From my point of view, energy never will be free even production cost will be very low.
Wee always need maintenance power plants and energy network.
And when I thinking about future energy source in next 20-30 years it is Tohorium MSR *( Molten salt Reactor),
Predicted thorium resources on the earth would suffice humanity at least for 100+ years.
Of course 50-100 years it is Fusion Reactors 🙂
