Energy is literally raining from the sky and sitting in the oceans in quantities that make keeping 20 billion people alive a trivial thing to do. So trivial that if that's all we can do 100 years from now, we've completely failed to capitalize on our scientific advances.

The trouble isn't making power, the trouble is capturing it: as someone once said, soup is raining from the sky, if only we had a bucket to carry it in.