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Old 22nd August 2005, 00:02   #1
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Exclamation Fuel Cell question

This question is on my mind for a long time

In fuel cells by product is H2O (water) in gaseous form (Steam)
now H2O is in liquid state at normal room temprature
It converts into gaseous form only at 100 deg. C (at sea level)

now considering height & pressure drop lets say steam will be formed at 80 deg C

and from thermodynamics laws it is clear that steam coming out from car will loose its heat to surrounding

now imagine all of the cars in world running on fuel cell. consider the amount of steam emitted per second & it will all be lost to surrounding

will this again lead to global warming? because in current IC engines by product is mainly CO2 which doesnot allow heat waves escape atmosphere coming from sun & after reflecting from earths surface thus causing temprature rise & atleast for now trees use CO2 thus reducing its level (slightly) now with steam the temprature will rise but there will be no way to absorb this heat
and also since this steam once cooled will turn in liquid & resulting in rainfall so will it disturb water cycle?

is this issue being address previously?
is my thinking correct?
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Old 22nd August 2005, 00:29   #2
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Quote:
Originally Posted by adya33
This question is on my mind for a long time

In fuel cells by product is H2O (water) in gaseous form (Steam)
now H2O is in liquid state at normal room temprature
It converts into gaseous form only at 100 deg. C (at sea level)

now considering height & pressure drop lets say steam will be formed at 80 deg C

and from thermodynamics laws it is clear that steam coming out from car will loose its heat to surrounding

now imagine all of the cars in world running on fuel cell. consider the amount of steam emitted per second & it will all be lost to surrounding

will this again lead to global warming? because in current IC engines by product is mainly CO2 which doesnot allow heat waves escape atmosphere coming from sun & after reflecting from earths surface thus causing temprature rise & atleast for now trees use CO2 thus reducing its level (slightly) now with steam the temprature will rise but there will be no way to absorb this heat
and also since this steam once cooled will turn in liquid & resulting in rainfall so will it disturb water cycle?

is this issue being address previously?
is my thinking correct?
in hydrogen fuel cells the hydrogen and oxygen gases are mixed to produce water(the chemical energy of this reaction is stored as electrical energy and powers the car).there is no steam generated.hence exhaust will only be water.but because it uses so less quantity of hydrogen and oxygen the water produces is not much.it will fall as droplets from the tail pipe.

now they are also trying to use the generated(exaust) water as fuel by seperating it into hydrogen and oxygen(by process of electrolysis).so there is no emission in such systems.and the milege will improve by a large extent(maybe double or even 3times).but......it is very very costly.
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Old 22nd August 2005, 00:47   #3
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Quote:
there is no steam generated.hence exhaust will only be water.but because it uses so less quantity of hydrogen and oxygen the water produces is not much.it will fall as droplets from the tail pipe.
follow this link
http://corporate.honda.com/environme...fuel_cells_how

most importantly read the last (5th) point
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Old 22nd August 2005, 00:54   #4
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yeah maybe the water is released in vapour form because of the temp at which the reaction takes place.BTW that will be in such small quantity.also it will probably condense on the exaust pipe itself and hence water droplets will fall from the exaust pipe.
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Old 22nd August 2005, 11:10   #5
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Just on yr warming question itself-
Even if there is steam , it is just water vapour,
The major cause of warming is not the temprature that the CO2 or the Steam are release from the exhaust at , it is their effect after release into the atmosphere
where the CO2 produced will provide a greenhouse effect which then leads to warming / global warming,
Steam/WaterVapour on the other hand will not contribute this effect


Also consider this
When Co2 is release from the exhause it is also very hot, in fact the initial gas relese temprature is very high , a few Hundred degress (dont have specifics) but i can easily speculate it woule ba around 400-500 deg C. Steam on the other hand would only be a 100 Deg unless is was superheated steam

So you worry about the heat generated should not have any untoward effect.
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Old 22nd August 2005, 12:10   #6
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Quote:
Originally Posted by merve_extreme

now they are also trying to use the generated(exaust) water as fuel by seperating it into hydrogen and oxygen(by process of electrolysis).so there is no emission in such systems.and the milege will improve by a large extent(maybe double or even 3times).but......it is very very costly.
the only way they can gain from the electrolysis is using regenerative braking, when the braking energy can be used to separate Hydrogen and Oxygen.

otherwise they need more energy to separate than they got by combining them ( remember Entropy :-D)
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Old 22nd August 2005, 12:17   #7
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Quote:
Originally Posted by vivekiny2k
the only way they can gain from the electrolysis is using regenerative braking, when the braking energy can be used to separate Hydrogen and Oxygen.

otherwise they need more energy to separate than they got by combining them ( remember Entropy :-D)
i think they are using some dynamos fitted on the flywheel and the wheels to generate electricity as the car is in motion.it is still a prototype in its preliminary stage.that is why it is so costly.it may never make to production stage(in the near future) due to its complexity and cost.

Last edited by merve_extreme : 22nd August 2005 at 12:19.
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Old 22nd August 2005, 16:18   #8
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Well it is something to think about ... Global warming might not really be such a big issue as one cant really fathom what might happen in reality...u guys are considering that the water vapour or droplets are in small quanities but imagine when u have millions of car emitting vapour/ steam into air what will be the scenario ... Also what about relative humidity level ... in places of high humidity condensation of steam will also take a lot of time .. so relative atmospheric humidity might reach alarming rates ... I mean imagine this happening in mumbai or chennai where humidity is already so high ???
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Old 22nd August 2005, 16:38   #9
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Adya33: Water also exists in gaseous form at ambient temp, called water vapour (not steam) :-)
The heat produced by the fuel cell reaction is nowhere near the heat produced by IC engines. The maximum energy of conversion is given out as electricity directly without converting it into heat first (like IC). The exhaust will be a gentle stream of water vapour and droplets at slightly more than ambient temp. Dont worry about global warming from fuel cells.

Vivekiny2k: Fuel cell cars anyway need to use regenerative braking to store energy (for acceleration) as the peak output of fuel cells is limited by the cost. Entropy does hold true. The only way they can use electrolysis is maybe if they add solar cells on the car, but then it will be like buying one car for the price of 5 ;-)
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Old 22nd August 2005, 19:37   #10
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Quote:
Originally Posted by merve_extreme
BTW that will be in such small quantity
if you consider this problem for
1 car = negligible effect
100 cars = noticible effect
100000 cars = considerable effect
100000000 cars = serious problem

Quote:
Originally Posted by merve_extreme
also it will probably condense on the exaust pipe itself and hence water droplets will fall from the exaust pipe.
again imagine all cars on fuel cell & then it will turn out to be one slippery road (safety concern)

Quote:
Originally Posted by Revvhead
Even if there is steam , it is just water vapour,

The major cause of warming is not the temprature that the CO2 or the Steam are release from the exhaust at , it is their effect after release into the atmosphere

where the CO2 produced will provide a greenhouse effect which then leads to warming / global warming,
Steam/WaterVapour on the other hand will not contribute this effect
where will heat go when in atmosphere
to the lower temprature body (surrounding)
so the steam will loose its heat & cool down (turn into liquid)
surrounding will absob heat & get a little warmer

in case od CO2 don't forget trees absorb CO2 for photsynthesis & then release oxygen back into atmosphere
so we can say that CO2 is converted in oxygen (not exactly but into various other things one of which is oxygen)
so essentially CO2 is being utilised & the remaining CO2 is then causing the green house effect
but in case of steam the entire heat energy will be given out to surrounding

Quote:
Originally Posted by Revvhead
When Co2 is release from the exhause it is also very hot, in fact the initial gas relese temprature is very high , a few Hundred degress (dont have specifics) but i can easily speculate it woule ba around 400-500 deg C. Steam on the other hand would only be a 100 Deg unless is was superheated steam
Quote:
Originally Posted by nitinbhag
The heat produced by the fuel cell reaction is nowhere near the heat produced by IC engines. The maximum energy of conversion is given out as electricity directly without converting it into heat first (like IC).
agreed I am not comparing IC engine to Fuel Cells here.
also another thing to remember is when the steam will cool down then it will turn into liquid, which will mean frequent spells for rain which will mean disturbance in water cycle

Quote:
Adya33: Water also exists in gaseous form at ambient temp, called water vapour (not steam) :-)
Quote:
Originally Posted by nitinbhag
The exhaust will be a gentle stream of water vapour and droplets at slightly more than ambient temp.
as for vapours, what will happn if surrounding reaches its maximum carrying capacity of vapour?
also like EVO said the humidity level will increase immensly



Quote:
Originally Posted by nitinbhag
Dont worry about global warming from fuel cells.
I am not saying that because of fuel cells global warming will take place tomorrow.
but if my theory is correct then somewhere down the line after next 50 years humans will face the problem of global warming due to fuel cells.
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Old 22nd August 2005, 21:27   #11
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You may say that you are not comparing the IC engine to the fuel cell here, but you still need to look at the total effect

Insofar as your hear question goes
An IC engine as a whole will run Much hotter than a fuel cell one, thus the total heat being given out to the surroundings will reduce. This comparison matters. You will already be adding less heat to the system from a fuel cell car than you are already doing
In addition as said before, the emissions will not add to the greenhouse gases, thus the total warming effect will be far less.

1. No Greenhouse gases - No warming effect
2. Less heat from an F cell engine- less heat into system
result- The running of this engine will drastically cut down the warming. and the surroundings will saty cooler than if you were running an IC engine

You are also ignoring the rest of the emmisions such as Nitrous oxides and Sulphur Oxides which are even more harmful than CO2 emmisions ( Think acid rain for an example), as well as particulate matter and soot


You could have a valid point re the amt of water vapour in the air, but i dont think it will affect it that much,as to make the Hydrogen for the cells, you will have to take it out of water to start with, which will essentially more or less balance the amount of water sent out.
It may however icrease the humidity in areas of dense population, but at the same time it will reduce the smoke and the heat generated, the air will be cleaner and breathable, and there will be no particulate suspension in the air


b- there is enogh CO2 in the atmosphere for photosysthesis to occur anyway, It was taking place before the IC engine was invented and will continue to do so

Last edited by Revvhead : 22nd August 2005 at 21:29.
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Old 22nd August 2005, 21:58   #12
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Few problems, though the level of CO2 has gone up, tree cover has gone down extensively. The amount of CO2 that stays up in the atmosphere trapping heat has increased so has Ozone depleters.

Also, aeroplane vapour trails have been long known to affect weather, often the difference in temperatures upto one degree celsius. But their effect is overshadowed by the emissions of the same aeroplane's jet engines.
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Old 23rd August 2005, 23:28   #13
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Quote:
Insofar as your hear question goes
An IC engine as a whole will run Much hotter than a fuel cell one, thus the total heat being given out to the surroundings will reduce. This comparison matters. You will already be adding less heat to the system from a fuel cell car than you are already doing
In addition as said before, the emissions will not add to the greenhouse gases, thus the total warming effect will be far less.

1. No Greenhouse gases - No warming effect
2. Less heat from an F cell engine- less heat into system
result- The running of this engine will drastically cut down the warming. and the surroundings will saty cooler than if you were running an IC engine
nice explanation & thank you for that
however I wouldn't say no green house gases no warming effect
lets just say LESS WARMING EFFECT

Quote:
You could have a valid point re the amt of water vapour in the air, but i dont think it will affect it that much,as to make the Hydrogen for the cells, you will have to take it out of water to start with, which will essentially more or less balance the amount of water sent out.
Hydrogen is not taken from water. rather it is taken from other means (if i remember correctly then from certain metal hydrides) & oxygen is obtained from air. Water molecule is a very stable molecule

so the water level won't be balanced, rather it will be increased (another worring problem)

Quote:
It may however icrease the humidity in areas of dense population, but at the same time it will reduce the smoke and the heat generated, the air will be cleaner and breathable, and there will be no particulate suspension in the air
it may reduce the air pollution (main advantage) but it will at the same time increase humidity very much. imagine in place like mumbai humidity increasing sufficiently (don't consider one car, consider all cars in mumbai to run on fuel cells)

Quote:
b- there is enogh CO2 in the atmosphere for photosysthesis to occur anyway, It was taking place before the IC engine was invented and will continue to do so
with IC engine there is ATLEAST a way to get rid of CO2 (not entire but some of it)
where can steam be absorbed & say converted into other useful form (without loosing heat into atmosphere & without disturbing water cycle)

don't forget the water cycle being disturbed

Quote:
Few problems, though the level of CO2 has gone up, tree cover has gone down extensively.
that is the main cause of the problem
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Old 24th August 2005, 00:55   #14
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adya, if even only the oxugen is taken from the water as you say-
then that still reuces the the amount of water and when it is converted
back to water you still get more or less a balanced equation
]
Secondly ,if you extract the oxygen from the water,
then it means you have alkso seperated the Hydrogen atoms as well, and one would collect those as well, rather than let them vamosse, no??


With the IC engine, you are ADDING CO2, not getting rid of it in any manner,
Co2 is formed when an IC engine operates as the main byproduct of combustion

By having the fuel cell engine you stop adding additional Co2 into the atmoshere


You initial query and worry was about the additional heat being generated,
As you have accepetd the amount of heat generated simply by running the engine would be significantly less, in addition to that you are not adding
CO2 to the atmosphere and therefore bringing down the main contibutor to the whole warming process


Quote from Adya"

with IC engine there is ATLEAST a way to get rid of CO2 (not entire but some of it)
where can steam be absorbed & say converted into other useful form (without loosing heat into atmosphere & without disturbing water cycle)

don't forget the water cycle being disturbed
UNquote""

What r you trying to say here? That an IC engine gets rid of co2, or co2= steam??

As i have said, there is the distinct possibility of humidity going up in High density pockets
and i am considering the number of vehicles involved, there exists the possibilty of shift in the weather pattern. that will have to be a sudject of some expert study, i cant give you any concrete answer on that.However like i said that as far as your initial main question on the heat generation goes, i believe i have shoen you how a Fuel cell engine will in all respects add less heat to the system.

And at any rate, i would much rather that the engine i use spewed water vapour , Rather than Carbon Monoxide, Dioxide & Nirtous & suphurous oxides
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Old 24th August 2005, 01:40   #15
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Quote:
adya, if even only the oxugen is taken from the water as you say-
read what I have said earlier

oxygen is obtained from air. & then I said Water molecule is a very stable molecule
two different sentences

Quote:
What r you trying to say here? That an IC engine gets rid of co2, or co2= steam??
nope.
I am saying that Co2 produced is ABSORBED by trees & they give out Oxygen
& in comparison I am asking same about STEAM
where will steam be absorbed? in the surrounding air. & its heat will loose to surrounding air.

Quote:
i believe i have shoen you how a Fuel cell engine will in all respects add less heat to the system.
please go through my previous post.
I have accepted what you have said

and as the topic says its not only about warming (though its major concern) but there are other effects too viz., HUMIDITY LEVEL, WATER CYCLE DISTRIBUTION

Quote:
And at any rate, i would much rather that the engine i use spewed water vapour , Rather than Carbon Monoxide, Dioxide & Nirtous & suphurous oxides
Like I have said earlier I am NOT COMPARING Fuel cells to IC engine, but rather have some questions about fuell cell technology whoes answers I haven't been able to find.
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