The Drake Landing Solar Community (DLSC) is a neighbourhood in the Town of Okotoks, Alberta (Canada). It is one of the few communities in the world that has a central solar heating system. On average, it is able to provide about 90% of the community’s heating needs. In 2015-2016, the system was able to meet 100% of the community’s heating requirements with solar.
The central solar heating system consists of 3 main sets of components: 1) solar thermal collectors, 2) short term thermal storage tanks, and 3) borehole thermal energy storage. The idea is to store heat from the warm months for use during the cold months.
Solar thermal collectors. The community utilizes 800 flat plate solar thermal collectors (2.45m x 1.18m). These collectors work by using sunlight to heat up a glycol solution. On a hot a sunny day, the glycol solution can get heated to over 150 degrees Celsius just from the solar radiation. Each home has roughly 15 solar thermal collectors, and the heated glycol is transported to a heat exchanger which heats up water that is in the short term thermal storage tanks. The cooled glycol then returns to the solar thermal collectors to be heated up again.
Short term thermal storage tanks. These tanks are located in the primary energy center of the Drake Landing Solar Community. The purpose of these thermal storage tanks is to hold the heat captured from the sun for a short period of time. During the warm months, the hot water from the thermal storage tanks is diverted underground to the borehole thermal energy storage (BTES). The cooled water then returns to the short term thermal storage tanks to be heated up again by the glycol from the solar thermal collectors.
Borehole thermal energy storage (BTES). The BTES consists of 144 holes that are 37 meters deep. The purpose of these holes is to provide long term storage of the heat captured by the solar thermal collectors. The hot water from the short term thermal storage tanks is directed through these holes, and the surrounding earth is heated up to roughly 80 degrees Celsius. When heat is needed by the community (and the need cannot be met by the solar thermal collectors alone), the hot water from the BTES is passed back to the short term thermal storage tanks, and then sent to each home in the community. The hot water is used to heat up the air in the ducts of the homes in order to provide heat for the occupants.
Drake Landing Solar Community (DLSC) has proven that community scale solar projects can work. The key for future projects will be one of cost as DLSC received over 5 million dollars in federal and provincial grants. Future projects will need to be economically feasible without incentives if they are to be adopted on a large scale.