[RedMonqey]

I know a Stanford egghead who thinks water is a greenhouse gas.

Depends on the context.

Vapor is just water turned to steam. And water vapor in the atmosphere IS the major greenhouse affecting the temperature on earth.

NOT carbon dioxide.

[Huskrrrr]

Thanks, I see your point. We were talking about hydrogen fuel cells. Hydrogen fuel derived from water, then returning to H2O as vapor after combustion.