Visiting the Geothermal site at Rosenamowes, Cornwall

I recently had the chance to visit the geothermal site at Rosenamowes. You would think this site has recently been set up, but shockingly, this site and its three geothermal boreholes were drilled over 30 years ago. These boreholes have stood idle since the initial testing and have only been recently recommissioned . Imagine how far advanced we would be in Cornwall in delivering geothermal heat and power if the original test site had continued.

The geothermal map of the UK

The geothermal map of the UK

Cornwall is ideally placed to be the UK’s geothermal centre due to the geological of the rock under our feet as the following picture will show. Engineered Geothermal Systems water temperature when you drill down to a depth of  2km is will extract water at  79°C and when you go down to the depth of 4.4km, you can  expect water temperatures to be at 160-180°C. The Rosemanowes test site has three such boreholes of various depths.

The current project has been designed and managed by Geothermal Engineering Ltd (GEL), with funding assistance from the Department of Energy and Climate Change. After a month’s testing GEL are now successfully extracting hot water at 60 0C from depths of 1.8km, sufficient to heat homes and businesses. GEL are now hoping to use the technology at suitable sites across Cornwall to demonstrate the benefits of delivering affordable and clean heat to existing buildings. Furthermore, the impact on the landscape is minimal after the initial drilling of the shaft has taken place. On average a 2km shaft takes six to eight weeks to drill.

Cornwall’s energy bill is estimated at £1 billion per year. We are at the end of the grid with 50% of homes no mains gas and at least 20% of homes are  in fuel poverty. Geothermal heat and power could make a real difference to Cornwall’s energy issues.

Geothermal could help with a reductions in emissions. Cornwall’s targets are  a 34% reduction in emissions by 2020 . Currently renewable energy installed accounts for 22% of electricity and 7% of energy in Cornwall. So geothermal heating and power will be a real opportunity for Cornwall.

Now the plan is to look at delivering geothermal heat to 10 schools who have shown an interest in harnessing this tech after a letter was sent out to all schools. It is disappointing that not more schools replied, but I will be sending out another letter  asking for more schools to come forward. The current 10 schools who have expressed an interest are: Treviglas Community College, Probus Community Primary School, Cubert School, Humphrey Davey School, Upton Cross Primary School, Gwinear School, Newquay Tretheras, St Neot Primary School and Sir Robert Geffery’s School. If any other school is interested, then either contact me, or Green Cornwall.

By having heat supplied by this technology will help schools reduce their heating bill and their carbon footprint. The tech is not intrusive either, as after the initial drilling, which could take place over summer, there is little to show.


My visit also to the site also coincided with a group of South Korean students who were being hosted by Camborne Science and International Academy (CSIA) as part of their student exchange programme. I also joined the students for a lesson with a lesson from Caroline Carroll, Geothermal Policy Officer for Cornwall Council, who gave students an outline of the history and plans for deep geothermal in Cornwall.

I really think geothermal technology could be a real asset to Cornwall in tackling fuel poverty, reducing emissions and heating from a sustainable source. I am looking forward to seeing how this can be delivered in Cornwall.