Helen Bone, Chartered Geologist
It was a pleasure to attend the 11th Geothermal Symposium at the Geological Society in London. I must start by thanking the organising committee for wrangling a wide range of topics into such an interesting and varied programme. Topics ranged from the subsurface, through the many varied geothermal technologies, to surface electricity generation and regulation.
The conference kicked off with a keynote presentation from the Department for Energy Security and Net Zero (DESNZ) which recognises that 85% of heating provision in the UK is currently from gas. As we move to Net Zero, alternative sources of heat are clearly required at a very large scale. However, our national electricity grid would not be able to cope if the load required for heating were transitioned to electrical solutions. Geothermal energy in the UK has the potential to make a contribution to solving this dilema. Currently there are several barriers to this, including the lack of regulatory framework, high capital expenditure (drilling and surface infrastructure), geological uncertainty, the cost of the produced heat and the rate of return for investors. These issues are currently being addressed to enable the wider roll out of geothermal projects. One clear step forward is ‘heat network zoning’, which is currently in-development. This aims to define areas where heat networks should be put in place as the low-cost carbon option. This, in conjunction with a stated aim of DESNZ to source 20% of heat from geothermal, looks to provide more certainty to developers and investors. However, heat from geothermal is not going to be a widespread near-term solution as it requires significant infrastructure development. Indeed, it was speculated in coffee break discussions that DESNZ does not expect significant development towards its 20% target until after 2030.
The National Geothermal Centre has made a lot of progress over 2024, having only been established in January and formerly launched in June. This not-for-profit organisation aims to enable geothermal development at speed and scale by addressing key issues required to unlock geothermal potential. Its CEO, Charlotte Adams, highlighted the requirement for geothermal to be attractive for investors who often do not have the background to understand the complex risk profile. This is where geo-communication skills come in, so those of us working on the technical side of the equation need to be clear and concise when sharing information with different stakeholder groups.
The majority of the talks covered the wide and varied range of subsurface geothermal solutions. Indeed, a number of interesting talks covered live projects including Lanchester Wine’s mine water geothermal heating scheme, the United Downs Deep Geothermal project, the Leeds University campus ‘Living Lab’ geothermal project and the Gateshead mine water geothermal scheme. Further talks focused on modelling of geothermal solutions in different subsurface conditions. Projects ranged from shallow to deep and involved open or closed systems. There is no ‘one size fit’s all’ solution, which clearly muddies the waters. Going back to the comment above, clear concise messaging will be key for investors to understand the differences and benefits between the many solutions.
Another key area of discussion was around improving the efficiency of geothermal. In the subsurface, continual exploitation of heat resources for shallow ground source heat pumps or deeper Aquifer Thermal Energy Storage (ATES) solutions, causes their gradual decline. By combining winter heating with summer cooling solutions, heat can be replenished through the summer months by injection of waters heated by warmer surface temperatures. This allows heat resources to be extended thereby reducing the long-term investment in the geothermal solution .
The symposium wrapped up with two workshop sessions. I attended the Optimising Geothermal Deployments session which was targeted at identifying what is required to enable the wider roll out of geothermal solutions. We looked at the risk factors of the various geothermal solutions, which really isn’t as easy as it sounds! “IT DEPENDS” was a frequently used phrase which sums up my take-away from this! The type of geothermal technique you can use depends on a wide range of factors, both surface and subsurface. The risks are also highly dependent on the individual situation, and they could be geological, technological, societal or regulatory. For example, thinking about mine geothermal. ‘Reservoir risk’ is a lot lower in a recent mine, where you have good records and a good understanding of the mine and mining techniques employed, compared to a mine that was shut in 200 years ago.
With the barriers outlined by DESNZ, it is clear a lot needs to be done to move geothermal forward. The decline of the UKCS hydrocarbon supply looks certain to accelerate, given the increased windfall tax and reduced approval of field development plans. In order to provide UK energy security, we need to speed up the establishment of alternative energy solutions, and unlike wind and solar, geothermal does provide a possible baseline energy solution.
