Are air powered buses next?

[kyle4501]

http://www.flixxy.com/zero-pollution-automobile.htm

A coworker sent me this link. He is convinced it is not only possible, but quite practical.

Needless to say, I think the video is a funny spoof & my coworker has no comprehension of the most basic laws of physics involved. 

[Jeremy]

Hmmm..well, I doubt that the video is actually meant to be a spoof, but it is certainly misleading. The narrative throws around phrases like 'powered by air' and 'zero emissions', which are guarenteed to give the wrong impression to a viewer who doesn't understand that the air is only a way of storing energy produced by electricity (and thus fossil fuels etc). You might just as well say that a Prius is powered by acid

Jeremy

[Nusa]

Compressed air is a valid energy-storage medium, but that doesn't mean it's practical...you run into the same problems as electric-only cars with finding places to fill up/recharge. You either need very large tanks or very high pressure tanks to get any decent range. There have been experimental air-powered cars for over the last 100 years. Trains have been run on compressed air in the underground mining industry. It wouldn't surprise me if a compressed-air commuter-type car becomes commercially available, but it will only appeal to a small market. Might make a great toad for a bus.

It may be pollution free to drive, but that doesn't mean the energy used to compress the air was pollution-free.

Perpetual-motion claims, like always, are hogwash. If it's not a spoof, then the really sad thing is if the commentator really believes what he's saying.

[kyle4501]

I would like nothing more than to see this in action & available for consumer use.

A few simple details would go a long way to confirm / deny 'spoof' status.
Air pressure required to 'fill up' the tanks.
Stored volume of compressed air.
Efficiency of the air motor.
What is the actual driving range in normal commuter traffic?

The practicality of it seems awfully dubious to me.
We have problems with air leaks on our buses & that is only 120 psi!

Overcoming wind & rolling resistance requires HP which is easily determined, kinda hard for me to imagine getting that kind of power (for 200 miles) out of that seemingly limited stored volume of compressed air.

What about lubrication in the air motor?

Any time I see "perpetual motion" is used in the marketing hype, red flags go up. In my mind, the blatant misdirections concerning zero emissions & 'free fillups' undermine any credibility that may be left.

[ToppDog]

The technology is real, & the 2 big leaders on making this happen are in India & Australia.  The US is supposed to start receiving imports of a compressed air powered car from India within a few years.  Someone else was working on a hybrid version that used a combustion engine to power an on-board air compressor to keep replenishing the air pressure in the tanks, & the prototype was able to travel 400 miles before needing more gas (if I remember correctly).

What they failed to state was that this was all possible because the vehicles weight was so light that it would never pass US safety standards.  I would venture to guess that the air compression engines would perform equally to combustion engines if the vehicles they powered were the same weight.  The only upside I could see from all the various info given over the past several years is that there is much less moving parts in some of the air compression engines & they should last much longer with very little maintenance.  They were also smaller & took up a lot less space, but in practicality I think that would be offset by the additional weight/space needed for an engine powered air compressor which would be essential for any realistic long range applications.

[NewbeeMC9]

things can be propelled with compressed air.    Ever seen a nitrogen tank valve knocked off and become a missile  There are also heat losses in the compression & expansion  phases that should be considered.  

I hope we do run it off air because I have a bad case of the winds ,, would be good for farting around town.




But the claim of using the compressed air in the car to compress its own air


There is a better chance of a bus filling itself up with fuel.

[kyle4501]

I got to thinking about why I am so skeptical about the practicality of this, so I wanted to run a few numbers to see if it really was practical.

Since I have no specifications to work from, I'll have to make some assumptions.
engine displacement = 1/2 liter = 30 cubic inches
1000 rpm for 40 mph
The volume of the compressed air tanks on the car = 15 cubic feet(3 tanks 12"diameter x ~6 ft long)
The desired run time is 30 minutes (200 mile range is 5 hours, so that is a 10% duty cycle)
Since a gasoline engine has a peak cylinder pressure of 600psi, we'll assume 300 psi will work here.
We'll also assume the ideal gas law applies PV=mRT & we'll also assume there is no heat loss.

30ci/rev x 1000rev/min = 30,000 ci = 17.4 cubic feet per min (Stop & think about the HP required to provide 17.4 CFM at 300 psi !)
17.4 cfm x 30min = 522 cf

300psi x 522 cf = ? psi x 15
? psi = 10,440psi


10,440 psi! ? ! ? ! ? ! ? !
DAMN! That's scary! ! ! !

Seems to me the skeptics have good reason to want some details.

[PCC]

In my mind, the blatant misdirections concerning zero emissions & 'free fillups' undermine any credibility that may be left.

Aw, come on - He showed us how the fill-ups are for free; did you not see the balloon demonstration in the video?

[Hard Headed Ken]

You anti-green people just piss me off. Most everyone knows that air and electricity are generated by atmosphere surrounding the earth and both fall to the surface awaiting the daily harvest, . The only thing us environmentally friendly people have been waiting on is for manufactures of vehicles to build  ones that will plug into the appropriate electrical or air outlet, which of course is supplied by the daily harvest. I just don't understand why some insist on ignoring the truth. You people who have common sense, excellent math skills and can think for yourselves will be the down fall of this country.

Ken

[Iceni John]

Instead of all this high-fellutin' compressed-air hypothesising, why not simply put a mast or three on the roof, then unfurl a galleon's-worth of sails to take advantage of the prevailing winds.   Isn't there a reason that some of us call our buses Prairie Schooners?   Tacking into the wind may be a slight problem on a crowded freeway, but with the cooperation of everyone else on the road I don't see why this wouldn't work.   No worries if the winds die down  -  buses have passengers, passengers have arms and legs, make 'em work their passage by muscle power:  50 passengers could move an MC-9 well enough.

Ahoy there,
John (listening to Johann Strauss's "Perpetuum Mobile" waltz while typing this)

[Eric]

who needs air powered cars?

WE COULD USE METHANE! A few beers some beans and VOILA! a full tank! just run a hose from the bottom of the seats and have a dispenser for bush's baked beans in the console

Oh and when you REALLY need to get there add a little hot sauce!

happy trails
eric

[ToppDog]

I wouldn't call myself anti-green, but there is much within the green movement that is full of bunk.  The idea within that piece about perpetual motion fueling the car indefinitely is pure fantasy.  Here is a link to some of the info I was referring to earlier:

Air Car Water Car Fuel Clean Motor Save Gas Best Engine

Of the two, I prefer the Australian's design better - much less moving parts & a very compact size to do the same job of a much larger engine.  If combined in a hybrid setup that uses another engine/generator to power an on-board air compressor, it has the potential to travel very far.  Some estimates were around 3000 miles (LA to NYC) on a single tank of fuel.

[ToppDog]

I also thought it was interesting that the exhaust is very cold air, which made me think there is probably a good way that could be used instead of traditional air conditioning.

[NewbeeMC9]

I also thought it was interesting that the exhaust is very cold air, which made me think there is probably a good way that could be used instead of traditional air conditioning.

Air conditioning was invented by a doctor to cool a room in a house for his patient.


Same basic principles,  Compress the air, which gets hot when compressed, cool the compressed air, then expand the air which cools when expands.

so yes,  the exhaust could be used for air conditioning.  May smell funny.    But for heat, you would need another source.

[kyle4501]

Thanks topdog for that link. Much better information & a few essential setails too.

However, the air pressure of 300 Bar (4350psi) still concerns me. . . .

Still, I would like to see this succeed - even if only for short distances.