A pioneering plan for a giant central heating system to harness heat from deep underground is being developed in County Durham.
Scientists and engineers led by Newcastle University plan a twin borehole system to allow continual cycling of warm groundwater through rocks up to 1,000m deep.
Water at around 30°C will be brought to the surface and passed through a heat exchanger before being sent back underground for reheating.
Renewable, clean energy will be provided for homes and businesses in the planned Eastgate eco-village in Weardale, complementing four other forms of renewable energy to be harnessed there.
“By re-injecting water using a second borehole we are able to maintain the natural water pressures in the rocks and allow pumping to continue for many decades,” said project leader Professor Paul Younger, of Newcastle University.
The Department of Energy and Climate Change is providing £461,000 to drill a reinjection borehole to complement the 995m deep exploration borehole drilled three years ago and there are plans to prepare the existing borehole for long-term pumping service.
Used water reintroduced to the granite about 420m down will reheat as it flows through a maze of fractures on its way back to the pumping borehole.
The system can produce an almost carbon-neutral source of energy, said Prof Younger.