From the car park of the Toys R Us store in Southampton a deep geothermal borehole delivers heat through a network of pipes to thousands of homes and businesses in the city.
In Paris, a network of 40-or-so boreholes, at intervals of one kilometre, provide low carbon, renewable heat to millions of Parisians.
Now North Tyneside, Weardale and Bishop Auckland are at the forefront of multi-million pound plans to deliver emission-free heat to thousands of North East properties.
Despite the recent announcement that the Newcastle Science Central borehole had failed to find sufficient water to support a geothermal network, scientists say the potential for the rest of the North East is excellent.
London-based Cluff Geothermal, headed by George Percy, son of the Duke of Northumberland, has identified a site close to the A19, near Shiremoor, to drill a geothermal borehole.
The aim is to tap into water – at a temperature of 70°C - at a depth of two kilometres which will then be brought to the surface to deliver heat to homes and businesses.
Michael Feliks, UK operations manager at Cluff Geothermal, said: “The future is looking very bright for geothermal energy, especially in the North East.
“We are confident that the right conditions for geothermal energy will be found in the North East, where the geology is as good as you will find in the UK.”
Cluff Geothermal say the geology at Shiremoor is highly promising as it is close to the junction of the Ninety Fathom Fault and the Rising Sun Fault.
This should greatly increase the chances that water is flowing at depth. The Science Central site in central Newcastle, where a deep geothermal borehole recently found good temperatures but disappointing permeability, is relatively far from these large faults.
Dr Feliks said: “The only thing stopping us from delivering this first class green energy scheme in North Tyneside right now is securing a customer for the heat.”
He said it was talking to several potential customers at Cobalt Business Park as well as housebuilders.
Meanwhile Cluff Geothermal is also working with Auckland Castle Trust on a project in Bishop Auckland which aims to use two deep boreholes to bring hot water to the surface where it will be used to heat buildings including the castle itself.
Cluff Geothermal is advising the trust and is currently assisting with preparation of the planning application.
It was a little over 10 years ago that Newcastle University scientists sank a geothermal borehole in Weardale and determined the underground conditions as being excellent for both heat and power projects.
The Eastgate borehole was sunk into granite at the site of the former Lafarge cement works to a depth of 995 meters, encountering abundant warm water supplies.
Supported by former regional development agency One NorthEast, plans were developed for an energy village on the site, in partnership with Cluff Geothermal.
Dr Feliks said: “The investigations in Eastgate discovered that the Weardale Granite has the highest permeability ever found in granite worldwide, which makes it a great resource for geothermal heat.
“However the scheme has been put on hold as the public money for the wider development of the site is no longer available, which means the heat customers we need have not materialised.”
In October this year North East academics helped establish a new body to drive forward geothermal energy in the UK.
BritGeothermal Research Partnership consists of Durham, Newcastle and Glasgow universities and the British Geological Survey.
It says that deep geothermal sources in the UK could supply heat to meet the domestic heating demand for 100 years. Its plans include further investigations into the Eastgate borehole next year.
Professor Jon Gluyas, Dean of Knowledge Exchange at Durham University, is involved in the BritGeothermal and one of the region’s leading experts in the geothermal energy.
He said: “The results at Science Central are disappointing, although we should not be too disheartened.”
He went on to say the key to success is the permeability of the rocks, and the quantity of water in these can vary within the space of half a kilometre.
The tests at Weardale have already determined its suitability Prof Gluyas believes there are many similar promising locations in the region.
He said: “We very much still believe in the long-term potential of geothermal energy. An individual borehole might not work, but we would anticipate a pretty high success rate across the North East.”
He added: “The North East has the opportunity to lead the country. The heat is here in the earth and we should aim to exploit it. We have the right energy source, in the right setting and it’s an energy source with no emissions.”
Dr Charlotte Adams, who is the Durham-based research manager for the BritGeothermal Partnership is lobbying the Government for greater support for the industry.
She said: “Geothermal is a carbon neutral, home-sourced, sustainable and reliable source of heat and power which can help the UK become more self-sufficient with respect to energy.
“The UK’s comparatively low temperature deep geothermal resources are best suited to heating. With the potential to provide a massive 100GW (gigawatts) of heat, this could theoretically satisfy the entire space heating demand in the UK.”
BritGeothermal is talking to a number of councils across the country about the possibility of establishing heat networks supported by geothermal sources.
Cluff says it is hoping to attract interest from a housing developer for its first scheme, as it will be easier to establish a heating system on new build properties rather than retro-fit.
The country has been through something similar when the nation’s homes and business were converted from town gas to North Sea gas in the 1960s and 1970s.
The geothermal plant at Southampton has supplied homes and businesses with heat for the past 25 years this scheme centres upon a borehole that extends 1.8 km into water-bearing sandstone and supplies water at around 60°C.
It arose from a Government initiative to assess the UK’s geothermal resource during the oil price shock of the early 1970s, when soaring prices alerted the nation to the issues of energy security and price.
Most of the UK plans were shelved when oil prices later fell, but despite the oil price tumbling 40% to $60 in recent weeks, the need to secure low-carbon energy should drive the geothermal industry in the years to come.
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What is geothermal energy?
While areas with active volcanoes, such as Iceland, are generally singled out as being exemplars for geothermal energy they are not the only source.
In volcanically active regions, geothermal power is produced from steam brought to the surface at temperatures in excess of 200°C.
In non-volcanic areas geothermal energy is used successfully to provide heat. For example, there are dozens of geothermal schemes in Paris, including one that heats Orly Airport.
Geothermal energy is ultimately derived from the decay of radioactive elements deep within the Earth’s crust, and this heat naturally dissipates towards the earth’s surface.
Geothermal energy projects can run for a very long time – one power station in Italy has been running for over a century, while a system in Idaho was switched on in 1892 and is still providing heat to the town of Boise.
In the UK several geological features at depths of a mile or more could deliver the potential for geothermal energy.
Geothermal heat is accessed by drilling a deep well to target water in permeable rocks, or flowing through faults, at temperatures generally in a range of between 60 to 80°C.
The hot geothermal fluids are pumped to the surface where the heat is removed and the cooled water returned below ground, usually through another borehole. The water can be used to heat buildings or – if it is hot enough - for power generation.
The North East geothermal resource
THE North East and Cornwall have been singled out as the two best areas in the UK for exploiting geothermal energy.
The North East’s geothermal potential is derived from the Weardale Granite, which is a huge mass of granite buried beneath the North Pennines.
Geologists deduced the Weardale granite was there by measuring small changes in the strength of gravity. A borehole drilled at Rookhope in the early 1960s proved they were right.
A 2012 report into UK geothermal potential estimated that the Weardale Granite contained 220,000 terawatt hours of thermal energy – an amount similar to the world’s energy demand for a year.
The Eastgate borehole in Weardale was drilled in December 2004 at the site of the former Lafarge cement works.
It was the first deep geothermal exploration to be drilled in the UK for over 20 years. Very high flows of water were found and pumped to the surface the water was warm enough to go swimming in.
Scientists believe that water flows through the large faults and fractures in the Weardale Granite, and that these faults carry heat out across the North East.
There is also the potential to generate heat from warm water which has flooded abandoned coal mines – with the North East sitting on top of a maze of old workings.
Durham University is researching how to utilise water which has lower temperatures than that from deep geothermal wells.