The UK is missing a trick by not exploring its geothermal potential
With COP26 just around the corner, and after a gas crisis which still looms over much of the UK, Professor Jon Gluyas argues the UK already has, in the form of geothermal, an energy source to ensure both decarbonisation and energy security.
About half of all the energy we use in the UK is for heating. 77 per cent of all the heat is generated by direct or indirect combustion of fossil fuels and more than 30 per cent of all the greenhouse gases emitted by the UK comes from generating heat. There has been almost no reduction in the carbon footprint of heating in 20 or more years in the UK. Few developed countries are so reliant upon burning fossil fuels for heat.
Our journey to today reflects the phenomenal technological advances in the UK which first brought us town gas, derived from coal, and then natural gas from the North Sea; but 'the times they are a-changin'. We ceased to produce enough gas to supply the national need in 2004 and security of supply has been a growing issue since. Supply issues have seen the price of gas rocket six-fold in the past few months to the crisis point in late September 2021.
Gas is not a globally traded commodity, while the USA presently has abundant gas, most countries in Europe, need a top up and in the case of the UK that amounts to be about 60 per cent of demand. Much comes from our next door neighbour, Norway but about 20 per cent comes from less reliable and/or less responsive suppliers and we store little so are exposed and our energy security compromised.
There is good news though, we can improve the nation's energy security and dramatically cut the carbon footprint of heating UK homes and much of the answer is right under our feet. The UK may not figure in most people's top 10 geothermal hotspots around the globe but our research has demonstrated that even at our most profligate we could supply heat to the nation for at least 100 years and potentially, if properly managed, indefinitely and sustainably.
This is not a pipe dream. The Southampton District Energy Scheme has been operating since the mind-1980s with much of the heat for 1000 customers coming from a single deep borehole drilled in the wake of the 1973 oil crisis to prove geothermal potential – providing flowing water at 75°C. Near to Southampton is Dorset's aging Wytch Farm oilfield. Few will realise that whilst it does certainly produce oil it also produces copious quantities of unwanted and unused hot water – about 40 times more heat than comes out of the Southampton bore. For the past 40 years such water could easily have been utilised in Bournemouth, Poole and surrounding areas.
Further north in the depleted oilfields of the East Midlands, hot water at 50°C can and is being produced but goes unexploited. Cheshire, Shropshire, Derbyshire, County Durham, North Yorkshire, Larne and the Midland Valley of Scotland wells have been drilled, most often in the search for petroleum, and found instead hot water. Such water remains unexploited. The Netherlands, unlike the UK, requires companies that have tried and failed to find petroleum to evaluate the geothermal potential of the well. The costs from petroleum exploration, in the form of infrastructure, can then be reused for geothermal energy.
This philosophy can be applied not just to deep wells but also to the 23,000 UK coal mines dug in the past millennia. All are now abandoned and flooded with water, water which has taken heat from the surrounding rock. Temperatures range from 12°C to 25°C – all usable for heating our homes with or without a boost from heat pumps. A 3.6 MW scheme heats wine warehouses in Gateshead and there are housing developments and council initiatives in Durham, South Tyneside and elsewhere which will utilise mine heat at a similar scale. The opportunity to develop our abandoned mines for sustainable, low-carbon heat was the subject of a briefing session in the House of Commons on 20th October 2021 hosted by the Coal Authority with support from Durham Energy Institute. The UK built its towns where it mined its coal and 9/10 of UK's largest cities as well as 25 per cent of its housing stock could benefit from the coal heritage, a real circular economy and one which will attract inward investment. This has been shown by a mine heat scheme for the whole of Heerlen in Limburg Netherlands. For 20 years it has collected surplus heat from local industry, storing it in the mine system and only releasing it for use when needed in winter.
The shorelines of the UK do not bound our geothermal potential. Boiling water in the North Sea oilfields is so hot it can be used to generate power and so help decarbonise our offshore industry. SHIFT Geothermal is a not-for-profit company formed in the UK in 2020 to do just that, helping to transform an industry and save jobs in North East Scotland.
The UK's geothermal resources could be used to decarbonise our heating bills and add security to our energy supply. We could electrify all our heating or possibly use hydrogen but both are profligate in energy terms.
There is a catch, the UK has never sold heat, there is no legislation or regulation and the profit margin on hot water will always be less than oil. Operating expenses (OPEX) are low for geothermal but capital expenditure (CAPEX) is high and payback times are long. Market economics will improve the efficiencies of geothermal developments, but will not kick start this new industry. The Government needs to create the regulatory framework, as it did in the very early days of the North Sea exploration, to provide the underlying support to initiate this low-carbon, sustainable, heat solution.
