Water vapor? Really? (Score 1)

We don't really want freeways full of cars spewing out water vapor, do we?

Water vapor is a MUCH worse greenhouse gas than CO2. Yes, really. Look it up. And that's just looking at it from a global climate-style standpoint. On a much more local level, what do you think it does to the weather to have thousands and thousands of power plants giving off water vapor like crazy?

Not to mention, what does a freeway full of water-vapor-spewing cars look like in Minneapolis in January? All of that water condenses almost immediately, falls to the pavement and... instant ice sheet.

Very much like biodiesel (Look! I can run my car off the waste leavings from Sonic! Isn't that awesome?! Now we just need a fried food restaurant dedicated to each car, or thereabouts, and we'll have fixed the energy crisis!), fuel cell vehicles just won't scale in a reasonable manner. A few of them won't hurt anything, and look very green. Millions of them are FAR more problematic. The same could be said for internal combustion gasoline engines, naturally.

Batteries are the best way to go, but that solution is also far from perfect. Compressed air vehicles are fine for low-speed inner-city driving, but I still think the idea of a high-pressure tank going down the highway at 100 kph+ is frightening.