Cooling Toronto Using Lake Ontario

An anonymous reader writes "Air cooled by the frigid waters deep in Lake Ontario started bringing relief to buildings in downtown Toronto on Tuesday after the valves were symbolically opened on the multi-million-dollar project. The company says that they have the capacity to air condition 100 office buildings or 8,000 homes - the equivalent of 32 million square feet of building space. They note that the cooling system reduces energy usage, freeing up megawatts from the Ontario's electrical grid, minimizes ozone-depleting refrigerants and reduces the amount of carbon dioxide entering the air."

Comments

Just two questions

[cyclop]

(1). What will happen when the lake water will be warmed up? Ok,it will perhaps take a long time,but...

(2). How does the energy required for pumping / distributing the water and maintaining pipelines and machinery compares with electrical conditioneers?

Said that, it looks like a nice idea.

Messing with lakes: NOT a good idea

[Capt'n Hector]

Several times in recorded history, lakes have "belched" massive amounts of carbon dioxide, killing off not only fish, but people in surrounding areas. Lake Nyos is one such example. The circumstances vary, but always involve extremely deep water, saturated with CO2, being shifted to a shallower depth. When this happens, water has a much lower capacity for CO2, and it is released into the air.

Not that I'm predicting this will happen here, but it's usually best not to heat deep water like that.

"The cold is extracted"?

[Bertie]

Er, how? What does this mean? Cold's just the absence of heat, the only way to "extract" it is to heat something up.

Re:The lake is NOT warming up !

[frovingslosh]

Actually, it's unlikely that the city was drawing it's drinking water from this deep before. They were almost certainly taking it from a point higher up and warmer. So the city drinking water may not be warmer at all as a result of this; it might even be cooler. And, since the lower water can hold more CO2, it might be slightly carbonated! (Look for the interesting side effects when somewhat more acidic carbonated water is flowing through old pipes.)

On the other hand, since the cold water is being taken from the lake now rather than warmer water, the thermal barrier between the warmer top water and the lower cold water may slowly lower (and it is a very sharp layer, not the gradual drop in temperature you might expect). This may indeed have some effect, but that doesn't seem very likely.

They could have gone the simpler and more direct route of just building a power plant that used the difference in tempersture between the cold bottom water and the top water to pump up that water and generate electricity. Such plants have been proven to work with ocean water, and should be even simpler in an environment without salt water's effects. I'm assuming they didn't because in Toranto that top water would also get pretty cold in the winter. Still, I don't expect they will need much air conditioning in the winter anyway, so a seasonal power plant might have been as good or better of an idea.

It's a GREAT Lake

[Titusdot Groan]

Just a reminder folks, Lake Ontario is one of the Great Lakes, it's REALLY big. Like you can't see the other side of it from the shore line. Big. Really big. Like it's huge. Average depth of 86 meters, surface area of almost 19000 km2. Big.

Did I mention it's big?

Plus water turns over automatically at 4C (that's the temperature when water is it's coldest). Lake Ontario is not meromictic and has a natural turnover anyways.

Re:Environmental effects

[L0C0loco]

What??? Water is its densest at a temperature of 4C. Cold water pumped out during the summer cooling months has a chance to be replenished during the next winter. As the winter ice melts and the melt water warms it begins to sink due to the relative increase in density as it approaches a temperature of 4C. So long as the winter cooling capacity of the lake exceeds the summer cooling needs of the city, this should be a sustainable practice. It is true that the thickness of the cold layer will thin during the summer pumping season, but it will thicken again during winter. Obviously, this pumping will cause the mean thickness to decrease - they just need to hope it doesn't thin too much. The problem with free lunches is that people eat too much, get fat, and die!

Re:Environmental effects

[macthulhu]

I live about 90 miles south of the Canadian border in Western NY... The winter cooling capacity 'round these parts is pretty high. It's about time somebody figured out a way to use the area's largest natural resource... Snow. My only question is what happens to algae growth if the lake warms up even a couple of degrees?

Also an interesting fact about water

[ShadowRage]

and the water will never reach freezing at the bottom, it'll always be a degree or just afew hundreths of a degree above freezing at the least, never lower than that? why? water in its solid form is lighter than its liquid form, it's one of the few elements that does this, which makes its liquid form rare in the universe. However, by utilizing this, they can cool office buildings and never worry about heating up the lake, unless they pumped the warmer water they used to the very bottom, but even then the water would chill, and would get colder again, because the amount of cold water outweighs the warm water.

hell, if you wanna see a good example, look at the bottom of the ocean where there is no sun, but there are volcanic vents, the water at the bottom of the ocean isnt hot due to that, and that's more constant heat output than any city could produce in a million years.

Re:Environmental effects

[pilgrim23]

200 yers ago men with horse buckboards and hacksaws went out on the lake, cut up massive blocks of ice, hauled these back to underground brick lined cellars and packed them in straw. All summer this ice was used to cool those who could afford it. This pumping tech just strikes me as an extension of the earlier tech.