September 20, 2019
The temperature inside a subway car in London’s Underground (subway) system can sometimes exceed 100 degrees Fahrenheit in the summer — and even in the winter, heat can be high, due to the trains’ operations. However, by the end of 2019, one London subway line will start sending that excess heat to nearby homes and businesses.
Specifically, hot water heated by the Underground will be piped into an existing district heating system that currently harvests waste heat from a power plant to warm 700 homes. The system heats water for showers and laundry, and also connects to radiators. This replaces a typical furnace in a home.
Climate-control-by-subway is an example of projects in the United Kingdom that are using waste heat from various sources to replace the standard gas furnaces, through district heating. The sources range from factories to abandoned mines. According to Tim Rotheray, director of Association for Decentralised Energy, the process involves taking a source of waste heat, that would ordinarily end up in the atmosphere, and providing it to someone who needs the heat. “Because it’s waste, it’s relatively low cost,” he told Fast Company. “And because if you didn’t capture that waste heat, you’d have to make it somewhere else, it’s more energy efficient and lower carbon.”
The system tends to make more sense in densely-populated areas, as heat is lost, the further it travels. “They work really well in cities and dense urban areas, and they’re not so well suited to suburban or, particularly, rural areas,” Rotheray said. “That said, we’re seeing many, many more people moving to cities, and more than half of the [U.K.] population lives in a city.
District heating is in use in other countries, as well. More than 90% of homes in Iceland are connected to a district heating system that relies on the country’s volcanic power or underground reservoirs. And, in Copenhagen, just about every house is connected to a district heating system.
For comments, questions or concerns, please contact Amy Sorter