I remember from somewhere where it was said that mankind will not run out of natural resources because as we begin to grow short on one resource for our energy then we simply change to another. It was that way when we burned trees and hunted whales and then switched to crude oil. Of the three trillion gallons of crude oil in this planet we have used up 1 trillion of it so we have two trillion left, but with that said we are already looking for alternative fuels like hydrogen, wind, solar, and geothermal. It may seem like we are taking our time in switching over, but you have to remember that this world is not run by politician or even by military leaders, but rather by business men who if they cannot turn a profit on something will axe the project no matter how much mankind can benefit from it.
I think it was either in the late 19th century or maybe in the early 20th but supposedly Nicola Tesla had found a way to turn the entire world into a battery and everybody on the planet would be able to get all the power they needed for free, but since the business men could not figure out a way to make a profit form it the invention was panned and Nicola Tesla died a pauper.
