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.

Show me the numbers

[Stephen Samuel]

This is one of those things that looks good when you start -- but what happens when everybody starts doing it? What I'd love to see is some info on the volume of water extracted from the lake for this project vs. the volume of water in the lake. This would give geeks like me a much better chance of being able to figure out for ourselves just how much this is going to affect Lake Ontario and how much the basic idea is going to affect the lake as the idea becomes more popular (as I expect it will).

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?

This is happening elsewhere

[samjaffe]

Cornell University recently did this with the deep water of Cayuga Lake (http://www.worldchanging.com/archives/000839.html ). As you can imagine, it caused quite a spirited debate in such a liberal town as Ithaca. In the end it was approved and the University is gauging the environmental effects very carefully(http://www.town.ithaca.ny.us/PEZ%20proje cts/Lake%20Source%20Cooling/lake_source_cooling_mo nitoring_p.htm). So far, there's been little effect. Although some (http://www.cldf.org/tt_981216/chap1.html) might disagree. I would like to point out to the concept's cheerleaders that there's nothing wrong with asking questions about the fundamental ecological effects of our engineering projects. Those questions should be answered thoroughly and carefully. Yes, global warming appears to be a severe problem, however let's not replace it with a bigger problem by stifling debate and rushing in with an ABCO2 (Anything But Carbon diOxide) attitude that might be more harmful than the disease.

Re:5 Tonnes CO2 per Car?!

[the_twisted_pair]

Run the numbers for burning gasoline and you'll find out.

1 Imperial gallon of petrol ~8lbs. Stoichiometric combustion requires 14.7:1 air:fuel ratio by mass, so burning that gallon in travel requires about 118lbs of air. Estimate about how much fuel you burn in a year, multiply by 118 (or 95 for US gallons) - and suddenly five tonnes of CO2 as a byproduct is eminently feasible.

Example: SUV driven 18000 miles/year at, say, 15mpg US: 114,000lbs of air consumed, representing nearly 24,000lbs of oxygen to be bound up in combustion products. That's TWELVE tons of shit right there...

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.

As a pedestrian I welcome this

[geoswan]

There is one advantage of this system that I haven't seen mentioned yet.

Have you ever had an errand in the downtown office area, and walked through a big blast of hot air?

Not only does this save energy. But because those downtown buildings are not using conventional air conditioners for cooling, they are not dumping megawatts of waste heat into the outside air. I read that the use of this technique should reduce the local ambient air temperature on the downtown streets, where it is used, by several degrees.

As a pedestrian I welcome this.

Re:As a pedestrian I welcome this

[WindBourne]

Interestingly enough, most large buildings do run AC during the winter. Add up all the heat from ppl, computers, lights, etc. and the fact that buildings are better insulated than 50 years ago, you will see that you have to pump heat out (at least during the day). Bizarre though, huh.

In fact, Denver International Airport was ripped for choosing to do a white cloth roof. But once it got out that DIA would be running A.C. 24x7, then it became apparent that the roof lowered the heating costs. I first became aware of the need for a.c. in large buildings when the sears tower and O'hare were running a.c. while the outside temp. was -40F/-40C.

Residential applications?

[swb]

I've always wondered why you couldn't use a similar system in a residential area. We have a lake behind our house that's about a mile around and about 8 feet deep on average; couldn't we (at least the immediate lakeshore residents, if not a larger amount of neighbors) use the lake water to augment our air conditioners?

You'd dump warm water back in, but this could be augmented somewhat by holding tanks and underground piping that cooled it back to ground temperature. If the lake was man-made, the environmental effect would be essentially nil, and you'd only have to worry about thermal calculations.

This might not make sense for retrofitting, but what about for new developments? People like lake/park areas, and there's no reason that a cooling pond couldn't be framed in a naturalistic setting.

I suppose it all comes back to commercial viability; it'd take a more expensive air conditioner capable of combining water cooling with electrical compressor cooling, the "community" would be responsible for the cooling pond and piping, and the electrical savings might not matter.

Re:Convection?

[berzerke]

...The question is whether this kind of pollution is better than the carbon dioxide/refrigerant chemicals/coal power plant pollution. It is likely the answer is "yes".

As with any change, there will be winner and losers. In this case, I think the extra heat could make far more winners than losers.

I used to work at a coal fired power plant, the outflow channel (where we dumped warm (but clean!) water) was a haven for fish. Everytime I went past the channel outside the plant, there were always people fishing. Employees could fish closer to the outlet and they would. I watched them and most didn't even bother baiting the hook there were so many fish! Large fish for that area of the bay.

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.