Like a giant thermos bottle, the earth has remarkable insulating properties that enable it to maintain temperatures underground for extended periods of time. Environment Canada is applying this unique capability to store available, surplus processes - for heating and cooling buildings.
Underground thermal energy storage (UTES) uses permeable, water-bearing rock formations called aquifers - or, where aquifers are unavailable, a network of plastic tubing inserted into boreholes drilled into the earth - as underground storage areas for water. With the aquifer system, two well fields are tapped: one for cold storage and the other for heat. These wells, which are usually around 200 meters deep, are capable of maintaining storage temperatures of between 4 and 90 degrees Celsius.