Car powered by compressed air?

"Greegor"

See:

" Last year, Schipper co-authored a study showing compressed air's inefficiency: per volume, it contains only 12 percent of the energy in lithium-ion batteries and 1 percent in that of gasoline. Worse: as clean as it sounds environmentally, the air vehicle isn't all that clean-but the emissions come from the power plant instead of the tailpipes. "

To coin a phrase - it's all a load of hot air.

..... Phil

Correct. In addition, you cannot recover the released energy without reducing the driving energy. TANSTAAFL.

John

Somebody commented that to get 100 HP output the compressor would burn 800 HP worth of electricity.

Is that true?

Dragging 400 Lbs of battery plates and electrolyte around and replacing it at $20K every few years sure doesn't seem very efficient either.

Buying foreign oil just seems like it supports our enemies too much.

We've got a lot of LP/Natural gas, right?

Can it be made safe enough and economical enough for trucks and cars?

"Greegor"

.... Phil

Yes.

Nope.

Yup.

Yup.

Well, probably, since they've been doing it for decades.

What do they use for free energy on Planet Googlegroups?

Thanks, Rich

Worse is the "Excuse me, I have to stop and blow up my car..."

Just like electric cars - they run on coal.

Sylvia.

He'll huff, and he'll puff and he'll... blow your car up!

Air motors couldn't even haul three little pigs, much less at American highway speeds.

Hello Greegor,

Their website shows some figures:

Tank volume: 175 liters, pressure 350Barg

When isothermally discharging this volume to 1 Barg, you will get 28 MJ from the tank. I can hardly imagine that the exhaust gas temperature will be equal to ambient temperature, so the net energy will be less.

For comparison, Petrol and Diesel have energy densities of about 35 MJ/ liter.

This shows that the amount of stored energy in the pressure cylinders is less then that of 1liter petrol. To have a useful range, this requires extreme change in driving behavior and car design.

Overall efficiency is another issue. Air compression is inefficient if you can't use the generated heat. You need to add more then twice the mechanical energy to the gas to compress the air to 350 bar.

Given the efficiency of the compressor itself (friction, leakage, etc) I have doubts whether they will reach 25% efficiency for pressurizing the tanks. Of course, during winter the generated heat can be used for heating.

When you "charge" the tanks at home (from the mains), you also have to include the (low) overall efficiency of the electrical energy (from power plant to the socket at home).

Besides some niches (explosive environments?), electric traction will outperform the "air" variety in my opinion (better efficiency, better control).

With kind regards,

Wim PA3DJS

Not to mention being a lot safer in a collision.

Cheers

Phil Hobbs

Since they'll only do 30 kph when (lightly)loaded!

Tell that to the truck that knocks a hole in a 5000 psi carbon fibre air tank a foot away from you!

Cheers

Phil Hobbs

J/

Hello Phil,

They mention to have approval for road use and they use same type of cylinders as used for natural gas. They also mention rupture pressures

We have public transport and private cars that run on CNG, as far as I know, without accidents involving failure of the gas cylinders. The cylinders are on top of the bus.

Probably you know the Seoul bus explosion.

Best regards,

Wim PA3DJS

Five of them, so far.

Yikes! google

cng tank explosion

I wonder how much energy it takes to convert methane into something more reasonable, like propane or butane or even octane? The USA has lots of natural gas.

John

It might be, but I don't know offhand. Consider that, when you compress air, it heats up. Most compressors have fins for cooling. This implies that there is a large heat loss in the compression process. So, it seems to me that you start off with a loss before you ever get around to putting it in the engine.

We could make some calculations, if we weren't too lazy :)

Cheers, John

Far better to use a standard reciprocating piston engine and compressed Hydrogen.

I would sit at home, watching TV, and pumping the exercise bike to run the H O separator each night. Could let a small sterling engine sit out in the sun all day and do it while I am at work too!

CNG tanks are NOT 5000 psi cylinders. (If they are, they gas is certainly not being kept at that level.

LNG is at a higher pressure.

Why 'convert' it first, idiot?

LNG doesn't need to be at high pressure. It only needs to be cold.

Typical pressure is only a few PSIG.

John