Cooling lakes and reservoirs to reduce bacteria and algae blooms and maintain healthy fish stocks?

[chrisjones]

Cooling lakes and reservoirs to reduce bacteria and algae blooms and maintain healthy fish stocks?

Hi, I have posted this idea several times in the Guardian newspaper's environment and climate sections several times over the last six years.

I'm proposing the cooling of reservoir and lake water sources powered by renewables to reduce algae blooms, bacteria, and to create healthy conditions for resident fish stocks.
I envisage water pumps onshore or offshore to cool the water via cooling machines powered by solar, wind, and water mills, the water mills being placed at the tributaries to the lakes.

Edited October 7, 2022 by chrisjones

[John Cuthber]

Unfortunately, I can't see that being cost effective.
There's no reason to assume that lakes are much warmer than they were before mankind got involved.

[TheVat]

5 hours ago, John Cuthber said:

Unfortunately, I can't see that being cost effective.
There's no reason to assume that lakes are much warmer than they were before mankind got involved.

https://climate.nasa.gov/news/2378/study-climate-change-rapidly-warming-worlds-lakes/

Sorry to bear bad news, sir.

[Sensei]

9 hours ago, chrisjones said:

I envisage water pumps onshore or offshore to cool the water via cooling machines powered by solar, wind, and water mills, the water mills being placed at the tributaries to the lakes.

I advise you to calculate the volume of water, calculate the energy needed to lower the temperature, calculate possible energy harvested per device (not just peak maximum), and calculate the number of devices that will be needed.

[Moontanman]

How much cooler do the lakes need to be or is it a matter of oxygenation? 

[sethoflagos]

10 hours ago, chrisjones said:

Cooling lakes and reservoirs to reduce bacteria and algae blooms and maintain healthy fish stocks?

... to cool the water via cooling machines...

All practical machines when viewed from a global perspective produce nett heat. How do you propose to dispose of this reject heat (the heat you have removed from the water plus that due to inefficiencies) in such a way that you do not end up increasing the rate of global warming?

[CharonY]

Despite the lack of feasibility of cooling whole lakes, algae bloom are also driven by nutrient influx (e.g. agriculture). Cooling the system down would slow it down a bit, but it seems like trying to address the wrong issue with a lot of effort.

 

[TheVat]

Cooling lakes does increase oxygenation of the waters, but it's hard to see an active system not being a waste heat producer, as Seth noted.

Seems like a passive shading of some kind would be better, and cheaper.  Some kind of netting spread over the water that allows air and light to reach water, but cuts insolation a few percent?  As the NASA report (posted above) suggests, most lakes are only a degree C. or so above their normal temps.  So maybe a partially shading net would compensate for that.  Net would be bad for aquatic birds, though, so scratch that idea.   What about a more natural material that floats and doesn't break up into harmful microparticles or mess up feeding activities?  Something cellulosic, that would float for a while?  

I like the intellectual challenge of this thread, even if it's not essentially feasible.  

[sethoflagos]

2 hours ago, TheVat said:

Cooling lakes does increase oxygenation of the waters, but it's hard to see an active system not being a waste heat producer, as Seth noted.

Seems like a passive shading of some kind would be better, and cheaper.  Some kind of netting spread over the water that allows air and light to reach water, but cuts insolation a few percent?  As the NASA report (posted above) suggests, most lakes are only a degree C. or so above their normal temps.  So maybe a partially shading net would compensate for that.  Net would be bad for aquatic birds, though, so scratch that idea.   What about a more natural material that floats and doesn't break up into harmful microparticles or mess up feeding activities?  Something cellulosic, that would float for a while?  

I like the intellectual challenge of this thread, even if it's not essentially feasible.  

Many of these ideas are covered from a slightly different perspective here:

 

 

Edited October 7, 2022 by sethoflagos

[John Cuthber]

I'm not saying it's a good idea but...

If you use solar power to drive the cooler then the heat (including the waste heat from the electrics etc) is exactly the same as if the sunlight just warmed up thee ground.
The conservation of energy leads to the question "how could it be different?".

 

20 hours ago, Sensei said:

I advise you to calculate the volume of water, calculate the energy needed to lower the temperature, calculate possible energy harvested per device (not just peak maximum), and calculate the number of devices that will be needed.

I realise the temperature of lakes will go up more or less in line with global warming.
But is there any reason to believe that the lakes are particularly susceptible?
Why focus on cooling lakes rather than, for example, cooling fields?

[Sensei]

It is possible to cool the Earth by sending a "very large" number of satellites-mirrors into cosmic space, where they will reflect sunlight and prevent it from reaching the Earth at all..Satellites can be remotely controlled to control the amount of energy reaching our planet.

Alternatively, cheaper and easier, without an important remote control, spread gas between the Earth and the Sun.

Alternatively, white balloons that will reflect sunlight. But that would be a devastation/pollution of the sky.

But it is OT, as these ideas would decrease global warming rather than directly fight with algae.

Edited October 8, 2022 by Sensei

[TheVat]

1 hour ago, John Cuthber said:

 

I realise the temperature of lakes will go up more or less in line with global warming.
But is there any reason to believe that the lakes are particularly susceptible?
 

Not sure what happened with notifications, but I replied directly to your earlier post, quoting it, and providing a NASA paper that directly answers your question.  In the paper's first two paragraphs, in fact.  To save you some scrolling, here it is again:

https://climate.nasa.gov/news/2378/study-climate-change-rapidly-warming-worlds-lakes/

(A secure, encrypted website, should be safe to click)

"Will go up," it turns out, should be present tense.