Cooling is a pretty big factor in the energy usage of datacenters, and there's a lot of room for creative use of technology there - or simply geographic advantages.
It's a lot smaller than you think these days with all the effort that has gone into it.
Google reports an average PUE[1] of 1.11 over the past year, 1.09 over the past quarter, and the latest/best data centers are at 1.06 [2]. In simple terms this means that the total power overhead for cooling etc is just 6% of that to power the machines in them.
Google (and others) have gone to great lengths using AI, and radical new ideas for cooling.
Disclaimer: I work at Google, but not in Datacenters. All info public domain
No, because computer chips don't operate at 100°C (let alone 300°C like a nuclear reactor). Low-temperature heat flows contain little usable work. Typically the best option is to dump the spare heat into the nearest body of water, or into the air.
