Converting abandoned coal mines to create green energy for the future
For many years, the mining of coal and other fossil fuels has been associated with pollution and environmental damage. Energy produced from coal alone contributes to around 25% of greenhouse gas emissions. But today, the work of NTU researchers is harnessing the power of closed and abandoned mines to provide a vital new source of renewable energy.
When coal mines were operational, water was pumped out of the underground shafts and galleries to keep workers safe and dry. After closing, most of these subterranean areas are now filled with water. Under the surface, the UK’s disused coal mines hold millions of cubic metres of empty space – with a water capacity that could fill 400,000 Olympic swimming pools.
Researchers from NTU’s Product Innovation Centre, led by Amin Al-Habaibeh, are now taking advantage of this. Because the water is generally at a stable temperature – between 12C to 20C – it's perfect for warming or cooling buildings, or for use in vital industrial processes.
Our researchers have developed new technology that takes the water from the abandoned mines to create green, sustainable energy to homes and businesses. With the introduction of Ground Source Heat Pumps (GSHPs) into the abandoned coal mines, warm water can be extracted (with cooler water then injected back into the same shaft) to provide heating to buildings.
This provides an opportunity for efficient heating and cooling applications. Furthermore, there is an associated reduction in overall carbon emissions, with GSHPs generating more thermal energy than they consume in electricity.
The technology is straightforward, working similarly to a refrigerator or air-conditioning system by extracting the heat from underground water and using it to warm buildings. It produces no noise or local air pollution, and it is also three or four times more efficient than a standard electric heater or gas boiler.
The team have tested this new technology using two systems: one at Markham Vale and one at the National Coal Mining Museum for England. In collaboration with Alkane Energy, the site at Markham Vale was converted into a water-pumping station to remove water from the local mine. Using a GSHP, that water was used to heat the office building on site. When compared to a modern boiler with 90% efficiency, the GSHP will produce 300% and 433% more energy for the same cost.
The use of water from abandoned coal mines has revealed another opportunity for our researchers: in the UK, coal mining technology programmes already pump circa 112 million megalitres of water for environmental reasons - such as avoiding the pollution of drinking water, springs and rivers, for example. The new technology developed by NTU’s researchers could use this water, which is being pumped anyway, and potentially generate an additional 63 megawatts of heat, which should be consistent year after year. This is equivalent to the heat generated by 31,500 kettles.
It doesn’t stop there – this new approach can be integrated with other heating technologies, and in many cases it can be implemented with existing building infrastructure, providing a low-cost solution to an expensive problem.
Successful, large-scale studies have already taken place to show how effective this repurposing technology can be. In Asturias, Spain, a hospital and university building are already being heated using coalmine water. NTU’s research shows that this technology could give the world’s abandoned mines a new, greener lease on life, whilst also reducing carbon emissions and lowering energy costs.
The team is currently exploring further collaborations with key partners to develop more efficient heating systems using coalmine water.
You can read the team's latest publication on this research here.
Professor Amin Al-Habaibeh is Professor of Intelligent Engineering Systems within the Product Design team at Nottingham Trent University. His research and teaching activities focus on several multi-disciplinary topics in the broad area of product design and innovation, automation, energy, condition monitoring and artificial intelligence.
This research is drawn from the strategic research theme of Sustainable Futures.
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Product Innovation Centre
The Product Innovation Centre is an internationally leading multidisciplinary Centre which offers innovative research and technology solutions through an interdisciplinary product design and engineering team, addressing global challenges towards creating a positive impact to industry, people’s lifestyles and society.
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