Fossil fuels currently dominate the production of electricity and heat. Although renewable energy accounts for around a quarter of electricity produced in the UK, the production of central heating is dominated by natural gas, which supplies around 70% of UK heat demand (the UK has been a net importer of gas since 2004). There are fewer low carbon alternatives for heat production than there are for electricity. Solar hot water and biomass are the two main touted alternatives. Solar hot water is usually produced at a domestic level and requires access to a south facing roof. Biomass can be used as a heat source but may be constrained by availability and the transportation of fuel. And so it is unclear how future heat demands could be met from low carbon sources. Geothermal heat is one solution that offers a low carbon, secure and continuous energy source. Classic geothermal regions such as Iceland and New Zealand capitalise on their volcanic landscapes by capturing the steam and hot fluids produced as a result of tectonic activity. Geothermal fluids in the UK are over 100°C and hot enough to drive turbines, produce electricity and also supply heat. Also, geothermal fluids may issue naturally at the surface as hot springs and geysers, avoiding the need to drill to access them. Of course, the UK is not characterised by such tectonic activity. But we believe that abandoned deep mines contain good geothermal potential. Abandoned coal mines seem incredibly promising due to their networks of flooded galleries and shafts lying at depths of up to several hundred metres below the surface. One can be almost certain that the water flow necessary for deep geothermal wells will be found in these flooded underground voids. The risk of not finding flowing water underground can inhibit deep geothermal developments elsewhere.
The Conversation 27th Nov 2017 read more »