I'm all for fuel-cell cars, and assuming they take over the market in the next two decades, has anyone thought about the fact that the amount of water we would be adding to our environment is also a pollutant of sorts as well? That's a lot of H2O being emitted
Water vapor is also a greenhouse; however, it's not toxic like CO2 or other byproducts of engines that utilize petroleum as a fuel source. So, yes I think there could be a threat to the environment from the emissions of water vapor from hydrogen fuel cell cars. Also, you need to understand that it takes more energy to make hydrogen gas compared to the amount of energy it provides. Hydrogen right now has a negative energy output. For example, if it takes 10 joules of energy to make 1 pound of hydrogen gas, then the hydrogen gas will only give you 8 joules of energy. So, we need to find a more efficient way to convert water into hydrogen.
This is actually quite a good question. Not only could the emission be significant, just consider how the hydrogen would be produced. Right now hydrogen can be produced from natural gas, but doing so creates the same amount of CO2 as if you had burned the natural gas. So, the eventual source for H2 has to be water. If you take as a rough estimate that you would need the same weight of H2 to run a car as you currently use gasoline, then you would need about 100 pounds a week or more for a small car, Anyone who took Chem 101 understands that to get 100 pounds of hydrogen from water you have to split up 900 pounds of water. So, that's 25 tons a year or more of water per each small car, If Los Angelese had 10 million cars, times 25 tons a year, then you would be supplying, and then returning into the air, at least a conservative 250 millions tons a year of water just for LA. And, to split the original water, you would need a lot of electricity which you would have to get from some completely non-fossil fuel, renewable source such as solar or wind or tide. It's all possible, but we are a very long way from having such a system in place.
It could but using hydrogen is not a great idea. First of all you need to break down water to make the hydrogen. Where does that energy come from.? Secondly, the molecules are so small that they leak through tanks even if they are made of thick steel. Fill a tank with hydrogen, don't use the car and the tank is empty in a week.
its no doubt that the water has to go somewhere after it is produced,but a shortage or non-salinated water is not a problem. in fact, there are many parts of the world access to fresh water is the number one problem and its not just in poor countries. the island of bermuda off the east coast of the u.s. depends upon rainwater or water brought in by tanker ships for their supply and they're not close to being a poor nation. also, it would take a lot of people driving a lot of miles in cell vehicles to make much of a difference. the real issue with cell cars was brought up earlier by the comment about the amount of electrical energy needed to produce the hydrogen. i'm afraid that unless we start giving some thought to how we use public transportation, how items are shipped and consumed and how our communities are planned relative to the distances to get to work, school, shopping, etc. there may be a lot more bicycles in the future out of necessity rather than because they're fun!