Barriers and enablers to dual use of transportation tunnels for heating and cooling decarbonisation

The potential to source thermal energy from buried infrastructure such as tunnels and metro stations may offer significant potential to reduce the carbon dioxide emissions of heating and cooling, and reduce the costs associated with dedicated drilling for traditional ground-sourced systems. However, this remains a niche approach with few commercial schemes globally, partly due to high initial costs, long payback periods, technical uncertainties and the need to minimise construction risk and delays. To help address these challenges, the energy resource potential, technical and economic barriers and ways of overcoming them were examined for tunnels beneath Manchester and Crewe that were proposed as part of the HS2 Phase 2b railway construction. A worthwhile thermal resource was established, along with enthusiasm for use of the energy by the infrastructure developer and third parties in the vicinity. The economic case is set out, which establishes financial viability but with significant uncertainty based on future market conditions. This demonstrates the need for a supportive future policy environment to encourage the uptake of all available heat sources.