The Air Car

Sounds like this car has better range than a typical electric car and that it can be re-charged in a fraction of the time.  Looks like they also have a hybrid version…

Re: The Air Car

Here's a funny little benefit, too :)

”The temperature of the clean air expelled by the exhaust pipe is between 0 - 15 degrees below zero, which makes it suitable for use by the internal air conditioning system with no need for gases or loss of power.”

(This article was written in English English, so I think they're talking about Celsius degrees, but I don't know for sure)

Re: The Air Car

Questions for Ox:

How does the energy density of a compressed air tank compare with lithium-ion batteries and gasoline?

Would this thing get better mileage at high altitude than at sea level?

Re: The Air Car

Howdy Booner -

This is the French car. The Austrailians are ahead of them in terms of a street-ready compressed air vehicle. The French, on the otherhand, are ahead in terms of industrial powered vehicles, and already have compressed air forklifts in play for real.

It not fair to talk about the energy density of compressed air versus any fuel that one burns. Nobody is burning the air. Therefore none of it's molecular energy density is being released. The energy employed here is purely mechanical in nature.

We also can not fairly compare it by volume, so miles/gallon is not a good metric.

Nor is their any comparison it on emissions to any combustible.

What does that leave us with? Top speed. Dollars per mile. Frequency of recharge. Safety upon impact.

Compressed air has the true potential to win on all of these points within the next 5 years. I beleive that, in a true fight, it will obsolete hydrogen fuel cells before they ever come to market. However, Hydrogen has some powerful political allies in the US, mainly because it is the easiest alternate technology to convert our existing petro-refining infrastructure to.

As to efficiency at higher altitudes, that depends largely on the contour of the vehicle. Thinner air produces less aerodynamic drag, so if the contour causes the vehicle to drag heavy, the engine will have to work less hard on level surfaces at higher alitutudes.

On the same hand, the lower the ambient air pressure, the more likely it is that the pressure vessel holding the compressed air will burst.

Best,
Ox

Re: The Air Car

I find this very exiting!
:))
Now for the politicians…
:((

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It not fair to talk about the energy density of compressed air versus any fuel that one burns. Nobody is burning the air. Therefore none of it's molecular energy density is being released. The energy employed here is purely mechanical in nature.

Look, the tank + air has a certain weight and contains a certain number of joules or kilowatt-hours of mechanical energy.  Likewise a battery has a certain weight and contains a certain amount of electrical energy.  A gas tank has a certain weight and contains a certain amount of chemical energy.

I'm not an engineer, I'm a software nerd and “energy density” may not be the correct term, but it seems to me that all three things can be compared in terms of energy/mass, and further, that the energy density has a huge effect on the range of the vehicle.

Compressed air has the true potential to win on all of these points within the next 5 years.

The cost comparisons that I have seen use European numbers, counting the embedded taxes as part of the cost of gasoline, but not assigning taxes as part of the cost of compressed air.  This overstates the case for compressed air, because the roads have to be paid for and in the long run, air cars are going be taxed to pay for the roads.

Re: The Air Car

There is no comparison in terms of mass.

The mass of a combustible is converted to energy. That's where that unit of Joules becomes important…to measure the amount of energy liberated from the molecular structure of the fuel when burned. That's the only reason we care about energy density…to rate which fuels give the most energy when burned.

The mass of the air in a compressed air car is essentially unchanged…crammed into more or less space, yes, but the energy we get out comes from almost purely from the mechanical energy we put into it's compression. Fundamentally none is being liberated from it's molecular structure. It is not undergoing a chemical reaction that converts any of it's mass into energy. It's molecular energy density is not relevant…we are not utilizing it.

Furthermore, extra energy is needed to propel a heavier vehicle. The Austrailian air engine is on it's way to weighing a mere 6 kg. Compare that to the obsoleted internal combustion engine.

We can't even compare on the basis of the pressure generated to move a piston…the Australian air car engine doesn't employ a conventional piston.

If one presumes that the compressor would be electric, and one knew about that specific compressor's efficiency and wattage, one could estimate the amount of energy expended to compress the air. It's still not fair for comparison though. Because if we insist on counting the energy used in creating the fuels, then you've got the count all of the energy used to process crude oil into gasoline with additives, and then transporting that, in some cases halfway around the world, to your local filling station.

You're better off talking in terms of money to charge the vehicle.

Let's say I fill my tank with gasoline today, and that full tank costs me $25 USD. Let's say I also have the current Australian air car and I fill that with enough compressed air to drive the same distance. The electicity to compress that air costs me, peak rate, in my garage, with a compressor that I buy at a store like Wal-Mart, 62 cents. Even if you take embedded taxes out of the price of the gasoline, and amortize the price of the compressor over he life of the air vehicle, gas can't win.

The question of how governments will pay for road construction and maintenance is an interesting one. It is first important to note that not all of the current gasoline taxes go to this purpose. It is second important to note that it is leaking gas and oil itself that helps to degrade road surfaces, and that the possibility of tanker truck accidents help neccesitate the overhead cost of state and local hazmat teams. In many states here in the US, combustible fuels also cost tax dollars for mandatory emmisions testing stations and the people who man them, another external cost that air cars could eliminate. Air cars reduce the need for taxes in the first place.

Most importantly, we must remember that gas itself comes from a dwinding resource, is produced at tremendous overhead, and that most of it is controlled by a pricing cartel. Air, on the otherhand, is freely and locally available to all.

Bottom line, while I have every confidence that the governments of the world to find a way to tax air cars, I see no reason why they still wouldn't beat combustion, hands down, in terms of dollars per mile. 

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Let's say I fill my tank with gasoline today, and that full tank costs me $25 USD. Let's say I also have the current Australian air car and I fill that with enough compressed air to drive the same distance. The electicity to compress that air costs me, peak rate, in my garage, with a compressor that I buy at a store like Wal-Mart, 62 cents.

A 40X cost advantage?  Sounds too good to be true.  Are you sure you haven't misplaced a decimal point?  If not, I'd really like to see how you came up with those numbers.

Re: The Air Car

The $25 comes from the last time I filled my tank with 87 octane unleaded. The peak rates come from my local utility, residential.

The distance estimate comes from my own experience driving my current car, knowing how far I get on a single tank, and the estimates from the Australians on air requirments for the same distance. Finally, I picked a compressor off the shelf at the WalMart down the street and found it's ratings.

Frankly, I was being conservative. I don't know why you should doubt this ratio…gasoline has a huge amount of overhead in production and transport before you ever see it.

Why on earth would the free stuff you are breathing right now NOT be much cheaper than stuff that's not only price fixed by a hostile cartel, but also had to be first located and then dug up from miles beneath the Earth's surface, distilled, and shipped halfway around the world, all before your local filling station added their profit margin on top of it?

I wonder, do you appreciate the shear number of people that were involved in bringing that gasoline to you? Do you realize that the cost of their employment is not merely what goes to their pay, but their benefits, their machines, lighting, and comfort in their places of work, their housing and food if they are on an oil rig, the insurance to cover all of the hazards to those workers and to the public, customs and tariffs through multiples jurisdictions, and once here in the US, the SPCC countermeasures to comply with both DOT and OSHA regulations?

When you pay for gas, you pay for all of that. Geologists, multi-million dollar boats and platforms, diamond/carbide drill bits, chemists, failed attempts to tap, territorial drilling rights, lawyers, death settlements, television ad campaigns, and thousands of other hands.

What does compressed air cost? A compressor and a few pennies worth of electicity.

There's a reason that compressed air is already used extensively in industry to drive rotary tools and machine assets…it's much cheaper than just about any other means of accomplishing machine motion. This is not a radical concept, it's been with us for decades. There's no magic here. It's just the inevitable next step of a tried and true technology.

Furthermore, the Australian car only need 1 PSI to overcome friction and get the motor turning. That's means you can spend mere pennies on the electricity to compress a tank, and have that tank last a long time.

Best,
Ox

Re: The Air Car

Ox, do you have a link for the Australian air car?

Re: The Air Car

The distance estimate comes from my own experience driving my current car, knowing how far I get on a single tank, and the estimates from the Australians on air requirments for the same distance. Finally, I picked a compressor off the shelf at the WalMart down the street and found its ratings.

Oh, come on, Ox, I don't want a story about where the numbers came from, I want to see the actual numbers.  Humor me.

Frankly, I was being conservative. I don't know why you should doubt this ratio…gasoline has a huge amount of overhead in production and transport before you ever see it.

Here's why I doubt your 40X ratio:  I googled for generators and the first one I found will hold 3.2 gallons of gasoline and produce 2200 watts for 8 hours.  Watch the math:

   2200 watts * 8 hours / 3.2 gallons = 5.5 kwh/gal

This is a very inefficient way to produce electricity, but never mind.  Let's assume your gas is expensive, say $3/gal:

   $25 / ($3/gal) * 5.5 kwh/gal = 45.8 kwh

Now you said that 62.5 cents worth of compressed air will take you as far as $25 of gasoline.  62.5 cents worth of electricity at peak rates is what, 4 or 5 kwh?  Let's assume you live next to a big dam and can buy 10 kwh for 62.5 cents. 

So if we take your car and replace the V-6 with a generator and a compressor and an air tank and an air motor, we get 4.5 times the mileage?  And Detroit never figured this out?  Well, maybe.  But Toyota never figured this out?  I don't think so! 

Somebody's math is wrong.  Maybe mine.  Maybe yours.  Maybe the numbers from Australia are bogus.  But something is wrong here.  Show me your numbers and let's find out.

Re: The Air Car

Sorry, I've been away from Zaadz for about two weeks.

At no time did I claim that a small gasoline generator was involved. I'm not sure why you would take your calculations there… using such a device makes no sense whatsoever in this case. My argument was for a small, grid-powered electric compressor for home use.

For the record, I don't live near a big hydroelectric dam. However, I do live by two tiny dams and one big nuclear reactor. And I pay 7.1 cents per kwh, peak.

This argument is not specific to my location. You can check out your own residential peak rate, without involving irrelevant factors like the price of gasoline or non-utility generation. You can also go to WalMart, like I did, pick out a typical small electric compressor off the shelf, and see how little electricity it take to compress enough air. Remember, the Australian car only takes 1 PSI to overcome it's own rolling resistance.

Did Detroit know about compresed air? Did Toyota? My friend, EVERY car on the road today is a compressed air vehicle. Think about it.

In most of them, the combustion of a fossil fuel is used to heat and pressurize the air, which in turn moves a piston. The only difference here is that the air would be pre-compressed. Once again, there's nothing magic in this. We've been running factories (yes, even Detroit and Toyota auto factories) for decades.

There is an increase to be made in miles per charge, but it will come from weight reduction, because we would no longer have the powertrain or the weight of liquid fuel. It is not likely to be the 4.5x leap that you have somehow calculated. Precisely because moving the piston with air pressure is really nothing that different from what cars already do today.

Now, the Austrialian car doesn't use a traditional piston, so there's some intrigue there. I personally believe their design will yield greater reliability before it implies greater miles per charge over the French vehicle, apart from  that gained by further weight reduction. The weight reduction over the French car's drive system is significant.

The big gain here, as I have claimed from the start, is in dollars per mile.

Actually, the Discovery Channel just broadcast two days ago that my argument here is incredibly conservative. Episode three of the four-part series “FutureCar” was all about alternate fuels, and included the French air car. They announced that the next French air car will carry it's own air compressor on board, which will not even be driven by electricity, but rather by the wasted motion of the vehicle and recycled compressed air! This running recharge means that, with the exception of the initial charge, and possible rescue charges, we're are now talking about fueling the vehicle virtually for FREE.

That means instead of my rather conservative estimate of fuel economy gain, we could now approach infinity.

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~C4Chaos found some video of both the MDI (French) and Australian air cars: