Compressed air as future fuel?
Discussion
Okay excuse me for not having a total and utter hard-on for having to use a petrol car every single day for the dull drive to work and i like the idea of something that doesn't involve me giving me all my money to the government.
Would a compressed air car be capable of replacing a day to day commuter wagon.
Upsides
It can be refilled quickly from a storage tank for everyone those has the 400 mile commute
It can be refilled at home by using small compressor running off your electric which can come from any energy source
When you compress air you get lots and lots of heat which could be used for domestic heating
It makes a vroom vroom noise
no degration in storage capacity
Downsides
OH MY GOD IT DOESN'T RUN ON PETROL
Compressed air tanks aren't the safest things in the world but niether is petrol
Would a compressed air car be capable of replacing a day to day commuter wagon.
Upsides
It can be refilled quickly from a storage tank for everyone those has the 400 mile commute
It can be refilled at home by using small compressor running off your electric which can come from any energy source
When you compress air you get lots and lots of heat which could be used for domestic heating
It makes a vroom vroom noise
no degration in storage capacity
Downsides
OH MY GOD IT DOESN'T RUN ON PETROL
Compressed air tanks aren't the safest things in the world but niether is petrol
thinfourth2 said:
i like the idea of something that doesn't involve me giving me all my money to the government.
... and that is IMHO why there is so little development and progress re: air cars. The government would have to introduce road pricing/tolls to offset the loss of revenue. The oil companies and 
ish speculators would also lose out, big time.A few quick sums for you.
You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
thinfourth2 said:
wildoliver said:
Slight problem being energy per volume (if that's even a unit) is very low from compressed air. A petrol tank sized tank would most likely take my car out of the village and not much further.
Surely that depends on how far you compressed itspikeyhead said:
A few quick sums for you.
You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
They are possible, and have been done. Too many problems, though.You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
http://en.wikipedia.org/wiki/Compressed_air_vehicl...
spikeyhead said:
A few quick sums for you.
You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
okay how much power would you get from your 1 litre engine?You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
And why are you limited to a 60 litre tank
spikeyhead said:
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
With thinking like that we would all still be in caves and riding horses
eldar said:
spikeyhead said:
A few quick sums for you.
You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
They are possible, and have been done. Too many problems, though.You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
http://en.wikipedia.org/wiki/Compressed_air_vehicl...
i live in scotland i really can't see a problem with waste heat
spikeyhead said:
A few quick sums for you.
You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
As spikeyhead says, there is an upper limit of compression.You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
The challenge is that that with compressed air you are only going to liberate the energy in it changing from being compressed to being uncompressed, unlike hydrogen, petrol or diesel where you are liberating the energy from the chemical reaction which is orders of magnitude higher.
As the OP rightly says compressing will generate heat.
But the overall efficiency of using energy to compress the gas is going to be significant. You might as well have used that energy to power the vehicle in the first place.
I could imagine a small / ultra light smart car with a compressed air tank with a shopping range <5 miles with a backup ultralight engine or similar once the gas had run out, but I think it would be an exercise in engineering rather than a sustainable option for vehicles.
The big issue with carbon emissions is also one of net efficiency.
Fossil fuel cars: extract, refine, transport, deliver to garage, all have CO2 impacts. In your car it is then converted once via a fairly inefficient engine:
http://www.fueleconomy.gov/feg/atv.shtml
Now if you replace that with hydrogen, you have the same as above, but higher costs of storage, increased leakage, and much higher energy costs in production (assuming you use some form of catalysis on water, requires a huge amount of electricity - produced by what? - though power stations do have more efficiency) - and then you have many of the same drive line losses (but nicer emissions at the point of consumption)
Now if you look at battery cars you have a similar challenge - a double hit in efficiency - once to convert a fuel or source to electricity (fossil fuel power is about 35-40% efficient) and then the transmission to the home, and then the losses when converted to a battery, and then the driveline losses in propulsion.
Similar for hybrids, except then you still have, to some extent the worst of all worlds (localised inefficient combustion, conversion to battery and localised pollution)
Compressed air would give no localised pollution, assuming it was not being topped by an engine, but would not solve the issue of overall system efficiency, or liberate enough energy to provide sufficient range for a car... sorry...
Sorry for the essay - in my view the mid term view is ultralight hybrids with highly controlled emissions, at least for the next 20+ yrs.
Buy into futures of lithium. Did you know the largest reserves of lithium (aside from China) are in Burma/Myanmar?
Fossil fuel cars: extract, refine, transport, deliver to garage, all have CO2 impacts. In your car it is then converted once via a fairly inefficient engine:
http://www.fueleconomy.gov/feg/atv.shtml
Now if you replace that with hydrogen, you have the same as above, but higher costs of storage, increased leakage, and much higher energy costs in production (assuming you use some form of catalysis on water, requires a huge amount of electricity - produced by what? - though power stations do have more efficiency) - and then you have many of the same drive line losses (but nicer emissions at the point of consumption)
Now if you look at battery cars you have a similar challenge - a double hit in efficiency - once to convert a fuel or source to electricity (fossil fuel power is about 35-40% efficient) and then the transmission to the home, and then the losses when converted to a battery, and then the driveline losses in propulsion.
Similar for hybrids, except then you still have, to some extent the worst of all worlds (localised inefficient combustion, conversion to battery and localised pollution)
Compressed air would give no localised pollution, assuming it was not being topped by an engine, but would not solve the issue of overall system efficiency, or liberate enough energy to provide sufficient range for a car... sorry...
Sorry for the essay - in my view the mid term view is ultralight hybrids with highly controlled emissions, at least for the next 20+ yrs.
Buy into futures of lithium. Did you know the largest reserves of lithium (aside from China) are in Burma/Myanmar?
thinfourth2 said:
eldar said:
spikeyhead said:
A few quick sums for you.
You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
They are possible, and have been done. Too many problems, though.You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
http://en.wikipedia.org/wiki/Compressed_air_vehicl...
i live in scotland i really can't see a problem with waste heat
thinfourth2 said:
spikeyhead said:
A few quick sums for you.
You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
okay how much power would you get from your 1 litre engine?You'll struggle to compress air above 3000psi, so that's the upper limit I'll assume. That's about 150 atmospheres worth. If we have a 60 litre tank in the car then you could turn over the engine on a 1.0 car 150*60 tunes.
That's six minutes at 1500rpm. That's only a rough calculation, there's various other factors that could be taken into account but its close enough to show that it's not feasible.
And why are you limited to a 60 litre tank
spikeyhead said:
The question is not why there aren't compressed air cars, but why anyone would think they were possible.
With thinking like that we would all still be in caves and riding horses... and if someone drives into the back of you with that behind you, you'll take off, not for long but it'll be a good flight.
eldar said:
thinfourth2 said:
The main problem seems to be the amount of heat the compressors chuck out
i live in scotland i really can't see a problem with waste heat
Trouble it takes energy to generate the waste heat....i live in scotland i really can't see a problem with waste heat
if that makes sense
thinfourth2 said:
eldar said:
thinfourth2 said:
The main problem seems to be the amount of heat the compressors chuck out
i live in scotland i really can't see a problem with waste heat
Trouble it takes energy to generate the waste heat....i live in scotland i really can't see a problem with waste heat
if that makes sense
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