Watch the debate on what bitcoin did podcast between Peter Schiff and Foss Grant.

How do they claim that energy is being stored in bitcoin? 

Bitcoin isn't storing energy. Bitcoin uses up energy when it is created and every 10 min.

Stranded energy- that can't hook up to the transmission line- why are producer producing this stranded energy if you can't sell it or deliver it. Why are they uses resources to 'waste' it if they can't sell it?

Bitcoiners can sell bitcoin for dollars and then take these dollars to go buy energy if they want to buy new energy in the future. But they can't use 'stored' energy inside their bitcoin. 

https://www.youtube.com/watch?v=4FyujZmvC84&ab_channel=WhatBitcoinDid