Water found in disused coal mines has been identified as a new source of renewable energy for the UK, following a two-year study by Nottingham Trent University. In conjunction with renewable energy firm Alkane Energy, research has established that thermal energy found in groundwater in mines – which is naturally lukewarm due to ground heat – can be condensed and used to heat or cool buildings above the ground. This is similar to the work being done in the USA by Michigan Technological University, as posted to this website on April 13.
“In a way we may never have previously envisaged, coal mines could once again be used to provide warmth to thousands of homes across the UK,” said Professor Amin Al-Habaibeh, of the School of Architecture, Design and the Built Environment, who led the study. “But the key difference between yesteryear and tomorrow is that we now have the ability to harness their energy potential in a completely sustainable way.”
The technology is based on the use of a ground source heat pump system which takes the water from the mine shaft and pumps it to the surface where the latent thermal energy is extracted using a heat exchanger. Thereafter a heat pump is used to produce a much higher temperature than the original mine water by condensing the energy and circulating it in a separate central heating-type system. The cooler groundwater is then returned to the mine where it becomes lukewarm again via ground heat.
For the purposes of the study, the Coal Authority provided Alkane Energy with permission to explore redundant mines over a 30 km area with the potential to produce enough energy to heat around 45,000 homes.
The system also was tested at the former Markham Colliery, northeast Derbyshire, where the abstracted heat was used in an industrial building owned by Alkane.
The project was funded by Innovate UK and the research findings were presented at the global Applied Energy Conference, in Abu Dhabi, March 28-31.
Among the findings were that for periods when solar or wind energy is insufficient to power the ground source heat pump, the technology could still be four times more efficient when running on mains electricity than a modern gas boiler with 90% efficiency rating.
Al-Habaibeh has also developed with the research team and his students a small scale simulator of the technology for educational purposes (pictured).
Keith Parker, the Project Director at Alkane Energy, added: “Alkane has traditionally utilised gas contained in disused coal mines to power its core electricity generation business. The utilisation of heat from mine water gives rise to a further opportunity to make use of the mines to provide green, sustainable energy to homes and businesses in the UK.”
