NHS Grampian could drill deep into ground for heat from granite

NHS Grampian is looking into whether it should drill deep underground in Aberdeen to source heat from granite.

The potential geothermal heat project could ultimately mean drilling a borehole to a depth of 1.5 miles (2.5km).

It follows a feasibility study aimed at finding a way of cutting the health board’s heating bills, and NHS Grampian is now looking into funding options.

Deep geothermal technology works by pumping cold water deep underground, where it is warmed by the earth before then coming back hot enough to be used to help heat buildings.

It is most commonly used in volcanic countries such as Iceland, but also in the Eden Project visitor attraction.

A 3.1 mile (5km) well on the Cornwall site started to generate heat in June 2023 and started to supply heat as the weather became colder.

NHS Grampian said there was also “immense potential” for drilling for geothermal heat underground in Aberdeen.

You’ll have seen the postcard images of Icelandic geysers projecting bursts of hot water high into the air.

That water is heated by the hot volcanic rock close to the surface and is responsible for heating 90% of the country’s homes.

We obviously don’t have geysers in Scotland but in the north east we do have granite, both below the ground and in the fabric of the city’s buildings.

That unseen granite is ideal for holding and conducting the deep earth’s colossal heat.

Like with the naturally occurring geysers in Iceland, that heat is best brought to the surface in the water and so digging deep will create that constant flow of hot fluid that effectively fills up the radiators.

At a million pounds a kilometre, it’s an expensive hole.

But once the infrastructure is completed, the costs of producing that heat would be relatively cheap and genuinely renewable.

The feasibility study was completed by TownRock Energy in partnership with the health board.

It concluded that a geothermal solution could supply significant quantities of renewable heat for NHS Grampian’s main Foresterhill Health Campus in Aberdeen.

The next phase of the project would mean proving the viability of the technology proposed in the feasibility study.

It is estimated drilling the borehole would cost at least £2.45m.

NHS Grampian said the process used similar skills and technology to those used in the North Sea oil and gas industry.

NHS Grampian’s energy manager Michael Black said the energy bill for the Foresterhill Health Campus alone was about £1m a month.

He said that cost estimates compared to gas made a “strong” case for exploring the geothermal option further.

“But there is a huge amount of work to do with partners to look at the options on the table and explore potential funding sources,” Mr Black added.

NHS Grampian is also exploring a larger project with the city’s two universities looking at the potential to heat local homes.

TownRock Energy chief executive David Townsend said: “The feasibility study enabled us to look in detail at how deep geothermal wells would have to be drilled to achieve the temperature and heat generating capacity we’d need for NHS Grampian, and start to build a business case for further development.

“The findings are promising so far, and an exploration drilling phase would prove the commercial viability of the system and determine how best to design and build it.”

He said that, with the right design, a geothermal system could produce enough heat not just for the Foresterhill campus but for other people in Aberdeen relying on gas.

“When people hear the word geothermal, they often think about areas like Iceland,” Mr Townsend said.

“But recent advances in engineering mean that lower temperature resources in geologically stable regions like Aberdeen are now viable.”