Digging deep for hot rocks to cut city’s carbon footprint
A 100-metre hole being drilled in the centre of Plymouth could bring a warm glow to shops and offices in the city.
Contractors Dunelm Geotechnical have already reached 80 metres in their search for warm water in the limestone rocks under Plymouth.
Using heat-pump technology, the warmth from the water extracted from underground reservoirs, known as aquifers, could be concentrated and used initially to heat a refurbished Civic Centre.
Plymouth City Council has commissioned the £25,000 work as part of an EU-funded project called HeatNet.
Mark Lowry, Plymouth Cabinet member for finance, said Plymouth was moving towards being a carbon neutral city by 2050.
“We have pledged to seek out renewable energy sources. As we have recently heard from the UN Intergovernmental Panel on Climate Change, we all need to play our part in preventing rising global temperatures.
“This is a very early step in our search for fossil fuel alternatives, and has the potential to be very exciting.”
He said the long-term ambition was to sell heat to businesses and hotels in the city centre. “The prize is huge.”
Alistair Macpherson, the council’s low-carbon manager, said water found at the 80metre level was already being tested. The experts will know within a couple of weeks whether it is suitable for the heating scheme. “We don’t yet know how much heat is down there,” he said. “But all the signs are positive.”
The technology is tried and tested in Europe, with schemes already operating in Belgium and the Netherlands, Mr Macpherson said.
The process is a passive one and different to the controversial fracking technology being used extract oil in Lancashire. It is also different to the Cornish “hot rocks” project, which is seeking to extract much higher levels of heat deep below the surface.
Water from the Plymouth borehole will be pumped into a plant room in the basement of the Civic Centre, where it will be concentrated and used in a central heating system.
The cooled water will be returned to the aquifer, where it will mix with the constantly replenished water, theoretically creating an unending supply of heat.
In summer, different levels with cooler water could also be used for cooling.
If successful a number of unobtrusive wells will be drilled, using EU funding.
Maritime and Environment Correspondent ‘We have pledged to seek out renewable energy sources’
Councillor Mark Lowry