HaysooChreesto!

Okay, I'm really ignorant on this subject, that's why I'm asking.
With all the hullaballoo lately about hydrogen cars, I've heard that the only emissions are a little bit of water.
For example, say if every vehicle on the road today were powered in this manner, they would all be emitting some type of water vapor, right? So with all this water vapor in the air, wouldn't that cause some rise in humidity?
What would be the consequences if any? Or all my questions are lame and this thread should thrown in the garbage. Thanks.

Undercurrent

I've wondered that myself. Would millions of hydrogen cars effectively put more of earth's water into the atmosphere causing more rain and/or more global warming.

My half-assed guess is that the amount of water vapour produced by a bunch hydrogen car would be dwarfed by the amout of water vapour continually being liberated from the huge surface area of the oceans. But some numbers would be nice.

simian

Current fuel systems release water as well. The fuels we use are hydrocarbons (C, H, & O). If I remember correctly, most of the energy released is from the H-C bonds. The C-C bonds don't release much (by comparison). As a first pass, I would say there will be minimal difference between the two in a combustion engine, as far as water released.

Very rough guess at this time.

Simian

Corwin

The thing is, water from a fuel cell (unlike water from an IC or EC engine) is clean. No CO or CO2 or nastier components. So it can be captured and either re-cracked to get the hydrogen back out, or used for other purposes. (Irrigation, drinking, etc.)

Abacus

Of course, if you use electricity from fossil-fuel burning power plants to begin with, have you really gained much?

Shadowy Man

Yes, and water is the most important green house gas!!! All these cars putting out water vapor would only increase the global warming problem!!!


NB: sarcasm

Corwin

Not a lot, no.

But if you use electricity from solar, wind, geothermal or atomic sources, you've gained quite a bit.

I've mentioned exactly that point in several places... specifically about the administrations new position on hydrogen. Bush is endorsing it becuase he FINALLY figured out the petrochem companies could make more money off of hydrogen... now let's screw the whole thing up and use isotopic power cells instead.

Shadowy Man

Yes, I think you can. The idea lies in containment of undesirable emissions. It is possible that it might be much, much easier to restrict pollution at a single fossil-fuel burning power plant than in millions of individual automobiles.

I don't know what studies have been done along these lines, but it's not a trivial additive answer. A power plant that produces a million times as much energy as a million cars doesn't necessarily produce a million times the pollution.

HaysooChreesto!

Ah yes, a new face of oppressive terror. "Big Hydrogen". Will the madness never end?

Nataraja

Animals release water vapor into the air when they breath, including humans. Mammals and birds create their own body heat, including humans. Hydrogen powered cars do not release CO or CO2. The fuel isn't really the problem, the problem is how it is to be manufactured.