April 2013: This week’s New Scientist features how “Smart heat is helping building the next energy revolution”. The article (subscription only…) looks how the use of technologies such as combined heat and power (CHP) and heat pumps could help “reverse some of the damaging effects that waste heat from our towns and cities is having on the climate ” – and the use of waste heat from London Underground is also examined:
“As passengers often complain, exhaust heat accumulates in the train tunnels under many of our largest cities. Even on a cold day, temperatures on platforms in the London Underground can reach 20 °C. To harvest that warmth, German companies Züblin and Rehau, together with Arup, have designed a liner for tunnel segments that functions like the buried coils in ground source heat pumps, using the heat generated by engines and braking along with that from the surrounding ground to warm the refrigerant, again by compression. As this transfers the excess energy from the tunnel to the refrigerant, the process also causes the tunnel to cool.”
“The lining – dubbed Energietübbing – was placed into a 54-metre-long stretch of a new high-speed rail tunnel in Jenbach, Austria, to supply the municipal building above with enough heat to completely replace the existing boiler. It is still being optimised, but in its first successful winter it coped with outside temperatures as low as -15 °C. London commuters could soon benefit as well. Crossrail, a railway being constructed under the city, is considering Energietübbing for several segments of the new tunnel, where it too would both cool the tunnel and provide the resulting heat to buildings above.”
A recent question to the Mayor highlights which of the stations on the Crossrail route are planned to integrate heat pump technology to provide waste heat to buildings above. “Out of the twelve oversite development schemes Crossrail is developing only two will not include a capability for using ground source heat pumps. These are at Woolwich and Limmo, where Crossrail is constructing a vent shaft. At these sites a large proportion of the oversite development schemes are not integrated with Crossrail infrastructure. Future owners of these oversite development schemes will however be able to install ground source heat pump technology within the buildings foundations. “