How heat from trains and sewers can warm our homes
- 05 December 2013 by Paul Marks
- New Scientist
Europe wastes more heat than it uses to keep buildings warm. Now projects across the continent will tap everything from subways to sewers to keep homes cosy
TAKE the escalator down to platform level at any deep London Underground station and a wave of warm air wafts over you. Dug in the 19th century, the poorly ventilated tunnels were not designed for today’s train and passenger volumes, trapping heat from engines, brakes and the bodies of London’s commuters. It is not just unpleasant on a summer’s day – that heat represents a huge amount of energy going to waste.
And so it was announced last month that some of this energy will be channelled to nearby homes. It is one of five such projects in the works. Urban heat sources across European cities, such as waste water from baths and washing machines, could soon be tapped to cut heating bills and help Europe hit its carbon emissions targets.
That is the aim of Celsius, a €25-million project funded by the European Union to investigate whether waste heat can be economically recovered and put to good use. There is certainly plenty of heat available to be tapped. One startling statistic unearthed by researchers working on the Heat Roadmap Europe project, led by Aalborg University in Denmark, is that Europe currently wastes more heat than it uses to heat all of its buildings. “We just need to direct it more usefully,” says Jonas Cognell, the project’s coordinator in Gothenburg, Sweden, where he is an engineer with the power utility Göteborg Energi.
In London, hot air will be captured from electricity substations as well as the metro system. Gothenburg’s task is to find a way to use the heat from waste incinerators and giant industrial fridges. In Cologne, Germany, the warmth of the sewer waste water will be the energy source of interest, while in Genoa, Italy, researchers will be investigating whether pressure differences in the gas distribution network can be used to drive turbines. In Rotterdam, the Netherlands, heat from the massed ranks of servers in data centres will be scrutinised.
Sewers and incinerators have perhaps the greatest potential, says Cognell. Cologne will use heat pumps, a mature, well-developed technology, to boost sewer water temperatures from around 20 °C to 70 °C. “Incinerators are a vastly underestimated source of energy,” Cognell says. Although they actively burn refuse, much of the heat is simply dumped in the atmosphere. “It is not a good way to use resources.”
The first project to be up and running is likely to be in London, where Islington Council is spending £2.3 million to harness heat for local homes by 2016. The project is based at Bunhill power station, which is close to “Silicon Roundabout”, the hub for London’s technology start-ups. Bunhill already pumps hot water to 900 nearby homes via a network of district heating pipes. Once air-to-water heat exchangers have been fitted in the nearby Northern Line’s ventilation shaft and a local substation, project chief Charlotte Large hopes at least 500 extra homes will benefit. “Probably many more,” she says.
Cognell hopes to have 50 cities adopting Celsius technologies by 2017, provided they can be shown to be economically viable. Matthew Pencharz, a senior adviser on energy for the Greater London Authority, is feeling confident: “We’ll prove the case. Our calculations show these energy sources are well worth pursuing,” he says.
This article appeared in print under the headline “Can’t stand the heat? Use it”