Geothermal power plant in Cornwall secures funding

Geothermal Engineering has finalised the design of its plant, which it hopes will be generating power by 2015.

Exploration of Cornwall’s geothermal potential dates back to the 1970s with the ‘Hot Dry Rock’ research project, which aimed to characterise the mechanical properties of the underlying granite.

Data from this project has formed the basis of Geothermal Engineering’s proposals, which will include three wells 4.5km deep and a binary power plant capable of generating up to 300MW.

The injector well will fire cold water down to the rocks to migrate through natural ‘heat reservoirs’ in the granite towards two producer wells 800m apart, which will take hot water to the surface for electricity generation.

‘The crux of this whole deep thermal business is that reservoir and how it functions,’ said Ryan Law, managing director of Geothermal Engineering and a former geotechnical engineer for Arup on the original Hot Rock Dry project.

‘This is a big fault zone where the granite has been messed around and turned into almost a rubble, so there are very small openings within the granite, almost natural fissures or faults, through which the water can move. It’s a big heat exchanger effectively and all you’re trying to do is get the water to pick up as much heat as possible between the injector and producers.’

While the major challenge of the project has been a funding one, Law admits he still does not know exactly how the rock will behave when they start to send water down.

Part of the most recent £6m tranche of funding will include the setting up of a research centre with Exeter University’s Sustainability Institute.

‘As the project develops, the aim is to use some of that data, the problems we have encountered, to spur academic research and eventually to form potential spin-out companies to develop some of the tools that are needed for the industry,’ Law said.

He believes that Cornwall as a whole has around 1GW of geothermal potential, with more to tap into in Devon.

‘Germany has left us behind, it’s so far ahead of us, there is catch-up to do, but there are very smart areas where we can potentially produce high-end technology products.’