Executive Summary

• Public opposition of data centres in their communities has come to the fore with the not in my backyard sentiment. But what if AI’s neighbours were thousands of feet underground instead?
• Sat in old mines, thousands of feet below us, is perfectly chilled water, just waiting to be utilised in the UK’s cooling strategies and take the pressure off the water scarcity crisis.coa
• Tapping into “thermal debt” of the 19th-century coal industry could power the 21st-century AI boom, a full circle moment where the energy that once built the UK is now cooling its digital brain.

“Not in my backyard” is a formidable force in the UK, as residents fight back against data centres built right next to their communities. Overall, the public has a negative view of data centres- from the guzzling of community water, dominating the skyline and the weird side effects of having a “grey box” for a neighbour – with some in the US having to stop gardening and growing vegetables due to new infrastructure built on their doorstep.

With the opposition and backlash, maybe it’s time to plan our data centres elsewhere; how about 2,000 feet underground or under the sea?

Geothermal electricity in Cornwall

The UK have several projects occurring around tapping into “thermal debt”, using the sea or underground to cool data centres. For example, there are projects in Cornwall that are using its unique geology (heat-generating granite) to create the UK’s first “always-on” energy and cooling hubs. They have drilled three miles into the UK’s deepest wells into the Porthtowan fault zone, where waters hit 190 degree celsuis. This 3MW site provides a superior thermal sink for AI. By matching data centres to these local sources, operators recover the 40% of electricity typically consumed by cooling systems.

The surface footprint of this project is small, seeing as the rest of the infrastructure is three miles deep, so that negates the “not in my backyard” debate, whilst providing 24/7 baseload power and cooling, a far more reliable renewable energy source than wind or solar to handle the demands of AI.

The flooded Coalfield network up North

Up North, around one-quarter of UK homes sit on former coalfields, now sitting pretty, filled with gallons of naturally chilled water. It’s quite the opportunity!

Projects in Gateshead and Seaham are “reanimating” the ghosts of old coal mines, using the naturally chilled water within them to cool data centres.

Gateshead have a “living lab” project, which reached its one-year milestone in January this year. Led by the Mining Remediation Authority, it uses 6MW heat pumps to pull heat from water 150m underground. It became a global research hub for US and European scientists who are looking at how they can utilise this water to cool huge compute clusters.

Furthermore, Seaham Garden Village in Durham is a project next to the Dawdon Mine Water Treatment Plant; it abstracts 100-150 litres per second of water at around 18-20 degrees Celsius. Just picture a huge radiator for the region’s new digital infrastructure, that’s what it’s like.

In 2026, the UK’s former industrial heart will no longer be forgotten and in memory only; they are now potential heat sinks for the future digital revolution. Tapping into “thermal debt” of the 19th-century coal industry could power the 21st-century AI boom, a full circle moment where the energy that once built the UK is now cooling its digital brain.