Geothermal energy captures underground reservoirs of hot water and steam and converts it to electricity or can be used directly to heat or cool buildings.
The UK government states: It currently delivers less than 0.3% of the UK’s annual heat demand, using only a fraction of the estimated available geothermal heat resource.
Heat energy is commonly described as shallow and deep geothermal:
Shallow Geothermal Energy generally refers to heat stored in the ground up to 200 meters down. This heat is mainly created by solar radiation and artificial structures such as flooded coal mines. A heat pump is required to modify the temperature from the captured geothermal energy so that it can be used to heat or cool domestic or commercial property
Deep Geothermal Energy, generally refers in the UK to a heat resource found below 500m. The heat increases as you go deeper and is known as geothermal gradient. The heat at this depth is partly created from the decay of mild radioactive elements in the earth crust and primordial heat from when the Earth was formed. In the UK subsurface temperatures can range between 39°C at 1000 m to 139°C at 5000 m.
In the UK although there are geothermal resources across the country, the UK’s current usage is lower than a number of European countries.
The Scottish Government commissioned the British Geological Survey to conduct a study in 2013 to assess Scotland's potential for producing deep geothermal energy. Three geothermal energy sources were identified by them:
• Abandoned mines, such as those in the Midland Valley of Scotland.
• Hot sedimentary aquifers are large, permeable rock formations that can conduct a sizable amount of groundwater.
• Granites with a high heat production, like those in East Grampian and to the north of Inverness, are likely to contain hot, dry rocks.
Currently, there are no deep geothermal plants in the UK. For geothermal energy to be viable it will require long term government support, but this is currently held back due to a lack of information relating to the application of technology to extract deep geothermal energy efficiently.
This section provides examples of a research, teaching or innovation taking place at Robert Gordon University and/or The National Subsea Centre, Aberdeen related to this topic.
Module Title - Sustainable Energy Resources
Sustainable energy technologies, including solar (photovoltaic and thermal), wind, pico-hydro, waste, biogas, biomass, geothermal and heat pumps. Fluid dynamics and thermodynamics of systems, energy transfer from environment to output. Assessing flows of energy and matching flow to demand.