I recently read a post by someone who was concerned that if we introduced fuel cell technology into cars, that instead of smog, the water vapor would cause LA would turn into a tropical environment and we haven't studied the environmental impact. Is this possible?
There are different types of fuel cellsthus I will assume the one that makes the most environmental sense. The one that takes water and disassociates into hydrogen oxygen right before entering the combustion chamber (reference Stanley Meyer patent in Google patents). After combustion water vapor is releasedhoweverit is released within a closed systemand since the car takes water as fuelit would make more environmental sense to take some of the energy from the engine to cool the water vapor returning it to the liquid state to reinsert into the fuel cell. If nottwo things may happencars would be competing for the limited fresh water (this type of water cell does not work with salt water as it must be current limited)and the water vapor would imbalance the current water cyclewhich would lead to increased global tropical environmentshard to pinpoint it to LA though At any rate I would see this as a vast improvement for LAwouldn't you(-:
Water consumption in the Los Angeles County area is roughly 5,000 times greater than the water vapor that would be generated by such cars. About half of that water consumption goes into landscaping. How much of that just evaporates into the atmosphere? My guess is more than 1/50% of the water used. Addendum: I was thinking of hydrogen powered cars not fuel cells. The other answerers are right, the product is just water, not water vapor.
The water vapor from the many acre feet of water being collected in reservoirs and brought in through aqueducts makes water vapor from fuel cells look pretty tiny.
Did you mean C7H16? Heptane? If you look up the enthalpies, you'll probably find that burning gas produces more water per energy than the fuel cell. Assuming a perfect burn heptane + 11 oxygen mollecules ---7 carbon dioxide + 8 water so subtract 8 times the deltaH of water vapor (241.8) and 7 times the deltaH of CO2 (393.5) from the deltaH of gas (188). Divide that by 8 to get the energy produced per water mollecule released. I get 562.6. Compare that to the deltaH of water (241.8). So the fuel cell produces 2.3 times as much water per energy as burning gas (in lieu of the CO2 and other nasty stuff). So much for that theory. The chemistry of the atmosphere is a funny thing. Often, air quality is worse on weekends when nobody is driving. Go figure. LA is a desert anyway, though. We've got some room to play with to make it a bit more humid before the cactus and chaparral start to complain.
