I hear you and completely agree that the input/output ratio is less than "naturally flammable" materials. I'm just excited that the most abundant resource on earth HAS been found to be flammable.
What if the radio frequency's could be powered by solar or wind, which in turn would burn salt water? I wouldn't think it's a question of input/output feasibility, but that we CAN burn something beyond wood, coal, oil, natural gas and other more expensive and more finite materials. I would think the base fuel which can create HEAT is the key here. Finding a way to cleanly power the radio transmitters should be easy enough given a big enough solar array or wind farm.
Now, powering a car?

I'm just shootin' from the hip here. ;-)
edit: I just read the forum you posted and the thing those eggheads (yes, as an ex-civil eng. student i include myself

missed is what I'm saying. It ain't about the numbers. It's about the most abundant resource can burn without emitting carbon to power it. Well, at least, the H does.
Maybe I'm the cracked egghead here, but then again I always clap for Tinkerbell.