Why are we still using internal combustion engines?

[Evadman]

Originally posted by: Linux23
Range is 200 miles, with speeds up to 60 miles an hour. Not too bad for an everyday commuter.

The page says 2000km, which is 1240 miles. That is utter bullsh!t. In reality it is likely 2000 meters. they may be going for 2000km, but you would need an air tank the size of a battleship.

Simple math:
10 kg of gasoline has about 140 KWH of energy. if we have a super efficient engine, lets say 30% efficient, we end up with 42 KWH of energy. (Pay no attention to the fact that compressing air is about 20% efficient, so it would take 210 KWH or 15 kg of gasoline to get the same energy storage)

Generators that run on compressed air are actually very efficent, running in the 80% range. So only 20% is lost as waste. So we would need 42 * 1.2 = 50.4 KWH of stored energy to equal 10kg of gasonline in actual output.

So how much air do we need to get 50.4 KWH of energy?
50.4 kilowatt hours = 181,440,000 joules
ENERGY = volume * pressure change
181,440,000 joules = volume in cubic inches * 5000 psi (max pressure before things start exploding)
181440000/5000 = 36288 square inches = 252 cubic feet.

So it would take about 252 cubic feet of compressed air at 5000 PSI to get the same amount of energy as 10 kg of gasoline. A gallon of gasoline weighs about 3 kg and a normal tank of gasoline would be about 10 gallons. So 252 * (10/3) = 840 cubic feet of air at 5000 PSI would have the same energy as 10 gallons of gas.

Your compressed air tank would be a cube 9.5 feet tall, 9.5 feet wide, and 9.5 feet long, way bigger than your entire car.

You could sit on top of it with a lawnchair maybe.

 

[FallenHero]

Originally posted by: Evadman

Originally posted by: Linux23
Range is 200 miles, with speeds up to 60 miles an hour. Not too bad for an everyday commuter.

The page says 2000km, which is 1240 miles. That is utter bullsh!t. In reality it is likely 2000 meters. they may be going for 2000km, but you would need an air tank the size of a battleship.

Simple math:
10 kg of gasoline has about 140 KWH of energy. if we have a super efficient engine, lets say 30% efficient, we end up with 42 KWH of energy. (Pay no attention to the fact that compressing air is about 20% efficient, so it would take 210 KWH or 15 kg of gasoline to get the same energy storage)

Generators that run on compressed air are actually very efficent, running in the 80% range. So only 20% is lost as waste. So we would need 42 * 1.2 = 50.4 KWH of stored energy to equal 10kg of gasonline in actual output.

So how much air do we need to get 50.4 KWH of energy?
50.4 kilowatt hours = 181,440,000 joules
ENERGY = volume * pressure change
181,440,000 joules = volume in cubic inches * 5000 psi (max pressure before things start exploding)
181440000/5000 = 36288 square inches = 252 cubic feet.

So it would take about 252 cubic feet of compressed air at 5000 PSI to get the same amount of energy as 10 kg of gasoline. A gallon of gasoline weighs about 3 kg and a normal tank of gasoline would be about 10 gallons. So 252 * (10/3) = 840 cubic feet of air at 5000 PSI would have the same energy as 10 gallons of gas.

Your compressed air tank would be a cube 9.5 feet tall, 9.5 feet wide, and 9.5 feet long, way bigger than your entire car.

You could sit on top of it with a lawnchair maybe.

That would be the most badass car in the world. Where do I sign up?

 

[Iron Woode]

Originally posted by: Zenmervolt

Originally posted by: BigPoppa
Because external combustion is super inefficient.

I dunno, steam wasn't too bad as far as efficiency, just very, very, very hard to make convenient. Sh*tloads of torque though. I know a guy who restores old steam traction engines and those things can pull pretty much anything you can hook up to them. They would have shows where they'd load up a sled from a tractor pull as heavy as it could get and the old steam engines would just slowly pull it all the way down the track. The tractors from the tractor pulls were much faster off the line, but the steam engines just chugged right along and never slowed down, they took it to the end of the run every single time.

Of course, 99% of people aren't mechanically-able enough anymore to mind a steam boiler with all that pressure.

ZV

Jay Leno has a collection of steam powered cars. He has one made in 1921, the last steam car made. It starts like a regular car. It cost $20,000 when new, but it was the pinnacle of steam car production.

 

[Iron Woode]

the NHRA still has it's ban in effect for compressed air engines after a disastrous demonstration.

 

[So]

Originally posted by: Evadman

Originally posted by: Linux23
Range is 200 miles, with speeds up to 60 miles an hour. Not too bad for an everyday commuter.

The page says 2000km, which is 1240 miles. That is utter bullsh!t. In reality it is likely 2000 meters. they may be going for 2000km, but you would need an air tank the size of a battleship.

Simple math:
10 kg of gasoline has about 140 KWH of energy. if we have a super efficient engine, lets say 30% efficient, we end up with 42 KWH of energy. (Pay no attention to the fact that compressing air is about 20% efficient, so it would take 210 KWH or 15 kg of gasoline to get the same energy storage)

Generators that run on compressed air are actually very efficent, running in the 80% range. So only 20% is lost as waste. So we would need 42 * 1.2 = 50.4 KWH of stored energy to equal 10kg of gasonline in actual output.

So how much air do we need to get 50.4 KWH of energy?
50.4 kilowatt hours = 181,440,000 joules
ENERGY = volume * pressure change
181,440,000 joules = volume in cubic inches * 5000 psi (max pressure before things start exploding)
181440000/5000 = 36288 square inches = 252 cubic feet.

So it would take about 252 cubic feet of compressed air at 5000 PSI to get the same amount of energy as 10 kg of gasoline. A gallon of gasoline weighs about 3 kg and a normal tank of gasoline would be about 10 gallons. So 252 * (10/3) = 840 cubic feet of air at 5000 PSI would have the same energy as 10 gallons of gas.

Your compressed air tank would be a cube 9.5 feet tall, 9.5 feet wide, and 9.5 feet long, way bigger than your entire car.

You could sit on top of it with a lawnchair maybe.

Pwned by physics. :beer: evadman!

 

[Chaotic42]

Originally posted by: Zenmervolt
Of course, 99% of people aren't mechanically-able enough anymore to mind a steam boiler with all that pressure.
ZV

IIRC Modern Marvels said that a steam engine produces the most torque at ~0 RPM.

 

[Rogodin2]

Mainly because oil is cheap.

Once production cannot meet demand the price will rise and we will HAVE to create an alternative.

Rogo

 

[Zenmervolt]

Originally posted by: Jeff7181
I've always thought a diesel/electric hybrid would be a great idea. A high torque, low RPM turbo diesel engine turning an electric generator. The engine would be efficient because it would operate at the same RPM all the time regardless of speed and load. Therefore, components could be designed for optimum performance at a specific RPM. And of course the engine would shut off when not needed... and cylinders could be "turned off" like they're doing with the new Hemi engines.

That's how diesel locomotives work actually. The diesel engines are really just generators that produce electricity for electric motors that drive the wheels. That was the only way to get similar performance to the old two and three cylinder steam locomotives.

ZV

 

[Rogodin2]

Worry about tires.

Rogo

 

[Zenmervolt]

Originally posted by: Chaotic42

Originally posted by: Zenmervolt
Of course, 99% of people aren't mechanically-able enough anymore to mind a steam boiler with all that pressure.
ZV

IIRC Modern Marvels said that a steam engine produces the most torque at ~0 RPM.

Correct. Max pressure in a steam cylinder is just the instant before the piston starts moving. Just like electric motors, a steam engine will produce the most torque at 0 RPM.

To Iron Woode: Yeah, I've seen the old steam cars, love 'em. But despite Leno's claim in Popular Mechanics that "a steam boiler itself is safe. Things would break or crack internally before they'd explode.", the simple fact is that they aren't. I've seen the wreckage from a traction engine's boiler exploding. I've talked with the people who saw it happen and lift 6 tons of steam engine 15-20 feet into the air.

Yes, with a smaller boiler on a car there's not quite the massive risk that a locomotive or traction engine has, but it is still something that has to be watched closely. Your average driver who doesn't pay attention to the water temperature guage on his car and keeps driving only blows a head gasket. The driver who does that with a steam engine, even a Doble like Leno's, has a good bit more at risk.

All this isn't to say that it wouldn't be possible, just that they require an owner to be a little more attentive than the average driver is today.

ZV

 

[Jeff7181]

Hehe... so ignoring the temperature light thinking, "it'll get me home" isn't an option with a steam engine?

 

[Linux23]

Originally posted by: Evadman

Originally posted by: Linux23
Range is 200 miles, with speeds up to 60 miles an hour. Not too bad for an everyday commuter.

The page says 2000km, which is 1240 miles. That is utter bullsh!t. In reality it is likely 2000 meters. they may be going for 2000km, but you would need an air tank the size of a battleship.

Simple math:
10 kg of gasoline has about 140 KWH of energy. if we have a super efficient engine, lets say 30% efficient, we end up with 42 KWH of energy. (Pay no attention to the fact that compressing air is about 20% efficient, so it would take 210 KWH or 15 kg of gasoline to get the same energy storage)

Generators that run on compressed air are actually very efficent, running in the 80% range. So only 20% is lost as waste. So we would need 42 * 1.2 = 50.4 KWH of stored energy to equal 10kg of gasonline in actual output.

So how much air do we need to get 50.4 KWH of energy?
50.4 kilowatt hours = 181,440,000 joules
ENERGY = volume * pressure change
181,440,000 joules = volume in cubic inches * 5000 psi (max pressure before things start exploding)
181440000/5000 = 36288 square inches = 252 cubic feet.

So it would take about 252 cubic feet of compressed air at 5000 PSI to get the same amount of energy as 10 kg of gasoline. A gallon of gasoline weighs about 3 kg and a normal tank of gasoline would be about 10 gallons. So 252 * (10/3) = 840 cubic feet of air at 5000 PSI would have the same energy as 10 gallons of gas.

Your compressed air tank would be a cube 9.5 feet tall, 9.5 feet wide, and 9.5 feet long, way bigger than your entire car.

You could sit on top of it with a lawnchair maybe.

That's not what the Discovery HD Theaters program "Future Car" has to say about this.

 

[Linux23]

Originally posted by: RossMAN
Have you seen "FutureCar" on Discovery HD Theater?

http://dsc.discovery.com/convergence/future-car/future-car.html

:beer:

 

[Oscar1613]

Originally posted by: Evadman

Originally posted by: Linux23
Range is 200 miles, with speeds up to 60 miles an hour. Not too bad for an everyday commuter.

The page says 2000km, which is 1240 miles. That is utter bullsh!t. In reality it is likely 2000 meters. they may be going for 2000km, but you would need an air tank the size of a battleship.

Simple math:
10 kg of gasoline has about 140 KWH of energy. if we have a super efficient engine, lets say 30% efficient, we end up with 42 KWH of energy. (Pay no attention to the fact that compressing air is about 20% efficient, so it would take 210 KWH or 15 kg of gasoline to get the same energy storage)

Generators that run on compressed air are actually very efficent, running in the 80% range. So only 20% is lost as waste. So we would need 42 * 1.2 = 50.4 KWH of stored energy to equal 10kg of gasonline in actual output.

So how much air do we need to get 50.4 KWH of energy?
50.4 kilowatt hours = 181,440,000 joules
ENERGY = volume * pressure change
181,440,000 joules = volume in cubic inches * 5000 psi (max pressure before things start exploding)
181440000/5000 = 36288 square inches = 252 cubic feet.

So it would take about 252 cubic feet of compressed air at 5000 PSI to get the same amount of energy as 10 kg of gasoline. A gallon of gasoline weighs about 3 kg and a normal tank of gasoline would be about 10 gallons. So 252 * (10/3) = 840 cubic feet of air at 5000 PSI would have the same energy as 10 gallons of gas.

Your compressed air tank would be a cube 9.5 feet tall, 9.5 feet wide, and 9.5 feet long, way bigger than your entire car.

You could sit on top of it with a lawnchair maybe.

close but no cigar

if 252 cf is equivalent to 10 kg of gas, and 1 gal of gas is 3kg, then 10 gal of gas is 30kg, so the final volume is 252 * 30kg/10kg = 252 * 3 = 756 cf

 

[Zenmervolt]

Originally posted by: Jeff7181
Hehe... so ignoring the temperature light thinking, "it'll get me home" isn't an option with a steam engine?

Well, if you've only got a couple blocks and it's a Stanley (and not a Doble), pieces of you might make it home...

A Doble would probably "just" blow the hood off or send shrapnel into (through?) the firewall.

There's a helluva lot of power in steam, it's a really neat power source. In fact, nuclear reactors are really steam turbines. They just use nuclear reactions to generate the heat to make the steam. It's a very, very cool technology.

ZV

 

[BrownTown]

Originally posted by: Zenmervolt

Originally posted by: Jeff7181
I've always thought a diesel/electric hybrid would be a great idea. A high torque, low RPM turbo diesel engine turning an electric generator. The engine would be efficient because it would operate at the same RPM all the time regardless of speed and load. Therefore, components could be designed for optimum performance at a specific RPM. And of course the engine would shut off when not needed... and cylinders could be "turned off" like they're doing with the new Hemi engines.

That's how diesel locomotives work actually. The diesel engines are really just generators that produce electricity for electric motors that drive the wheels. That was the only way to get similar performance to the old two and three cylinder steam locomotives.

ZV

heh yeah, tis actually kinda funny, my school has two old diesel-electric locomotives to provide backup electrical power in case of a blackout (they also have a 20 MW coal unit and 2 5MW gas turbines along with several other gas turbines on the roof of the hospital). ITs just kinda funny though walking by and you are like "WTF are there 2 locomotives behind this building for", and its for 10MW of backup generation.

 

[RU482]

Originally posted by: Iron Woode
the NHRA still has it's ban in effect for compressed air engines after a disastrous demonstration.

I'd be interested in hearing more about that one
Steam powered cars sound kinda cool

 

[JulesMaximus]

There's always human power! :thumbsup:

 

[Linux23]

A little more info for you skeptics.

Air powered goodness

 

[Jeff7181]

So really... does anyone know why something like that isn't being done? Cost? Weight? Efficiency? I can imagine there's quite a bit of loss from converting kinetic energy to electrical energy and back to kinetic.

 

[Goosemaster]

Originally posted by: Zenmervolt

Originally posted by: Jeff7181
Hehe... so ignoring the temperature light thinking, "it'll get me home" isn't an option with a steam engine?

Well, if you've only got a couple blocks and it's a Stanley (and not a Doble), pieces of you might make it home...

A Doble would probably "just" blow the hood off or send shrapnel into (through?) the firewall.

There's a helluva lot of power in steam, it's a really neat power source. In fact, nuclear reactors are really steam turbines. They just use nuclear reactions to generate the heat to make the steam. It's a very, very cool technology.

ZV

yeah...not many people stop to think that in the end, if you are using electricity provided by a Nuclear Power Plant, you are still relying on steam...

..obviously the energy is drawn from something else, bust still....

 

[Evadman]

Originally posted by: Oscar1613
if 252 cf is equivalent to 10 kg of gas, and 1 gal of gas is 3kg, then 10 gal of gas is 30kg, so the final volume is 252 * 30kg/10kg = 252 * 3 = 756 cf

Whoop, you are correct. So the tank is 9 feet by 9 feet by 9 feet.

 

[0roo0roo]

Originally posted by: Linux23
A little more info for you skeptics.

Air powered goodness

author is a journalist, it needs far more information on how this energy storage is actually physically possible. proof you can make something move a bit is nothing, its like having a lead acid battery electric car. impractical gadget.

 

[Pacfanweb]

Originally posted by: Chaotic42

Originally posted by: Zenmervolt
Of course, 99% of people aren't mechanically-able enough anymore to mind a steam boiler with all that pressure.
ZV

IIRC Modern Marvels said that a steam engine produces the most torque at ~0 RPM.

Most all our Navy ships are steam powered. The carriers and all. Steam is awesome.

 

[RossMAN]

Originally posted by: Linux23

Originally posted by: RossMAN
Have you seen "FutureCar" on Discovery HD Theater?

http://dsc.discovery.com/convergence/future-car/future-car.html

:beer:

When you quoted the $15k pricetag that sorta gave it away