Case study: Mount Wellington Mine, Truro

Kensa Heat Pumps’ manufacturing facility is heated using a ground source heat pump and mine water in a disused mine shaft beneath the site.

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Mount Wellington Mine in Chacewater, Cornwall, was the last deep tin mine ever to be built in the world. From a three-man operation started by the Wellington brothers in the 1920s, to what was the most advanced tin mine in the world in the 1970s, the site’s chequered past spans over 100 years.

After closing its doors on the mining operation in 1991, the site was subsequently acquired by Richard Freeborn of Mount Wellington Mine Ltd in 2007. As opposed to demolishing the existing buildings, he was granted planning consent to create the UKs first privately funded renewable energy business park, spearheaded by the relocation of Kensa Heat Pumps in 2007, which was co-founded by Richard Freeborn and fellow engineer Guy Cashmore in 1999.

Practicing what he preached, Richard chose to use a Kensa ground source heat pump to heat the Kensa manufacturing facility. With a wealth of water available in the mine shafts below, a sustainable new lease of purpose was granted to the disused mine workings.

The granite rocks deep beneath Cornwall are enriched in natural radioactive isotopes, including those of uranium. The energy from the decay of these radiogenic elements is dissipated as heat, which is why Cornwall was the epicentre of exploration of the Hot Rocks Project as a source of geothermal energy.

The project at Mount Wellington Mine is the first of three of Cornwall’s four large modern tin mines exploiting the heat found in their mine shafts to heat the converted mine buildings for commercial use. Nearby sister mine Wheal Jane and Geevor at Pendeen are planning to follow suit.

Geevor’s Chairman Bill Lakin explained the new idea:

Any miner will tell you just how hot it is down a Cornish tin mine. Kensa has pioneered a simple and robust way to harness this heat energy using a ground source heat pump. A large quantity of special plastic pipe – called a geothermal array – is lowered into the mineshaft, and a mixture of water and antifreeze is pumped down from the heat pump. What returns to the surface is warm water at between 12 and 20 deg C, which the heat pump then upgrades to a more useable 35 to 40 deg C for use in underfloor heating.

Mark Giddings, Manager at Wheal Jane, is now planning to use the new technology to heat some of their planned new buildings.

Our subsidiary Carnon Contracting will be putting the geothermal arrays into one of our old shafts for us. They can also offer to install this technology to heat all the new buildings in the CPR Regeneration area, using the extensive local mine workings as a heat source. So often, old mines are seen as a problem whereas in fact they hold the key to reducing our dependence on fossil fuels – there is a source of renewable energy right under our feet!

Richard Freeborn, the owner of Mount Wellington Mine and founder of Kensa Heat Pumps confirms:

This is the first building in Europe to use heat from the decay of radioactive isotopes, and it is working very well indeed. The heat energy from the mine is 100% renewable. The geothermal arrays have no servicing or maintenance, and a predicated life of over 100 years. The heat pumps are running at an incredible efficiency, thanks both to the warmth of the mine, and the very high standards of insulation in our manufacturing building.

Since acquiring the site investment of over £4m, Mount Wellington Mine has attracted a range of tenants working on renewable technologies including offshore wind and solar thermal, culminating in an official opening in 2012 of the Mount Wellington Mine Renewable Energy Park.

In a speech given by Sir Tim Smit during the celebrations, Mr Smit remarked:

I truly admire Richard for what he has achieved here – his vision has been realised and it is quite remarkable. What has forged Britain has been technical skills, manufacturing, and design ingenuity. Britain at the moment is going through a green renaissance the likes of which there has never been on planet earth, and it is all being led by British science.

Pete Goss MBE commented:

I love what Richard and his team have achieved so far at Mount Wellington – it’s just great to see so much activity in the Cornish renewable energy industry. I wish them fair winds as they build national businesses from their Cornish base.

Key Facts

  • Historic tin mine
  • Pipework in flooded mine shaft heats ground source heat pump manufacturing facility
  • Twin Compact Kensa ground source heat pump