Carbon News

Thursday 23 April 2009

The 2.9MW turbine in Landau, Germany, supplied by Ormat Technologies Inc, is the first commercially operating power project to use enhanced geothermal systems technology

World-renowned geophysicists met with Liberal Democrat energy spokesman Lord Teverson this week to seek help in challenging the government's "blind spot" when it comes to geothermal energy.

The meeting came ahead of a gathering of the Geological Society's engineering group on Tuesday night, in which the potential for so-called "heat mining" in the UK and Europe was likened to the scale of the nuclear industry.

For the price of a single "clean coal" power station, they believe the technology could become a fully commercial venture - providing valuable "baseload" power alongside wind and solar power projects, operating as much as 90% of the time, without emissions.

By December 2008, there was around 11GW of geothermal projects installed across the word, but this has been "hydrothermal" geothermal technology - relying on existing aquifers being available to provide hot water - deep underground natural stores of water heated by the surrounding rocks, which can be pumped to the surface to provide heat and electricity.

The potential for this kind of project has been limited in the UK geology so far, but a different form of geothermal technology, known as engineered or enhanced geothermal systems (EGS), is now beginning to move towards commercialisation with plans taking shape for a 3MW pilot plant in Cornwall.

EGS technology takes advantage of modern drilling techniques to drill down to depths of 3,000 to 10,000 metres, pumping water down to be heated by the hot rocks to temperatures of 200 degrees centigrade.

Pumped back to the surface, this water can be used to drive turbines to generate electricity, or supply heat to nearby homes and businesses.

Martin Culshaw of the Geological Society's engineering group, said: "Cooling one cubic kilometre of rock by one degree provides the equivalent energy of 70,000 tonnes of coal. This has the potential of equalling the nuclear industry in providing 10-20% of Europe's energy."

Experts who met yesterday with Lord Teverson included Professor Jeff Tester of Cornell University, who led a landmark MIT study of the potential for large-scale geothermal energy deployment in 2006. The study found that just 2% of the energy beneath the US could provide the country with 2,500 times its energy needs. 

Prof Tester told New Energy Focus that the field of engineered geothermal systems had been on a "starvation diet" with regard to research funding so far, with the Bush administration in the US cutting its funding to zero.

"This should be like the space race," he said, "except that this is much more important than NASA's attempts to put man on the moon, because we have to have affordable low-carbon energy."

UK demonstration

Although EGS technology is not yet fully commercial, a 2.9MW plant is operating commercially in Landau, western Germany, while projects are now being developed in Australia, the US and Japan. Preparations are now underway for a similar-sized demonstration plant to be set up in the UK.

Scientists including Roy Baria, who also worked on the MIT study, have now formed a company to develop the demonstration project in Cornwall, which could be operational in 2012.

The company, called EGS Energy, is currently seeking £500,000 in seed funding for the early stages of its demonstration project.

It is also seeking to persuade the government to devise a licensing system for geothermal projects, similar to that in the oil and gas drilling sector. This is so that projects can secure investment, since being awarded a licence would give a project a tangible value on which to borrow money.

Dr Baria, technical director at EGS, told New Energy Focus: "We are now looking for seed capital to take forward the development, and we hope to start the study some time in the Spring of 2010, with a business plan ready, then we will go to industry for financing."

The firm believes the 3MWe demonstration project could lead to a number of 50MW-scale power plants being set up in Cornwall as well as in Cumbria, Derbyshire and Durham, where there are also suitable granite rock formations - making use of skills in the existing oil and gas industry.

Planning permission would be relatively straightforward as the plants have a very small footprint and are generally non-polluting, according to EGS, which said the plants could be developing in the middle of towns and linked up to district heating networks.

Reservoirs created by EGS projects could last 20-25 years before the heat resource is depleted beyond commercial requirements - after which a new reservoir can be created underneath, Dr Baria said.

The technology still has issues to overcome in achieving its power generation at costs competitive to other forms of energy, including drilling capabilities and the opening up of underground reservoirs with high enough flow-rates for commercial power generation. EGS is not without project risks, with high temperatures making drilling difficult, while forcing open the reservoirs with high-pressure water injections can risk causing small earth tremors in earthquake-prone areas.

But EGS pioneers are optimistic that with the right government support, geothermal could generate 10% of the UK's energy. A full presentation of the technology is to be made in the House of Lords on June 1 in order to raise awareness of the potential of geothermal energy in the UK.

"There's a huge resource available," said Dr Baria. "A cubic kilometre of reservoir cooled from 200 degrees by 20 degrees would generate the energy equivalent to 1,750,000 tonnes of oil."