what is the range of the bike in one tank full of compressed air ?
2nd November, 2011 @ 1:27 a.m. (California Time)
Already far better than any electric vehicle; its energy storage device wont loose capability an have to be replaced every few years, it fills faster as well.
2nd November, 2011 @ 4:58 a.m. (California Time)
Yet another compressed air engine. This is about the fourth one I've seen announced in as many years. None of them have come to market for a simple reason. They won't work.
Compress air, what happens? The container gets hot. That heat radiates away. That is the energy you just put into compressing the air bleeding away. You haven't stored it.
Don't believe me, get one of those compressed air cans for cleaning your keyboard. Use it for more than a few seconds and that can gets very cold, and the pressure drops.
In order to use compressed air you need to add heat back. So add fins to the tank, but you still have a few problems. You need a very high ambient temperature, so forget using this in winter. If it's at all humid you'll get ice build up on the fins. Ice is a pretty good insulator. Either way, not enough heat input.
All that cold air causes other problems. If there is any moisture in the stored air it will ice up your lines. It will also super cool your pistons/cylinders shrinking any gap, potentially causing a siezure.
Insulate the tank you say. Then the pressure builds up very quickly and any practical size of tank actually has very little capacity.
It's just not a practical invention.
2nd November, 2011 @ 6:30 a.m. (California Time)
re; Ken Waldron
The cooling of the tank happen in accordance to the ratio of the amount of gas being vented to the volume of the tank.
Those compressed air cans for cleaning your keyboard, are not filled with air but a low pressure compressed to liquid gas, usually used a refrigerant. Once the temperature of the liquid has dropped to below its boiling point it wont produce \"Steam\" until it is warmed.
I have seen pneumatic tool fed CO2 from a compressed to liquid tank without any ill affect. The problem pneumatic powered vehicles have getting to the market is not with the technology; it is with the opinionated fools who won\'t give them a chance.
2nd November, 2011 @ 8:56 a.m. (California Time)
@ ken...you need to do some reading and inventing, and less naysaying. First off, those compressed air keyboard cleaners ARE NOT compressed air. (how can you not know this?) Air motors ARE very practical... have you seen any workshop on the planet that doesnt have an air compresser powering every type of tool imaginable? I\'ve never seen a body shop close its doors because of cold weather. Never seen air lines ice up either. frictionless bearings? all use air. Storage tanks are lighter and hold more pressure than ever. How often do good quality air tools sieze? pretty much never if maintained. All good PRACTICAL pieces to the puzzle.
2nd November, 2011 @ 9:38 a.m. (California Time)
the Flat Earth Society is looking for a new president - you\'d be perfect.
Seriously - you COULD NOT be more wrong about this.
2nd November, 2011 @ 10:35 a.m. (California Time)
Right you are, Lance. Air has been the tool-powering medium of choice for years because there are devices that address those various problems that have popped up, such as air driers and filters. The biggest problems for applying air to mobile/vehicular use have been, it seems to me, efficiency and weight, along with capacity. The more research into solving these problems, the closer we get to an ideal state. Innovation should always be encouraged. New and strong lightweight materials are being developed every day and new approachs to motor design and engineering - such as this di Pietro - continue to narrow the gap between \"it doesn\'t work\" and \"amazing how well it works.\"
2nd November, 2011 @ 10:59 a.m. (California Time)
Workshop compressors are not comparable, unless you plan on adding an electric compressor to the bike and a long extension cord. The tanks on a compressor act like a capacitor to allow the compressor to not have to keep running and smooth out the psi variances due to cycling. They don\'t fully cycle from empty to full and back to empty. And there are water traps on those things, because the air DOES cool and the water condenses causing all sorts of nasty issues. They also don\'t have the heat loss issue since they\'re at equilibrium with the compressor providing more energy as needed. Run the tank down without the compressor running and you\'ll find it gets cold. You\'ll also find there\'s not anywhere near enough air in there to run any kind of engine for long. Very low comparative PSI to what is proposed for these engines.
Yes, those cans don\'t have compressed air, they have a compressed gas, same difference. They use those gases since they liquify at a higher temperature. That state change results in a dramatic hike in density and thus more is able to be stored in a can.
Air motors work great when driven by a compressor since you have an equilibrium state and thus little cooling, and they run at much lower PSI.
This a straight physics issue. Look up laws of thermodynamics, Boyle\'s law, etc. If you want that compressed gas to do work for you for any prolonged period of time you\'ll need a darned good heat exchanger and source of heat.
I\'m not a naysayer. I actually thought of this solution as a way to keep wind turbines more efficient by compressing air when overloaded to keep the blade speed within safe parameters, and use the compressed air to keep them up to speed when wind is low. Put the storage under the Wind Turbine. But I realized it wouldn\'t work due to the reasons I cited. Put the tank in a large body of water and it might work, but you\'ll need to use some energy to keep the water flowing over the heat exchanger.
Inventors who ignore the laws of physics are destined to be foiled by them.
2nd November, 2011 @ 11:28 a.m. (California Time)
According to VitalMX.com, he can ride around for 3 hours at 60kph on a tank of air. That\'s a little over 37mph, a figure which is more familiar to me. Since this is a motocross bike (I think it is...I don\'t know that much about bikes), high speed is not the aim, though power would be and it\'s likely quite powerful. Otherwise, why even build the thing if it can\'t be competitive? Nevertheless, that\'s 111 miles in distance traveled. I would guess that when that bike was gas-powered it didn\'t have much more range than that on a single tank of fuel. By a photo I saw on VitalMX.com, tanks of air are kept on hand and the setup looks like they can be easily and quickly swapped. Now, move those figures around a little and assume the bike is geared to go twice as fast, say 75mph. Can it then be assumed it will be able to travel only half the distance on that one tankful of air? Probably not because of increased wind resistance, but if so, that\'s still a respectable 55 or so miles on a single tank. Even if range is reduced to 50 miles, just add one more tank onboard and bingo! 100 miles on a single filling. Not bad in my estimation.
2nd November, 2011 @ noon (California Time)
The news here isn\'t \"air vehicle.\"
It\'s the engine design. The DiPietro rotary-air is in it\'s 5th or 6th generation.
It has been well demonstrated. It works. Power to weight ratio has increased with each development iteration.
They are testing it now in a food market in Melbourne ... powering carts and forklifts & getting the exhaust fumes out of the building.
If it pencils out in that environment - if they can prove endurance, performance and maintenance - it is suddenly an exciting product for development or licensing or whatever.
2nd November, 2011 @ 12:56 p.m. (California Time)
Quote \"but energy is still needed to compress the air\" so as an enviromental focused offering it fails completely. Compressors run on Elecricity from a coal fired power station or a petrol/diesel engine. Nothing more than a curious novelty. At least electric vehicles \"can be\" charged by the sun. Solar compressor anyone?
2nd November, 2011 @ 5:15 p.m. (California Time)
After reading the above article and all of the comments, you still sound like a nay-sayer to me. If everyone always listened to that type of people then we would all still be living in caves.
Who said that any invention HAS TO BE PRACTICAL?
2nd November, 2011 @ 5:20 p.m. (California Time)
I agree with the majority thinking that Ken has overstated adiabatic problems. Yes one generates heat when compressing air (losing energy), but as with all energy storage systems, there are losses. But after filling, tank returns to ambient temperature, and engine then cools somewhat when running... a bit like an internal combustion engine generates heat when running. But obviously these engines work running fork-lift trucks around the Melbourne city markets... so ice is unlikely to be a problem in temperate climates.
The tiny number of moving parts is what is amazing. Compressed air is a beautiful energy-storage medium in that regard.
As others have noted, only real issue is range... which is a function of tank pressure. And if swappable tanks, or ability to strap second onto rear rack, then magic! Just as people recharge electric battery packs at work (for the commute home), people could have small/slow compressor at work to recharge tank. Indeed, even leaving tank in-situ, one could have a small 110-240v compressor in under six-inches square (150mm square) which you carry on bike and plug-in to mains power at any destination, or cafe/truckstop en-route to extend range.
But pity the designer was not a commute cyclist in his youth, rather than dirt-bike enthusiast - as then he might have started with a mountain bike (off-road bicycling) frame and parts, rather than motorcross frame and componentry. MTB frame, suspension etc are about 50% of the weight of motorcross... Other benefit is that if you construct as an \'ancillary\' motor (ie if you leave pedals in place), you can more easily construct something that is legal in most jurisdictions to use on the road.
But good Aussie ingenuity!
Graeme, Sydney, Australia
2nd November, 2011 @ 5:50 p.m. (California Time)
This is great news if true. I was hoping air would make it back, this with batteries could be a mean cheap hybrid
2nd November, 2011 @ 6:13 p.m. (California Time)
re; Ken Waldron
Seriously, did you just state that boiling a liquid is the thermodynamic equivalent of expanding a gas?
Not even close.
2nd November, 2011 @ 6:34 p.m. (California Time)
I\'d be interested in seeing somebody do a gas/compressed air hybrid. Compare it then to the gas/electric hybrid vehicle. The compressed air system would probably be hundreds of pounds lighter than the battery electric system. Carbon fiber air tanks compared to a multiple hundreds pound battery. Non degrading tanks compared to constantly weakening batteries.
3rd November, 2011 @ 1:04 a.m. (California Time)
Here is a refuelling station for compressed air cars and relevant engines!
Air Pur des Vosges
3rd November, 2011 @ 6:40 a.m. (California Time)
This will be my last post on this topic. To the gentlemen who called me a naysayer, thank you. I've come to realize you could not have paid me a higher compliment.
I've never been one to accept the printed page without some kind of critical analysis.
I've seen concepts come and go on this and other sites, yet never see the light of day in real production. The causes are many, including funding, design challenges, patent infringement, or it won't work (either cost effectively, or it just plain doesn't work).
When I see the same concept reported from many different places over many years, and no real large-scale production happens I start to look at the last. So, your criticism caused me to do two things: Investigate my own knowledge, investigate the state of this industry.
For the first I knew that my knowledge was incomplete, and I have educated myself as to where my errors were. I now know my discussions of heat exchange issues were overstated, as heat loss is a lesser aspect at high pressures. Boyle's Law is not effective at high pressures. It is however still an issue as the reference I used states both in filling and emptying the tank.
The dual loss of energy, electrical to compressed air to kinetic also significantly reduces the efficiency, so forget about clean air, unless you are using solar or wind as your source
I also now know that there is a limited amount of energy available in any practical storage tank, about 50 Wh per litre at 4500 psi. If you're planning on filling such a tank at home you're in for a very long wait, and going to see a very low energy transfer efficiency. Only commercial compressors can achieve this with any sort of efficiency and speed, and you'll still lose a significant portion of the input energy. By comparison a Lithium Ion Battery has 5 times the energy density, and even an old fashioned Lead Acid Battery beats air pressure. I of course am assuming that my references are correct, which by the way I will be confirming. I am after all a skeptic.
As for the industry, there are about eight companies mentioned in my reference. Read the summary of each. One Chairman got charged with fraud. Tata said limited range and LOW ENGINE TEMPERATURES were causing problems. This is a company in India, not exactly know for low air temperatures. One company uses fuel to heat the air.
I feel justified in my skepticism as all the issues I raised are real, and proud that I don't believe anything just because it is in print. As I said those who are ignorant of the laws of physics are doomed to be foiled by them. As for the flat earth society, they don't take skeptics, they take people who will believe anything.
Gentlemen, bring a critical eye to what you read. And don't misinterpret what someone says to criticize them. Thank you for making me question myself, I feel better having been vindicated in my skepticism.
I do believe this technology can be useful in some situations. It's great in my Air Hog model plane, although I'd like a lot more flight time. I think I'll install an electric motor and batteries.
3rd November, 2011 @ 7:11 a.m. (California Time)
Oops, sorry, forgot the reference:
This is my last last post. :)
3rd November, 2011 @ 7:17 a.m. (California Time)
re; Terry Penrose
You can compress air using solar, and the air tank is vastly more environmentally benign than batteries.
re; Leonard Foster Jr
the compressed air tank is the \"battery\".
3rd November, 2011 @ 9:48 a.m. (California Time)
Ken!!! Don\'t go so soon. I don\'t blame you though. The problem when arguing with a fool is that sometimes bystanders might not be able to tell the difference.
Anyway, there is a simple way of looking at this. A gas powered vehicle heats up COLD air using fuel to expand the air to make work. The air engine does the opposite. It heats up air by compressing it for storage, therefore causing the pressure to go up and lose energy via heat loss. It then is released from a high compressed state (storage tank) to a low, cooler state (motor) which in turn also loses energy.
So when you want the air to compress, it heats up and wants to expand instead, and when you want it to do some work, it cools down, shrinks and loses pressure. Atoms work that way. Think of steam instead.
3rd November, 2011 @ 6:33 p.m. (California Time)
Ken can you link to the Vital mx quote i cant find it. I to am convincing non believers.
4th November, 2011 @ 10:24 a.m. (California Time)
The problem is that people see the heating and cooling of the gas as a problem rather an opportunity. Using a Sterling Cycle engine you can harvest mechanical energy from the generated heat differential.
4th November, 2011 @ 7:29 p.m. (California Time)
I am with Ken, there is a reason this fails every time it is tried. The people doing it don\'t have an engineering background, if you were to add heat to the compressed air then you might get somewhere otherwise the energy used to compress the air will make this a lot like making hydrogen from water. This is not to say there are not some applications where it might make sense but it would not be energy efficient or energy dense. Go ahead make my day, prove me wrong, I will be the first to admit I don\'t know everything but history says this will be another lesson in what not to do.
5th November, 2011 @ 7:17 p.m. (California Time)
Steel and aluminum air tank are too heavy to make the idea practical except in special circumstances. But with carbon fiber, and the possibility of carbon nano-tube tanks make pneumatic propulsion more practical than electric vehicles, especially if the heat is harvested during compression and the cold during expansion.
Just as an aside I prefer the injuries of an exploding air tank to those of a flaming gas tank.
6th November, 2011 @ 6:22 a.m. (California Time)
Here is a link to the DiPietro Air motor site:
It sounds spectactular - and a nice animation on there too:
Outstanding efficiency up to 94.5%, Constant high torque, Low parts count, Low number of moving parts, Virtually no friction\' Smooth speed control characteristics, Compact and light, No vibration, Only 1 PSI of pressure is needed to overcome the friction.
8th November, 2011 @ 7:10 a.m. (California Time)
Want it to work .....Add a second sprocket that can go faster than the actual sprocket and pump air back into pressueized tank....Have fun.
8th November, 2011 @ 2:28 p.m. (California Time)
Wikipedia: A 2005 study demonstrated that cars running on lithium-ion batteries out-perform both compressed air and fuel cell vehicles more than threefold at the same speeds. MDI claimed in 2007 that an air car will be able to travel 140 km in urban driving, and have a range of 80 km with a top speed of 110 km/h (68 mph) on highways, when operating on compressed air alone, but in as late as mid 2011, MDI has still not produced any proof to that effect.
The Flying Crowbar
10th November, 2011 @ 6:57 a.m. (California Time)
The problem with compressed air vehicles has been the low energy density of compressed air, which leads to very short range.
The engines have a high horsepower/kg ratio, but the compressed air and compressed air tank have a very low ratio of kilowatt-hours to kilograms or liters.
In simpler terms, a compressed air bike may be able to go very fast, but it will be for a very short distance.
MDI (mdi.lu) has been fighting this problem since the late 1990\'s. They have announced almost every year since 1999 that production of a compressed air vehicle would start \"next year\", but they have never even gotten to the point of having a prototype that they are willing to let automotive journalists use to do independent tests.
11th November, 2011 @ 8:25 p.m. (California Time)
re; The Flying Crowbar
That is with new batteries. The air tank won\'t have to be replaced every few years to maintain the same level of performance.
12th November, 2011 @ 9:51 a.m. (California Time)
HEY nice concept. a carbon fibre tank is STRONG and light and may be expensive but is capable of taking a bullet and would withstand some damage. Carbon fibre helmet and shin pads please.
15th November, 2011 @ 1:55 p.m. (California Time)
@Charlie Allen - November 11, 2011 @ 08:25 pm PST
\"In simpler terms, a compressed air bike may be able to go very fast, but it will be for a very short distance.\"
What\'s the matter, Charlie?
... since 92% of car drivers run a a maxi range 44 km (28 miles) a day in most countries.
\"MDI (mdi.lu) has been fighting this problem since the late 1990\'s.\"
Right! And he proved the concept was good.
Just a lack of money,
... when 900 Millions of euros were given by Sarkozy administration to BollorÃ© staff and mates for the poisoned Lithium batteries.
I guess you know this, Charlie!
Would be better to support these courageous pionneers,
Angelo Di Pietro , Guy NÃ¨gre and Gilles Saint-Hilaire.
Les Triplettes de Bonneville - Salon Moto Legende - Paris 2011
Air Pur des Vosges
19th November, 2011 @ 4:14 a.m. (California Time)
Shop air tools use high powered compressors to store energy to supply very low power hand tools. Certain grinders do well as high RPM and air motors are useful in tools that develop almost no torque at all.
So far no air powered vehicle has proven to deliver any real distance ability at all. The one air car that was produced was a disaster than ran out of air in just a handful of miles. Batteries are currently far superior to are motors for mobility. It is a shame as air motors are not heavy or bulky. A low speed air car with continuous air compression from a small petrol motor might work in areas with heavy, urban traffic as so much time is spent at idle and a crawl speeds that a small compressor might keep the air bottles full. But in my climate the need for year round air conditioning trashes most new ideas and in other areas a need for serious heating inside a vehicle has the same effect making many new ideas sort of worthless. AC in a car may take more energy than pushing the car does.
22nd November, 2011 @ 10:18 a.m. (California Time)
\"So far no air powered vehicle has proven to deliver any real distance ability at all. The one air car that was produced was a disaster than ran out of air in just a handful of miles\"
My brother-in-law first saw an air powered car in the late 50s and I\'ve been hearing about it ever since. He put it into his giant \"Great Conspiracy\" folder along with the 100 MPG carburetor and the engine that can run on water.
30th November, 2011 @ 4:31 a.m. (California Time)
\"I\'ve never been one to accept the printed page without some kind of critical analysis.\"
Thank the Universe. I thought I was all alone here.
30th November, 2011 @ 4:36 a.m. (California Time)
first of all, i really like the idea of air powered car/bike. I\'ve even made some designs based on that tehnology but when i was looking for some data about air engines, energy density etc I\'ve found that its rubish. It just cant work, it cant work on this planet and probably not even anywhere else. Maybe some other universe with different laws of physics.
That company which claims they have engine with 95% efficiency ... they dont realize that it would have to have 1000 % efficiency to work ( perpetum mobile here we go ). Compressed air has energy density of the potato, maybe even lower (gassoline has around 100 times better). Ye you can say that gasoline engine has poor efficiency (18 to 35%) still superior to compressed air propulsion not to mention there are diesel engines with 50% efficiency .
Im not naysayer even had long discusion with teacher from automotive department. He just laughed when i asked him about compresed air cars.
If you like the idea of non gassoilne/disel vehicle, go watch \"who killed electric car\" movie, its american so its kinda stupid, but if you dont take it too serius you will find out why we still use 100 years old technology in cars.
The only hope is graphene bateries ( or some other technology ). Electric motors are simple easy to use and manage with high efficiency and maybe few years later we will have electric motors with carbon nanotube / graphene windings ( just my idea, dont take it serious) which will have high power/weight ratio.
PS: sorry for bad english, hope you can understand the meaning :D
PPS: NO, the air powered vehicles cant work!
18th February, 2012 @ 10:41 a.m. (California Time)
What you guys are saying about efficiency is right but everyone seems to be overlooking the fact that this is just a dirtbike. It's capabilities are just fine for that use. I can think of situations where this bike could be used when gas engines would not be a real good choice. Personally, I would prefer electric but this is a nice simple setup that should be very reliable.
16th November, 2015 @ 1:30 p.m. (California Time)