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Comment by _8j50 | Hacker News Reader

Is it practical to have giant nuclear powered facilities that either pump cooled air or artificially cool surface ocean water? Or just use the electricity to break down water for O2 production and use the hydrogen to power other things?

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> Is it practical to have giant nuclear powered facilities that either pump cooled air or artificially cool surface ocean water?

That would be like opening your refrigerator to cool your room - more heat is emitted from the radiator on the back of the refrigerator than is removed and so the room as a whole gets hotter. (Because movement of the heat from the interior to the back cancels out, but the energy used to move it creates additional heat resulting in a nett increase.)

I am a bit upset about all the downvotes,i know it's bad etiquette to complain about that but I just wanted to say how questions of curiosity shouldn't be looked down upon. This isn't my field but climate change is concerning, so I simply wanted to know why certain solutions (however naive) were not being pursued.

Cheers.

Don't let it worry you. Downvoting is essentially a thoughtless act so you can pretty much ignore them. It just means some people dislike what you wrote without considering the substance of it.

In reality it's a good question and it prompted some good answers.

Thank you, sorry for being so petty

That would be a heat pump and say it worked at a COP of 3 which is typical you would need 1 watt of power to move 3 watts of heat to somewhere, probably deep underground.

Nuclear power is what maybe 40% efficient so 60% of the nuclear energy is waste heat, so for every watt of energy 1.5 watts of heat released.

So now your only netting 1.5 watts for every watt. To make a difference the numbers would be staggering as the earth receives on the order 170,000 terawatts of solar energy.

Solar power rather than nuclear would make more sense but again the scale to make a difference is staggering.

I think more "realistic" would be using energy to split CO2 back into C and O2 and sequestering the carbon in the ground which is basically what plants do through photosynthesis. If we could make machines that do that more efficiently on a large scale from solar power we might make a difference.

Thank you for the detailed explanation. Would the logistics still be the same if you're talking about cooling spcific subsets of the polar regions? For example, the "rim" of the arctic?

Perhaps the excess heat from nuclear can be used to clean up CO2, I remember reading a few articles that suggest CO2 cleaning plants are actually practical

> or artificially cool surface ocean water

Good curiosity, but they would have to put out atleast an equal amount of heat into the atmosphere! (2nd law of thermodynamics).

People are still trying to work out if we can make black bodies that are biased to radiate more heat in frequencies that the atmosphere is permeable to.

We have some materials that are much more thermally conductive in one direction than the other. Pair the two, and it might just be possible to shed some heat into space at night.

Entropy always wins. It’s the heat trapped in the atmosphere that’s killing us. The universe is a mighty big heat sink though.

Interesting. Do you have resources/keywords I can use to know more about such research?

Search for radiating heat into space. There were some reports about 8-10 years back. Occasionally you will see people working on materials that have narrow emissions spectra, but I think they may have other things in mind, like combining them with photovoltaics to make solid state heat engines. Which has the potential to be much more efficient than thermocouples. Thermocouples are so far from their theoretical limits that boosting the conversion rate by single digit percentage points is more than doubling efficiency, which is how we ended up with a new thromocouple material on the front page of HN a month ago.

> heat sink

Bad analogy and you cannot rely on conduction to transfer heat in space. The only means of heat transfer is radiation.

The question was why can’t we just make hot things cold.

The answer is “you can, if you have some place to put the heat”. What would you call the counterpart to a heat source?

Why the atmosphere? Deep ocean water is already super cold right? Plus water does a good job of absorbing heat.basically transfer the surface heat energy to deep waters,that way surface level glaciers are kept frozen?

Water is a good insulator, but not a perfect insulator. If the temperature difference between the bottom and top changes so does the heat transfer and given time the effects will spread. But most important is, warm water/moisture is less dense than cooler water, that means large heat transfer by convection currents in addition to the low conduction (inverse of insulation).

To create that cooled air you have to heat something else right? I'm not sure that's the right direction...

Something other than the atmosphere and surface ocean water? A mile or so under the earth crust, or 5k meter+ under ocean water heat release/transfer

If we have this level of surplus energy, we should be using it to first replace all fossil fuel consumption and then secondarily start drawing CO2 down from the air. We can't out-cool the sun.

Some companies are working on carbon scrubbing tech that removes CO2 from the atmosphere and converts into something else — a liquid fuel in one case, if I remember correctly. These processes, I believe, are energy intensive — so using something like nuclear to power them would make a lot of sense, if you can find a way to install new plants with less money, and less regulatory hurdles than today. (Bill Gates is funding a nuclear plant design that seems promising in this regard — Terra Nova, I think it’s called.)

You would have to find a way to move the heat away from the earth.

This would have the net effect of warming the atmosphere, unless you developed new technology to simultaneously beam significant heat energy into space.

Does it have to be space? Can't you send the excess heat to deep ocean waters or into the earth's mantle?

The "to space" method has the smallest probability of backfiring in surprising ways. For instance, heating deep ocean waters could disrupt the local ecosystem down there, and we don't fully understand yet how the deep ocean is connected to everything else on an ecological level.

True, the situation at the surface seems much more dire and urgent though.

Underground is generally warmer than the surface, and warming the ocean causes problems of its own. But really the problem is that the amount of heat you'd have to move is absolutely massive - the best we can do is alter the atmosphere to increase the amount of heat radiated to space, because we can't out-cool the sun.

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