Energy as a "vital, clean energy resource," geothermal energy refers to heat from below the Earth's surface which can be used to produce renewable energy. The DOE adds that geothermal energy "supplies renewable power around the clock" but emits little or no greenhouse gases.

Last year, geothermal power plants in the U.S. generated around 16 billion kilowatt hours, according to the U.S. Energy Information Administration. This represents 0.4 percent of utility-scale electricity generation in the U.S.

At the Cornwall site, two "deep geothermal wells" will be drilled into granite rock, with the deepest reaching 4.5 kilometers below the surface.

Water from the deepest well will be pumped at a temperature of around 190 degrees Celsius. It will then be fed through a heat exchanger at the surface before being re-injected into the ground to gather extra heat from the rocks in a "continuous cycle." This heat will be turned into electricity and sent to the National Grid.

"The largely untapped geothermal resources in the U.K. have the potential to deliver up to 20 percent of the U.K.'s electricity and heat energy needs in a reliable and sustainable way," Ryan Law, GEL's managing director, said in a statement Tuesday.

"As coal-fired power stations are switched off, the need for renewable, baseload energy can only increase," Law added.

The demonstration project has benefited from around £18 million ($23.54 million) in funding, with £10.6 million alone coming from the European Regional Development Fund. Partners for the project include the British Geological Survey, GeoScience Ltd., and the University of Plymouth Sustainable Earth Institute.

Engineering consultancy Arup has signed a deal to buy "renewable energy guarantee of origin" certificates from GEL, which amount to 9,000 megawatt hours per year. GEL said the agreement would enable Arup to supply zero carbon electricity to all of its U.K. offices.