An interesting video from the BBC website:
BBC Media Player
or if the above link doesn't work:
BBC Media Player
Ian
BBC Media Player
or if the above link doesn't work:
BBC Media Player
Ian
Forget Electric, use air
- Thread starter imellor
- Start date
Nice link Ian. If those figures come true and it's reliable, I'll buy one without question at anything up to 10,000 euros. Far better than battery electric.
The air tank could power the horn as well, but care would be needed to avoid that sounding like a certain inadvertant bodily function.
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The air tank could power the horn as well, but care would be needed to avoid that sounding like a certain inadvertant bodily function.
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I have heard of them developing cars based on compressed air canisters, but never in connection with bikes which is an excellent idea. apparently the energy potential of a gas canister is very high. there's probably some figures online.
apparently one of the concerns is the safety, the canister could explode in an accident. although presumably on a bike it would be padded.
aside the development costs of pistons for a bike motor, perhaps it might be less weight efficient than lithium because of the weight of the canister shell.
maybe the motor of the bike would only weigh a kilogram.
excellent video!
apparently one of the concerns is the safety, the canister could explode in an accident. although presumably on a bike it would be padded.
aside the development costs of pistons for a bike motor, perhaps it might be less weight efficient than lithium because of the weight of the canister shell.
maybe the motor of the bike would only weigh a kilogram.
excellent video!
Crazy Idea
I read somewhere that someone had tried this on a bike and it went a few hundred yards. Of course this was done with an off the shelf compressed air tank that would hold air at something like several hundred pounds per square inch. I googled "compressed air" and "car" and found the story about the Tata Company's car. So if you can build the air tank that will hold air at 4350 psi, you can make it work. None of our local filling stations has a compressor that works much above 100 PSI. Besides which, if you have a homebuilt air tank with air compressed to 4350 PSI on your bike, I don't want to riding next to you.
Here is what I found on the web:
Barring any last-minute design changes on the way to production, the Air Car should be surprisingly practical. The $12,700 CityCAT, one of a handful of planned Air Car models, can hit 68 mph and has a range of 125 miles. It will take only a few minutes for the CityCAT to refuel at gas stations equipped with custom air compressor units; MDI says it should cost around $2 to fill the car’s carbon-fiber tanks with 340 liters of air at 4350 psi. Drivers also will be able to plug into the electrical grid and use the car’s built-in compressor to refill the tanks in about 4 hours.
I read somewhere that someone had tried this on a bike and it went a few hundred yards. Of course this was done with an off the shelf compressed air tank that would hold air at something like several hundred pounds per square inch. I googled "compressed air" and "car" and found the story about the Tata Company's car. So if you can build the air tank that will hold air at 4350 psi, you can make it work. None of our local filling stations has a compressor that works much above 100 PSI. Besides which, if you have a homebuilt air tank with air compressed to 4350 PSI on your bike, I don't want to riding next to you.
Here is what I found on the web:
Barring any last-minute design changes on the way to production, the Air Car should be surprisingly practical. The $12,700 CityCAT, one of a handful of planned Air Car models, can hit 68 mph and has a range of 125 miles. It will take only a few minutes for the CityCAT to refuel at gas stations equipped with custom air compressor units; MDI says it should cost around $2 to fill the car’s carbon-fiber tanks with 340 liters of air at 4350 psi. Drivers also will be able to plug into the electrical grid and use the car’s built-in compressor to refill the tanks in about 4 hours.
Air car
Thanks for excellent post. Gives me some hope that the planet may not end up ploughed over for bio-fuels. The air engine in the second part of the You Tube video looks small enough for a bike. http://http://uk.youtube.com/watch?v=QmqpGZv0YT4
Thanks for excellent post. Gives me some hope that the planet may not end up ploughed over for bio-fuels. The air engine in the second part of the You Tube video looks small enough for a bike. http://http://uk.youtube.com/watch?v=QmqpGZv0YT4
As with so many news stories the numbers don't quite add up, the vehicle would need a perpetual motion engine to do 200km on 1.5 Euros worth of electricity unless the electricity powering the compressor came from a very generous sponsor. To put it in perspective most pedelecs, with overall efficiencies of >75%, will use about 0.33 Euros worth of electricity and some effort from the rider to do 200Km so it is clearly impossible for a Transit van size vehicle to only consume the power of 5 pedelecs, especially given the higher speeds involved and the fact that air compressors and air motors are not particularly efficient machines.
Vehicles running on compressed gas are not a new idea, having been used for many years in mines and other hazardous environments requiring a spark free power source, amongst the more successful were those using high pressure stored steam, the steam also storing thermal energy helping to maximise range. Many hundreds of locomotives using this principle were in use in paper mills and chemical works up until the 1970's.
Vehicles running on compressed gas are not a new idea, having been used for many years in mines and other hazardous environments requiring a spark free power source, amongst the more successful were those using high pressure stored steam, the steam also storing thermal energy helping to maximise range. Many hundreds of locomotives using this principle were in use in paper mills and chemical works up until the 1970's.
C
Cyclezee
Guest
I like the idea of vehicles running on nothing but air, but how much electricity does it take to compress 340 litres of air to 4350 psi
I really hope it works and hopefully it will be more environmentally friendly then the infernal combustion engine apart from the emissions from power stations, nuclear, coal, oil or gas fired. Of course the big gain would be the reduction in pollution from conventional motor vehicles
One thing is for sure if it does take off, it will almost inevitably lead to Air Tax
John
I really hope it works and hopefully it will be more environmentally friendly then the infernal combustion engine apart from the emissions from power stations, nuclear, coal, oil or gas fired. Of course the big gain would be the reduction in pollution from conventional motor vehicles
One thing is for sure if it does take off, it will almost inevitably lead to Air Tax
John
Not sure of the answer to that John but whatever the figure is it will be a lot higher than putting the equivalent energy into a battery. Air compressors are inherently inefficient due to the large amount heat produced in compressing air, unless this heat can externally recycled then it will be wasted.I like the idea of vehicles running on nothing but air, but how much electricity does it take to compress 340 litres of air to 4350 psi
Another factor to be considered is safety, a 340 litre pressure vessel charged to 4000 psi has unbelievable destructive potential. In 2001 a traction engine boiler exploded in the USA, this boiler would have been of a similar size to a 340L tank but in spite of operating at a much lower pressure of about 150psi killed 5 people and injured 40 more, some of whom were over 100' away. In view of experiences like this I doubt that a large vessel at very high pressure on a motor vehicle would be insurable,
Anyone willing to take the risk could experiment on a small vehicle such as a bike with divers scuba tanks and the motor from an air powered tool, something like an impact driver being already geared for suitable rpm.
hmmmm
Set me thinking, the Citreon suspension pump delivers 350 bar and is a pretty compact wee beast, could be powered by a 12v motor. If there is a storage system then the whole package required could be lying in every scrap yard in the country
anyway, nice find, certainly looks like a very cost effective form of transport, until as Aldby says ... they introduce the air tax
This is always the issue that is brought up when hydrogen as a propellent is mentioned. I read recently that if petrol had been discovered today, it would never be allowed in cars!!!! The pro hydrogen lobby argue that in an explosion hydrogen goes vertically and petrol spreads out.
I assume the air lobby would argue that an air tank exploding is of small risk to the surronding people / objects if designed correctly.
They will probably make the tax the fact that you must only use purified air, therefore making the exhaust better for the environment rather than neutral (exluding the cost of compression and air purification)One thing is for sure if it does take off, it will almost inevitably lead to Air Tax
John
Ian
Hydraulic systems are different to pneumatics Bob, it it relatively easy to achieve high pressures with liquids, the catch is that they can't be compressed and therefore can't store energy.hmmmm
Set me thinking, the Citreon suspension pump delivers 350 bar and is a pretty compact wee beast, could be powered by a 12v motor. If there is a storage system then the whole package required could be lying in every scrap yard in the country
Too true, even more so with LPG I think!
There is a difference though in that if a pressure vessel bursts all of the energy will be released in a a few milliseconds, if a petrol or gas tank "explodes" it will do so relatively slowly, the fuel having to mix with air before it can burn, the intensity of the blast being much less than with a pressure vessel explosion. Some idea of how dangerous pressure vessels are can be seen from the fact that if a fuel tank explodes inside a building then it will normally burn the building down, if a pressure vessel explodes inside a building then it will demolish the building, instantly. This is currently reflected in the regulations governing pressure vessels which are far more stringent than those affecting fuel storage vessels.
Good topic this Like Ian though, I'd also run some figures & found that from those costs given it would appear to be somewhat cheaper to power a bike with compressed air than electricity .
However, putting aside costs, air tax (nice one John!) & dangers of explosion which make lithium cobalt seem like child's play by comparison I can't help but try to work out what sort of size & capacity canister and resultant mileage might be used for bikes, and how heavy the compressed air would be?
Does about 50-60 times less than large vehicles sound about right? That would be 6 or 7 litres for 200km/120 miles, around 1.5-2 litres for 30 miles? Sounds ok, but I'm sure the canisters would be heavy, though the motor may be lighter than now, as said.
Stuart.
Like Ian though, I'd also run some figures & found that from those costs given it would appear to be somewhat cheaper to power a bike with compressed air than electricity .However, putting aside costs, air tax (nice one John!
) & dangers of explosion which make lithium cobalt seem like child's play by comparison I can't help but try to work out what sort of size & capacity canister and resultant mileage might be used for bikes, and how heavy the compressed air would be?Does about 50-60 times less than large vehicles sound about right? That would be 6 or 7 litres for 200km/120 miles, around 1.5-2 litres for 30 miles? Sounds ok, but I'm sure the canisters would be heavy, though the motor may be lighter than now, as said.
Stuart.
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Does anyone know at what pressure air turns to liquid? Are the large pressures we are talking about here enough to turn the air into liquid?Does about 50-60 times less than large vehicles sound about right? That would be 6 or 7 litres for 200km/120 miles, around 1.5-2 litres for 30 miles? Sounds ok, but I'm sure the canisters would be heavy, though the motor may be lighter than now, as said.
Stuart.
In that case in stuart's example we could end up cycling around with 1.5-2 litres of liquid air, which would be reasonably heavy.
Ian
Despite all the objections, if I could get enough range for town use I'd prefer air to battery in a car. Although more electricity will be needed to produce the compressed air, there's no local after effect, scrap batteries and pollution for example, and the performance is predictable and reliable over time in a way a battery's can never be.
An air system can easily include braking and downhill regeneration topping up the tank, and I think this could possibly be more efficient than the typical electrical regeneration using a motor which is not designed for generation.
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An air system can easily include braking and downhill regeneration topping up the tank, and I think this could possibly be more efficient than the typical electrical regeneration using a motor which is not designed for generation.
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The electric Smart car is again being promised, for 2008 this time after missing 2006 and 2007.
Also, the electric version of the Mitsubishi i car is again indicated, this time for 2008/9, but tellingly, Mitsubishi say much depends on the Li-ion batteries. Seems we are not the only ones suffering problems with getting them to do the job. Clearly they haven't been performing to design expectations in cars.
Again, another argument for reliable compressed air.
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I'm not sure whether it would be liquid or not Ian, though seems likely (air is around 70-80% nitrogen, isn't it? so would be like liquid nitrogen pressures): either way, it would be quite dense & heavy, I imagine.imellor said:
Seems a long running venture, this air powered car in Africa in 2000 (30 U.S. cents per 200km?!) and in France in 2002... also this 'halfbakery' nitrogen powered bike idea might give some ideas & inspiration to DIYers - paintball gun canisters that store compressed air at up to 4500 PSi?
Interesting what you say about cars too flecc - food for thought
.Stuart.
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The air tank explosion risk is manageable easily enough and it looks at if the French company have it cracked. Anyway, we understand containment system design very well now, thanks to 60 odd years of aero engine development (next time you're flying, look out the window at the engine and work out how much energy is available in the rotating parts).
We also understand high pressure CF tank failure modes well, as we've been using pullwound pressure vessels and rocket motor casings for years, so know well how they fail. As the video says, CF tanks fragment into small, very light, fibres that are easily contained, if they rupture.
The energy sums as given don't stack up though, and it's most certainly not in any way "green" (unless, perhaps, someone comes up with a wind, wave or solar powered compressor). The conversion from fuel to electricity to compressed air is grossly inefficient, as has already been pointed out.
Compressed air as a home energy storage recharging system might work though, especially if powered by a wind turbine or solar array. It wouldn't matter if it took a several hours to build pressure in the home storage tank, at least not for a short journey, commuting, type vehicle. At a guess, a compressed air plant capable of storing about the equivalent of 500W/h to 1000W/h should be enough for commuter use.
Jeremy
We also understand high pressure CF tank failure modes well, as we've been using pullwound pressure vessels and rocket motor casings for years, so know well how they fail. As the video says, CF tanks fragment into small, very light, fibres that are easily contained, if they rupture.
The energy sums as given don't stack up though, and it's most certainly not in any way "green" (unless, perhaps, someone comes up with a wind, wave or solar powered compressor). The conversion from fuel to electricity to compressed air is grossly inefficient, as has already been pointed out.
Compressed air as a home energy storage recharging system might work though, especially if powered by a wind turbine or solar array. It wouldn't matter if it took a several hours to build pressure in the home storage tank, at least not for a short journey, commuting, type vehicle. At a guess, a compressed air plant capable of storing about the equivalent of 500W/h to 1000W/h should be enough for commuter use.
Jeremy
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