Tapping+deep+water+for+cooling

For over a century engineers have experimented with different kinds of lake-based cooling systems. But modern technology has finally made it possible to apply what's known as district cooling (using chilled liquids to cool groups of buildings) on a larger scale with more benefits to the environment. Toronto just announced that its 170-million-dollar (U.S.) deep-lake water cooling system, the largest of its kind, was up and running. Also known as "lake-source cooling" or "deep-source cooling," the process uses water pumped from the frigid depths of adjacent lakes or oceans to cool municipal buildings. This process is clean, renewable, and sustainable alternative to conventional air conditioning and is used around the world. But such systems can have their critics. The Canadian city's new cooling project draws water from five kilometres offshore and 83 meters down, where the temperature of Lake Ontario stays near 4 degrees Celsius throughout the year. Water is pumped to an island-based filtration plant and then sent through heat exchangers at an onshore pumping station. The heat exchangers allow the lake water to cool a separate, self-contained water circulation system, which flows through buildings in downtown Toronto. The lake water, meanwhile, ends up as drinking water for the city. The project will keep 44,100 tons of carbon dioxide out of the air, according to the company's Web site. The greenhouse-gas savings is equivalent to keeping 8,000 cars off the road. The project currently cools ten Toronto buildings, including the tiny Steam whistle Brewery and three skyscrapers in the Toronto Dominion Centre, a financial-and-business office centre. While Toronto has the largest deep-source cooling project yet, it's not the first city to plumb the depths of North America's glacial lakes. Four years ago Cornell University inaugurated a 57-million-dollar (U.S.) lake-source cooling plant. The system cools university buildings and a nearby high school in Ithaca, New York. The plant draws 3.9-degree Celsius water from 70 meters below the surface of Cayuga Lake, a glacially carved lake that is 132.6 meters deep at its lowest point. So far deep-source cooling is only practical for communities with numerous buildings located near large bodies of water. Back To Contents
 * Tapping Deep Water for Cooling **