Over 250,000 passengers pass through Stockholm Central Station every day, completely unaware that their body heat is being harvested for energy.
Passengers at Stockholm Central Station move freely, and the more they move, the more energy they produce, according to Amusing Planet. In 2017, engineers at the real estate company Jernhusen in Sweden discovered a way to harness this excess energy and transfer it to another building in the area.
Stockholm Central Station welcomes over 250,000 passengers/day. (Photo: Amusing Planet).
Using body heat to warm a building is not a new idea. Almost every crowded building, such as shopping malls or cinemas, does this in winter to reduce heating costs, as the heat generated by many people raises the natural temperature of the space. What sets Stockholm Central Station apart is how engineers collect the excess heat and transfer energy between two different buildings, according to Klas Johnasson, one of the system’s creators and the head of the environmental department at Jernhusen.
The system at Stockholm Central Station works as follows: Heat exchange devices installed in the station’s ventilation system absorb excess body heat and use it to warm water in an underground storage tank. This water is then pumped through pipes to the 13-story office building Kungbrohuset, located over 30 meters away, and integrated into the main heating system. This system is not only environmentally friendly but also reduces the office building’s electricity costs by 25%.
This technology is effective in countries like Sweden, where electricity prices are high and winter temperatures are very low. Other countries, such as the United States, may not see similar financial benefits after investing in insulation, piping, and pumps. Additionally, there are some limitations; buildings must be located close to each other, or else heat will be lost if it needs to be pumped over long distances. High electricity prices have compelled Swedish engineers to devise creative solutions for heating homes.
The heating project at Stockholm Central Station is not the only example of this type of body heat harvesting system. At Rambuteau Metro Station in Paris, a similar system has been in operation for nearly 10 years. The heat generated by passengers as well as the subway itself is used to heat the residential apartments located directly above the station. In Oslo, waste heat from raw wastewater is used to warm homes. Other projects have also been implemented in Finland and Austria. The Mall of America in Minnesota, USA, also utilizes the body heat of shoppers to support its heating system during the winter.
