Compressed air as an alternative energy

[jmccull68]

I'm currently collecting parts for a simple device that will demonstrate how we can use the force of compressed air to spin a common car alternator.

I start with a fully charged 12V car battery. To the battery I attach a large DC air compressor. VIAIR sells a compressor rated at 20 amps max @ 12VDC capable of maintaining between 165 psi - 200 psi in it's tank.

This is stored energy that can be precisely released through a small pipe against small metal blades set into the outer edge of a 26" bicycle rim. Attach this rim to an axle with another 26" rim so that both rims spin.

Run a belt around the second bicycle rim down to the alternator. 300 rpm on the 26" bicycle rim would be over 2400 rpm at the alternator. More than enough for the alternator to become self-sustaining. Rpms can be controlled with valve on air line.

This isn't perpetual motion, it's just using an air motor to spin an alternator. As alternator spins it monitors system voltage and adjusts itself to added loads such as the compressor kicking on, or an inverter attached to the same battery for AC power.

Can a basic 63 amp alternator be made to put out 48V DC instead of 12V DC? If so, you could maintain batteries for an inverter rated for 48V DC - 120/240V AC to power your entire house.

ALL comments welcome

[spacecase0]

many alternators I have seen will put out 48V DC,
just have to build your own voltage regulator for it,
and check the voltage rating on the diodes, and make them higher if you need to,
but you are sure not going to get any current running it at 300RPM and might not even make 48V at that low of RPM

to get good power out of a car alternator you have to have the car over idle by a bit,
in my car (and most cars I have had) the alternator spins about 3 times faster than the engine, so at idle the alternator is running at about 1500RPM
to get good power out I need it to be running at about 3 times that speed

[Iamnuts]

Trouble with compressed air is loss of potential. A good storage battery
will hold its voltage over a great deal of its capacity whereas as soon as
you use air from your receiver the pressure is going to drop. The same
sort of thing happens with a super cap. Some form of regulation is needed
set at the lowest useful pressure. Thermal losses are also going to be quite
significant when using air pressure. There doesn't seem to any easy
solution to this sort of problem.
John.

[kenssurplus]

Hey if your just trying to show the concept, then here is a direct drive type solution:
T50-P Turbine Air Starters - TDI Tech Development

49 hp at 100 psig.
Or this one caught my eye:
TURBOSTART 56 Low Pressure Series Air Starters for Gas Turbine Engines - TDI Tech Development

155 hp at 50 psi max.

Here is a chart from ingersoll-rand vane air motors:

SS100 Series Performance Information
Pressure PSI (bar) Breakaway Torque ft-lb (Nm) Speed @ Max HP RPM Max Power HP (kw) Flow @ Max HP SCFM (L/s)
30 (2.1) ----------------------------18 (24) ----------------1,290 ------------2.5 (1.9) --------------------110 (52)
60 (4.1) ----------------------------43 (58) ----------------1,625 --------------7 (5.2) --------------------215 (101)
90 (6.2) ----------------------------60 (81) ----------------1,800 -----------10.5 (7.8) --------------------315 (149)
120 (8.3) ----------------------------82 (111) ---------------1,900 -----------15 (11.2) -------------------415 (196)
150 (10.3) ----------------------------82 (111) ---------------1,900 -----------15 (11.2) -------------------415 (196)

from here:
Air Starters - Small Engine Air Starters by Ingersoll Rand

Or use a air wrench and socket. All depends on what you want your demo to show.

[jmccull68]

You're right spacecase0 about the rpm, that's why i have the pressurized air spinning two 26" bicycle rims in order to spin the alternator with a belt and 3" pulley. Now the 300rpm at the 26" rims becomes over 2400 rpm at the alternator. Thanks for the info on the 48V alternators!

Iamnuts please remember that as air is released from the tank, the air pressure switch on the tank monitors the pressure and restarts the compressor when it drops to 165 psi. The compressor will run for about 1 1/2 minutes to restore the tank back to 200 psi. The DC compressor is rated 20 amps max @ 12V DC.

That's 200 pounds per square inch of force available and being restored from the same battery that the alternator is connected to. Planning to use lower pressure to spin my rims, so compressor will stay off longer. Just using air to spin the 26" bicycle rims at least 300 rpm.

I'm not sure you understand what i'm doing kenssurplus. I'm basically pulling out your cars charging system in order to connect a large DC powered air compressor to the battery, then use the high-pressure air to spin two 26" bicycle rims mounted on a single axle.

Once i release enough air to spin my large rims at least 300 rpm, my alternator will be spinning at more than 2400 rpm. 26" rims down to 3" pulley = better than 8:1 ratio. Once alternator becomes self-sustaining, it adjusts itself internally to added loads such as the air compressor kicking on or an inverter.

[alvarohn]

compressed air

Great idea!!

There is/was this guy Regusci in Uruguay that developed bike/car working only with compressed air.

But I think it was just converting the compressed air into mechanical movement.

Not OU or anything it was just a compressed air motor, but it was like 100 times cheaper than gas. And of course no polution or anthing.. is it just air.

best

Alvaro

[altrez]

I'm currently collecting parts for a simple device that will demonstrate how we can use the force of compressed air to spin a common car alternator.

I start with a fully charged 12V car battery. To the battery I attach a large DC air compressor. VIAIR sells a compressor rated at 20 amps max @ 12VDC capable of maintaining between 165 psi - 200 psi in it's tank.

This is stored energy that can be precisely released through a small pipe against small metal blades set into the outer edge of a 26" bicycle rim. Attach this rim to an axle with another 26" rim so that both rims spin.

Run a belt around the second bicycle rim down to the alternator. 300 rpm on the 26" bicycle rim would be over 2400 rpm at the alternator. More than enough for the alternator to become self-sustaining. Rpms can be controlled with valve on air line.

This isn't perpetual motion, it's just using an air motor to spin an alternator. As alternator spins it monitors system voltage and adjusts itself to added loads such as the compressor kicking on, or an inverter attached to the same battery for AC power.

Can a basic 63 amp alternator be made to put out 48V DC instead of 12V DC? If so, you could maintain batteries for an inverter rated for 48V DC - 120/240V AC to power your entire house.

ALL comments welcome

Hello,

Have you calculated how much mechanical energy is used to get the Alternator to the right speed for true charging? There is a lot of drag on the pulley system and in my experiments with wind turbines it takes a lot of moving air to get good power.

Have you tried out the concept with just a small fan and DC motor?

To run even a small 300 watt inverter it takes around 20 amps. Add in the air compressor and you are looking at a 30 Amp draw.

So if you have a fully charged 12 volt 100ah battery your run time would be a bit over 3 hours.

I think it might work if you get the loads correct and if the air compressor can spin your alternator fast enough to keep a charge on the main battery.

Very interesting project!





-Altrez

[sprocket]

I'm just after replacing the bridge rectifier of an alternator from an old car I was planning to make road-worthy again - only for it to blow its head-gasket! So I have a refurbished alternator kicking about doing nothing.

Anyone know what kind of life-expectancy you could expect from a compressor running constantly, such as jmccull68 is working with - is it the 480c model you have? I've checked Viair's website and they don't include that kind of information. I recall finding information on vacuum pumps in the past that was underwhelming and was wondering if compressors were similar.

Two other points, especially when talking about "self-sustaining" systems. I read I think that alternators are about 60% efficient. And according to Bedini, pulling 20-30 amps for any period of time will knacker your battery - I think he said that a 100Ahr battery should have no more than 5amps constantly drawn from it - down to the C20 rating I believe.

[wrtner]

Great idea!!

There is/was this guy Regusci in Uruguay that developed bike/car working only with compressed air.

... and a Frenchman called Guy Negre
Guy Negre, Compressed Air Car

Welcome to the Guy Negre Fan Website

I can't see anything very clever here. The losses compressing will be added to the losses in the final device. The efficiency should not be very high.

[dutchdivco]

Have to agree,

This is like theidea every 12 y.o. comes up with; hook an electric motor up to a generator, mechancally and electrically; the motor turns the gen, which provides electricity to the motor. Doesn't work, obviously.

I see nothing in the proposed idea which is going to get around physics.

I have thought of hooking a compressor up to a windmill, and just using the resulting compressed air where appropriate. In order to benefit, would need a large holding tank, (perhaps an old house-size propane tank) so you could store the compressed air whenever the wind blew. In THAT way, you ARE getting some 'free' energy. Also thought of a windmill with a vacuum pump and tank. There are a lot of ways to use both compressed air and negative pressure. Jim