[Frank]

Thanks for the links to Youtube; they didn't change my mind but it was interesting.

I don't understand your cost analysis. If a 6-volt golf cart battery (Trojan T-125) is used with your assumptions I calculate battery costs of $.025/mile. With electricity at $.20/kwh and 100 whr/mile that's $.02/mile electricity cost or $.045/mile total.

If an air car is five times less efficient wouldn't it use $.10/mile electricity which is twice as expensive as the BEV in this example?

- One battery = 240 AH * 6 volts = 1440 watt-hr (nominal)

- 80% DOD gives ~1100 watt-hr available, call it good for 10 miles range at 100 wh/mi

- 800 cycles would therefore provide 8000 miles range

- 7 wh/$ works out to ~$200/battery

- battery cost = $200/8000 miles = $.025/mile

BTW, I purchased twenty T-125's 5 months ago for ~$130 each and our electricity cost is $.19/kwh here in Maine so this analysis is very a-propos for me. (In fact I did it before I built my own conversion vehicle.) Good AGM's would easily cost that though. Most vehicles would use 2-3 times the energy but the 100 whr/mi is probably a good assumption for the smaller prototypes.

I think the most interesting thing that may develop from this is the so-called hybrid version.

[JRP3]

$this->bbcode_second_pass_quote('', 'I')f I can... Where can I buy a new BEV and replacement battery pack for less than what MDI is stating will be the cost of the air car?

[yesplease]

$this->bbcode_second_pass_quote('Frank', 'I') don't understand your cost analysis. If a 6-volt golf cart battery (Trojan T-125) is used with your assumptions I calculate battery costs of $.025/mile. With electricity at $.20/kwh and 100 whr/mile that's $.02/mile electricity cost or $.045/mile total.

If an air car is five times less efficient wouldn't it use $.10/mile electricity which is twice as expensive as the BEV in this example?

[yesplease]

$this->bbcode_second_pass_quote('JRP3', 'W')here can I buy an Air car at any price?

[loveandrage]

Most techno fantasies won't save us because they are all consumers of energy not replacements of energy or use alternative power sources. But could compressed air reduce consumption enough to make a difference?

1 video, 2 solutions. 1 compressed air car, the other a redesigned engine.

http://www.youtube.com/watch?v=QmqpGZv0YT4

It has me second guessing my fears of the future ....

I believe they call that hope, but is it unfounded?

[TreeFarmer]

A car like that would be fine for commuting. You have to remember though that it takes energy to compress the air, in this case electrical energy.

We use a tremendous number of BTU's of oil everyday for commuting. If you want to replace gasoline/diesel with compressed air you will need that many BTU's of electricity from somewhere. This will mean coal, nuclear, wind, solar in enough volume to replace the oil you are not using.

I think the bottom line on this technology is that it can (apparently) replace a significant amount of oil consumption but, you have to have the electrical infrastructure in place to replace it. I am doubtful that the current electrical grid can handle it.

TF

[jlw61]

I was under the impression that the electrical grid at night is not as heavily used as the day time. Something like an air compressor could easily be set to run automatically at night.

[WisJim]

Compressing air takes a LOT of energy. It is not a very efficient process even at the industrial level, and for personal transportation, electrical storage in available batteries is at least as efficient, and readily available for use.

[chakra]

I think if first world nations were stirred enough, and a huge focus was placed on quickly replacing the fleet with these motors, it could happen.

Placing huge tariffs on gas engines while giving huge tax rebates on these would be a good step. If it cost 15,000 to buy one of these cars but there was 10,000 dollar rebates on them, just watch how many people would demand them. Every car company in the world couldn't build them fast enough.

It would take massive intervention to get the patents to all car manufacturers and drive in the necessity to start building these almost exclusively as fast as humanly possible.

IF, and that's a big if, that did happen we'd probably do alright. We'd probably float along nicely for decades.

Too bad it probably won't happen but it's nice to know that there are options if there was enough fire under our feet and people did the right things very soon.

[mos6507]

I've heard the air car has a really low range and the performance degrades quickly. Really, compressed air is basically the equivalent of a wind up toy. It's not the best way to move a car.

[loveandrage]

big tex,

can you sight your source instead of "i heard ..." ?

and as far as to the poster that says it takes a lot to compress air, the video sighted an extremely cheaper price than gasoline and farther range. Yes it takes electricity to compress, no it's not free, but a vast improvement.

i had a friend take some time reviewing and responding by email which i'd like to post his thoughtful comments here ....

--------------------------------------------------------------------------------

Probably the most dramatic point of the YouTude video was when the second inventor held up his air engine which can power a car but is only about the size of a shoe box! Per Wikipedia, the advantages seem to *far* outway the disadvantages... Mike

Advantages
The principal advantages of an air powered vehicle are:[7]
Much like electrical vehicles, air powered vehicles would ultimately be powered through the electrical grid.
That makes it easier to focus on reducing pollution from one source, as opposed to the millions of vehicles on the road.
Compressed air engine reduces the cost of vehicle production by about 20%, because there is no need to build a cooling system, spark plugs or silencers.
Most compressed air engines do not need a transmission, just a flow control.
Transportation of the fuel would not be required due to drawing power off the electrical grid. This presents significant cost benefits. Pollution created during fuel transportation would be eliminated.
Very low self-discharge rate (most batteries will deplete their charge without external load at a rate determined by the chemistry, design, and size, while compressed gas storage will have an extremely low leakage rate)
Long storage lifetime device (electric vehicle batteries have a limited useful number of cycles, and sometimes a limited calendar lifetime, irrespective of use). This means that batteries in operation are much more expensive than compressed air storage, and are more polluting because a lot more pollutant material needs to be used (typical car batteries are made from sulfuric acids and lead).
Lower initial cost than battery electric vehicles when mass produced. One estimate is €3,000 less.
Compressed air not subject to fuel tax at present (one taxing method would apply also to electric cars by taxing the electricity used for compression or charging).
Expansion of the compressed air reduces its temperature and heat from the passenger compartment may be cooled using a heat exchanger, providing both relief from hot weather by air conditioning and increased efficiency.
Zero pollutant emissions from the vehicle itself.
Compressed air is not a fire hazard, only a rapid depressurization hazard (this can be mitigated by using carbon fiber tanks).
Air turbine technology, closely related to steam turbine technology, is a practice over 50 years old. It is simple to achieve with low tech materials. This would mean that developing countries, and rapidly growing countries like China and India, could easily implement a less polluting means of personal transportation than an internal combustion engine automobile.
Possibility to refill air tank at home (using domestic power socket).[8]
Lighter vehicles would mean less abuse on roads. Resulting in longer lasting roads.
The price of fueling air powered vehicles will be significantly cheaper than current fuels.
Disadvantages
The principle disadvantage is that of indirect energy use. Energy is used to charge the high pressure tank, which tank - in turn - energizes the propulsion. Any indirect step in energy usage results in loss. In the case of a compressed air car: (1) energy loss when fossil fuel energy is converted to electric energy; (2) energy loss when electric energy is converted to compressed air energy.

Further disadvantages:

When the air is expanded in the engine, it will cool down via adiabatic cooling and lose pressure thus its ability to do work at colder temperatures. It is difficult to maintain or restore the air temperature by simply using a heat exchanger with ambient heat at the high flow rates used in a vehicle, thus the ideal isothermic energy capacity of the tank will not be realised. Cold temperatures will also encourage the engine to ice up. thermodynamics.[9]
The major problem of all compressed air or liquified air cars is the lack of torque provided by the compressed gas and the high cost to compress the gas. This was shown to be the case starting in 1903 with the Liquified Air Company car of London England [10]
Long refill time when refilled using a home or low-end system (circa 4 hours). However, at a commercial station refilling would take only 3 minutes.[11] But for that, fueling stations would have to invest in new low-cost dispensers.
Governments would either lose tax income or have to adapt their taxation strategies.

http://en.wikipedia.org/wiki/Air_vehicle

Mike in south Austin

[JRP3]

Compressed air is an inefficient use of electricity. Most of the "positive" arguments presented are even more positive for BEV's. The self discharge "issue" for batteries is a non issue. How many vehicles sit unused for months at a time? Discharge rates for batteries are extremely low anyway.
No matter how simple an air motor is an electric motor is even more simple, with one moving part, and will last longer. Remember with your air car you have 2 motors to maintain, the compressor and the air motor.

[lper100km]

My recollection of air compressors is that they are used industrially only where absolutely necessary. They power tools in hazardous environments and provide high pressure air for industrial processes. Wherever else, electrical power has been shown to be more effective and certainly more efficient as a driver for localized, portable tools. Air compression is highly inefficient. Most of the energy of compression is ‘wasted’ as heat – in fact up to 80% . Leakages can add another 30% loss to the stored compressed air. Then, the energy represented by the compressed gas has to be converted to mechanical motion via motor, which again is an efficiency nightmare. Plus the noise, though this can be assuaged at the cost of more efficiency loss. I think that maybe, some 10% or less of the energy input – the electrical outlet – is actually delivered to the road wheels. ie 10 US galls of gasoline equivalent are required to get 1 US gall gasoline equivalent to the road wheels. That’s being generous.

I am somewhat rusty on this, but storing the energy equivalent of one US gall of gasoline in a compressed air tank would require a 2,750 l capacity tank (725 US gall) at 70 bar (1,000psi). This is five to ten times the size of an SUV gasoline tank. Let’s say that the efficiency from the tank to the road is approx the same for a gasoline and an air motor, then the effective range is roughly the same, dependent upon the size and load, but around 25miles plus/minus. To be sure, the pressures and tank sizes can be played around with, but that’s a mere detail. It’s the uselessness of the concept that I am addressing.

If someone sees an error in the numbers please comment. Otherwise, I have to conclude that this is among the worst of ideas ever brought forward.

[tsakach]

Web references to this technology:

MDI Enterprises

Zero Pollution Motors

US Patent: Method for operating pollution-free engine expansion chamber and expansion chamber therefor

$this->bbcode_second_pass_quote('', 'T')he ZPM compressed air vehicle is built with the high performance Compressed Air Engine (CAE) technology developed by Formula One race car engineer Guy Negre.

The technology has been tested, prototypes have been running. and the Air Car is now entering its final development stage.

ZPM will begin taking reservations in mid-2009 for US deliveries of our compressed air vehicle in 2010.

Range: 848 miles (8 gal tank)
Power source: Electronically injected compressed air

Fuel Characteristics:
Compressed Air: 3200 ft3 @ 4500 psi
Charger: On board 5.5 kwh 110/220 v compressor generating 812 ft3 /hr.

[JRP3]

$this->bbcode_second_pass_quote('', 'R')ange: 848 miles (8 gal tank)

[tsakach]

$this->bbcode_second_pass_quote('JRP3', '')$this->bbcode_second_pass_quote('', 'R')ange: 848 miles (8 gal tank)

[lper100km]

$this->bbcode_second_pass_quote('tsakach', '
')
Range: 848 miles (8 gal tank)
Power source: Electronically injected compressed air
Fuel Characteristics:
Compressed Air: 3200 ft3 @ 4500 psi
Charger: On board 5.5 kwh 110/220 v compressor generating 812 ft3 /hr.

[tsakach]

$this->bbcode_second_pass_quote('lper100km', 'T')here is something seriously wrong with those numbers.

8 US Galls is equivalent to 1 cu.ft. To travel the claimed 845 miles, it would be necessary to recharge the tank 3,200 times.

It says that the onboard charger can refill at a rate of 812 cu.ft per hour. Presumably it means to the pressure of 4 500psi. This would charge the tank in 4.5 secs. Without taking into account any of the inefficiencies, the straight power conversion requires that the charger is rated at 200kWh, yet the blurb claims it is only 5.5kWh. With inefficiencies brought in, the charging motor should have about an 800 – 1 000kWh rating, (nominal 750hp). So what gives?

A 5.5kWh charger might develop 5 cu.ft at 4 500 psi over an hour in practical terms, giving a recharge rate of around 12 mins.

Presumably the vehicle has to stop to recharge, since the onboard charger is indicated as being electrically powered (110 v no less). 3 200 stops of 12 mins each to go 845 miles? That's 640 hours minimum round the clock! There’s something sadly amiss with this whole thing. It’s completely nonsensical.

[lper100km]

tsakach: I did check the web site and find it high on ideals but not specifically informative. They do seem to have ideas about hybrid cycle and multi fuel engines but after some 15 years of operation, the company should have a better range of products than patents and concepts. Maybe I’m just being cynical – a state of mind I can very easily slip into these days – but I have seen several ‘wonder’ engine schemes looking for believing investors over the years. At least MDI does not appear to be touting for investor money. Regardless of whoever is pushing the idea, an auto being propelled from a compressed air cylinder is a ludicrous concept.

[runcar]

According to this video, the MDI air car in the video has a range of 93 miles, and travels at 40 mph or below on air alone and at any higher speeds, it uses a fossil fuel burning engine.

http://www.youtube.com/watch?v=jgwfpIOOb-c

The car is also loud compared to a BEV or FCV, so it may have a few fans but I think either of the two technologies I’ve just mentioned would be better alternatives.