6 ms·

The largest deep lake water cooling project just got bigger

47 points by throw0101b 3y ago

throw0101b 3y ago
https://archive.ph/IZSDQ https://archive.ph/IZSDQ https://archive.today/IZSDQ https://archive.today/IZSDQ
throw0101b 3y ago
* https://en.wikipedia.org/wiki/Deep_water_source_cooling https://en.wikipedia.org/wiki/Deep_water_source_cooling * https://en.wikipedia.org/wiki/Deep_Lake_Water_Cooling_System https://en.wikipedia.org/wiki/Deep_Lake_Water_Cooling_System
Cieric 3y ago
I'm kind of a novice on this, but what happens to the heated up water? I assume returning it to the bottom of the lake could have effects on local wildlife, so is it returned to the top? That seems like it'd have the same effect but take longer since the hot water will remain toward the top. Or is it assumed to be fine since when winter rolls around the heat will be dissipated then. I'm mainly curious about the result to the native wildlife since practice engineering's videos on the dams and how fish are handled.
- timr 3y ago
  The article says that the water is returned to the lake at about the same temperature that it leaves...though I'm unclear how that's possible.
  - FredFS456 3y ago
    The heated up water is consumed as drinking water. Excess water is returned to the lake.
    - timr 3y ago
      That makes sense, but is a bit misleading (on the part of the article) if true -- you'd have to be pretty lucky to have your water consumption needs exactly match the heat capacity of the system.
      - bducycy 3y ago
        [dead]
      - thsksbd 3y ago
        Most of the water is returned to the lake, not sent to plumbing.
      - thsksbd 3y ago
        They dump the excess.
  - bunabhucan 3y ago
    If you presume the return pipe is much smaller, placing it inside the inlet pipe makes a counter flow heat exhanger. https://learnmech.com/types-of-heat-exchanger/ https://learnmech.com/types-of-heat-exchanger/
    - timr 3y ago
      And so what do you do with the heat you've exchanged? It has to go somewhere.
      - thsksbd 3y ago
        The cold, dark sky of the 4K Universe. This is net cooling L. Ontario because Darlington (hence the its cooling loop) doesn't have to run as hard to power all the displaced ACs
    - yetihehe 3y ago
      That will just make your extracted water hot, making the whole thing a waste of energy? Return pipe is municipal wast treatment, which is probably enough to make that water essentially the same temperature as surface level waters once it returns to the lake.
  - deleted 3y ago
    [deleted]
  - TrainedMonkey 3y ago
    Not sure if that is the solution here, but the easy way is high volume. If you have enough water volume compared to the amount of dumped heat the temperature rise will be tiny.
  - Alex3917 3y ago
    > The article says that the water is returned to the lake at about the same temperature that it leaves...though I'm unclear how that's possible. The most plausible explanation is that the article is wrong, and that the author meant to say that the lake is about the same temperature as it was before. Which is generally true; although the water being returned is slightly warmer, once you get more than a few meters away the difference is negligible. There is a ton of research on this phenomena with respect to the lake source cooling plant in Ithaca, because people obviously had the same concerns about that one before it was built.
    - thsksbd 3y ago
      this system is probably locally cooling the water since the 4C water picks up relatively little heat from the city and is returned to the warmer surface layer. Although L. Ontario's surface can hardly be described as "warm"
    - timr 3y ago
      Well, heat capacity of water is 1 calorie (4.18J) per gram. The interwebs hand-wavily say it takes about 25 BTU/hr to cool 1 square foot in a commercial HVAC system. 1 BTU is about 1kJ, so every 1 square foot of cooling (per hour) could theoretically be offset by 25,000J / 4.18J = ~5980g of water being heated 1 degree C. Density of water is 1g/mL, so it takes approximately 6L per hour per square foot if you assume that you don't raise the temperature of the water more than 1 degree C. They're talking about 50 million square feet with this system, so that's 300 million liters per hour, or about 80 million gallons per hour, or 1.3M gallons per minute. For context, the third water tunnel project in NYC was supposed to deliver 1.3B gallons per day, or about 903,000 GPM assuming constant flow. That's a big pipe. I tried to find actual citations of their flow rate, but haven't found anything yet. Regardless, I am skeptical of the claim that they aren't returning warmer water to the lake. I'm not worried about it (lake Ontario is gigantic), but I don't believe the article. (edit: 1BTU is the energy required to heat 1lb of water by 1 degree F at maximum density, so you could work it out directly from the bizarro-world units of HVAC systems.)
  - _3u10 3y ago
    It’s likely returned at a different depth. It would be about 120 psi at 85m.
    - thsksbd 3y ago
      It is. Its returned very shallow
  - thsksbd 3y ago
    Its not that exciting, really. They're just running the pumps fast. The system has the ability to absorb: H2o_heat_capacity*mass flow rate * delta(T) = cooling_power. The first term is know and very large. The last term is determined by the number of users and is estimated with forcast usage models. Ask an Env Eng a desired delta(T) and you get the mass flow rate required.
    - timr 3y ago
      I made another comment down the thread where I estimate this at 1.3 million gallons per minute if you want to have no more than a 1 degree C heating effect. It's a lot of flow.
- ZeroGravitas 3y ago
  > The water goes through Toronto’s Island filtration plant where it is treated for use as drinking water.
- michaelrpeskin 3y ago
  Because water is densest at 4 degrees, the bottom of every (big enough) lake is that temperature. If they pumped warm water in at the bottom, it would rise because it’s less dense. Regardless that lake is so huge, it would have negligible impact on the overall temperature.
- pkulak 3y ago
  Doesn’t Toronto have far more cold days than warm? So wouldn’t the water mostly be cooled? And if that’s the case, there’s not a lot of headroom above freezing.
james_david 3y ago
For the uninitiated, this is in many ways similar to networked geothermal: https://www.gastogeo.wiki/wiki/Main_Page https://www.gastogeo.wiki/wiki/Main_Page When I lived in Toronto, I toured Steam Whistle brewery and they featured this system prominently in their setup.
deleted 3y ago
[deleted]
thereisnospork 3y ago
>Although many environmentalists say they like DLWC, there is some concern that its reliance on electricity for pumping and running the giant heat exchangers could contribute to carbon emissions if the power is from coal- or gas-fired plants or pose other risks if the source is nuclear energy. Is there anything environmentalists won't try to complain about?
- pstrateman 3y ago
  It's especially dumb in Ontario where electricity is almost entirely from nuclear and hydro.
  - throw0101c 3y ago
    > […] almost entirely from nuclear and hydro. Click "Supply" for near real-time data: * https://www.ieso.ca/power-data https://www.ieso.ca/power-data Depending on how much wind is generating, (natural/methane) gas generators are dialed up and down. Ontario is planning to expand nuclear: * https://www.cbc.ca/news/canada/london/ontario-new-nuclear-build-1.6897701 https://www.cbc.ca/news/canada/london/ontario-new-nuclear-bu... Both large and small: * https://news.ontario.ca/en/release/1003248/ontario-building-more-small-modular-reactors-to-power-provinces-growth https://news.ontario.ca/en/release/1003248/ontario-building-...
    - pstrateman 3y ago
      Yeah today the gas usage is higher then usual and it's still pretty low.
  - kevin_thibedeau 3y ago
    Canada has high levels of immigration and needs to plan for the demands of a significantly larger population in the future. You can keep ratcheting up the demand on existing infrastructure or offload some demand with better solutions.
- msandford 3y ago
  Environmentalism suffers from the same "purity test" mindset as other things these days. Better than incumbent alternatives is nowhere near good enough. It has to be blameless now and forever. It's really too bad because perfect often is the enemy of good. And when nothing is good enough to be perfect people burn fossil fuels instead and get on with their lives. It's an ugly truth but it's true.
boringg 3y ago
Interesting project -- walk me through how it isn't bringing warm water back. Last I checked thats how cooling loops work. There is an argument that since it is small it won't impact the lake -- however if you have it en masse it certainly would have an adverse impact. It's like all things -- the pilot project is cool and fascinating but what are the impacts of something in a very large scale. Also what is the advantage over something like this instead of say renewable backed heat pumps? Is it essentially efficiency of centralized system similar to district heating a la NYC?
- Retric 3y ago
  The advantage over heat pumps is simplicity lower total investment. If you need 1/10th as many PV panels that’s not just less cost but less land use and less pollution from mining the materials etc. In terms of impact, lakes are heat sinks that average out energy gain and loss over a year, but the numbers get huge. For scale a single hour being cloudy or sunny could be an ~10 terawatt-hours worth of energy being dumped into the lake or not and that doesn’t have a significant impact. Meanwhile Canada total electricity demand at 577 terawatt-hours in 2022. Even cooling every house in the country across a full summer just isn’t going to move the needle here.
  - timr 3y ago
    > For scale a single hour being cloudy or sunny could be an ~10 terawatt-hours worth of energy being dumped into the lake or not and that doesn’t have a significant impact. Meanwhile Canada total electricity demand at 577 terawatt-hours in 2022. Even cooling every house in the country across a full summer just isn’t going to move the needle here. I'm not worried about it, but I don't think you can just assume that energy input from sunlight at the surface of the lake is going to be equivalent to slurping up cold water from the deep, heating it, and re-injecting it. Sunlight doesn't make it more than about 200m underwater, and deep bodies of water have distinct layers of temperature and density, largely because the water doesn't circulate freely through those layers. At the very least, you're creating a current where none existed before.
    - 3y ago
deeesstoronto 3y ago
The system in Toronto takes cold water from deep in Lake Ontario, runs it through heat exchangers that feeds the district cooling loop downtown. The lake water continues out of the heat exchangers into the intake of the water treatment system, feeding drinking water to the city. The water eventually returns to the lake after being used by people and flowing through the sewers and wastewater treatment system (returned at a shallower level).

47 points by throw0101b 3y ago

https://archive.ph/IZSDQ https://archive.ph/IZSDQ https://archive.today/IZSDQ https://archive.today/IZSDQ

* https://en.wikipedia.org/wiki/Deep_water_source_cooling https://en.wikipedia.org/wiki/Deep_water_source_cooling * https://en.wikipedia.org/wiki/Deep_Lake_Water_Cooling_System https://en.wikipedia.org/wiki/Deep_Lake_Water_Cooling_System

Cieric 3y ago

I'm kind of a novice on this, but what happens to the heated up water? I assume returning it to the bottom of the lake could have effects on local wildlife, so is it returned to the top? That seems like it'd have the same effect but take longer since the hot water will remain toward the top. Or is it assumed to be fine since when winter rolls around the heat will be dissipated then. I'm mainly curious about the result to the native wildlife since practice engineering's videos on the dams and how fish are handled.

timr 3y ago
The article says that the water is returned to the lake at about the same temperature that it leaves...though I'm unclear how that's possible.
- FredFS456 3y ago
  The heated up water is consumed as drinking water. Excess water is returned to the lake.
  - timr 3y ago
    That makes sense, but is a bit misleading (on the part of the article) if true -- you'd have to be pretty lucky to have your water consumption needs exactly match the heat capacity of the system.
    - bducycy 3y ago
      [dead]
    - thsksbd 3y ago
      Most of the water is returned to the lake, not sent to plumbing.
    - thsksbd 3y ago
      They dump the excess.
- bunabhucan 3y ago
  If you presume the return pipe is much smaller, placing it inside the inlet pipe makes a counter flow heat exhanger. https://learnmech.com/types-of-heat-exchanger/ https://learnmech.com/types-of-heat-exchanger/
  - timr 3y ago
    And so what do you do with the heat you've exchanged? It has to go somewhere.
    - thsksbd 3y ago
      The cold, dark sky of the 4K Universe. This is net cooling L. Ontario because Darlington (hence the its cooling loop) doesn't have to run as hard to power all the displaced ACs
  - yetihehe 3y ago
    That will just make your extracted water hot, making the whole thing a waste of energy? Return pipe is municipal wast treatment, which is probably enough to make that water essentially the same temperature as surface level waters once it returns to the lake.
- deleted 3y ago
  [deleted]
- TrainedMonkey 3y ago
  Not sure if that is the solution here, but the easy way is high volume. If you have enough water volume compared to the amount of dumped heat the temperature rise will be tiny.
- Alex3917 3y ago
  > The article says that the water is returned to the lake at about the same temperature that it leaves...though I'm unclear how that's possible. The most plausible explanation is that the article is wrong, and that the author meant to say that the lake is about the same temperature as it was before. Which is generally true; although the water being returned is slightly warmer, once you get more than a few meters away the difference is negligible. There is a ton of research on this phenomena with respect to the lake source cooling plant in Ithaca, because people obviously had the same concerns about that one before it was built.
  - thsksbd 3y ago
    this system is probably locally cooling the water since the 4C water picks up relatively little heat from the city and is returned to the warmer surface layer. Although L. Ontario's surface can hardly be described as "warm"
  - timr 3y ago
    Well, heat capacity of water is 1 calorie (4.18J) per gram. The interwebs hand-wavily say it takes about 25 BTU/hr to cool 1 square foot in a commercial HVAC system. 1 BTU is about 1kJ, so every 1 square foot of cooling (per hour) could theoretically be offset by 25,000J / 4.18J = ~5980g of water being heated 1 degree C. Density of water is 1g/mL, so it takes approximately 6L per hour per square foot if you assume that you don't raise the temperature of the water more than 1 degree C. They're talking about 50 million square feet with this system, so that's 300 million liters per hour, or about 80 million gallons per hour, or 1.3M gallons per minute. For context, the third water tunnel project in NYC was supposed to deliver 1.3B gallons per day, or about 903,000 GPM assuming constant flow. That's a big pipe. I tried to find actual citations of their flow rate, but haven't found anything yet. Regardless, I am skeptical of the claim that they aren't returning warmer water to the lake. I'm not worried about it (lake Ontario is gigantic), but I don't believe the article. (edit: 1BTU is the energy required to heat 1lb of water by 1 degree F at maximum density, so you could work it out directly from the bizarro-world units of HVAC systems.)
- _3u10 3y ago
  It’s likely returned at a different depth. It would be about 120 psi at 85m.
  - thsksbd 3y ago
    It is. Its returned very shallow
- thsksbd 3y ago
  Its not that exciting, really. They're just running the pumps fast. The system has the ability to absorb: H2o_heat_capacity*mass flow rate * delta(T) = cooling_power. The first term is know and very large. The last term is determined by the number of users and is estimated with forcast usage models. Ask an Env Eng a desired delta(T) and you get the mass flow rate required.
  - timr 3y ago
    I made another comment down the thread where I estimate this at 1.3 million gallons per minute if you want to have no more than a 1 degree C heating effect. It's a lot of flow.
ZeroGravitas 3y ago
> The water goes through Toronto’s Island filtration plant where it is treated for use as drinking water.
michaelrpeskin 3y ago
Because water is densest at 4 degrees, the bottom of every (big enough) lake is that temperature. If they pumped warm water in at the bottom, it would rise because it’s less dense. Regardless that lake is so huge, it would have negligible impact on the overall temperature.
pkulak 3y ago
Doesn’t Toronto have far more cold days than warm? So wouldn’t the water mostly be cooled? And if that’s the case, there’s not a lot of headroom above freezing.

james_david 3y ago

For the uninitiated, this is in many ways similar to networked geothermal: https://www.gastogeo.wiki/wiki/Main_Page https://www.gastogeo.wiki/wiki/Main_Page When I lived in Toronto, I toured Steam Whistle brewery and they featured this system prominently in their setup.

deleted 3y ago

[deleted]

thereisnospork 3y ago

>Although many environmentalists say they like DLWC, there is some concern that its reliance on electricity for pumping and running the giant heat exchangers could contribute to carbon emissions if the power is from coal- or gas-fired plants or pose other risks if the source is nuclear energy. Is there anything environmentalists won't try to complain about?

pstrateman 3y ago
It's especially dumb in Ontario where electricity is almost entirely from nuclear and hydro.
- throw0101c 3y ago
  > […] almost entirely from nuclear and hydro. Click "Supply" for near real-time data: * https://www.ieso.ca/power-data https://www.ieso.ca/power-data Depending on how much wind is generating, (natural/methane) gas generators are dialed up and down. Ontario is planning to expand nuclear: * https://www.cbc.ca/news/canada/london/ontario-new-nuclear-build-1.6897701 https://www.cbc.ca/news/canada/london/ontario-new-nuclear-bu... Both large and small: * https://news.ontario.ca/en/release/1003248/ontario-building-more-small-modular-reactors-to-power-provinces-growth https://news.ontario.ca/en/release/1003248/ontario-building-...
  - pstrateman 3y ago
    Yeah today the gas usage is higher then usual and it's still pretty low.
- kevin_thibedeau 3y ago
  Canada has high levels of immigration and needs to plan for the demands of a significantly larger population in the future. You can keep ratcheting up the demand on existing infrastructure or offload some demand with better solutions.
msandford 3y ago
Environmentalism suffers from the same "purity test" mindset as other things these days. Better than incumbent alternatives is nowhere near good enough. It has to be blameless now and forever. It's really too bad because perfect often is the enemy of good. And when nothing is good enough to be perfect people burn fossil fuels instead and get on with their lives. It's an ugly truth but it's true.

boringg 3y ago

Interesting project -- walk me through how it isn't bringing warm water back. Last I checked thats how cooling loops work. There is an argument that since it is small it won't impact the lake -- however if you have it en masse it certainly would have an adverse impact. It's like all things -- the pilot project is cool and fascinating but what are the impacts of something in a very large scale. Also what is the advantage over something like this instead of say renewable backed heat pumps? Is it essentially efficiency of centralized system similar to district heating a la NYC?

Retric 3y ago
The advantage over heat pumps is simplicity lower total investment. If you need 1/10th as many PV panels that’s not just less cost but less land use and less pollution from mining the materials etc. In terms of impact, lakes are heat sinks that average out energy gain and loss over a year, but the numbers get huge. For scale a single hour being cloudy or sunny could be an ~10 terawatt-hours worth of energy being dumped into the lake or not and that doesn’t have a significant impact. Meanwhile Canada total electricity demand at 577 terawatt-hours in 2022. Even cooling every house in the country across a full summer just isn’t going to move the needle here.
- timr 3y ago
  > For scale a single hour being cloudy or sunny could be an ~10 terawatt-hours worth of energy being dumped into the lake or not and that doesn’t have a significant impact. Meanwhile Canada total electricity demand at 577 terawatt-hours in 2022. Even cooling every house in the country across a full summer just isn’t going to move the needle here. I'm not worried about it, but I don't think you can just assume that energy input from sunlight at the surface of the lake is going to be equivalent to slurping up cold water from the deep, heating it, and re-injecting it. Sunlight doesn't make it more than about 200m underwater, and deep bodies of water have distinct layers of temperature and density, largely because the water doesn't circulate freely through those layers. At the very least, you're creating a current where none existed before.
  - 3y ago

deeesstoronto 3y ago

The system in Toronto takes cold water from deep in Lake Ontario, runs it through heat exchangers that feeds the district cooling loop downtown. The lake water continues out of the heat exchangers into the intake of the water treatment system, feeding drinking water to the city. The water eventually returns to the lake after being used by people and flowing through the sewers and wastewater treatment system (returned at a shallower level).