Okay, here's my piece:
Wind and solar are becoming more practical. Most of the trouble with photovoltaic energy is that it's mostly thermal output instead of electrical; we are constantly searching for new materials and methods to solve this problem. Furthermore, solar and wind are far more practical when you break it down to a localized level and network it, rather than the national conglomeration of energy we know today.
Clean coal: no such thing. One look at a coal miner will tell you that. Yet we continue to derive most of our energy from coal. Solar and wind ease the burden.
Oil: hybrids help, but electricity doesn't come from magic. This is an issue of its own. Biodiesel also helps, except we're getting it from all the wrong places, and thinning our food supply in the process.
Natural gas: Still pollutes, just not as badly.
Nuclear: Lots of electricity, but always the hazard of fallout. Doesn't help America's "under-the-rug" habit in terms of waste disposal.
Hydrogen fuel: 100% clean (if derived from water instead of methane), but still impractical due to the energy requirements of electrolysis. (Solar electrolyzing plants?)
Fusion: for some reason we can't get it right, but it's still worth looking into.
Perpetual energy: Still likely a ways off, although there is promise in emerging technologies and unconventional thinking.
Overall point: it's not about whether the source is practical, at least not from the environmentalist's point of view. It's about restoring the natural balance before we take a cliffdive. And to the naysayers out there, I'm sure you're familiar with the expression "better safe than sorry."
I think I'm done.