Energy

Toronto, Canada

Lake water air conditioning reduces energy use by 90%

What is it?

By using the natural low temperature from water in Lake Ontario, Enwave Energy Corporation air conditions 29 million square feet in 51 high-rise buildings in downtown Toronto, reducing CO2 emissions by 79,000 tons and reducing electricity consumption by 90% compared to conventional chilling. Using deep lake water to cool enables annual savings of 128 million kWh annually in electricity.

How does it work?

Enwave owns and operates Toronto's downtown district energy system. The company is co-owned by a pension fund and the City of Toronto.

Up to 100 million gallons of water per day is transported through three large intake pipes - stretching-out 5.1 kilometers from the shore and lying 83 meters below the surface of the lake - to a filtration plant and then onto a pumping station downtown. There, the cool water is used to extract thermal energy from water in the district heating network. This heat exchange provides cooling to district heating customers and allows the lake water to reach normal drinking water temperatures, prior to distribution to the network and consumption as tap water.

Next steps

Enwave's Deep Lake Water Cooling project currently has a maximum capacity of 75,000 tons of refrigeration. The facility was at 73% of capacity as of February 2007 – less than 3 years after launch and two years ahead of the projected sales schedule. Given the huge public demand, there is a possibility that Enwave will invest further to expand the system capacity by an additional 25%.

Application

• A system such as this requires a concentrated high cooling demand
• Source of water with 4 degrees Celsius or cooler is necessary
• Patient investors with long-term investment horizons
• Environmentally-conscious consumers