Drilcorp has been awarded a contract to install a 420 metre re-injection borehole at Weardale, County Durham, as part of a project that will provide renewable, clean energy for homes in the planned Eastgate eco-village, complementing four other forms of renewable energy to be deployed there.
In a first for the UK, the project team of scientists and engineers, lead by Newcastle University, plan to complete the installation of a twin borehole system that will recirculate warm groundwater continually through rocks as deep as 1,000 metres, in effect creating a giant central heating system using the heat from deep underground as its primary source.
The underground water, which has an average temperature of 30 degrees C, will be brought to the surface and passed through a heat exchanger to redistribute the heat to surface applications before being sent back underground for the reheating process to begin again.
Some of the natural hot water will also be used in a new spa installation at Eastgate - the first such development in the UK since the Romans tapped the hot springs at Bath.
Drilcorp’s Chairman, Dave Gowans said “Drilcorp Ltd are proud to be associated with such a prestigious project and are delighted that our expertise in the field of geothermal energy has been recognised and deployed at the Eastgate site.”
Project lead Professor Paul Younger, of Newcastle University, says that using a twin set of boreholes solves problems which have hindered other attempts to use deep-seated hot water.
“Water from such depths is twice as salty as seawater, so unless you happen to be on the coast, you can’t let the spent water flow away at surface,” he explained.
“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 to come.”
The project, which has had financial support from the Department of Energy and Climate Change, involves drilling a reinjection borehole to complement the 995m deep exploration borehole which was originally drilled three years ago.
Used water will be reintroduced to the granite at about 420m depth, and will heat up again as it flows through a complicated maze of fractures on its way back to the pumping borehole. By recycling the hot water through what is essentially a huge central heating system deep underground, this will create an almost carbon-neutral source of energy.
The new twin borehole system is to be analysed by a team of experts which also includes Professor Jon Gluyas from Durham University, and the world-leading engineering consultancy Parsons Brinckerhoff.
This pioneering project is set to become a geothermal prototype that could be used at other ‘hotspots’ across the UK.
