Even if all you have is wind and solar, you can still turn it into baseload power by pumping water up behind dams, storing it in battery grids, or turning it into green hydrogen via electrolysis. Hell, you could even use it to heat up salts until they turn into a molten salt, which can be used for about 12 hours, going off of solar towers with molten salt generators...
Even if that's their strategy you're not guaranteed a return when mining. If you or your cluster don't mine the block all of that energy was absolutely wasted. If we didn't have a shitty ass isolated grid we could just sell the energy to another part of the country.