I am told that water vapour is a potent greenhouse gas. Aren't hydrogen fuel-cells therefore eco-unfriendly?

Question

Water vapour, although present only in small amounts in the atmosphere, is a much stronger greenhouse gas than CO2. Many say that the solution to global warming lies in the use, especially in vehicles, of hydrogen fuel cells, which emit only water vapour. If this water vapour is not forcibly condensed, at the expense of more energy, before being emitted, is it not likely that, in the long run, say 50 years later, be in itself a cause of climate change. Even if the water vapour condenses in the atmosphere and falls as rain, would it not increase global rainfall? Also, what is the truth about suggestions that hydrogen fuel cells emit dangerous levels of hydrogen peroxide, and if so, how may this affect global climate and/or human health?

Answer 1

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No. You forget that all hydrocarbons (like gasoline) also emit water vapor as a product of combustion. So there should be no difference. In fact, since fuel cells utilize energy more efficiently than gas, I would predict a net decrease in water vapor from hydrogen.
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However, I will nevertheless object to fuel cell cars on the grounds that it is one of the alt-fuel options that makes the least sense. Fuel cell cars are electric cars. They even have batteries (providing current for acceleration.) So a fuel cell car will always be more expensive than a plain electric car.
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The next problem is that hydrogen is less efficient than batteries, requiring more electricity (to separate hydrogen) than plain battery electric cars use. The only advantage fuel-cell cars had was fast fueling - but now that 10-minute recharge batteries have been developed (see http://www.phoenixmotorcars.com ), even that advantage no longer applies.
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Answer 2

The water cycle can handle any of this water vapor. That's not the problem with hydrogen fuel cells. The problems include building the right tanks for the pressurized hydrogen, having an infrastructure so that consumers can actually get hydrogen fuel, and producing fuel cell vehicles that are cheap enough to be consumer-friendly.

Answer 3

No. There's a natural "water cycle" that recycles water between the atmosphere and the Earth. It's reacts pretty rapidly and so is very stable, and can handle additional input without problems.

The natural "carbon cycle" moves much more slowly and is more easily overwhelmed by our input.

Look at this graph.

http://scrippsco2.ucsd.edu/graphics_gallery/mauna_loa_record/mlo_record.html

The little squiggles are nature doing its' thing. CO2 falls a bit during summer when plants are active, and rises during the winter. The huge increase is us, burning fossil fuels (in addition to the shape of the graph, the increase numerically matches the increase in fossil fuel use). The scientists can actually show that the increased CO2 in the air comes from burning fossil fuels by using "isotopic ratios" to identify that CO2. The natural carbon cycle buried carbon in fossil fuels over a very long time, little bit by little bit. We dig them up and burn them, real fast. That's a problem.

Man is upsetting the balance of nature. We need to fix that.

Answer 4

water vapor exists in the atmosphere in huge amounts, the addition of water vapor from hydrogen fuel cells, even if these replace fossil fuel use in cars, would be negligible. the atmosphere has a way of ridding itself from excess water, but CO2 is much more difficult to expel from air.

Answer 5

I learned it was the other way. Water is much more abundant in the atmosphere, therefore contributing a large amount to the greenhouse effect, but the ratio of contribution is very low. I don't think there would be more carbon dioxide than water.

Answer 6

This sounds totally bogus to me. about 3/4 of the Earth is covered in water and there are large amounts of water vapor in the atmosphere at all time - what do you think clouds are?

Answer 7

Would you stop thinking and just do as AL has told us to.
Obey Him!

Just one other problem with hydrogen. In it normal state as a gas it has no potential energy. It must be under pressure or as a liquid. The energy it take to do this far out weighs the out put of the hydrogen.

Answer 8

Relative to what? Historically high concentrations of gases which had not been present in the atmosphere so profligatly before?

Scapegoat the minnows, the whole planet wallows.

Answer 9

Whoever you heard that from needs to pull their head out of their ***.

Answer 10

its the blanket cover above clouds that holds heat onto earth .... thats the problem