Dumb question, why is the water in the Rhine warm?
It isn't. It's just warmer than air in winter
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The biggest heat pumps
11–20 of 197 posts
Re: The biggest heat pumps
#12Dumb question, why is the water in the Rhine warm?
The river is not warm or warmer than the air. Heat pumps are amazing at extracting thermal energy. I think water is very dense compared to air, thus making the processes more efficient in such a large scale.
The best thing about using watercourses as your heat source for heat-pumps - the water flow naturally takes away your "colder" output and brings you more "warmer".
Ground source heat pumps are limited because the ground they have chilled stays stubbornly in the same place, so the only way you can extract more heat from it is to make it even colder, which gets less efficient. Watercourses don;t have that problem.
Re: The biggest heat pumps
#13> heat-pump equipment costs roughly €500,000 per megawatt of installed capacity
Interestingly enough the price for these giant heatpumps is pretty much in line with domestic ~10kw units.
Re: The biggest heat pumps
#14In the nordics we love heat-pumps! Something like 70% of houses are heated by heat-pumps, and 90% of apartment buildings are heated by district heating and that is often generated by huge heatpumps.
Apparently 95% of new heating installations in Swedish houses are heat-pumps these days: https://publications.jrc.ec.europa.eu/repository/handle/JRC1...
Heatpumps have been heating nordic homes for decades. Even in the countryside where many houses have small woodland attached, people I know have moved to heatpumps for convenience and because its affordable.
PS: shoutout to to the JRC, found their reports when doing a super quick dig for stats. Those reports were super easy to read :D
Re: The biggest heat pumps
#15Dumb question, why is the water in the Rhine warm?
It not warm as in ”warmer than the typical living space”, but it is warmer than zero Kelvin, so heat can be extracted from it. Doing that takes energy, that’s why it is called a heat pump . That moves heat from the water to an already warmer place, against a heat gradient, just as a water pump moves water against a gravity gradient. If the water were warmer than your typical living space, they wouldn’t need a heat pu…
Practically, the water would need to be somewhat warmer than 0℃ because you don't want it to freeze and clog the plumbing after you have extracted a useful amount of thermal energy. :)
Re: The biggest heat pumps
#16Earlier quoted context omitted.
The river is not warm or warmer than the air. Heat pumps are amazing at extracting thermal energy. I think water is very dense compared to air, thus making the processes more efficient in such a large scale.
The best thing about using watercourses as your heat source for heat-pumps - the water flow naturally takes away your "colder" output and brings you more "warmer". Ground source heat pumps are limited because the ground they have chilled stays stubbornly in the same place, so the only way you can extract more heat from it is to make it even colder, which gets less efficient. Watercourses don;t have that problem.
The opposite effect is also why thermal stations (including but not only nuclear) are usually on the coast or near large rivers: you can dump a lot of water heat into water and have it carried away.
Not always good for the local ecosystem without mitigation, but at least one Japanese reactor allowed local colonisation by tropical fish and local legend said the same about Sizewell.
Sizewell C claims to plan recover waste heat and use it for carbon capture somehow, about which all I can say is a big old hmmmmm.
Re: The biggest heat pumps
#17So $235 million for 162MW, or $2.35B for 1.6GW
A 1.6GWe nuclear reactor is around $8B.
Re: The biggest heat pumps
#18Earlier quoted context omitted.
It isn't. It's just warmer than air in winter
The air temperature isn't relevant.
It is, since the obvious alternative to taking the heat from water would be taking the heat from the air or from the ground.
The air is colder in winter than the water, and the ground only provides a limited amount of heat before you can't extract any more. So water beats both.
Re: The biggest heat pumps
#19Earlier quoted context omitted.
It isn't. It's just warmer than air in winter
The air temperature isn't relevant.
It is a bit relevant because if the air was warm enough you would be better building huge air source heat pumps.
And if it was really warm enough you wouldn't need heating in the first place.
Re: The biggest heat pumps
#20Earlier quoted context omitted.
It not warm as in ”warmer than the typical living space”, but it is warmer than zero Kelvin, so heat can be extracted from it. Doing that takes energy, that’s why it is called a heat pump . That moves heat from the water to an already warmer place, against a heat gradient, just as a water pump moves water against a gravity gradient. If the water were warmer than your typical living space, they wouldn’t need a heat pu…
Practically, the water would need to be somewhat warmer than 0℃ because you don't want it to freeze and clog the plumbing after you have extracted a useful amount of thermal energy. :)
Moving water will get much colder than 0℃ before turning solid. -10℃ or even -25℃ are easily possible. If the water is also under pressure, it can get even colder.