Question about hydrogen cars

http://www.pcmag.com/article2/0,2817,2429185,00.asp

Toyota on Monday announced that it plans to start selling electric vehicles powered by hydrogen fuel cells by 2015.
The car maker showcased two demo fuel-cell vehicles (FCVs) on the first day of the Consumer Electronics Show in Las Vegas, including a blue four-door sedan that looked like it could appear on a showroom floor immediately, and a "camouflage-taped engineering prototype," which Toyota said it has been using over the past year to conduct "extensive and extreme on-road testing in North America."

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It is about as green as you can get, with emissions consisting entirely of water vapor.

Isn't water vapor a potent greenhouse gas? How is releasing additional water vapor into the atmosphere going to alleviate global warming?

Originally posted by sh76
http://www.pcmag.com/article2/0,2817,2429185,00.asp

[quote]Toyota on Monday announced that it plans to start selling electric vehicles powered by hydrogen fuel cells by 2015.
The car maker showcased two demo fuel-cell vehicles (FCVs) on the first day of the Consumer Electronics Show in Las Vegas, including a blue four-door sedan that looked like it could ap ...[text shortened]... ? How is releasing additional water vapor into the atmosphere going to alleviate global warming?

Considering the oceans cover 70% of the Earth, I don't think the extra moisture coming from even a billion H2 cars will amount to a hill of beans.

Originally posted by sh76
http://www.pcmag.com/article2/0,2817,2429185,00.asp

[quote]Toyota on Monday announced that it plans to start selling electric vehicles powered by hydrogen fuel cells by 2015.
The car maker showcased two demo fuel-cell vehicles (FCVs) on the first day of the Consumer Electronics Show in Las Vegas, including a blue four-door sedan that looked like it could ap ...[text shortened]... ? How is releasing additional water vapor into the atmosphere going to alleviate global warming?

Water vapor is a greenhouse gas, but from what I've read it quickly "rains out" of the atmosphere. It doesn't accumulate like carbon dioxide does.

EDIT: Since CO2 accumulates in the atmosphere and takes a long time to get rid of, it creates a long-lasting warming effect, and warmer air can hold more water vapor -- which exacerbates the problem. Just increasing water vapor alone triggers a negative feedback process that causes water vapor to decrease back to normal levels. But increasing CO2 triggers a dynamic that causes water vapor levels to equilibrate at a long-lasting, higher level.

Originally posted by Soothfast
Water vapor is a greenhouse gas, but from what I've read it quickly "rains out" of the atmosphere. It doesn't accumulate like carbon dioxide does.

EDIT: Since CO2 accumulates in the atmosphere and takes a long time to get rid of, it creates a long-lasting warming effect, and warmer air can hold more water vapor -- which exacerbates the problem. Just ...[text shortened]... riggers a dynamic that causes water vapor levels to equilibrate at a long-lasting, higher level.

Exactly.

Basically if you increase water vapour levels over the current local maximum humidity it rains.

Also, it should be noted that hydrogen fuel cells are much more efficient than petrol/diesel
engines... And that internal combustion ALSO produces water vapour as WELL as CO2

Burning hydrocarbons [CH] produces CO2 and H2O [as well as other products from the other
elements present and incomplete burning ect]

Hydrogen Fuel Cells JUST produce water vapour.

And if you really wanted you could condense that out and just have it drip onto the road as
a liquid to drain away.

Originally posted by googlefudge
Exactly.

Basically if you increase water vapour levels over the current local maximum humidity it rains.

Also, it should be noted that hydrogen fuel cells are much more efficient than petrol/diesel
engines... And that internal combustion ALSO produces water vapour as WELL as CO2

Burning hydrocarbons [CH] produces CO2 and H2O [as well as other ...[text shortened]... ted you could condense that out and just have it drip onto the road as
a liquid to drain away.

Or drink it🙂

I think there is a dark underbelly to H2, making H2 is not as environmentally benign as people would like to think. For instance, there is the old way of making H2, electrolysis, the original way with just cramming electrons through brine is only about 3% efficient and so you lose 97% of your effort to get H2.

Nowadays there are much more efficient means, like chemical catalyst photocell conversion but I don't think it is even as much as 60% efficient yet anyway.

Most means of making H2 require a lot more energy than you get with the final product, at least for now.

If you generate a ton of CO2 for every ton of H2 you make, you have not changed anything in terms of environment for example.

I believe that going for hydrogen power, at least in the very long run, is a seriously flawed strategy.
Although it is true that hydrogen as a fuel would by far have the highest specific energy ('specific energy' means energy density of fuel per Kg rather than per litre ) and this is one reason why such a big deal is made of hydrogen fuel, except for fuelling aircraft, energy density is not really the critical factor here. For most applications except for fuelling aircraft, a fuel with a specific energy only a quarter of that of diesel would be more than adequate.

And there are big problems with hydrogen fuel that other fuels don't have: it is very difficult to store in a compact way; it forms an extremely explosive mix with air so is not good for safety; it so far has been difficult to manufacture efficiently without burning fossil fuels in the process although that is bound to change as technology advances, and, perhaps most devastating of all, although it is often cited to be a 'green' fuel, molecule for molecule hydrogen gas has many times (I don't recall the exact figure on this but I remember it was extreme) the greenhouse effect than CO2 so, if hydrogen is to be used as a substitute for burning fossil fuels, there better be strict international laws strictly enforced everywhere in the would to stop all accidental hydrogen leaks else all the hydrogen that constantly would leak into the atmosphere rather than getting burned would result in hydrogen fuel contributing more to the greenhouse effect than burning fossil fuels! Hydrogen is NOT the answer to our environmental problems at least not quite like many hydrogen enthusiasts hope it would be.

For these reasons, I believe most money currently spent on research into hydrogen fuel would be better currently spend as extra money on research into such things as biodiesel, biofuel fuel cells, solar, wind and magnesium-sulfur batteries (which will surely one day replace lithium batteries because Mg-S batteries would have higher specific energy than lithium ones but be much cheaper ) . Haven said that, hydrogen fuel would be the fuel of the far future for aircraft (but nothing else ) because the specific energy of a fuel for aircraft IS of great critical importance to aircraft fuel economy.
But, since none aircraft vehicle are much more critical to our economy than aircraft, I still think that, for now, research into hydrogen fuel should be given very low priority.

Originally posted by sonhouse
Or drink it🙂

I think there is a dark underbelly to H2, making H2 is not as environmentally benign as people would like to think. For instance, there is the old way of making H2, electrolysis, the original way with just cramming electrons through brine is only about 3% efficient and so you lose 97% of your effort to get H2.

Nowadays there are much mor ...[text shortened]... for every ton of H2 you make, you have not changed anything in terms of environment for example.

This is true.

However...

Any fuel that is made rather than found will have an energy cost greater than it releases.

The fact that we use plants to (rather inefficiently) produce fuel from sunlight doesn't
necessarily mean we are getting the energy for free.
The sunlight being converted into sugars [ect] in plants that we then convert to biofuel
is energy that could potentially otherwise be harvested to produce hydrogen or electricity
and the land could otherwise be used for producing food crops.

At 60% efficiency we are already way more efficient at turning energy into fuel than nature
is. Which means you need less land area collecting energy to make your fuel than you would
need with plants (plants being about 10% efficient at converting sunlight into biomass, and then
there are energy costs turning that biomass into fuel). And that area saved can be used for food
production or left as wild natural habitat.


Obviously hydrogen has [many] issues, and it may well be that we only use it in spacecraft and
aircraft and use batteries or other for cars because of those issues... However ANY fuel that we
use that must be made and not mined or otherwise harvested will have similar drawbacks.

So unless you want nuclear cars, they will have to have an energy storage system like batteries or
hydrogen to store energy generated elsewhere (by nuclear, solar, and renewables).

Originally posted by sh76
http://www.pcmag.com/article2/0,2817,2429185,00.asp

[quote]Toyota on Monday announced that it plans to start selling electric vehicles powered by hydrogen fuel cells by 2015.
The car maker showcased two demo fuel-cell vehicles (FCVs) on the first day of the Consumer Electronics Show in Las Vegas, including a blue four-door sedan that looked like it could ap ...[text shortened]... ? How is releasing additional water vapor into the atmosphere going to alleviate global warming?

The water vapour has zero influence on global warming. It's an extremely small amount and the excess rains back to Earth anyway. The advantage of hydrogen fuel cells is that the exhaust fumes cause no pollution on a local level (exhaust fumes from cars kill thousands per year), but you still need power to produce it. If the power is produced in a polluting way, you've just moved the pollution. Another advantage compared to electric cars is that hydrogen is lighter (batteries are a significant part of the mass of an electric car) and that it is easier to refuel (charging batteries takes a lot of time). It does require, however, more investment in the infrastructure since you need to transport all the hydrogen to petrol stations, which also need to invest in hydrogen storage tanks etc.

Originally posted by googlefudge
This is true.

However...

Any fuel that is made rather than found will have an energy cost greater than it releases.

The fact that we use plants to (rather inefficiently) produce fuel from sunlight doesn't
necessarily mean we are getting the energy for free.
The sunlight being converted into sugars [ect] in plants that we then convert to biofu ...[text shortened]... batteries or
hydrogen to store energy generated elsewhere (by nuclear, solar, and renewables).

This is also true. Any energy source that doesn't effect Earth's environ would be ok even if it is only 1% efficient, for instance, having energy beamed down from a solar array in a sync orbit, a few terrawatts, you could use the energy to generate H2 even if it was not efficient as long as it got the transport job done.

Originally posted by sh76
http://www.pcmag.com/article2/0,2817,2429185,00.asp

[quote]Toyota on Monday announced that it plans to start selling electric vehicles powered by hydrogen fuel cells by 2015.
The car maker showcased two demo fuel-cell vehicles (FCVs) on the first day of the Consumer Electronics Show in Las Vegas, including a blue four-door sedan that looked like it could ap ...[text shortened]... ? How is releasing additional water vapor into the atmosphere going to alleviate global warming?

If you are concerned about global warming a natural gas powered car would make more sense until fossil fuels stop being the cheapest source of hydrogen. Good luck trying to find fueling stations that have it though. That is the advantage of gasoline and diesel, the infrastructure is already there and convenient for us. CNG will only attain that status if the demand is there. That means people have to buy the cars first and endure the inconvenience of finding those rare CNG fueling stations. Hydrogen has the same problem.

http://automobiles.honda.com/civic-natural-gas/

I should point out that natural gas production releases other greenhouse gases other than CO2 and that makes it uncertain if it really is better to reduce the rate of global warming. It is hard to measure. I guess I'm saying it is debatable.

Originally posted by Metal Brain
If you are concerned about global warming a natural gas powered car would make more sense [...]

No it wouldn't. If you are concerned about global warming, opt for a hydrogen-fueled or electric-powered car, where the electricy is produced using renewables or nuclear power.

Originally posted by KazetNagorra
No it wouldn't. If you are concerned about global warming, opt for a hydrogen-fueled or electric-powered car, where the electricy is produced using renewables or nuclear power.

That is not practical.

I'm not concerned about global warming personally, but CNG is the only practical solution in the short term. Maybe some day your suggestion will be practical but it will not be for many years.

Originally posted by Metal Brain
That is not practical.

I'm not concerned about global warming personally, but CNG is the only practical solution in the short term. Maybe some day your suggestion will be practical but it will not be for many years.

Actually it's eminently practical... and CNG is not a solution because it's still a
pollution emitting fuel. It also has almost all the drawbacks of hydrogen with
none of its benefits. Changing to CNG infrastructure would be highly expensive
and time consuming and still leave us with the same global warming problem to solve.

And the fact that you don't think global warming is something to worry about
demonstrates your inability to make good judgements.

Originally posted by googlefudge
Actually it's eminently practical... and CNG is not a solution because it's still a
pollution emitting fuel. It also has almost all the drawbacks of hydrogen with
none of its benefits. Changing to CNG infrastructure would be highly expensive
and time consuming and still leave us with the same global warming problem to solve.

And the fact that yo ...[text shortened]... lobal warming is something to worry about
demonstrates your inability to make good judgements.

"Changing to CNG infrastructure would be highly expensive
and time consuming."

And hydrogen would not?

Natural gas is lighter on carbon than the other fossil fuels. It has that benefit. Almost half of electricity produced in the USA is from coal and that is carbon heavy. Hydrogen will be supplied by fossil fuels because that is what is most cost effective. Technology may change that some day but not now. People buy what they can afford and is convenient for them. That gives fossil fuels the edge. That is the reality.

If you are implying that the hydrogen extracted from fossil fuels will allow the carbon from the fossil fuels to be sequestered please make that known so we can all judge for ourselves if that is practical.

Originally posted by Metal Brain
That is not practical.

I'm not concerned about global warming personally, but CNG is the only practical solution in the short term. Maybe some day your suggestion will be practical but it will not be for many years.

How is it not practical to just build a bunch of nuclear power plants?