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Ground Control

In France and Germany geothermal power is relatively widespread, yet in the UK there remains just one power plant under development. But new technologies could soon make this energy source more attractive.

Using the earth’s own heat to generate energy from just a few kilometres below your feet, has the potential to be one of the most compact and acceptable forms of renewable energy available.

Power stations can be small, but perhaps most significantly, the power generated can be run all the time if needed, making geothermal power ideal for ‘baseload’ power. Simply, water is pumped into faults where it is heated by the high temperatures found deep underground. The heated water is returned to the surface to drive turbines and produce power.

Internet connection

One of the reasons for increased interest in geothermal power has been serious scrutiny from internet giant Google. According to climate and energy initiatives director Dan Reicher, geothermal power has “the potential to deliver vast quantities of power 24/7 and be captured nearly anywhere on the planet. And it would be a perfect complement to intermittent sources like solar and wind”.

Google has invested in two US companies - Potter Drilling to develop hard rock drilling techniques and AltaRock Energy to develop advanced geothermal systems for energy production.

Here in the UK, there is just one company developing geothermal power, located in Cornwall. Geothermal Engineering plans to eventually set up 25 sites in the South West to produce 300MW of power. The first, a 60MW site at Redruth, is under construction. Research projects are also underway in other parts of the country, including one double borehole system in County Durham.

“These are small plants but subsequent ones depend on the success of this one. It is still not a proven resource, but we are confident we can prove it,” says Geothermal Engineering managing director Ryan Law.

One advantage of focusing on Cornwall is low costs.

“It is not the resource that is the limiter, but economically drilling to 4.5km. If we could drill to 6km economically then we could open up this resource to new areas of the country,” explains Law.

“If we could drill to 6km economically then we could open up this resource to new areas of the country”

Ryan Law

He says the barriers to developing geothermal power in the UK are finally being removed, following years of stagnation.

“Ten years ago, Germany had no market. There, they sold geothermal licenses and introduced feed-in tariffs (FITs), on which the industry was formed.

“This year, it is a €4bn (£3.4bn) industry. Here, geothermal has not been seen as economic,” he says.

The resource is not included in the new FITs that began to operate on 1 April this year. Instead, geothermal energy in the UK relies on Renewable Obligations (ROs) to force larger companies to purchase RO certificates.

Law says the coming few years will fundamentally change the geothermal market as new players such as Google push to reduce costs. “There are some interesting innovations coming. We are looking at a new technology, which means you can drill to the necessary depths in 30% of the time. We have also talked to Google.”

He says Google’s interest is specific, and will be a model that can be applied in many different ways. “Data centres consume a lot of energy - this sort of technology, because of the relatively small scale, could be worth pursuing.

“We have not seen economies of scale yet - we have 10-15 years to go before we do. But we are starting to see new and exciting plans for power plant designs. There are also some developments on the drill rig side. We are seeing innovative rigs with very small footprints.

“Originally the rigs developed from oil and gas rigs. The new designs have very small footprints and noise - you have to be sensitive to local residents,” he says.

New directions

New designs are coming particularly from the more mature German market.

However, the driver will be the US market. Law says the demand for power in the US is 200 times that of the UK, but with only 5% to 10% of land usable for other renewables like wind, geothermal is a good alternative.

However, power is just one application for geothermal plant. The other is heat. “Renewable heat is a huge challenge - to shift people’s mindset to the concept of district heating - this is a long way off. The construction and design of district heating is very complex.”

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