Freeman Dyson, many years ago, said the most simple and radical thing I've ever heard. It was the biggest idea. The second biggest idea I heard, also many years ago came from Nicolas Negroponte. He predicted the downfall of broadcast television. His explanation was simple. Everything is going to go digital because Moore's Law will make digital cheaper, and since video is digitally bulky, it's going to be easier to send it through cables than over the air. The content will follow the cheapest path. To be more comprehensive, he said that the phone companies and the broadcast companies would switch places because it was ironic to him that voice was going over wires and video was going over the air. It hasn't finished happening, but the simple beautiful truth of it is becoming manifest.
Freeman Dyson's idea was even larger. He said the way to go is to personalize energy distribution. Most of our energy is lost because it is centrally generated and hierarchically distributed. If you could find smaller energy sources and distribute them equally, it would alleviate the need for pipelines, high tension wire, truck and train transportation of energy. We'd save huge amounts. Moreover we could start living at a more reasonably human rather than sardine scale.
Dan Nocera has obviated a couple of basic assumptions about energy production and seems to be on the way to demonstrating how fuel cells can power all of our needs. Most excellentHere's long version.