question that i wonder on

[papertiger00]

i was looking at http://www.theaircar.com and they are using compressed air in order to power a vehicle. it is a fairly simply concept but i am curious every one talks about using diesel generators and such in order to make a hybrid but why not use the same concept as the air car but using the air power to charge the system, batteries etc. yes would require more computer parts to regulate when it would kick in etc. but if could simplify a little why would it not work. if can recharge the new lithium batteries that quick charge when say at 75% power till able to recharge then if able to produce enough power both run car and recharge battery. or just recharge battery at faster pace then it is draining.
the inventor has a us patient for a generator built on air but is a huge version so many other parts and such for buildings so not really an option.

i am also curious of using 4 small dc brushless motors at each wheel instead of keeping the tranny and such. this would be a big weight loss to the car but more batteries. so maybe the same. i am looking for help. thank you

[Peter VanDerWal]

> i was looking at http://www.theaircar.com and they are using compressed
> air
> in order to power a vehicle. it is a fairly simply concept but i am
> curious
> every one talks about using diesel generators and such in order to make a
> hybrid but why not use the same concept as the air car but using the air
> power to charge the system, batteries etc.

Two reasons:
A) this is the EV list not air car list
B) they are very inefficient.

You can't use compressed air as a power source, it's simply a storage
medium (like electricity).  I.e. you can't find compressed air lying
around, you can't mine it, and you can't dig a well for it.  Just like
electricyt you have to put energy into creating it.
Electricity is a lighter and more efficient way to store energy on a vehicle.


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[Joseph Ashwood]

----- Original Message -----
From: "papertiger00" <papertiger00@...>
To: <ev@...>
Sent: Tuesday, July 22, 2008 12:08 AM
Subject: [EVDL] question that i wonder on

> i was looking at http://www.theaircar.com and they are using compressed
> air
> in order to power a vehicle. it is a fairly simply concept but i am
> curious
> every one talks about using diesel generators and such in order to make a
> hybrid but why not use the same concept as the air car but using the air
> power to charge the system, batteries etc. yes would require more computer
> parts to regulate when it would kick in etc. but if could simplify a
> little
> why would it not work. if can recharge the new lithium batteries that
> quick
> charge when say at 50% power till able to recharge then if able to produce
> enough power both run car and recharge battery. or just recharge battery
> at
> faster pace then it is draining.
> the inventor has a us patient for a generator built on air but is a huge
> version so many other parts and such for buildings so not really an
> option.

The biggest problem I note is that according to the site it is only about
75% maximum efficiency. That is certainly higher than ICE, but not as high
as I would like. There is also the problem that in order to reach 75%
efficiency there is a series of compression and cooling cycles, so there is
still the recharge problem, although it is possibly to a lesser degree than
with lead-acid batteries, but still a far from optimal solution. I think in
terms of the overall costs and efficiencies the generator systems are
probably more cost, space, time, etc-effective. This is quite possibly only
temporarily true, but the losses due to the laws of thermodynamics have to
happen so the 75% isn't likely to change much, but nimbleness in the
compressed gas production system may provide net gains. And certainly in an
electric driven vehicle any device that can save weight and supply
recharging is good, so I don't want to dissuade you completely from
investigating it, just giving my two-cents that right now I don't see it as
superior to other range extending technologies.

>
> i am also curious of using 4 small dc brushless motors at each wheel
> instead
> of keeping the tranny and such. this would be a big weight loss to the car
> but more batteries. so maybe the same. i am looking for help. thank you

There are complications. A 2000 RPM motor would be capable of 100+ mph, but
engineering the connections are beyond what most people are capable
of, there is also the matter that the amplification effect of the gear
reduction would not be available unless you were to use a substantially more
exotic planetary gear reduction system (basically a single gear transmission
in each wheel) which would notably increase cost. This would to some degree
be balanced by the greater efficiency, but with the engineering capabilities
generally available would be very difficult to achieve. This of course
ignores the exact placement and the in-wheel versus shaft-driven debate can
be an extremely compelx engineering decision with no absolute correct
answer.
                    Joe


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[EVDL Administrator]

On 22 Jul 2008 at 0:08, papertiger00 wrote:

>  was looking at http://www.theaircar.com and they are using compressed
> air ... why not use the same concept as the air car ...

The "air car" has been discussed on this list before, even though it is off
topic.  Please look in the archives for more information before discussing
in further now.

http://www.evdl.org/archive/

and the old one,

http://www.mail-archive.com/ev@.../

Hope this helps.

David Roden - Akron, Ohio, USA
EVDL Administrator

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[markgrasser]

 
Electricity is a lighter and more efficient way to store energy on a
vehicle.

Really< I have read on the air cars, they impress me.

The compressed air is stored in tanks under the car. Heavier than batteries?
Air coming out the tailpipe is non polluting, pretty sure.
The inefficiency that I see is the running of the compressor, as a matter of
fact, it is the only recurring expense.

Enough said, I'm done David.

Mark


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[Peter VanDerWal]

>
> this message wasn't meant to spark everything about the air car. it was
> just
> meant that nothing is perfect and so why not try something else. i am not
> looking at a full size version like the car has or ones built as backup
> for
> hospitals and such. just thinking like a small rotational engine to
> produce
> power the rotaional can run without any real oil they make "air" bearings
> or
> standard bearing for rotaion.
> i am just looking for a way to recharge without haveing to stop and plug
> in
> is all
>

The oil issue is from lubricating the piston sleeves, not the bearings.

Where do you think you'll get the compressed air from? I assume you mean
to carry it with you?

If you're going to carry it with you, as a back up to your EV, read my
earlier post about the weight of SCUBA tanks.

A typical SCUBA tank stores as much energy as an Exide Orbital AGM
battery, and weighs the same amount.  The tank also takes up about two to
three times as much volume.

If you can carry the compressed air, then you can carry more batteries
instead, and save on the multiple conversion losses from the compressed
air (electricity to mechanical power to compressed air to mechanical power
to electricity)



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[Peter VanDerWal]

>
> this message wasn't meant to spark everything about the air car. it was
> just
> meant that nothing is perfect and so why not try something else. i am not
> looking at a full size version like the car has or ones built as backup
> for
> hospitals and such. just thinking like a small rotational engine to
> produce
> power the rotaional can run without any real oil they make "air" bearings
> or
> standard bearing for rotaion.
> i am just looking for a way to recharge without haveing to stop and plug
> in
> is all

I should add, once you include the extra weight/volume for the air motor
and generator, the compressed air solution weighs a LOT more and takes up
a lot more space than batteries.
Once you add in the losses, air motor ~75% and generator ~80%, it ends up
storing less energy.

So it ends up weighing more and/or storing less usable energy than batteries.


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[Peter VanDerWal]

>> Wow, So all those people that dive with 3000psi on their backs are
>> having
>> breathing problems.
>
> Acutally....without replacing the filter that fills up (2.5 quarts) of
> compressor oil in a period
> of 4.5 hours...nope...they wouldn't have any trouble breathing at
> all...because they would be
> quite dead.

What size compressor are you talking about?
I have an oiless compressor so I don't have to worry about it, but I don't
think the the guy at the local scuba shop goes through oil that fast.
Then again, his compressor can only fill 3-4 tanks in an hour.



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[lyn williams]

> Air coming out the tailpipe is non polluting, pretty sure.

With large high capacity air compressors, one of the huge
problems is filtering enough of the compressor OIL
out of the air to make the air useful.  The higher the pressure...the more oil.


--
lyn williams <lyn@...>


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[Roger Heuckeroth]

The only reason to consider a compressed air engine/ generator combo  
as an APU would be if its cost and weight was less than adding  
additional battery storage.  The combined system would need to have an  
energy density significantly higher than the LiFePO4 battery, and at a  
better cost basis.  I doubt that is the case.

On Jul 22, 2008, at 12:02 PM, lyn williams wrote:

>> Air coming out the tailpipe is non polluting, pretty sure.
>
> With large high capacity air compressors, one of the huge
> problems is filtering enough of the compressor OIL
> out of the air to make the air useful.  The higher the  
> pressure...the more oil.
>
>
> --
> lyn williams <lyn@...>
>
>
> _______________________________________________
> For general EVDL support, see http://evdl.org/help/
> For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ 
> ev

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[markgrasser]

Wow, So all those people that dive with 3000psi on their backs are having
breathing problems.

Obviously a special compressor or filtering, still very doable and a
possible solution equal to EVs.

Mark Grasser
Eliot, ME

-----Original Message-----
From: ev-bounces@... [mailto:ev-bounces@...] On Behalf
Of lyn williams
Sent: Tuesday, July 22, 2008 12:02 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] question that I wonder on

> Air coming out the tailpipe is non polluting, pretty sure.

With large high capacity air compressors, one of the huge
problems is filtering enough of the compressor OIL
out of the air to make the air useful.  The higher the pressure...the more
oil.


--
lyn williams <lyn@...>


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[markgrasser]

Roger,
I'm not suggesting an air hybrid, that was someone else.

The air car I have read about has 3000psi spun carbon fiber (I think) tanks.
It has an air motor to propel the car and a small petrol driven compressor
in case you get caught too far from home. At home you have an electric
compressor that maintains a set of dump tanks to quick fill the vehicle.

Again no batteries to replace. Only obvious loss I see is creating the
compressed air and having to replace the tanks periodically due to stress
and age.

Sorry, I don't like going off topic, especially after David says to stop but
I am finding it special.


Mark Grasser
Eliot, ME

-----Original Message-----
From: ev-bounces@... [mailto:ev-bounces@...] On Behalf
Of Roger Heuckeroth
Sent: Tuesday, July 22, 2008 12:19 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] question that I wonder on

The only reason to consider a compressed air engine/ generator combo  
as an APU would be if its cost and weight was less than adding  
additional battery storage.  The combined system would need to have an  
energy density significantly higher than the LiFePO4 battery, and at a  
better cost basis.  I doubt that is the case.

On Jul 22, 2008, at 12:02 PM, lyn williams wrote:

>> Air coming out the tailpipe is non polluting, pretty sure.
>
> With large high capacity air compressors, one of the huge
> problems is filtering enough of the compressor OIL
> out of the air to make the air useful.  The higher the  
> pressure...the more oil.
>
>
> --
> lyn williams <lyn@...>
>
>
> _______________________________________________
> For general EVDL support, see http://evdl.org/help/
> For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ 
> ev

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[papertiger00]

this message wasn't meant to spark everything about the air car. it was just meant that nothing is perfect and so why not try something else. i am not looking at a full size version like the car has or ones built as backup for hospitals and such. just thinking like a small rotational engine to produce power the rotaional can run without any real oil they make "air" bearings or standard bearing for rotaion.
i am just looking for a way to recharge without haveing to stop and plug in is all

markgrasser wrote:

Wow, So all those people that dive with 3000psi on their backs are having
breathing problems.

Obviously a special compressor or filtering, still very doable and a
possible solution equal to EVs.

Mark Grasser
Eliot, ME

-----Original Message-----
From: [e-mail] [mailto:[e-mail]] On Behalf
Of lyn williams
Sent: Tuesday, July 22, 2008 12:02 PM
To: Electric Vehicle Discussion List
Subject: Re: [EVDL] question that I wonder on

> Air coming out the tailpipe is non polluting, pretty sure.

With large high capacity air compressors, one of the huge
problems is filtering enough of the compressor OIL
out of the air to make the air useful.  The higher the pressure...the more
oil.


--
lyn williams <[e-mail]>


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[lyn williams]

> Wow, So all those people that dive with 3000psi on their backs are having
> breathing problems.

Acutally....without replacing the filter that fills up (2.5 quarts) of compressor oil in a period
of 4.5 hours...nope...they wouldn't have any trouble breathing at all...because they would be
quite dead.


--
lyn williams <lyn@...>


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[Peter VanDerWal]

> I must admit at one point I considered using some form of compressed air
> or
> hydraulic system as a braking system on the front wheels to recover a
> higher
> percentage of the energy of braking.  Compressed air was also interesting
> because, as previously noted, you can pick up a little at a gas station if
> it happens to be a hot day.

Sheesh, I guess I should have responded on list.  The 2-3 SCM @ 90-100 PSI
you find at gas stations is a far cry from the THOUSANDS of PSI these air
cars run on.

The compressed air at gas stations is practically useless as an energy
source for EVs.

Assuming you could build an incredibly efficient Air motor and couple it
to an incredibly efficient generator it would probably take 2-3 hours to
recharge you EV enough to go 1 mile.  It would only take 30-40 minutes to
push it that far.
If you are in moderately good shape, you could recharge faster with a
pedal powered generator.


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[Peter VanDerWal]

> I want to put a windmill on my EV so I will never have to chargethe
> batteries. The windmill can charge the batteries while I drive
> on the highway. Since it is so efficient, I dont have to have
> the windmill up while I am parked.

It's easier to put big wheels on the back and small wheels on the front.
That way you're always driving downhill.

;^)


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[Marty Mercer]

Thats just a personal choice for application. There may be an application
for a small air generator to effectively increase range, not as a primary.
I'm sure its a lot easier to find coin operated air stations than EV
charging stations.

Not that I would go the air engine generator route, but your dismissing a
technology based on personal preference. That I don't understand. Again,
lots of personal opinions flying around, but few facts....

On Tue, Jul 22, 2008 at 8:32 AM, Peter VanDerWal <evdl@...> wrote:

> >
> > this message wasn't meant to spark everything about the air car. it was
> > just
> > meant that nothing is perfect and so why not try something else. i am not
> > looking at a full size version like the car has or ones built as backup
> > for
> > hospitals and such. just thinking like a small rotational engine to
> > produce
> > power the rotaional can run without any real oil they make "air" bearings
> > or
> > standard bearing for rotaion.
> > i am just looking for a way to recharge without haveing to stop and plug
> > in
> > is all
>
> I should add, once you include the extra weight/volume for the air motor
> and generator, the compressed air solution weighs a LOT more and takes up
> a lot more space than batteries.
> Once you add in the losses, air motor ~75% and generator ~80%, it ends up
> storing less energy.
>
> So it ends up weighing more and/or storing less usable energy than
> batteries.
>
>
> _______________________________________________
> For general EVDL support, see http://evdl.org/help/
> For subscription options, see http://lists.sjsu.edu/mailman/listinfo/ev
>
>

--
Marty Mercer
Sacramento, CA

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[Marty Mercer]

For the rocket scientist who are hell bent in their ignorance....

http://www.engineair.com.au/index.htm

David, I'm done... So no need to comment.

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