DIY Electric Car Forums banner

1 - 20 of 67 Posts

·
Registered
Joined
·
5 Posts
Discussion Starter · #1 ·
Has anyone investigated (compressed) air powered cars? Seems to be an up and coming technology. Are they going to be a viable alternative? So far I cannot find any DIY-ers in this field. Or I don't know where to look.
 

·
Registered
Joined
·
369 Posts
Compressed air powered cars are very interesting.

They're basically the exact same design as a Steam Engine, minus the water boiler.

You could possibly actually use a large steam engine and run it right off the compressed air.


The most difficult part of building a compressed air vehicle is getting the very light weight composite air tanks.

A standard steel compressed air tank from your local Airgas is seriously heavy and won't work well.
 

·
Registered
Joined
·
661 Posts
The air car looks like crap to me. A really inefficient way to store electrical energy.
There are several advantages I see in a compressed air system (CAS) that makes it worth taking a look:

1) Weight reduction: With the use of carbon fiber tanks the weight of the system is essentially the weight of the tanks.

2) Cost: not the electric cost, which of course is higher due to inefficiency, but that the costs of the tanks will be significantly less than the costs of batteries. In addition, tanks don't wear, so you won't have to replace them.

3) Fast refillability: Air tanks can be quickly filled from tanks of precompressed air, which can then be later refilled. So at least in theory filling a CAS vehicle would be more like filling a gas tank, as opposed to having to plug in for an extended period of time.

4) Free AC: decompressing air cools it, by capturing that coolness and transferring it to the cabin, AC can be achieved as a byproduct of running a CAS engine.

5) Improved efficiency using waste heat. Heated air expands more. So more power can be obtained by heating the air as it is used. Any heat source is usable for this process. A lot of the wasted electricity in compressing air is generated as heat. By capturing this heat in the vechicle in an insulated system and reusing that heat (or the heat of braking)
to heat the gas, the efficiency of that CAS system will improve the range of the vehicle.

6) Regenerative braking. A CAS system facilitates recapturing the energy of braking by compressing air back into the tanks.

Using a electric traction motor and battery system coupled with a CAS system that drives a generator can facilitate a fast fillable, regen, lightweight plugin hybrid with extended range. And it's still an all electric hybrid instead of a gas electric hybrid.

Finally if we start using renewable energy such as solar, then the fact that air compression is inefficient isn't as critical.

I have another post on this subject on the forum. I'd love to discuss the idea some more.

ga2500ev
 

·
Registered
Joined
·
8,119 Posts
Carbon fiber tanks that can handle high pressures would be very expensive.
On board tanks just can't hold that much energy and range is limited.
The distances claimed for the air car have not been shown at all in the real world.
Both the compressor and decompresser, (engine), suffer from similar inefficiencies and wear and tear as an ICE. An ICE is essentially an air compressor after all. So now you would have oil changes on the compressor and air engine as well.
 

·
Registered
Joined
·
926 Posts
My main problems with the air car are:
1: Noise & Vibration
2: Cost of home-refilling
3: Time to home-refill
4: Paper-like vehicle construction

I guess noise & vibration could be reduced to an acceptable level with dampeners, mufflers and noise canceling matting throughout the car. It would weigh the car right down though reducing it's range.
You could always set up a rooftop solar array to generate electricity to power an inverter to power the compressor that refills the car (that ate the dog that ate the cat that lived in the house that Gavin built). LOL
Of course the range isn't toooo bad on those air cars because they weigh less than a toaster. But once you load them up with airbags. noise/vibration canceling equipment and make them solidly built - wham, there goes the range.
I'm still very very interested in the idea of the air car but electric strikes me as much more impressive for now.
 

·
Registered
Joined
·
398 Posts
Could someone post a link to the Aircar? I havent seen it.
I saw a fella on "The new Inventors" a few years ago that had what looked kind of like a Wankel type air motor that was supposed to be quite efficien.t It impressed the hell out of the judges. Wonder what happened to him?
 

·
Registered
Joined
·
114 Posts
Here's a short video on the MDI Air Car.

MDI Air Car

There company website at www.theaircar.com doesn't have any useful pics or videos that I could find. I think Air Car Factories is a new company formed with MDI as the designer.
 

·
Premium Member
Joined
·
882 Posts
I wrote a blog about them in case you missed it... It seems promising but it needs big infrastructure changes to have it work whereas EVs just need powerpoints, but i've collated a bunch of info in the blog post.
 

·
Registered
Joined
·
398 Posts
Here's a short video on the MDI Air Car.

MDI Air Car

There company website at www.theaircar.com doesn't have any useful pics or videos that I could find. I think Air Car Factories is a new company formed with MDI as the designer.
CHEERS!!!
It's uncanny. The later part of that video shows the bloke I saw on the new inventors:)
 

·
Registered
Joined
·
661 Posts
So what seems promising about it, the really inefficient use of electricity or the need for a completely new infrastructure? ;)
Let work on these two strawmen shall we?

Completely new infrastructure? That's like saying that EVs need a completely new infrastructure because they don't use gas stations. CAS vehicles only require a compressor that plugs into the wall. It's the equivalent of a battery charger in terms of infrastructure. Having large tanks with precompressed air would be convenient for fast filling, but that infrastructure doesn't need to be in place in order to get started with CAS. SCUBA and paintball have already created a compressed air infrastructure that can be utilized for CAS vehicles.

Now on to efficiency. On a theoretical basis, compressed air is 100% reversible. So in theory you can use all the energy used to compress air to generate work. Considering the fact that after 100 years ICE engines have gotten to 25% efficiency (after initially being absolutely miserable) working to improve the efficiency of a CAS vehicle should prove to be easier and more productive. The more important issue is that fact that changing pressure causes bit changes in the heat content of the air in question. Most current systems simple discard that waste heat, which leads to those currently large inefficiencies. But as I stated in an earlier post, that a compression system that makes a deliberate attempt to recapture the heat of compression and then reuse that heat at the time of decompression will be a lot more efficient in terms of energy use that current systems.

The true downside to compressed air is the simple fact that it takes a lot of air to carry sufficient energy for useful work. You just won't get very far without huge tanks.

The most promising use of compressed gas is using liquid nitrogen or liquid air as fuel. It has a lot high energy density than compressed air. A bunch of papers came out of the University of Washington on such a vehicle:

http://www.aa.washington.edu/aerp/CRYOCAR/CryoCar.htm

There's already an existing LN2 infrastructure. You can have the stuff pumped into a tank for less than $1 a gallon.

Also with a bit of infrastructure LN2 or liquid air can be condensed locally from electricity.

A LN2/electric hybrid would give you all the advantages of a electric car with the range and refillability of a gas car.

ga2500ev
 
G

·
My main problems with the air car are:
1: Noise & Vibration
2: Cost of home-refilling
3: Time to home-refill
4: Paper-like vehicle construction
And your knowledge of this comes from where again? I am assuming that you have full inside knowledge to make these claims and have actually driven and been fully involved in testing of the said vehicles. Or if the claims are pure speculation then you have no business stating them. Keep speculation to yourself please or figure out how to re-phrase your comments so they don't sound like you have full inside knowledge. I think you can do that. It's cool if you don't like the ideas of air power and I am on your side if you think the air power cars are ugly. That just happens to be visual and your claims of heavy go for any vehicle whether it's gas, electric, propane, NG or air. The heavier they are the worse the mileage will be. That is a given here on this and any other vehicle list. No need to repeat that statement. The need for large tanks is not always required depending upon the distance you want. They are after all designed for short distance runs. Kinda like an NEV and speeds are I am sure minimal. In places like Japan and China where the population density is very high these type of vehicles will prove perfect for the required short commutes. Perfect. For us on the other hand they may not be so perfect. Our population density is not nearly as dense and we do need to drive much further and what we think of as a short commute it actually quite a long distance for them. You must look at the over all picture before you make judgements on vehicles. Some folks do like the idea and there are millions who like that sort of look as well. It is not our culture to have cars that look like that and to us they are ugly. Some however will like them. Over there millions will like them. Go get-em cowboy. What kind of real world range do you get with your EV? What kind of real world speed at those distances do you have? Please post them.

Pete : )

Mine is not finished yes so I can't post that sort of thing. When I can I will be posting results so others don't have to speculate and guess.
 

·
Registered
Joined
·
398 Posts
And your knowledge of this comes from where again? I am assuming that you have full inside knowledge to make these claims and have actually driven and been fully involved in testing of the said vehicles. Or if the claims are pure speculation then you have no business stating them.
:mad:You are one of the most offensive persons I've ever come across.

Gav said " My main problems with the air car are....." They are HIS opinions. His feelings and he has a right to express them.

Keep speculation to yourself please or figure out how to re-phrase your comments so they don't sound like you have full inside knowledge.
I'll fire that straight back at YOU.

Yea! Usually the folks on the list don't need a good tongue lashing but sometimes one comes along that does. My passion is to help the others along that don't frequent the list and as a matter of fact usually don't frequent anything.
Who the hell appointed YOU to be the Auditor of all things posted! You self opinionated PRATT

You have opinions? Fine. I've got opionions too everybody does, and we ALL have a right to express them. Try phrasing yours so you dont come across sounding like an arsehole. You blasted a guy a few days ago after only his SECOND POST:eek: ASSHOLE!! Some welcome.

You MAY know more. But I'll remind you that you've only been a member here for a couple of months.
Show some manners
 

·
Registered
Joined
·
8,119 Posts
The need for large tanks is not always required depending upon the distance you want. They are after all designed for short distance runs. Kinda like an NEV and speeds are I am sure minimal.
Exactly, and if built to the same specs as the air car an EV version will outperform the air version, without the need to maintain a mechanical air compressor and a mechanical air motor. If all you need is very short range and low speed that is already easy to achieve with EV's and lead batteries.
I also have to agree that you are way over the top with your tone, you might want to back it down a notch.
 

·
Registered
Joined
·
8,119 Posts
CAS vehicles only require a compressor that plugs into the wall. It's the equivalent of a battery charger in terms of infrastructure. Having large tanks with precompressed air would be convenient for fast filling, but that infrastructure doesn't need to be in place in order to get started with CAS. SCUBA and paintball have already created a compressed air infrastructure that can be utilized for CAS vehicles.
Not really, a high pressure air compressor is going to be much larger and more expensive than a battery charger, and will need maintenance since it is a mechanical device. We aren't talking about an eight horse power 150 psi shop compressor here.
Now on to efficiency. On a theoretical basis, compressed air is 100% reversible. So in theory you can use all the energy used to compress air to generate work.
Well in theory you could also capture any heat generated by battery charging and discharging as well, but that's not realistic either.
Considering the fact that after 100 years ICE engines have gotten to 25% efficiency (after initially being absolutely miserable) working to improve the efficiency of a CAS vehicle should prove to be easier and more productive
The more important issue is that fact that changing pressure causes bit changes in the heat content of the air in question. Most current systems simple discard that waste heat, which leads to those currently large inefficiencies. But as I stated in an earlier post, that a compression system that makes a deliberate attempt to recapture the heat of compression and then reuse that heat at the time of decompression will be a lot more efficient in terms of energy use that current systems..
How do you figure, since an air compressor is essentially an ICE without the fuel charge? Attempts at recapturing the wasted heat from an ICE haven't improved the efficiency that much, why would it be different for an air car?
The true downside to compressed air is the simple fact that it takes a lot of air to carry sufficient energy for useful work. You just won't get very far without huge tanks.
That too.
The most promising use of compressed gas is using liquid nitrogen or liquid air as fuel. It has a lot high energy density than compressed air. A bunch of papers came out of the University of Washington on such a vehicle:

http://www.aa.washington.edu/aerp/CRYOCAR/CryoCar.htm

There's already an existing LN2 infrastructure. You can have the stuff pumped into a tank for less than $1 a gallon.

Also with a bit of infrastructure LN2 or liquid air can be condensed locally from electricity.

A LN2/electric hybrid would give you all the advantages of a electric car with the range and refillability of a gas car.

ga2500ev
Now you're really talking about a different animal than an air car.
 

·
Registered
Joined
·
398 Posts
Not really, a high pressure air compressor is going to be much larger and more expensive than a battery charger, and will need maintenance since it is a mechanical device. We aren't talking about an eight horse power 150 psi shop compressor here.
On the youtube video posted by uncle Joseph I think they claimed it would recharge itself in 4 hours plugged into a normal power point. I may be wrong, (I often am:rolleyes:) but I think thats what they said. I know that the really serious compressors that can fill a tank in a few minits are awsomely expensive machines but then again arnt the hi power chargers that can do a EV pack in 15 minits prohibitively expensive for most people also?
 

·
Registered
Joined
·
8,119 Posts
Well I was assuming, maybe incorrectly, that these compressors would need to be built to develop and handle extremely high pressures, whatever the time frame involved, and would therefore need to be much more heavily built than your average compressor. Even a 5 hp home compressor will cost you over $1000.00
http://www.aircompressorsdirect.com/catalog/product_info.php?products_id=395
 
G

·
You are one of the most offensive persons I've ever come across.
What's offensive is folks who come across as having full inside knowledge and have absolutely none. It's fine to have an opinion but write it as such.
Who the hell appointed YOU to be the Auditor of all things posted! You self opinionated PRATT
Me! Don't like it! Good!
ASSHOLE!!
Now your just getting down right nasty. I prove my point that some do need a tongue lashing.

My main problems with the air car are:
1: Noise & Vibration
2: Cost of home-refilling
3: Time to home-refill
4: Paper-like vehicle construction
This is stated as fact not opinion.

But I'll remind you that you've only been a member here for a couple of months.
Has nothing to do with time or knowledge but how many posts I have made. And you have been here how long? You have 100 posts to my 73.

You are one of the most offensive persons I've ever come across.
By the way, I am only one person, not two. : )
 
1 - 20 of 67 Posts
Top