Geothermal Heat and Power

Baroness Sheehan Excerpts

Thursday 6th July 2023 Grand Committee

[Baroness Sheehan (LD)]

My Lords, I declare my interest as a director of Peers for the Planet. I thank the noble Lord, Lord Cameron of Dillington, for giving us an opportunity to debate the potential of geothermal for heat and power in the UK. We have only to look across the channel to see what is possible. France, Germany and the Netherlands share the same tectonic plate as us and have harnessed this deep heat source far more ambitiously than we have. That said, I want to concentrate on the potential opportunity of using the shallow geothermal energy under our feet—not necessarily as far down as even a shallow aquifer but just the heat differential that exists between the air and the ground.

Ground source heat pumps use ambient stored solar energy in the ground, where temperatures remain constant 24/7, 365 days a year, regardless of air temperature changes. The Government have invested much energy and enthusiasm—and, I think, money—into trials for hydrogen boilers in towns in the north-east. These are riddled with challenges, not least that of explosions from the leakage of a notoriously leaky gas. That is unsurprising, as hydrogen is the first, and therefore lightest, element in the periodic table.

I cannot help but compare the hydrogen trial to the Heat the Streets pilot in Stithians, Cornwall, carried out by the Kensa Group. This essentially uses the proven technology of ground source heat pumps to see whether it can be deployed at mass scale to retrofit whole streets with typical mixed housing stock of any tenure; that is, in a realistic UK town or village scenario.

We are used to hearing about ground source heat pumps in a single property where a ground loop is installed in someone’s garden. Imagine that you can pay for a heat pump in your home without the headache of sorting out the details of where the ground loop would go because someone else would do that part for you. In essence, the networked model of heat pumps is the same as the gas grid model. A white box ground source heat pump is installed in your home, and you pay a standing charge to connect to the street’s underground loop infrastructure, which has already been installed by experienced engineers. Consumers have total control over their heating. For utility companies, it is an investment that will last for decades, as shared borehole ground arrays have a lifetime of up to 100 years. For landlords, it means no more split-billing or metering requirements for tenants. I should add that the technology can easily switch to cool homes, which is becoming more necessary. In an FT article, the BBC’s Roger Harrabin referred to the Stithians scheme as “simple and elegant”. It has much to recommend it.

Such ground source heat pumps have many advantages—I shall list only a few of the most important ones. They last a great deal long longer than air source heat pumps, and therefore work out cheaper in the long run, and use 40% less electricity. Most importantly, there are advantages at an energy system level. With demand shifting and heat batteries, networked ground source heat pumps could reduce peak electricity demand by 37 gigawatts, which could save up to £15 billion a year in reduced generation and grid infrastructure costs, something that I am sure is of great interest to the Government.

It is appropriate at this stage to welcome the heat network zones that the Government have proposed in the Energy Bill, but they should be extended to cover all the UK and make a stab at identifying the right technology for the right place, working together with local authorities.

In Committee on the Levelling-Up and Regeneration Bill, I tabled two amendments asking for government support for pilots for a renewable-powered new town and an existing town, both using networked ground source heat pumps to provide heating. Does the Minister, who I believe is pretty conversant with this technology—probably far more so than I am—agree that properly constructed trials are essential to carry out evidence-based assessments for potential solutions that merit government support? That will be essential to evaluate which projects could meet our fast-approaching decarbonisation deadlines. I end by saying that I intend to retable my amendments to the Levelling-Up and Regeneration Bill on Report.