Heat Recovery Potential from Urban Underground Infrastructures

This paper describes the results from a collaborative research project in the UK, focussing on the recovery of waste heat from underground railway tunnels, using London as a case study. The aim of the project was to investigate the feasibility of combining cooling of London’s underground railway tunnels with a waste heat recovery system. The recovered heat will then be transferred to a heat pump to upgrade its temperature, before delivery to a district heating network for reuse. The paper describes the proposed design for the combined cooling and heating system and the model that has been developed to evaluate its performance. A range of results from the study are presented and the potential benefits in terms of energy, carbon and cost savings are highlighted. The paper also introduces a related project, which builds on this case study and aims to identify and quantify the potential for waste heat recovery from a range of urban subterranean infrastructures, such as sewers and cable tunnels, as well as underground railway tunnels. Potential heat recovery and delivery methods will be investigated, in relation to the size and location of local end-user heat demand. Both of these projects focus on waste heat recovery in London, however, the results are applicable to most cities with underground infrastructure systems, both elsewhere in the UK and around the world.