The energy of the future may have taken a step closer, as a groundbreaking Glasgow study into geothermal heating begins to produce data.
It’s estimated that the heat under the earth’s surface could be enough to power all of humanity’s energy needs, generating electricity through processes such as flash steam power stations, which use the heat of the earth to convert water into steam and power the turbines which create electricity.
The technology has typically been employed close to tectonic plates or existing areas of geothermal activity. One such example is the Larderello plant in Tuscany, Italy which is known for its hot springs and produces around 10 per cent of the world’s geothermal electricity. Similarly, Iceland produces around 30 per cent of its electricity via flash steam power stations.
The UK is committed to bringing all greenhouse gas emissions to net zero by 2050, with investments made in wind, solar and tidal energy, while Scotland aims to produce 50% of its energy from renewable sources by 2030.
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A project led by the British Geological Survey (BGS) is focused on heat energy from beneath the earth, with £31m spent on two underground observatories – one in Cheshire and one in Glasgow.
The latter is already operational, producing data on mine water energy, and released its full environmental baseline this week.
Former mines could be used for electricity generation or for heating, such as at the Glenalmond Street project in Shettleston. That sees water from a coal mine 100 metres below the surface heated year-round by geothermal energy, which is then raised and passed through a heat pump to provide heating for radiators.
Researchers across Scotland and the UK have been collecting data from the site, whether from samples of soil collected on the surface, data from the hundreds of borehole sensors or water from within the mines underneath.
This has allowed them to establish the ‘normal’ conditions at the site, enabling researchers to accurately measure any changes in geothermal activity which could be caused by human activity. One example could be that changing the flow of underground water could stimulate microbial activity, in turn releasing CO2 which would damage the underground environment.
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Dr Alison Monaghan said: “We now have a level of detail about a formerly coal mined, urban environment that doesn’t exist elsewhere. One of the main barriers to geothermal is data and places to confidently enable research for widespread, cost-effective deployment of the technology.
“That’s exactly what is available through the UK Geoenergy Observatories project.
“We need to characterise the environment at ‘time-zero’ to measure and understand any changes with geothermal activities. We also need novel monitoring tools for cost-effective and environmentally-sound geothermal operations.
“BGS has made time zero soil chemistry, ground gas, surface water and groundwater characterisation, ground motion and seismic monitoring data open access.
“This includes seasonal and temporal variability. In addition over 500 water, rock and gas samples collected during the observatory’s construction were distributed to university researchers for carbon, isotopic and microbiological analysis.
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“These give new insights into rock-water-gas-microbiological interactions in the subsurface and their significance for shallow geothermal heat and storage in flooded abandoned mine workings.”
Dr Ryan Pereira said: “We need to understand whether there are unintended consequences from changing the water flow in the subsurface. It could, for example, stimulate microbial activity that could generate greenhouse gases and cause damage to infrastructure, which of course we don’t want.
“BGS had the foresight to offer early access to researchers, which gave us the chance to be more experimental.”
“We used a rare instrument in the UK called a liquid chromatography - organic carbon detection - organic nitrogen detector (LC-OCD-OND).
“This set-up can quantify and resolve organic compound groups by molecular size, which is good because it allows us to explore food sources for microbes that may produce greenhouse gases”.
Dr Julia de Rezende agreed, “This was a rare opportunity because when samples are recovered from sites, the preservation methods to consider microbiology are not always a priority.
“The research is still in its infancy, but we discovered the potential for increased leaching which promotes the production of carbon dioxide and methane by microbes. Now we need to observe this under ambient conditions as the site is under trial for heating and cooling applications.
“The Glasgow Observatory offers a platform for finding a way forward for us to use former mine workings as a low carbon option for heating and cooling our cities. This fundamental research is how we take forward the deployment of geothermal in the UK, of that I am certain.”
Geothermal energy explained
Geothermal energy has been hailed as the wave of the future – but how would it actually work?
The technology is already used in many countries around the world, and essentially works in the same way as any other method of generating electricity.
In a coal or gas power station, the fuels are burned to create heat which boils water to create steam. The steam is then channelled through pipes to create pressure, which shoots the steam down the pipe where it spins the turbines to generate the electricity.
It’s the same process in a nuclear power plant, with a nuclear reaction generating the heat to boil the water, while with wind power the turbine is spun directly by the elements.
In the case of geothermal electricity, heat below the surface of the earth or naturally occurring steam is used to spin the turbine. Iceland, which is famous for its many geysers and hot springs, generates around 30 per cent of its energy needs by this method.
As things stand most geothermal energy is produced in places where such conditions exist – Italy, which sits on two tectonic plates, was the first country in the world to produce geothermal electricity and has 33 plants in Tuscany.
It’s hoped that research and investment in the technology could allow that to be replicated in Scotland.
As well as electricity, geothermal energy could be used to reduce Scotland’s reliance on gas heating. A University of Strathclyde project, called the HotScot, projected that the potential geothermal energy in disused mines could meet demand for up to 8% of heat demand in Scotland.
The Glenalmond Street project in Shettleston sees water from a coal mine 100 metres below the surface heated year-round to a temperature of around 12 degrees by geothermal energy, which is then raised and passed through a heat pump to warm it to 55 degrees and provide heating for radiators.
There is also the potential for decommissioned oil and gas wells, which already drill deep into the earth, to be retro-fitted for geothermal energy extraction. That would involve a loop system where cold fluid is pumped in at the top, circulated down into the earth to be converted to steam, then fired up an outlet pipe to generate the electricity.
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