[Aunche]

>Lastly, bitcoin mining to could sustained solely by using stranded energy, which would otherwise be unused.

You can make that argument about any sort of waste of electricity, like blasting your A/C with the windows open. The problem is you can't guarantee that people are only using wasted energy. People don't mine Bitcoin to generously find a use for surplus energy. They do so for a profit. Also, people will require mining for Bitcoin transactions regardless of whether there happens to be surplus energy.