Air Cars and Wind Power

"Could a large windmill generate enough torque to provide high volumes of air over 4000 psi?"

Sure; why not? Large windmills are largely torqueful, so that's not a problem. In general, torque X speed = power. Large windmills operate at relatively low speeds while producing a lot of torque, yielding power, which is a product of the two. How much air may be compressed to 4000 psi, (e.g., at what rate) for a given windmill, on the other hand, is something to be determined.

I did a rough calculation for a 100 cubic inch displacement motor, 8 cubic foot volume tank at 4000 psi, rear-end (differential) ratio of 3:1, tire circumference of 6 feet, and the best I could hope for is 14 miles, and that's at 100% efficiency.

I have written a lot about air powered cars. Check out US Patent 5,832,728.

If you cool the compressor with water/steam and mix the steam with the air, the efficiency is improved. I figure 30 cubic feet (roughly the volume behind the back seat of a car) shold be good for about 100 miles. Air-powered vehicles use no scarce or toxic materials, should cost much less than electric vehicles. The wind-generated "wet compressed air" can also be used in other applications, and a free byproduct is distilled water.

I'll try again . . .

I really don't know what to say except that writing about air-powered cars and building a feasible one are two very different animals.

Bill;

Don't waste your Email's. Hope lives eternal in the minds of Air Power being a way to move a vehicle the same as Perpetual Motion comes up every generation or so.

"Hope lives eternal in the minds of Air Power being a way to move a vehicle the same as Perpetual Motion comes up every generation or so."

Yes, and fools continue to do it. About a century ago, Chicago had air-powered street cars, which didn't need overhead wires. They would fill up downtown, go out to the end of line and back, in less time than the pokey old electric groaners took. Air powered locomotives (no sparks or carbon monoxide) were used in mines. Then, of course, you may remember the Lusitania, sunk by a single compressed-air-powered torpedo.

The problem with air-powered vehicles is not that they don't work; it is the mismatch between the energy required to compress the air and the energy recoverable from the compressed air. A great deal of energy, heat, is thrown away cooling the compressor. That is not a basic physical problem, like perpetual motion; it is a failure of imagination on the part of the engineers who build the systems. If one conserves heat and does not cool the compressor by contributing to global warming, air can be at least as efficient as electricity.

Everyone knew that steam power was uneconomical, until Watt invented the external condenser, which reduced wasted heat. "Everyone knows" that air power is uneconomical, until one uses an internally cooled (adiabatic, closed system) compressor. Or, looking at it another way, if compressing then expanding air were not an efficent way to store energy, pneumatic tires on automobiles would be flat after a few bumps.

You may consider Perpetual Motion to be "the same as" air power, but I don't. Can you point to a Perpetual Motion streetcar?

ESBuck wrote:

"About a century ago, Chicago had air-powered street cars, which didn't need overhead wires. They would fill up downtown, go out to the end of line and back, in less time than the pokey old electric groaners took. Air powered locomotives (no sparks or carbon monoxide) were used in mines. "

My point exactly. If Air Power was all that great why are all your examples "Past Tense?" I have read that NY City also used a compressed air utility system that piped air to houses and used it to power generators that ran electric powered devices, IN THE PAST.

The Amish community uses Diesel Power to run hydraulic pumps and air compressors to power everything that needs electric to run it to keep from using the Power Companies electricity. Not because it's cheaper but due to their religious beliefs.

ESBuck also wrote:

"

The problem with air-powered vehicles is not that they don't work; it is the mismatch between the energy required to compress the air and the energy recoverable from the compressed air. A great deal of energy, heat, is thrown away cooling the compressor. That is not a basic physical problem, like perpetual motion; it is a failure of imagination on the part of the engineers who build the systems. If one conserves heat and does not cool the compressor by contributing to global warming, air can be at least as efficient as electricity."

That would work if you don't use electricity to drive the compressor. However, it still seems more logical to use the electrical power generated to drive the compressor to power the devices. Or at least use the power source to drive a generator to produce the more efficient electricity.

Oh well, I've been wrong on other things in my life and another one that I have to admit to being wrong about will not cause me to crash and burn anytime soon.

"That would work if you don't use electricity to drive the compressor."

Quite so. The thread was using large wind mills to compress air.

However, even if you use electricity to drive the compressor, it will most likely be more efficient and cost less than charging batteries to power electric motors. Yes, the Tesla is a marvelous auto, but it might have been built for half the price as an air car.

The German Diesel-Pneumatic Hybrid Locomotive, 1930

Just before technical journals stopped reporting on compressed air locomotives, they carried stories on a 1200 horsepower full-size above-ground locomotive that had been developed in Germany. An on-board compressor was run by a diesel engine, and the air engine drove the locomotive's wheels. Waste heat from the diesel engine was transferred to the air engine where it became fuel again. By conserving heat in this way, the train's range-between-fill-ups was increased 26%.

That was 26 % less fuel consumed than with the competing diesel-electric drive, with the same diesel engine. The details of "conserving heat" were apparently a trade secret, but water/steam cooling the compressor was probably more inportant than heat transfer from the diesel exhaust.

Old technology isn't necessarily bad. (As they say, a stone knife can kill you as dead as a laser will) There used to be trolleys ("light rail") in the San Francisco Bay area. They were "replaced" with busses. (GM was convicted of engineering the death of light rail so as to sell more busses, but the fine was just a token, because GM rules!) Then the government built BART (Bay Area Rapid Transit). The thing is, it ain't no more rapid than the old trolley system. Engineering decisions are often influenced by greedy business practices or political considerations. The salesmen for General Electric locomotives were not about to say, "Of course, you will use less fuel with a diesel-pneumatic." When you are a hammer salesman, everything looks like a nail. When you work for General Electric...

a 1930 diesel is your grandfathers diesel and is at least 1/2 as efficient as todays, so the air compressor-diesel was better.

The thermodynamics say bull to the use of air energy storage systems. diesel-battery is thermodynamically better.

If you think air is better, run the thermo simulation and post it for use. For starters, what would the exit temperature be on a air motor with 4000 psi inlet and say 4 stages. Once you calculate this you will understand why they had a heat recovery on the diesel exhaust.

The German locomotives used 1200 hp diesels from submarines. The air pressure was not published, but judging from the driving cylinder dimensions, it was probably less than 300 psi.

There are two measures of merit which apply. One is the amount of useful energy
which can be stored in a given volume, energy density. Higher is better; it
affects the "unrefueled range" of a zero-emissions car. The other measure of
merit is thermodynamic efficiency, which affects the cost of operation. Higher
efficiency, lower cost, is better. None of the existing vehicles powered by air
or steam is efficient; they waste energy. Either compressed air or steam
involves losing heat from the system, hence lower efficiency, higher costs.
However, to make this clear, there follows a comparison of three energy storage
processes, as might be applied to a zero emissions vehicle.

For illustrative purposes, keeping the engineering challenges within the state of
the art, assume that temperatures may not exceed 600K, a value chosen as
metallurgically acceptable. Environmental effects must also be considered.
Exhaust temperatures are limited, as a lower bound, to 200K, which is still
frighteningly cold. Common lubricants thicken at such temperatures. Human
contact with such exhaust would result in frostbite, and, as the cold exhaust
mixed with ambient air, fog and/or snow would result. The same size storage tank
is assumed for each system, conveniently 1000 L, 1 m.sup.3. Such tankage would
fit behind the seat of a small car, or under the bed of a pick-up truck. A
specially built vehicle could accommodate more tankage.

The following calculations make certain assumptions as listed. Purists will
argue that they are imprecise, but they are adequate to compare systems.

1. Air is an ideal gas. k=1.4; PV=RT, where R for air is 0.28 KJ/(kg-K) or 2.8
L-bar/(kg-K) ; for isentropic processes, T.sub.2 /T.sub.1 =(V.sub.1
/V.sub.2).sup.k-1 ; P.sub.2 /P.sub.1 =(V.sub.1 /V.sub.2).sup.k ; Work at 100%
eff. is (U.sub.1 -U.sub.2)=mass(C.sub.V)(T.sub.1 -T.sub.2). C.sub.V =0.75
kJ/kg-K (It is not constant, but let's assume it is) The work done to compress
the air isothermally (impossible in practice, but assumed here) is P.sub.1
V.sub.1 In(V.sub.2 /V.sub.1). Ambient air, the intake to the compressor, is at
300K, 1 bar pressure, with a density of 1.18 g/liter. Exhaust pressure cannot be
below 1 bar.

2. Steam behaves as listed in steam tables.

3. Efficient expanders (motors) with variable expansion ratio and no internal
friction are available. (Zero friction is impossible, but assuming it treats all
the systems equally with regard to friction losses)

4. Another assumption, which can be questioned, is that all the stored gas is
useable. Clearly, as the pressure drops, the expansion ratio of the motor must
decrease, but assuming a variable expansion ratio (which may be achieved with
valve timing) for comparison purposes, there is no big error involved in
calculating energy density or efficiency. Batteries, of course, cannot be
totally discharged, either.

Process A: Energy storage with dry compressed air.

The Pneumocon Inc. car, "Spirit of Joplin", now running in Joplin, Mo., uses air
stored at 3000 psi (about 200 bar) and ambient temperature, about 300K. The
output is throttled, to reduce pressure to 33 Bar, still at approximately 300K,
but if expansion is limited by the temperature of the exhaust the power output
and efficiency remain essentially unchanged over a broad range of pressures. A
thousand liters of air at 200 bar would weigh 236 kg. The energy output,
ideally, would be (236 kg.) (0.75 kJ/kg-K) (300K-200K)=17.7 megajoules (4.9
kw-hr). The work required to compress the air isothermally would be P.sub.1
V.sub.1 ln(V.sub.2 /V.sub.1)=(10.sup.5 N/m.sup.2) (200 m.sup.3) (-5.52)=110
megaJoules. Efficiency, useful output divided by energy input, is 17.7/110 or 16
per cent. (Typical industrial compressed air systems rarely exceed 15 percent
overall efficiency)

Suppose, in an effort to improve energy storage density, the pressure is
increased to 600 bar, which is acheivable with available components. The amount
of air stored will triple, as will the weight of the tanks, approximately, as
the walls will be thicker. Now the output will be tripled, to 53 megaJoules,
14.7 kw-hr, and the input will be 384 megaJoules. Efficiency would drop to 14
percent. Since the energy density increase is large for a small drop in
efficiency, high pressures seem desireable.

Process B: Storing compressed air at 600K.

A multistage compressor would compress the air until it reaches 600K, the
maximum temperature allowed, then compress it isothermally until the pressure
reaches 200 Bar. The tank will hold only 118 kg of air at that temperature. The
first compression adds energy to the air (isentropically), 0.75 kJ/K or 225
KJ/kg, which is 26.6 megaJ total for the first stage. The pressure is 11.7 bar
and the volume 17 m.sup.3. The isothermal compression to 1 m.sup.3 and 200 Bar
consumes 56.3 megaJ, for a total of 82.9 megaJ. When the air is expanded with a
temperature drop of 400K, the energy recovered is 35.4 megaJ, 9.8 kw-hr, with an
efficiency of 43 percent. During the isothermal compression, about 56 megajoules
of heat is rejected (since the internal energy, U, of the compressed air was not
increased).

Suppose we prefer to store the air at 450 bar. We can store 265 kg of air, 22
kw-hr, but the energy to isothermally compress the air has risen to 163 megaJ,
189 MJ total input, for an output of 79.6 MJ, or an efficiency of about 42
percent. Again, higher pressures seem better. Since tanks are likely to be
stronger at 300K than at 600K, the 450 bar and 600K process and the 600 bar at
300K process are likely to be comparable in weight. It would seem Process B is
superior, with higher efficiency and higher energy density.

Process C: Energy storage in steam.

The greatest energy density occurs when we fill the tank with saturated steam at
600K (maximum temperature allowed). The pressure is about 125 bar, specific
volume is 13.5 L/kg, U=2500J/kg, entropy=5.47. The mass of steam in the 1000 L
is about 74 kg. Total internal energy, U, is 185 megaJoules. Since we started
with 74kg. of liquid water at 300K, which had an internal energy of 8
megaJoules, the work required to fill the tank with steam was approximately 178
megaJoules or 49 kw-hr.

Now, we need to know how much mechanical energy we can extract from that steam.
The perfect expansion process is isentropic; total entropy remains the same.
However, we know that as the steam does work it will cool, and some will
condense. (Steam is not an ideal gas) At 1 Bar (exhaust), we will have X kg of
steam and (74-X)kg. of water, both at about 373K. Water at that temperature has
entropy=1.30 and steam has 7.35. X(7.35)+(74-X)(1.30)=74(5.47) It follows, after
a bit of elementary algebra, that the exhaust had 51 kg of steam and 23 kg of
water. The total internal energy of the exhaust is 51 kg(2506 kJ/kg)+23
kg(419kJ/kg)=137.4 megaJoules. Subtracting that from the initial enegy, we find
that the greatest possible mechanical work we could get from the steam system is
40.6 megaJoules or 11.3 kw-hr., and the efficiency is only 23 percent. The
exhaust is dangerously hot, and it cannot be exhausted directly from a vehicle
without creating fog and raining on the following vehicles; a big condenser is
needed.

Summary of characteristics of the three ideal processes:

______________________________________
useful output
efficiency
fuel cost
______________________________________
A: 300K compressed air
14.7 kw-hr 14% 7
B: 600K compressed air
22 kw-hr 42% 2.4
C: 600K steam 11.3 Kw-hr 23% 4
______________________________________

Arguably, any of these state-of-the art processes is competitive with
electrochemical batteries. A battery powered car typically stores about 20 kw-hr
of energy; when that is exhausted, it takes hours to recharge the batteries.
Power output is limited to approximately 200 W per kilogram of battery, so the
power to weight ratio is poor. Compressed gas vehicles can release stored energy
at much higher rates and can be recharged from a stationary "filling station" in
minutes.

Relatively inexpensive and non-toxic materials are used (mainly ferrous metal
technology) in the three systems described, and there is little to wear out; no
expensive batteries are used which need periodic replacement/recycling. (The
cost of recycling the batteries periodically overwhelms the cost of electricity)
The impracticality of electric cars is nicely described in the February 1995
issue of Popular Science in an article titled, "It's The Battery, Stupid|" A
December 1994 report, "Electric Vehicles", by the U.S. General Accounting
Office, concludes, "The ultimate viability of EVS as a widespread tranportation
option cannot now be ensured." Economics favor compressed gasses over electrics,
both in low operating cost (no recycled batteries) and in first cost; an
electric van from Chrysler is priced at $120,000, while an air-powered vehicle
need not be substantially more expensive than current vehicles; it is
mechanically simple (eg. simple or no transmission, no radiator, no ignition
system, no catalytic converter, etc.).

Most of the disadvantages of batteries in vehicles also apply to stationary
storage schemes. Telephone companies use a lot of batteries, now, but it is hard
to imagine a public electric utility load-levelling with batteries. However,
large storage tanks at elevated temperatures appear to be feasible, perhaps
underground or under water or in remote locations, to allay public fears of an
explosion and to minimize real estate costs.

Parenthetically, hydrogen-air fuel cells might compete as sources of power for
vehicles, but there will be "consumer resistance" to hydrogen in cars. Will they
be allowed in tunnels? A fuel-cell powerplant in New York City was vetoed by the
city fire department.

SUMMARY OF THE INVENTION

This invention discloses a process of storing and transmitting/converting energy
by (a) compressing a working fluid, (b) adding a coolant fluid during the
compressing operation and (c) storing the mixed working and cooling fluids in a
pressure vessel, and then (d) expanding the stored mixture as through a fluid
motor to extract energy from the compressed mixture. In addition, a further step
of (e) condensing and returning coolant fluid may also be utilized.

Accordingly, several objects and advantages of my invention are:

(a) To provide an energy storage process which is more efficient than present
methods of energy transmission and energy storage. (b) To provide a way to
achieve high-density energy storage.

(c) To provide a process which can be scaled for large applications (utilities)
or small (portable tools).

(d) To provide a power transmission process (eg. from engine to multiple powered
wheels or fork lift) which is simpler and more convenient than commonly used
means, such as shafting or conventional hydraulics.

(e) To provide an energy storage process which requires no breakthroughs, uses
non-toxic materials and well understood mechanisms.

(f) To provide a means of energy storage which can be charged and discharged at
very high rates.

(g) To provide a process which, considering capital and replacement costs, is
more economical than existing methods of energy storage, such as batteries.

(h) To provide for the use of high-pressure gasses without the high temperatures
associated with high-pressure gasses compressed isentropically and without the
wasted heat energy associated with isothermal compression.

(i) To provide a process which facilitates heating and cooling.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a flow chart of the essential process.

FIG. 2 shows the addition of recycling a coolant.

FIG. 3 shows a closed-cycle process in which the mixed working fluid and coolant
are reused--useful for power transmission.

FIG. 4 shows a modification of the process of FIG. 3, in which the coolant and
working fluid are kept from mixing.

REFERENCE NUMERALS IN DRAWINGS

Comparable elements of each process bear the same number in each applicable
figure. Not shown are valves and controls, coolant pumps, etc., which are
obvious to anyone skilled in the art.

110: Energy input (eg. a turning shaft)

120: One or more compressors

130: Working fluid input to mixer.

140: Coolant input to mixer.

150: Mixer

160: Storage tank or tanks, insulated, as desired.

170: Expander (eg. motor or pneumatic cylinder)

180: Exhaust from expander.

190: Energy output from expander.

282: A device for removing coolant droplets from the working fluid.

284: Dry working fluid is exhausted.

286: Storage tank(s) for recovered coolant.

386: Storage container(s) for mixture of low-pressure working fluid and coolant.

420: Compressor(s) cooled by coolant.

421: Conduit for dry working fluid to expander(s).

422: Conduit for coolant to expander(s).

481: Conduit for low-pressure working fluid, returned to compressor(s).

482: Conduit for coolant, returned to compressor(s)

The invention consists of a process in which mechanical energy is expended to
compress gasses and said energy is recovered by passing the gasses through an
expander (motor) to provide mechanical energy again. The novelty lies in the use
of two fluids, a fluid with a high heat capacity to cool the compressor(s) and a
second, working, fluid. The cooling fluid may undergo a phase change from liquid
to gas, absorbing "latent heat of vaporization", which keeps the temperature of
the combined compressed gasses lower than would be the case if isentropic
compression of the working fluid were involved. The key point is that the heat
absorbed by the cooling fluid is not wasted, as it would be with conventional
(isothermal) compression. Heat from the cooling fluid is used to counteract the
cooling which results from the expansion of the working fluid as it drives the
motor, resulting in a process which is thermodynamically reversible, ideally
efficient, in contrast to existing fluid power systems. (This is not to be
confused with humidified compressed air, the CASH cycle)

FIG. 1 illustrates the basic process as a flow chart. One or more compressors,
120, are driven by energy input, 110. A working fluid (conveniently air), 130,
is mixed with coolant fluid (conveniently water), 140, in a suitable device,
similar to devices for mixing fuel and air, 150, and the mixture is fed to the
compressor. Upon compression, the air gets hotter and the water droplets
suspended in the air turn to steam, absorbing a great amount of heat which would
otherwise be wasted by the necessity to cool the compressor. The mixture of air
and water/steam may optionally be stored in an insulated tank or tanks, 160,
until energy is needed. To recover the energy used during compression, the mixed
gasses are conducted to one or more expanders, 170. As the gasses expand, doing
work, providing an energy output, 190, the gasseous coolant condenses, releasing
heat which it previously absorbed in the compressor. The exhaust of expander(s),
180, is close to the same temperature as the fluids fed to the compressor; hence
energy lost as waste heat is minimal.

FIG. 2 illustrates a modification of the process in FIG. 1, with enegy input,
110, compressor(s), 120, storage tank(s), 160, and expander(s), 170. In
addition, the exhaust, 180, is passed through a filter or particle separator or
other means, 282, to remove the coolant droplets from the exhaust, and the dry
working fluid is exhausted, 284. The coolant may be stored in tank(s), 286, and
reused, sent back to the mixer, 150. This has two beneficial effects; it
conserves coolant, and it prevents negative effects on the environment which
might result from releasing a cloud of coolant droplets. Again, pumps, controls,
valves, etc. which are obvious are omitted.

FIG. 3 illustrates a closed-cycle version of the process, with compressor(s),
120, and expander(s), 170. The mixed working fluid and coolant, 180, are
directly recycled, with (optionally) storage tanks, 160 and 386, to accomodate
variations in flow. This process may be preferred for simply transmitting energy
from one place to another, but the storage capacity will be limited because the
low-pressure working fluid exhausted from the expander(s) will consume an
inconveniently large volume and the coolant droplets may not remain suspended in
the working fluid.

FIG. 4 illustrates a process in which the working fluid and the coolant are not
mixed but are kept physically separate, with conductive heat transfer cooling
the working fluid at the compressorts) and heating the working fluid at the
expander(s). The compressor(s), 420, are different from 120 in that they are
cooled by circulating coolant (in a "water jacket" or intercoolers) which is
transfered by insulated conduit, 422, to the expander(s) 470. The compressed,
dry working fluid goes to the expander(s) though a separate conduit, 421. At the
expander 470, the working fluid is warmed by the coolant, most conveniently with
heat exchangers between stages of a multi-stage expander (not required when the
fluids are mixed). The separate fluids are returned to the compressor(s) through
conduits, 481 and 482. It might be advantageous to use alternative fluids in
special circumstances, aboard spacecraft or submarines, for example, where the
fluids (eg. helium and a liquid metal, or various organic substances) would be
recycled in a closed system.

Operation

The operation of the process is illustrated by use for a zero-emissions vehicle,
though the process is amenable to a variety of uses. Using the same assumptions
as described under Prior Art, the superiority of my invention is obvious. It can
be called "Process D." The working fluid is air, and the coolant is water,
resulting in what I call "wet compressed air" (WCA).

The use of a mixture of steam and air appears to be novel and not obvious, as
indicated by the lack of literature references to the practice. There are
references to warming air with steam, to ameliorate the chilling effect of the
exhaust of air tools in mines, but the steam was not generated by the
compression of the air. Handbooks and texts on compressed air technology
typically stress the desireability of removing moisture from the air, not adding
it. It appears that the patent classification list has no sub-class for power
plants which mix steam with air in a context which does not involve combustion;
hence a search turned up no relevant patents.

Process D: Energy storage in WCA.

This process resembles Process B (in Prior Art), except that the intercooler is
missing. Instead of throwing away about half the input energy, the heat of
compression is used to make steam, which is conserved. Let's assume water is
mixed with the air at the compressor as in FIG. 1 and FIG. 2. As the air is
compressed, the temperature increases, vaporizing the water droplets, so that a
mixture of steam and air passes to the storage tanks. 118 kg of air is pumped
into the tank at 600 K, with an increase of internal energy of 26.6 MJ. However,
the mass of air in the tank is less (60+%), because there is now steam in the
tank, also, from water boiled during the compression process. The energy used to
compress the air rises to approximately 66.5 megaJoules and that energy is
making about 30 kg. of steam, with the partial pressure of the air approximately
330 bar and the partial pressure of steam 125 bar, for a total pressure of 455
bar, which is feasible. (The mass of the contents is about 115 kg less than
Process B at 450 bar) The total energy in the tank, at 600K, is now about 93
megaJ, the same as the input energy, since no heat was rejected from the
insulated system. Now, when the mixture is expanded, isentropically, the exhaust
at 1 bar is at the original temperature, 300K, and no energy is lost in the
exhaust. The steam condenses to water droplets, and the heat released as it
condenses expands the air, so all the energy is recovered. The
compression-boiling and expansion-condensation is a thermodynamically reversible
process. The energy output is the same as the energy input, 93 MJ or about
26kw-hr. The WCA tank and motor can be in a vehicle, while the compressors and
bulk storage tanks are at various filling stations, with quick-disconnect hoses
to recharge the vehicle, or the vehicle can be a hybrid, with an engine and
compressor in the vehicle.

Summary of characteristics of the processes:

______________________________________
useful output
efficiency
fuel cost
______________________________________
A: 300K compressed air
14.7 kw-hr 14% 7
B: 600K compressed air
22 kw-hr 42% 2.4
C: 600K steam 11.3 Kw-hr 23% 4
D. 600K WCA 26 kw-hr 100% 1
E. Electric batteries
20 kw-hr 85% High*
______________________________________
*The cost of parking at a recharge station and of replacing the batteries
overwhelms the cost of the electricity.

Process D, Wet Compressed Air (WCA), is the clear winner in energy density,
cost, and environmentally harmless exhaust (ambient temperature air with
droplets of water which can be filtered out and recycled). It is useful over a
wide range of temperatures and pressures.

Sorry, the last message transmitted while I was trying to edit it. Most is an extract from a patent, and all the stuff about figures, etc. can be ignored. Go to the end for the comparison of different energy storage schemes. You will note that the conventional air storage is only 14 % efficient, but...

If anyone would like to repeat the calculations using better software, please post your results. The cited numbers are approximations, "slide rule accuracy."

By the way, why is there almost a total news black out on the air car?

See the numerous threads on CR4 regarding the aircar, compressed air as an energy storage, compressed air motors, etc. It has been discussed and explained in great depth by myself and others.

By the way, why is there almost a total news black out on the air car?

No blackout - the subject comes up periodically, is discussed and found to be impractical, and nobody is interested anymore.

I guess I use the work "blackout" in the context of the millions of articles written about hybrids, compared to the relatively few I have seen about air cars. For a year or so, all I could find in the U.S. press was one article in Popular Mechanics.

Its just like the media's coverage of the oil production from the tars sands in Canada. No real coverage of all the technological advances, and new projects being developed and planned (35 in all). The most coverage I have heard about tar sands, was the negative comments made by our new President on his trip to Canada, last week.

It takes 5-7 Electric or other HP to store enough compressed air at 100 PSI to run an Air Motor that produces 1 HP and you quickly see that is not the way to go.

On top of that, I really dont want to be within a mile of an Air Pwered cars 4,000 PSI Storage Tank when it explodes in a wreck or other mishap. It would be just as safe as riding around with a ready to drop 250# Bomb in the vehicle.

As stated before, this conversation comes up regulary. If anyone bothered to Google "Air Power Car" it would stop amost all the post' on the subject.

Hydraulic Assist is another stoty but is mainly for heavy vehicles that do a lot of Start/Stop motion.

"It takes 5-7 Electric or other HP to store enough compressed air at 100 PSI to run an Air Motor that produces 1 HP and you quickly see that is not the way to go."

Of course not. But you are using junk technology. If you do it right, it's more efficient.

"I really dont want to be within a mile of an Air Pwered cars 4,000 PSI Storage Tank when it explodes in a wreck or other mishap."

First of all, air tanks don't explode; they leak, even if you shoot them, as in "Jaws." If you make a big enough hole, which can't happen in a well-designed system, the tank may want to take off like a rocket (which is why they chain welding tanks to the wall), but if it is fastened down, the worst effect is probably scaring people with the unfamiliar noise. If air tanks were so unsafe, would firemen routinely carry them on their backs?

Batteries, however, have been known to explode, and almost any battery material is far more toxic than air and harder to clean up. Gasoline is user-friendly, and hardly ever burns harmfully, unless you drive a Pinto or smoke near a gas pump or...

"Hydraulic Assist is another stoty but is mainly for heavy vehicles that do a lot of Start/Stop motion."

And inside a hydraulic accumularor? High pressure gas/air.

There have been several air cars proposed over the years. The one that has been in the news most frequently since about 2000 is the MDI air car. Such cars have been disussed many times on CR4, with the prevailing mood being one of skepticism.

The MDI car (which is the same as the ZPM car -- ZPM being , ostensibly, a licensee) has never been demonstrated to go more than about 4 miles (7km). Negre, who claims to be a Formula One engine designer, never designed an engine that was used in Formula One racing. These factors, combined with the very high losses in compressing air (which relate to the physics involved rather than to a technological limitation that might be overcome by better technology) and the extraordinarily low energy density of compressed air (it takes a huge high-pressure tank to provide a small amount of energy) have led some to believe that the air car cannot work as advertised. Their claim, in 2000, that they would be starting production in 2001 does not help with credibility.

In a Popular Mechanics article, it was claimed that there would be 6000 air cars in India by August 2008. This has not happened, and Tata has no plan to produce the cars.

Compressed air has long been recognized, in industry, as being very inefficient method for transferring power: figures around 15% are often quoted, although this generally includes leaks etc. With electric motors being around 90% efficient, you never see compressed air used in manufacturing plants if an electric motor can be used instead.

There is no news blackout. A Google search will produce recent articles. MDI/ZPM is a Progessive Insurance Automotive X Prize entrant, so it will be interesting to see how they do.

The above comments are quite valid. Existing air systems are not very efficient, and the MDI car, like other air cars in the past, like "The Spirit of Joplin," don't seem very practical. Clearly, Blink and I disagree about the potential for air power.

Back in 1930, the German railways methodically studied the most efficient way to couple a diesel engine to the wheels of a locomotive. They tried a mechanical transmission, a hydraulic transmission, a generator with electric motors driving the wheels, and a diesel-pneumatic drive. The diesel engine drove a two-cylinder air compressor which fed a conventional steam locomotive chassis. The diesel- pneumatic used 25 per cent less fuel than the diesel electric, pulling the same train on the same schedule over the same route. Of course, in 1930, the German railways were not about to dieselize, but the fact is that the pneumatic drive was shown to be efficient. Again, the trick is to conserve heat, not thowing it away. It's perfectly straight forward engineering, if you are willing to ignor common practice (air cooled compressors). Experimental evidence trumps academic analysis every time, and the fact that most people do it the "wrong" way doesn't make it the best way.

Ingersol-Rand isn't about to scrap their line of air-cooled compressors. The Dept. of Energy, which has spent hundreds of millions of dollars on battery research, isn't about to admit that a simple air tank is more efficient. (Presented with my patent, they said it would work, but they had "something better." They would not reveal what that was) The Swiss are researching adiabatic air compression (by definition, without loss of heat), but otherwise it seems everybody believes they know the solution to the problem of energy storage. Quite beyond the question of vehicles, there are problems like electric utility load leveling. Is it conceivable that a sane engineer would propose to store many megaWatt-hrs in batteries or that you could buy enough of them? In contrast, large air tanks (think of a cavity in bedrock, an old mine, perhaps) are dirt cheap and don't use scarce materials.

Consider this scenario. You have a dirty old coal-fired electric utility plant, and you would like a "greener" source at a reasonable price. The turbines, generators, switch gear, etc. all work well and are paid for, but the environmental costs are high. You put up a wind farm of wind turbines, and they drive simple compressors (heck, make them from old diesel truck engines), steam cooled, and pipe the air-steam output in insulated pipes down to the old steam boiler, saving some in a convenient container, like a hole in the ground. The plant works as before, tied into the grid, but nothing comes out of the stack; there is zero polution. (Sell the old coal pile) There is no thermal pollution, either, as condensers aren't necessary. If the electricity demand goes down, more air-steam mixture (I call it "wet compressed air") is stored, and if the electricity demand exceeds the wind turbine output, draw on the stored energy.

Getting back to the hybrid vehicle, there are several approaches. I could convert my Prius, using an air motor in place of the electric motor and an air tank in place of the batteries (whch will have to be replaced in a few years -- the air tank won't). Alternatively, I could convert a diesel truck or car, replacing the transmission with a compressor and motor (like the German locomotive), with an air tank to store energy for drag racing Corvettes, pulling boats up Pike's Peak, and other demanding activities. Or, I can leave the air motor in place, put in more tanks, and have the compressor at home, driven electrically. If I have a big storage tank, I can recharge the vehicle in minutes; otherwise, recharge it overnight. A pick-up truck could carry enough tankage (about 70 cubic feet) to go 200 miles on the electrical equivalent of two gallons of gas (about 70 kw-hr) which, if there are 4 seats (crew cab), would win the automotive x-prize (~$10 Million). If you are on a tight budget, the air motor can be a diesel converted to compressed air. A common rail injector system will work with air, and a change in the cam shaft would deliver one power stroke per crank revolution. However, just as the world's railways use diesel-electric locomotives, wasting fuel, because "everyone knows" how to build them, none of the entrants for the auto x-prize will use wet compressed air, because it was "not invented here." I suppose that the postal service, UPS, Fed-EX and school bus operators might like such zero-emission vehicles, but they don't know that yet; they don't listen to suggestions. Ford, GM, and Chrysler have all informed me that, on advice from their lawyers, they do not read suggestions for innovations from outside the corporation.

Clearly, Blink and I disagree about the potential for air power.

It's not much of a disagreement, really. I note that your patent application quotes the same efficiency figure that I quoted above, for standard air compression and storage. When you stand by a traditional air compressor and feel the cylinder head, you can sense the problem -- loads of heat being thrown away.

But your system is fundamentally different than the typical industrial system (and the MDI system) and captures a lot of that heat that would otherwise be wasted. I'd love to see your system in the X Prize... there are still a few days open for entry... or maybe there is potential for working with one of the entered teams. Unfortunately, most are small outfits, with particular ideas they are pursuing, so you have the double whammy of NIH and lack of funds.

Honda, by the way, has a joint venture group, which will accept ideas from outside the corporation, so they may be worth contacting. They said "no" to me, but that doesn't mean they will say "no" to you.