In 2021, most people have heard of air-source heat pumps and ground-source heat pumps. But in this month’s Hole Report we are sharing how Drilcorp is working with organisations to harness the potential of mine-source renewable energy supply.

Over recent years there has been a sustained drive to reduce human influence on global warming and seek out environmentally friendly ways to generate energy without increasing carbon emissions.

Although the UK, and indeed the rest of the world, are still a long way from achieving net zero status, there have undoubtedly been great strides made in the way we heat and cool buildings using heat pumps. In essence, heat pumps collect low-grade heat from a sustainable source, pass it through a compressor and multiply it to become useful for heating water or space within a building. If reversed, the heat pump can also be used for cooling.

Sustainable sources of heat can include the atmosphere (known as air-source), the earth (known as ground-source) and now disused flooded mine workings, which are known as mine-source.

Old workings that have been allowed to flood following closure of the mine have become an excellent source of groundwater (minewater) with temperatures ideal for passing over a plate heat exchanger to convert to heat. Thanks to our engineering expertise, the Drilcorp team have been at the forefront of innovation and the development of techniques needed to drill through sequences of mine workings to exploit this resource.

In recent years, we have worked across a number of sites in support of leading organisations that have prioritised low-carbon initiative and are taking strides to improve their sustainability credentials. Here are a just a few of the projects the Drilcorp team have worked on.

Glasgow Observatory

Drilcorp drilled five large diameter mine-source boreholes using reverse circulation methods into the flooded workings of the Glasgow Upper and Glasgow Main seams. The boreholes will be used as an observatory to investigate the response of the workings to heat abstraction and storage, providing a great insight into the future of mine-source heating and cooling technology.

Mine-Source air conditioning for large wine storage warehouse in Gateshead
Drilcorp has been involved with the development and testing of a series of mine-

source boreholes on two sites for a Gateshead-based client. Work has involved the deepening of some boreholes into deeper mine workings, extensive developmen

t clearance to bring each borehole to optimum performance and test pumping between boreholes and workings at different levels.

Through intensive testing, Drilcorp has worked with the client to find the optimum scenario for the heat pumps to air condition the vast warehouses located above these mines. This client has been a pioneer in the research and development of mine-source as an option for reduced energy consumption and we are excited by the potential for this technology as a sustainable and cost-effective long-term solution.


Gateshead Council uses mine-source to “Green” the North East.

Once again Gateshead is at the forefront of mine-source technology development and Drilcorp is onboard to assist. This project involves the drilling of two deep ab

straction boreholes to take minewater from Hutton Coal Seam workings and one additional recharge borehole to dispose of the used Minewater into shallower High Main Coal Seam workings.

Due to the age and poorly mapped location of the target workings in Gateshead,

this project first involved a “de-risking” phase – to mitigate the chances of a borehole failing to hit the target work seam under existing conditions. This de-risking exercise involved both an exploration and production phase devised between Drilcorp’s design engineers and specialist Coal Authority advisors. Risk mitigation plans were implemented to ensure that the expensive large diameter production boreholes were drilled in locations guaranteed to intersect the target mine workings.


Exploration Phase (completed)

A series of exploration boreholes were to be drilled using very exacting coring methods to maintain verticality while obtaining high-quality cores of the coal measures being penetrated. Drilcorp’s specialist verticality survey tool was used to verify the accuracy of the borehole alignment and the exact location of mine workings discovered.

When mine workings were discovered in the Hutton Seam, they were test pumped to prove suitability for abstraction. Once workings were discovered in the High Main Seam, water injection tests were carried out to prove suitability for reinjection.


Production Phase (currently under construction, as of July 2021)

Work is currently underway on this exciting project to enlarge the successful exploration boreholes and convert them into production abstraction/reinjection sites. After extensive research, suitable casing materials were established that would withstand long-term contact with mine water chemistry.

With the support of Drilcorp, Gateshead Council and Gateshead Energy Company are leading the way in creating a “greener” North East.



To find out more about the mine-source drilling services provided by Drilcorp, please get in touch via info@drilcorp.vm or by calling 0191 5273970.

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