The word was meant to imply that sunlight wasn't going to be running out like oil is. I use paper bags at grocery stores because a million years from now, barring astronomical or other global disaster, there will still be trees.

I believe nuclear power is needed to supply energy in the amounts we'll need to support a planet-wide technological civilization (fusion would be lots better, but it isn't on the shelf yet). But I also believe there's a major role for solar power, too. Decentralized solar energy systems--panels on roofs, in yards, over parking lots--aren't going to supply the power needed for a major industrial civilization by themselves, but as I've said before, every watt that comes off of someone's roof is a watt you don't have to make in a power plant. Same for wind, tidal, and other relatively inconsistent or low-level power sources.

In the comic book "Transmetropolitan," the future civilization has spread solar panels all over Mercury and broadcasts power to the Earth. This is somewhat silly--the same thing could be much more easily accomplished from the Moon if that was the approach you were taking.