Borehole dug 5,275 metres deep will tap into geothermal energy from rocks to heat 3,800 homes in Cornwall

An artists impression of how the power plant will look when fully developed with a surrounding forestry with a driveway and multiple energy sources and pumps
This geothermal project is one of seven which have received approval for funding by the government as part of the Green Heat Network Fund with this being an artists impression of how the finished project will look (Image credit: Exergy International)

A new government project to encourage renewable energy has funded the UK’s first deep geothermal heat network that will gather energy by digging 5,275 metres to harness energy from granite rocks.

Located near Truro in Cornwall, Langarth Deep Geothermal Heat Network is a £22million project and one of seven sharing a £91 million grant under the Green Heat Network Fund (GHNF).

Energy and sustainability experts claim renewable energy like ground and air source heat pumps, solar, wind, geothermal, and tidal can help the UK achieve its goal of net zero emissions by 2050.

What is geothermal energy?

Geothermal energy is a form of renewable energy derived from heat from the earth. The energy is harnessed from reservoirs of hot water that already exist or can be human-made.

Karl Farrow, the CEO of CeraPhi, a British geothermal energy company founded in 2020 by four ex-oil and gas professionals, says it is far more viable than gas and oil.

“Every country should have a right to be energy, food, and water independent and I think every country can be" he claims. “Deep geothermal is available everywhere, it’s basically heat escaping from out of the ground from earth’s big battery. We’re sitting on 6,000 degrees of temperature from the centre of the earth trying to radiate out.”

Geothermal, therefore, provides another alternative to fossil fuels for energy which explains the government's funding for projects such as this and the Boiler Upgrade Scheme which gives grants to UK households to swap their gas boilers for heat pumps.

Geothermal project gathers heat from granite rocks more than 5,000 metres underground

Cornwall Council’s Langarth Deep Geothermal Heat Network will use a borehole drilled to a depth of 5,275m to tap into heat from granite rocks beneath the United Downs Industrial Site.

The geothermal energy will be distributed around the region to provide hot water and heating for around 3,800 homes and public facilities, similar to how a ground source heat pump works.

The British Geological Survey says the granites of south-west England have the highest subsurface heat flow of any rocks in the UK, which leads to the highest temperatures at depth.

“The Green Heat Network Fund award will contribute to the success of Langarth Garden Village and Cornwall Council’s mission to work with communities for a carbon neutral Cornwall, where everyone can start well, live well and age well," said Councillor David Harris of the Cornwall Council Portfolio Holder for Resources.

He added the heat network "will be a concrete example to others around the United Kingdom" of how local and national governments working together with the private sector "can make a real difference to people’s lives.”

The borehole drill going into ground which is a large drill stood high in the air with the surrounding development site and workers

The geothermal project in Cornwall is one of seven projects which have received approval as part of a government scheme to encourage net zero heating networks (Image credit: Exergy International)

What is the Green Heat Network Fund?

The Green Heat Network Fund (GHNF) is a three-year, £288 million capital grant fund that opened to applicants in March 2022. The government scheme aims to provide support to organisations in the public, private, and third sectors in England to support the development of low and zero carbon heat and cooling networks.

A GHNF document claims that heat networks will be vital to making net zero a reality in the UK. It adds: “They are a proven, cost-effective way of providing reliable, efficient, low carbon heat at a fair price to consumers, while supporting local regeneration.

“The Committee on Climate Change has estimated that around 18 per cent of UK heat will need to come from heat networks by 2050 if the UK is to meet its carbon targets cost effectively.”

Seven other GHNF schemes have also been approved, with notable projects including £20 million heat pump grant for a large air source heat pump (ASHP). This  will go towards air source heat pump installation, which will be the largest one of its kind in the UK.

Sam Webb

Sam is based in Coventry and has been a news reporter for nearly 20 years. His work has featured in the Mirror, The Sun, MailOnline, the Independent, and news outlets throughout the world.  As a copywriter, he has written for clients as diverse as Saint-Gobain, Michelin, Halfords Autocentre, Great British Heating, and Irwin Industrial Tools. During the pandemic, he converted a van into a mini-camper and is currently planning to convert his shed into an office and Star Wars shrine.