Is there a way to calculate the energy required to reduce the heat of oceans?

Am I wrong in thinking it is not as simple as reversing the calculation for specific heat of sea water?

  • $\begingroup$ it is literally as simple as calculating hte specific heat of seawater unless you are trying to coll it in some specific manor. $\endgroup$ – John Apr 19 at 15:35
  • $\begingroup$ Thanks - so the calculation would just be specific heat x mass of the oceans? I.e. the energy to raise by 1 degree is equal to the energy to reduce by 1 degree? $\endgroup$ – the4thv Apr 19 at 15:54
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    $\begingroup$ Note the very significant difference between the energy you need to extract from the ocean to cool it by 1°C and the energy required to extract that energy. In a similar way the energy used by a fridge to cool the food inside it is MUCH more than the energy actually extracted from the food, $\endgroup$ – Camilo Rada Apr 19 at 19:38
  • $\begingroup$ as your question is now it is a little theoretical so in real life you will need a plan for where you are going to dump the heat and that is the hard part of this(in the light of your tag climate-change) $\endgroup$ – trond hansen Apr 20 at 5:32
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    $\begingroup$ @trondhansen, my thoughts exactly and this is where I'm going with this line of thought; we can store it in a manner that we can later utilize it, or somehow 'vent' it to outerspace. Two immediate ideas: 1) Using a form of evaporation and salt storage (en.m.wikipedia.org/wiki/…). 2) Using the upper atmosphere to cool bodies of water by cooling something high up and then placing it in the ocean, kind of like a man made ice cube. I currently can't see how either might work at scale or what that scale would need to be. $\endgroup$ – the4thv Apr 20 at 14:32

The question is slightly confused, because reducing the temperature of the oceans, in a direct sense, doesn't require energy - it releases it. The amount that is released is simply related to the mass and specific heat capacity of seawater, as you suggest.

The missing question, though, is why the ocean is cooling. For it to happen naturally and simply release energy, it would need to be because its surroundings (e.g. the air) were cooler. If you want to actively cool the sea, then yes, that is going to consume energy. If the cooling has approximately the same level of performance as building-sized air conditioning, the power used by the cooling apparatus will be about 40% of the rate at which the energy is removed (and remember that this is not just the total energy divided by the time, because more heat will be leaking back in while you do it).

Leaving aside the, uh, engineering challenges of this scale of cooling, this leads to a question as to why one might want to do this. Remember that unless you devise some complex system to radiate this heat into space from above the atmosphere, you're going to be releasing the same heat into the same global climate system, plus the additional 40% that you've used to move it around.

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    $\begingroup$ this is how my closest city uses heat from a river for heating and cooling houses and industry bbc.com/news/business-31506073 $\endgroup$ – trond hansen May 23 at 3:58
  • $\begingroup$ Thanks @semidiurnal-simon, I was hoping my question implied 'active', but I grant you it isn't explicit - I've corrected that. $\endgroup$ – the4thv May 23 at 6:46
  • $\begingroup$ OK, in response to your answer, thank you. Starting with the last paragraph first, as per my last comment above - the why is environmental; the oceans are a huge influencer of climate and have a lot of heat energy stored, so as I see it, having the capability and system in place would be beneficial (that's not a topic for here though). $\endgroup$ – the4thv May 23 at 6:51
  • $\begingroup$ [Sorry, I hit return] ...Indeed, the idea would be reduce the addition of energy from fossil fuel stores, but it would definitely need to be done with a net reduction of overall energy release (compared to just using fossil fuels). Re the 2nd paragraph: thanks for the formula, but do you happen to have these numbers for heat-pumps (as per @trondhansen's link) or could help me calculate the equivalent number? I can't imagine using normal air-conditioning methodology. I envisage solar powered heat-pumps at sea, storing the energy as salt storage, periodically returning with their store full. $\endgroup$ – the4thv May 23 at 7:08
  • $\begingroup$ @the4thv air conditioners are heat pumps. Same technology. The coefficient of performance (the 40% I mentioned) will vary, maybe a lot, but it's going to be more than zero and less than one. $\endgroup$ – Semidiurnal Simon May 23 at 15:27

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