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Comment by IG_Semmelweiss | Hacker News Reader

I'd take a step back. How is the water heating in the first place ?

They are saying heat exchangers do the magic. OK. Lets consider first the use cases.

- Cool Water: I'm really confused as to how cool water is helping anything. Its not like this water is helping a nuclear reactor or some really hot tropical city. We are talking CAN here.

- Hot Water: I can see the usefulness. But I dont get how they get the energy. There's some electricity warming up the water so it can be useful, but how is that is more effective than other types of heating ? Sounds like a gimmick - Am I crazy to think that ?

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We have a similar thing over here, and the cooling capacity is pretty useful. ( https://www.helen.fi/en/housing-companies/cooling-for-housin... ) As the summers have gotten hotter, this has gotten more common to have a somewhat stable temperature indoors.

Heat pumps allow shifting the temperature that's in the cooling and heating circuits, so you can extract (or add) more heat, making it more effective. This is used to cool data centers and heat homes/offices, so it also allows to move heat between places instead of always having to have a cold sink and a heat source.

Sure, there is electricity warming up the water, but earlier the energy that was used to cool a space was just discarded into the air, now it's gathered and put into the circuit to be useful elsewhere.

Not a gimmick, it saves _a lot_ of energy.

OK, that makes a TON of sense. Thank you .

Your answer implies a circuit, which is logical and explans a lot, but its not what the article is saying directly.

The article just has a cold sink (the lake) which is being asked to expand for help. No idea what the heat sources (nuclear reactor, data center) are that could help close the circuit. Maybe this is where the buildings they mention with the expansion, come in? Yet its not clear if article's buildings are actually the heat sources - unlike your explanation, which is pretty clear.

When water is returned it's pumped to near the lake's surface, so will rise, cool down, then sink.

So it's just providing a higher quality source of 'cold' to make things efficient instead of requiring heat pumps that dump heat to the air directly when it's hot out.

Much more efficient overall.

The interiors of large commercial buildings that this loop is serving have no exterior exposure and therefore have only internal heat gain from people, lighting, and equipment. Therefore they are in cooling-only for a lot of the space and often only have heating around the perimeter of the structure where there is heat transfer to and from the environment.

I don't know why you're being downvoted—I'm wondering the same thing.

You get down voted when you question the current dogma. I happen to work in climate tech and i find people don’t like questions to their tech especially if its perceived to be exceptionally great and only providing upside.

They'll castigate you as a anti-progress environmentalist if you are on the green side of things or a pro oil toting fool if on the right. The space has become a mimic of our political disconnect. Sad state of affairs for engineers with real questions.

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