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To meet the UK's commitment of Net Zero greenhouse gas emissions by 2050, virtually all heat supply needs to be decarbonised. That means taking steps to transition away from fossil fuels to low carbon heat sources. 

The future of heating is likely to be a mix of efficient, low carbon technologies – covering heat pumps, heat networks, and a potential role for hydrogen. But with an increasing reliance on electricity for low carbon heat and the need to secure reliable, clean energy sources – should we be looking to geothermal energy?

What is Geothermal Energy?

Geothermal energy refers to heat stored within the Earth's crust which can be converted into heat and electricity. It is a natural source of heat that is low carbon and renewable. There are a range of ways of harnessing geothermal energy – and the most appropriate extraction technology is often determined by geography.

Shallow geothermal systems typically extract heat at a lower temperature and combined with ground source heat pumps, that heat can be adjusted to provide a usable heat source for residential or commercial purposes.

Deep geothermal systems typically produce heat with higher temperatures that can be used directly as heat sources or for electricity generation. These systems usually require boreholes and geothermal reservoirs miles beneath the Earth's surface to extract heat at required temperatures. Most of Iceland's heat demand is served by geothermal energy – and that is due primarily to its active tectonic geology.

There are also various examples in the UK of mine water energy systems which utilise thermal energy in abandoned mines – which benefit from consistent temperatures year-round.

Geothermal Energy in South West England

Running beneath the peninsula of South West England from the Isles of Scilly to Dartmoor (where it emerges so spectacularly) is a geological structure known as the Cornubian Batholith. Comprised of granite, an igneous crystalline aggregate of quartz, feldspar and mica, often used in construction, this structure plays as key role in the future of Cornwall's low carbon energy supply.

One high profile project that is harnessing the benefits of the unique geology of the region is the United Downs Deep Geothermal Plant near Redruth. This project is the first geothermal power plant in the UK and will produce heat and power from heat extracted from the Cornubian Batholith. The project has been underway since 2009, and will inject and extract heated water from deep underground to create vapour to power turbines and electricity generators, and produce a direct source of heat. The plant is due to supply heat and power to Langarth Garden Village (located outside Truro) via a new pioneering heat network from next year.

Given the size and capacity of the plant, there are likely to be various other opportunities for heat and power offtakes. We understand that it is proposed that farmers will also be able to access and use this network as a cost effective and efficient heat source. Possible uses include greenhouse heating, pasteurisation, and timber treatment, among others.

Geothermal heat and power potentially provide an opportunity for low carbon heat and power sources to new developments in the area, and for a range of domestic, commercial, or industrial purposes. Any heat offtake or power purchase arrangement needs careful consideration before it is entered into - particularly on the key terms of supply (including supply commitments, pricing and length of term). An understanding of the key commercial drivers and regulatory complexities are vital to ensuring that any such arrangement meets individual requirements.

Future of Geothermal Energy in the UK

When asked to consider geothermal power, most of us automatically think of Iceland or other regions with similarly elevated tectonic volatility. However, the UK has been cautiously investigating it since the 1970s, although we have fallen behind our European counterparts in realising its potential. For example, Paris utilises geothermal heating networks to supply a quarter of a million homes since first tapping into heated aquifers (underground layers of water-bearing rock) in the late 1960s.

In 2022, the House of Commons Environmental Audit Committee launched a review examining the potential role of geothermal technologies as part of the UK's commitment to achieve Net Zero. The committee raised concerns that Government policy had not integrated it as part of its Net Zero strategy and called on the Government to provide longer term support for geothermal heat. The Government's response highlighted that extracting lower temperature geothermal heat for use in heat networks was likely to represent the most 'widespread opportunity' for geothermal energy to decarbonise the energy system within the UK. That follows the Government's Heat and Buildings Strategy (published in 2021) which positions heat pumps and heat networks as the UK's primary routes to decarbonising heat.

With Government ambitions to grow the heat network sector with the aim that 20% of the country's heat will be supplied by heat networks from 2050, there is opportunity to utilise geothermal heat sources on a commercial basis. Regulation of heat networks is due to be introduced over the next few years which is likely to provide greater confidence in the market – but potential implications of regulation (especially for those carrying out regulated activities) need careful consideration.

Overall, there is a role for geothermal energy in the decarbonisation of heat and in the move away from fossil fuel power sources – but location restrictions, cost, and potential environmental impact are likely to remain key barriers to large-scale deployment.

Trowers & Hamlins property, land and energy teams have a wealth of experience in managing the complex transition to alternative land uses and development of renewal energy. Please get in touch if you'd like to know more about how we can advise you.