You know how ancient relics of incredible power have to be unlocked with some sort of magic incantation? And invariably, halfway through the incantation, they start throwing gigantic lightning bolts all over the place?
So here's what you do. You buy an ancient relic of incredible power and set it up so that the gigantic lightning bolts turn into usable power. Then you hire someone to say 2/3 or 3/4 of the incantation, over and over again, and sell the electricity.
I think this is a fantastic idea, and couldn't possibly be flawed in any way.