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Hot Dry Rocks: two geothermal companies are reviving Cornwall’s EGS legacy

First published in Cleantech magazine, February 2011. Copyright Cleantech Investor 2011

By Mel Poluck

It is estimated that geothermal power from the south west of England alone could meet 2% of the UK’s annual electricity demand. Two companies are gearing up to tap Cornwall’s extensive potential resources of deep geothermal energy and look set to convert the English county into a hot spot for enhanced geothermal systems.

Traditional geothermal energy is derived by pumping naturally occurring hot water from underground to the surface. Enhanced geothermal systems (EGS) manufacture geothermal resources by creating similar conditions to traditional geothermal energy in hot dry rocks. This is achieved by pumping high pressure cold water down into rocks at depths of around three miles (five kilometres). The rock then fractures, allowing the water to circulate and heat up – and subsequently re-emerge from a second borehole as very hot water to be converted into electricity.

Cornwall was the location for Europe’s first deep geothermal R&D initiative, the Hot Dry Rock (HDR) project, which took place in Rosemanowes. Triggered by the 1973 Middle East oil crisis and subsequent search for alternative energy sources, Cornwall was identified because its geothermal resources are large: the geothermal gradient (i.e. the temperature increase with depth) is higher than elsewhere in the UK (see chart).


Geothermal Energy - Natural power from the earth

First published in Cleantech magazine, July/August 2010. Copyright Cleantech Investor LtdThe Krafl geothermal power plant, Iceland

By Jon Mainwaring

Most renewable energy sources – including wind, wave and biomass as well as solar power – ultimately derive from the sun. Tidal energy is an exception, since it depends upon the moon. And geothermal energy is derived from the insides of the earth.

The geothermal power industry has been experiencing steady growth and support around the world from governments keen to find a cheap source of abundant energy. This support could see the geothermal industry take off during the coming decade in the same way as the wind and solar industries boomed in the last decade. According to the US Geothermal Energy Association (GEA), there is currently 10.7GW of geothermal power installed worldwide, compared with 8.9GW in 2005, which implies a growth rate of 4.8% annually.


The International Partnership for Geothermal Technology (IPGT)

The US, Iceland and Australia signed a charter to launch the International Partnership for Geothermal Technology (IPGT) in August 2008. The partnership will encourage research into and projects relating to enhanced gothermal systems (EGS). The partnership will explore policy aspects of EGS, including deep drilling and geothermal energy conversion. The countries will exchange information to promote the understanding of geothermal applications in different geologies. IPGT membership may be opened up to other nations in the future.

Geothermal Power

First published in Cleantech magazine, September 2008. Copyright Cleantech Investor Ltd., 2008

A suite of investments from Google.org in a new generation of geothermal technology may be the start of a fresh wave of investment.

by Tim Chapman
Geothermal power may be the sleeping giant of cleantech venture capital. It's regularly tipped as one of the next big things for venture investment, but, because the basic technology is already well established, early-stage and growth funding deals have been rare. A recent suite of investments from Google.org in a new generation of geothermal technology may be the start of a fresh wave of investment.


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