On a philosophical note.

Bitcoin's entire value prop is based on proof of work. At the end of the day, for something to be work, it must have some type of use. The usefulness is philosophically part of the definition.

So, if this power is actually indeed excess, if it actually has nowhere else to go, it cannot provide value to the bitcoin network. Think about it: if bitcoin were entirely run on "free" electricity, where would the value come from? If it doesn't take value to prove work, no value is provided. The "value" of bitcoin comes from its using useful electricity, electricity that would (not just could -- would!) otherwise go towards useful purposes.

Someone who puts a bitcoin miner e.g. next to a solar plant to capture power that is otherwise curtailed is performing an arbitrage. They are trading their worthless power for valuable power elsewhere and pocketing the difference -- and hence extracting value from the other parts of the network which utilize useful power.

Even if tomorrow we switched to bitcoin mining with only "free" power, one of two things would happen: (1) the power actually is truly "free" and hence it does not function as "work" for value purposes and hence the the underlying asset is worthless. Or, much more likely, (2) the power is not "free," the bitcoin is not worthless; it is a drain on our resources.

I mean, let's go further than that even... Imagine if somebody invented commercially viable nuclear fusion and achieved effectively free and infinite electricity, then by your logic, either of two things could happen:

- Bitcoin becomes immediately worthless, because suddenly many actors could afford to tap infinite energy to mount a 51% attack and destroy the security of the network

- Or, self-interested miners would try to "corner" the market, nearly infinite though it may be... Industrial players might try to outrace each other in terms of bringing more fusion power plants online that are dedicated towards mining -- "white hats" trying to preserve Bitcoin, vs "black hats" trying to destroy, and it's just an arms race... Maybe the end result is actually that, humanity only has productive need for 5% of the total energy that fusion generates (hey it's my thought experiment, just go with it), so what do you do with the other 95% that is otherwise pure excess? ... Maybe it all goes back into Bitcoin mining anyways, because maybe God loves a recursive joke