By Jeremy Williams

Did you know that Britain has a national supercomputer? It’s hosted at the Advanced Computing Facility at the University of Edinburgh and it’s used on our crunchiest problems, such as climate modelling or processing health data. It’s in the news this week because of a trial of a new heating idea – an idea that chimes nicely with the seasonal heat storage technologies I was writing about recently.

Supercomputers generate an enormous amount of heat and need to be kept cool. This heat is often wasted, and in Edinburgh it is currently captured through a pipe network and conveyed to rooftop cooling towers. A new trial has just been announced that will put it to good use. Instead of channeling warm water to the roof, the water will be piped underground to a disused mine. It will be held at a steady temperature in the old coal mine and then piped back up to the surface when needed. It can then be run through heat pumps for heating homes nearby.

The lab currently generates an impressive 70 gigawatt (Gwh) hours of waste heat every year, enough to heat around 5,000 local homes. The government recently announced an upgrade to the national supercomputer that will create 272Gwh of waste heat, so there’s further potential there in future.

There’s a nice sense of closing the loop here – and not just the idea of warming your home on the excess heat from a supercomputer running a climate model. It puts the left-behind remains of the coal industry at the service of low carbon heating, reversing the legacy of damage into something more positive and future-facing. And if it works, there are so many places where it could be applied.

I was visiting my parents in Wales over Christmas, and their Wrexham hillside is criss-crossed with old mine and factory rail lines, now taken down and wooded over. Those are still visible in the landscape if you know what you’re looking for. What you can’t see are the pits and tunnels the rail lines once connected, but they’re all over the hillside too.

All of them will be flooded – most active mines have to be constantly pumped out to prevent them filling up with water. The pumps are switched off when mines are closed, so they naturally flood. There have already been schemes that extract heat from this minewater, such as Seaham Garden Village. As far as I’m aware this is the first project in the UK where excess heat has been put into it, turning the mine into a giant ‘geobattery’.

If the scheme in Edinburgh is successful, there are many more places where it could be done. In fact, coal mining has been so widespread in Britain over the years that seven million households are close enough to old mines to theoretically tap into stored heat reserves. So whether or not you have supercomputers putting warmth in, using flooded mines for heating is something that we will hopefully hear a lot more about.

First published in The Earthbound Report.