Anyone who has ever travelled by subway can certainly agree on one thing: it’s really hot down there. Between the train motors, breaking mechanisms, lights, operating equipment, and millions of people hurrying in every direction, it should come as no surprise that subway systems produce so much heat. But what if we could harness that waste heat and use it to warm our homes? The London Underground is currently exploring this possibility.
The plan is part of Mayor Boris Johnson’s overall objective to cut London’s carbon emissions by 60% by the year 2025, while simultaneously aiming to generate 25% of the capital’s energy from secondary sources. Sweltering, stuffy subway heat definitely fits the bill. With this new heat recovery plan, the city of London could potentially reduce their annual carbon emissions by 500 metric tons.
The harnessed heat, taken from the Northern Line Tube, will be used to warm over 500 homes in the borough of Islington. The project, a collaboration between UK Power Networks, Islington Council, Transport for London, and the Mayor’s office, will join the Bunhill Heat and Power Network upon its implementation.
Since 2012, this network has supplied over 700 homes with surplus heat captured from a nearby cogeneration plant. The center uses waste heat from electricity production in order to warm a portion of the city’s buildings and water. Heat collected from the new subway initiative will use the same 1.4-mile-long pipe system belonging to the Bunhill network in order to direct heat into additional homes.
The London Underground isn’t the first to take action when it comes to innovative heat recovery plans. In 2010, the Paris Metro announced a similar project, which would redirect excess subway heat to a seventeen-flat public housing facility. However, the project is not expected to expand to other parts of Paris due to costly connecting passageways that must be built in order to transfer heat. The current experiment was only possible due to a preexisting stairway connecting the metro to the pilot building.
Recovered subway heat holds great potential for alleviating carbon emissions and creating greener forms of heating within metropolitan areas. However, there are still many obstacles that must be overcome. If this method is to become widespread and effective, city councils must be willing to cover the costs of heat transfer and piping networks. For a small initial investment, cities can reap huge benefits in the long run, drastically cutting carbon emissions while also implementing a more efficient heating system.
Check out London Underground's project to learn more.