UK, US invest in deep geothermal

Time to tap into the legacy of buried energy?

Not fossil fuels, but something much older, dating back to our planet’s violent birth – and trapped in hot and molten rocks deep beneath the earth’s surface. One UK city already makes use of this deep geothermal power. For 20 years, Southampton has been pumping up natural hot water and piping it round a district heating system. The technology should not be confused with the ground source heat pumps that the renewables industry is, rightly, excited about.

Deep geothermal is also the focus of fresh interest, and now has the promise of UK Government support. The Department of Energy and Climate Change’s Low Carbon Transition Plan will devote £6 million to exploring likely sites for deep drilling. The south west could be best, as Southampton’s pioneer status implies. The region could build an industry on deep heat with the capacity to meet 2% of total UK electricity demand, the Government has suggested.

If that sounds excitable, it’s nothing compared to the enthusiasm of US Energy Secretary Stephen Chu. He speaks of his country being “blessed with vast resources of geothermal energy, with enormous potential to heat our homes and power our economy”. Putting stimulus money into realising this potential, his department has recently announced $338 million in federal funding from the Recovery Act for a Geothermal Technologies Program.

Confusingly, $61 million of this funding is actually for the “other geothermal” – ground source heat pumps. The bulk of it, though, is split between: finding new exploitable fields of hot rocks (in Nevada, California, Oregon and elsewhere); making a nationwide database of such resources; developing the search, drilling and energy conversion knowhow; demonstrating power production techniques at three known hot rock sites; and getting hot water up from existing gas and oil wells. – Roger East

29 December 2009

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