The use of rail and sewer tunnels as a source of sustainable heating energy

With around half of the UK and EU energy usage associated with heating buildings, the provision of renewable heat is a key strategic priority for meeting our binding renewable energy and carbon dioxide reduction targets. Ground energy systems, where heat stored in the ground is extracted using a ground source heat pump will therefore play a key role in future energy provision. Recently, innovations in foundation engineering have allowed various geo-structures to be equipped with heat transfer pipes to enable them to act heat exchangers as part of ground energy systems. Railway or metro tunnels and sewer tunnels in urban areas offer a particular advantage for use with ground energy systems. They both offer an additional source of heat within the ground, as well as important nearby end-users for the heat energy that can be extracted.

In the next two decades London could see the construction of over 150km of new rail and sewer tunnels beneath the capital. This offers an unparalleled opportunity to offer sustainable heating to parts of the city by using the lining of these tunnels as heat exchangers. As well as extracting useable heating energy this will have the additional benefit of cooling the rail tunnels. However, while small trial sections of so called “energy tunnels” have been constructed in Europe, there is no full scale operational experience and no experience at all within the UK.

This project will investigate the energy potential of London’s future tunnels. It will involve exploration of the heat available from train breaking and sewerage, laboratory scale experiments to determine appropriate thermal boundary conditions for the tunnel lining and subsequent numerical simulation of tunnel linings and the surrounding ground under thermal load. The project will be run in collaboration with industry to ensure buildability is taken into account as well as to consider construction costs and payback periods.

If you wish to discuss any details of the project informally, please contact Fleur Loveridge, Infrastructure research group, Email: [Email Address Removed], Tel: +44 (0) 2380 59 2662.

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