GEOTHERMAL heating—using the warmth of the Earth’s interior to heat water—is an old idea. Using the planet’s natural coolness, though, is something of a novelty. Nevertheless, as cooling and heating are merely two ends of the same process, it could save money and reduce carbon-dioxide emissions. As long, that is, as you can find a suitable source of cold.
Fortunately for Toronto, it sits next to a very large supply of the stuff, in the form of Lake Ontario. Canada’s largest city has been pioneering the idea that instead of using electricity to power air conditioning, a useful supply of cold can be directly extracted from the environment.
The amount of electriciy saved is significant:
Some 36 buildings in the central business district have now been connected and a further sixteen have signed on to join the system. The project is expected to save the city 61 megawatts, enough to power 8,500 homes.
Toronto is not the only place this works, but one has to wonder why this hasn't been done in more places. The article states that several places have been looked at and rejected - Chicago and New York among them. In those cases, the water wasn't deep enough near shore and the cost of running pipes out to deep water was prohibitive. But certainly there are places this could be applied.