From the bottom of the lake – deep lake cooling in Toronto

Chilling downtown Toronto

Year-round cold water chills downtown Toronto

Take a city by a large lake with year-round cold water, install three 3.5 mile long intake pipes that reach 272 feet below the surface and what do you get? You get fresh drinking water and the world’s largest deep lake cooling system.

Thermal interfacing - two birds with one stone
The beauty of the Toronto solution is that it is really two solutions in one; a potable water system thermally interfaced with a district cooling system. Water only needs to be fetched from the bottom of Lake Ontario once to supply both systems.

Cold energy transfer
After filtration and treatment, the cold water from the lake is piped to an energy transfer station. Here, cold energy transfer ‘borrows’ the coldness from the lake water, but does not use the water itself for cooling. The 40 oF cold lake water is passed through plate heat exchangers to chill the water in the closed loop cooling system on the other side. This chills the water from a temperature of 55.5 oF to 41 oF. Finally, the chilled water is further cooled by mechanical chillers to a temperature of 38 oF before continuing on its way to provide customer cooling.

Warming the lake water
The cold energy transfer process not only cools the chilled water for cooling: it also warms the lake water itself to a temperature of 54 oF, perfect for the city’s potable water. Therefore, instead of being directly returned to the lake, the lake water is sent out into the city’s municipal potable water system.

Toronto has everything you need for deep lake cooling. A downtown with high-rise density, a high-level of year-round demand for cooling and air conditioning adjacent to a supply of consistently cold water.

Everything you need
Toronto has everything you need for deep lake cooling. A downtown with high-rise density, a high-level of year-round demand for cooling and air conditioning adjacent to a supply of consistently cold water. The waters of Lake Ontario become very cold during the winter, causing the cold water to become denser and sink to the bottom of the lake. Over many winters a reservoir of cold water has built-up, which remains in place even during the warm summer months, providing a year-round supply of cold water.

The system
Initially installed in 2004 the deep lake cooling system is able to provide up to 40% of the city of Toronto’s cooling needs, providing air-conditioning for 100 office buildings or 34,400,000 sq. feet of space. Customers include office towers, legislative and government buildings and sporting and entertainment facilities. The system is able to deliver 75,000 TR (260 MW) of refrigeration capacity.

Savings:
• 85 million kilowatt hours of electricity annually
• 185 million gallons (700 million litres) of water consumption from cooling towers
• 79,000 tons carbon dioxide from electricity production
• Reduced CFC emissions

All savings are compared to coal-fired electricity.





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