Recovery isn't the issue, the issue is that district heating systems are pretty much a rarity across the world for a number of reasons. Recovering waste heat - no matter if from datacenters, industrial processes or eve wastewater/sewage - is trivial, but getting the heat to somewhere it still can have a productive "secondary usage" is a massive and expensive problem.

Yes. There's eg combined power plants that use waste heat from power plants to heat houses. The problem is that this tends to make the power plants less efficient at electricity generation.

So this waste heat recycling should only be done where and when it makes sense.

(But that's pretty easy: absent any legal requirements, the involved parties have all the right incentives already. It's all internalised between the parties.)

> The problem is that this tends to make the power plants less efficient at electricity generation.

Huh what? Never heard of that one before.

> absent any legal requirements, the involved parties have all the right incentives already

Well... that's the problem, they don't. Sure, datacenter operators could go and offer to install district heating, waste heat recyclers and whatnot, and it would likely be profitable. But, and here it gets annoying, it's not profitable enough.

> the datacenter doesn't have a few million dollars to spare.

What makes you think so? Datacentres are already very expensive, and getting permissions quicker (or at all) might be worth a couple million dollars.

> The heat is waste heat. If it cannot be recovered as a profitable source of energy, [...]

Yes, they should make all deals that make sense for both parties, definitely. But it's only viable in some places some of the time.