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Geo-Mole simplifies installation of ground-source heat pumps

A device that could make installing renewable energy heating systems easier has made it through to the final of a government competition.

The Geo-Mole enables the installation of ground-source heat pumps into a narrow 100m hole in the ground without the need for large drilling rigs.

The device has been recognised in the Make it in Great Britain Challenge for its potential to make heat pumps more accessible to people whose homes have very little outside space.

‘You need a lot of room to get a drilling rig in and if you need more than one probe they need to be at least 6m apart, so you need a huge area and you’ve got to put up with a lot of mess and disruption,’ Mark Brice, Geo-Mole inventor and managing director, told The Engineer.

‘The benefits of this are that it’s portable, you can put it on your shoulder and go anywhere with it. You could walk through a terraced house into a tiny garden and lift up one paving slab and put a probe in the ground without making any mess.’

Ground-source heat pumps use buried pipes filled with water to transfer heat from the ground to houses above, or vice versa in the summer.

Instead of using the conventional method of drilling a hole and then feeding the pipes down afterwards, the Geo-Mole uses the pipes to carry air to a piston-driven pneumatic earth compactor that drills to depths of up to 100m. The mole and the pipes are then left in the ground and can be connected to the heat pump.

Traditional mole devices are commonly used to drill horizontal holes for utility infrastructure using a single pipe with exhaust holes. Brice came up with the idea of instead attaching a second pipe for exhaust connected by a patented valve, which then completes the heat-pump circuit once the pipes are installed in the ground.

The company estimates that a 100m-deep system would be sufficient for a 5kW heat pump that could provide heat for a typical two-bedroom terraced house. It plans to launch its initial product in six months, and follow this with an upgraded version that can dig deeper and wider holes for larger heat pumps.

As well as reaching the final of the Make it in Great Britain Challenge, which aims to promote pre-market products developed in the UK, Geo-Mole also received £40,000 from Shell’s Springboard programme to support companies creating products that will help combat climate change.

‘Geo-Mole was recognised by Shell Springboard because of the simplicity of the technology and the ease with which it can be deployed,’ said John MacArthur, vice-president of CO2 policy at Shell, via email.

‘It’s our belief that the innovative services and technologies that small businesses such as Geo-Mole provide can make an important contribution to reducing the UK’s carbon emissions.’

Readers' comments (5)

  • A superb idea, I can see this making a real contribution to the drive for energy efficiency.

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  • Where is the grout pipe? The size of the borehole looks to be very small compared to the pipe size, which would make it difficult to insert a tremie after the loop is installed. How do you grout the holes? How does it work in rock or when you hit a rock lens? How long does it take to reach a depth of 100 m?

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  • I'd be very, very surprised it can bore through solid rock. I'm sure it's a soil-only solution (nothing obvious on the website).
    Grouting is only needed if there is insufficient water migration through the borehole.

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  • It is for compactable or displaceable ground, not solid rock.

  • Very interesting if the production versions can be made to work. Looks like a tremmie can down with the U-tube. Grouting is required for all closed loop GSHP boreholes using U-tube style completions in the UK. Unless the EA or SEPA give dispensation otherwise.

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  • Wanting to design a heat pump system for my property, would I need a geo survey first, how much would a 100m bore hole cost and would I need planning permission or any council approval

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