If you are going to use electricity to heat human occupied spaces, you should use a heatpump which has much better efficiency, above 100%.

Cooling technologies just move the heat around. A datacenter produces a lot of heat that is then subsequently moved out of the building. Capturing that heat shouldn't be too difficult because it passes through central AC or central chillers.

Capturing as in storing? Simply knowing where the heat is/goes doesn't really make it easy usable. You can heat up water for example but what if no one need warm water there? Also often additional energy is useless just to move the heat away fast enough.

But if you're using electricity to power CPUs, may as well pump that heat into human-inhabited areas to keep us toasty warm.

Sure, that's not optimal way of heating with electricity. That's just a way of utilizing heat from computing.

There was an article on the front page of HN not that long ago about a guy using the waste heat from crypto mining to heat his home:

https://blog.haschek.at/2021/how-i-heat-my-home-by-mining.ht...

Then the argument of "we will just stick the miners in Iceland where renewable energy is cheap" falls apart. If you want to mine where humans are then you need to mine with grid electricity.

That'a very good point. Crypto heat use will be limited to windy cold places where some people live.

Unless there are some industrial processes that might use this mild heat. Maybe poultry production? Some green houses in cold climates?

The point is that there isn't enough renewable energy for population centers right now. So every clean watt used for mining btc takes that clean watt away from somebody else. This is why reducing energy use is so powerful. Even if X% of your energy use comes from zero-emissions sources, all marginal energy use comes from carbon.

The only way that btc mining can truly claim to have no impact on global emissions is if it uses zero-emission energy that otherwise couldn't be used in some other productive way. And that, almost by definition, limits the use of the waste heat.

> The point is that there isn't enough renewable energy for population centers right now.

Even when it will be enough when renewables work at 100% it won't be enough if they give 8% of their max output because it's not that windy today.

We should have at least 10 times the capacity in renewables than we actually need to have plenty on bad days (and nights).

> The only way that btc mining can truly claim to have no impact on global emissions is if it uses zero-emission energy that otherwise couldn't be used in some other productive way.

I agree, and that won't happen until we go 100% renewables, but we can't do that without a storage, and we don't have storage, but we can go 1000% renewables instead because that's the technology we have and already it is the cheapest way of making energy. And I think next crypto boom could put us on trajectory to achieve that by utilizing every bit of energy we'll overproduce and by being a mechanism to funnel money from the pockets of Wallstreet into renewable energy production investments.