Hi everyone.
I hope you don't mind me attempting to ask a sensible question despite not actually owning a hybrid. Actually, the question isn't really about hybrids specifically but more about hydrogen fuel-cell technology. The 'general' forum seemed the best place to ask. (Quick note for the ultra-green - whilst I don't own a hybrid, I grew up in the Netherlands where we've been recycling, separating chemicals in our household waste and using solar cells and wind farms since the 70's. I'm well aware of the environment ).
So my question / postulation is this : imagine a few years (decades?) in the future when we all drive some derivative of hydrogen fuel-cell vehicles. The emissions from those vehicles is basically water. I've searched around various articles and nobody as far as I can find has had a discussion on the side effects of the exhaust. Ok water seems innocent enough - certainly a lot less polluting than anything else in a vehicle. But what will happen to the environment in a world where all vehicles emit water and water vapour as exhaust?
For example, could it affect local weather? Imagine the environment in a large city and suburbs. The water content of the air would be higher - more water would be evaporating from vehicle exhaust. With the 'heat island' effect of a city, would that water rising into the atmosphere be enough to create clouds when it met a colder air layer? Could the clouds in turn produce more rain? Would cities become essentially cloudy, wet places? Would the increased water content and humidity be more or less beneficial for the city's inhabitants? Asthmatics etc?
I don't know the answers of course, which is why I thought this would be a good place to garner some opinions. So let's hear it - what do you think possible side-effects could be? Would the water from ALL those vehicles exhausts be enough to make a noticable difference to anything, one way or another ?
I would think that any nearby body of water is going to create about 10000X more water vapour than even a city of a million hydrogen fuel cell cars. However, I guess the potential exists for minor weather changes. I remember hearing a study about the cloud cover over North America. Those couple of days where no commercial jet traffic was flying at 9/11 allowed researchers to measure how contrails (water vapour from turbine engines) actually do affect the amount of cloud that occurs.
Two climate control systems, one inside and the other at the tailpipe.
2007 Camry Hybrid (in service June 2006)
FE: 6.67L/100km or 35.3 mpg (6.11L/100km or 38.5 mpg in summer)
First of all, one of the byproducts of burning hydrocarbons (gasoline) is the release of water. Look at your tailpipe on a cold day and you'll see the water vapor coming out.
Another thing to remember, the source of all of that hydrogen is going to be water.....whether broken down through electrolysis or sprinkled over a field growing switchgrass so I wouldn't worry too much about it.
-Tim
2006 Mercury Mariner Hybrid AWD
Black with Pebble interior
Premium Package with Nav & Moonroof
Current ODO: 26,152 Typical Drive: 20 min crosstown in heavy traffic (3.5mi there and back twice a day)
532 Gallons of gas saved
That's 10,642 lbs less CO2 emitted
Another thing to remember, the source of all of that hydrogen is going to be water.....whether broken down through electrolysis or sprinkled over a field growing switchgrass so I wouldn't worry too much about it.
That's a good point. I was just wondering about the increase and locality. Yes, water comes out of regular exhaust, but not so much as a pure H-car I presume?
I suppose the interesting time would be at about a 50-50 changeover, where half the cars are hydrogen. Would the increase in water vapour mix with the particulates from industries and regular cars and give some sort of smog?
That's a good point. I was just wondering about the increase and locality. Yes, water comes out of regular exhaust, but not so much as a pure H-car I presume?
I suppose the interesting time would be at about a 50-50 changeover, where half the cars are hydrogen. Would the increase in water vapour mix with the particulates from industries and regular cars and give some sort of smog?
I don't know if that is true. There are so many things impacting the amounts that I can't even guess. You have to consider the efficiency of the reactions, the amount of energy stored in each type of fuel, the amounts of each type of fuel, etc.
This comparison is pretty interesting, though it compares gasoline combustion to a Hydrogen fuel cell. The reactions for burning H2 should be the same but I believe the efficiency is lower than the FC. If that is true it would imply that burning H2 would produce over 2x the amount of H2.
My guess is that the amount of water added to the atmosphere would not make any significant difference. However, in a humid environment such as Florida the water would tend to condense and run off since the air is so saturated anyhow. In an area such as Phoenix the dry air could probably absorb the water vapor, causing a negligible, but measureable difference.
Note: I'm not a physicist, but I did stay at a Holiday Inn Express last night.
Note: Just a joke, I didn't stay at a Holiday Inn Express last night.
I think the true benefit would come from the fact that you wouldn't be burning any hydrocarbons, therefore your exhaust wouldn't contain any CO2, CO, or NOx pollutants. I think the water vapor byproduct is preferable to all of that. No matter what you are burning, heat is always a waste product of the process....at least until they perfect nuclear fusion powered cars...
There won't be an increase in water vapor-smaller, more efficient cars.
There won't be any increase in total water vapor from these future cars producing only water.This is true for a couple of reasons.
1)The average vehicle will be much lighter.The average wt(USA) is about 4100 lbs now.In the 80's it was about 3200 lbs. These future vehicles will probably be 2500-3000 lbs on average, so they will need much, much less energy than current vehicles.
2)The average total efficiency of an internal combustion engine car is about 30-40%.These future cars will have electric motors which are probably 85% efficient-and that includes drivetrain/tire losses. The conversion of H2 or alcohol to H20 in the fuel cell is claimed to be very, very efficient-90+%. In total these future vehicles should put 80% of the chemical energy into "moving the car".
Even though these vehicles will emit just water, they will probably emit a lot less than current vehicles.
The future vehicles will produce more water per unit of chemical energy used, but they will use much less chemical energy because of the light weight, and more efficient production of mechanical energy from the chemical energy.
Bottom line-these much lighter, all electric future vehicles will produce a lot less water because of the drop in weight, and the increase in efficiency. Just a guess, but... Thanks.Charlie
Last edited by phoebeisis; 07-21-2006 at 12:57 PM.
Hydrogen fuel cells are (in my opinion) unlikely to actually take off at all.
I know that there is a lot of development going on in this area, but the cost of the infrastructure required to transport, distribute, store and use hydrogen will be far greater than the development of pure electric cars.
The work being done on Lithium Sulphur batteries is extremely exciting, and if they manage to overcome a few problems, we'll all be driving electric cars powered by wind, solar, wave electric generators - a completely zero polluting structure - but not hydrogen.
These will be cheaper, lighter, more powerful and have vastly greater ranges than existing electric cars - up to 1,000 per recharge.
What about the water vapour?
).
Re: What about the water vapour?
Two climate control systems, one inside and the other at the tailpipe. 
