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[Tudor]

I just stumbled upon Dean Bensteads 02 Persuit, a dirt bike driven by the power of the contents of a scuba tank, air. A prototype, of course, but - WOW!

http://o2pursuitdeanbenstead.wordpress.com/

It looks really simple as and should be relatively cheap to mass produce. We all know the batteries are expensive on the e-bikes. Given the air bike take regular unmodified scuba tanks getting a "reserve battery" will be some $150 from e-bay.

What do you think, or do you have any more information/knowledge on this? Can't find anything on further development of this specific bike.

It seems to have all the possibilities to make a really cheap community bike.

[Richard230]

I have seen that before, but I really wonder how far you can go on a tank of compressed air?  Talk about range anxiety!  Plus, no doubt as the pressure slowly decreases, so does your top speed and performance.   

[NoiseBoy]

Air compressors and air driven motors aren't exactly the most efficient machines on the planet. It doesn't make sense to me.

[skeezmour]

Problem with air is it has a horrible energy density. A regular scuba tank carries something like 300-400wh (if released very slowly) with horrible recharging efficiency. They will pretty much stay in the novelty category for the simple physics involved.

[Tudor]

Wow,
I didn't expect the arguments against air driven motors sounds so similar to when I talk about e-bikes to the general guy. Well, not on this forum at least.
Range anxiety, efficiency, novelty etc. I'm sure you also heard it all before talking about your Zero's.

At least you don't mention 'loud pipes saves life'.

This was a prototype from 2011-12 made by a student, no doubt it can be made more efficient and be more thought trough.

/../ but I really wonder how far you can go on a tank of compressed air?  Talk about range anxiety!  Plus, no doubt as the pressure slowly decreases, so does your top speed and performance.

Article says 100 km (62 miles), no mention at what speed or anything but I would assume at minimum 50 km/h.

Range anxiety is all about how you use it. I have a one way 10km commute to work, a vehicle that manage, say 40km, would not give me range anxiety. Or taking the bike to dirt track and having a couple of filled tanks in your trunk would not cause any anxiety at all. But you know all this already.

The decrease of pressure might be an issue, hopefully not too dramatic - I wouldn't know.

Air compressors and air driven motors aren't exactly the most efficient machines on the planet. It doesn't make sense to me.

Is that an argument? Aren't exactly the most efficient machine on the planet?

It runs on air, that's very efficient in my book, no matter the actual efficiency %.

"The O2 Pursuit gets 62 miles of travel on a full tank, and can hit a top speed of 87 mph."
-Wired

How can this not be impressive on a prototype, talk about potential. And coming from something as accessible as a vanilla scuba tank?

Problem with air is it has a horrible energy density. A regular scuba tank carries something like 300-400wh (if released very slowly) with horrible recharging efficiency. They will pretty much stay in the novelty category for the simple physics involved.

Given the simple physics involved it has potentials to being a low-cost alternative to electric bikes, simple physics is a selling point to the e-bikes, why hold it against an air-bike?

 I can see potentials on dirt-tracks where the fuel/battery is great recharging efficiency relative to price and would require very little infrastructure installment.
Since Zero dropped the XU there is a market for a low-cost commuter and given it runs on scuba tanks and not batteries, low-cost is not just in terms on maintenance but also off the shelf.

Having all this said, I'm hope I don't sound harsh or give the impressions of being a total .... . If that is the case I'll pull the 'lost in translation' card and blame English being my second language.
I respect you all on this forums for your knowledge and interest in e-bikes, also I haven't had my second cup of coffee yet and might be a little grumpy. (I'll go have my coffee now)

[NoiseBoy]

By efficiency I am talking about full cycle efficiency.  You have a power station burning whatever to produce electricity, travelling through a network, where you then use it to power a motor which drives a compressor and fills a tank with air, you then use that air to drive another motor.  Why not just use the electricity to drive the motor on the bike in the first place.

I can see that being able to change a tank is quite fast, but they are also very heavy, have you ever lifted a full size scuba tank?  Im not sure I would fancy having my legs either side of a metal cylinder at 400 Bar in a crash either.

[BSDThw]

I think it is very different if you use a steel or aluminum Tank. As much as I know the fire service has carbon fiber tank with higher pressure as scuba.

The leg of efficiency is the filling station and the compressor. I have filled a lot of scuba tanks!

But maybe there is a lot of potential to improve the compressors?

The air idea is nice but I don't believe the 100km range. A Prototype 2011 and nothing happen than gives the idea it was not so successful.

BTH When I was young I had an Air-driven toy car 25cm long. You fill it with an (hand) air pump and it was really nice how it was accelerating.

[Tudor]

You have a power station burning whatever to produce electricity, travelling through a network, where you then use it to power a motor which drives a compressor and fills a tank with air, you then use that air to drive another motor. Why not just use the electricity to drive the motor on the bike in the first place.

It's not that the electricity through the network is powering the electric motor. You charge the batteries with it (converting AC/DC in the process) storing chemical energy. It's not that far from using a air-compressor to fill a tank. I'm not sure if it counts as chemical energy too or kinetic though.

Why not add of making of lithium-ion batteries vs steel (or even recycled aluminium) cylinders to your comparison. Let's not forget battery degradation, (or self-discharge if we're being picky).

This has potential to be a much cheaper alternative than the very much expensive batteries. I won't motivate further why that is an advantage.

I can see that being able to change a tank is quite fast, but they are also very heavy, have you ever lifted a full size scuba tank?

I have yes, I took divers license at age of 14 and I managed very well to handle the tank (not that I know of any 400 bar but that's not your point I'm sure). I've never lifted a FX/XU batteri pack though but I read they weight some 19 kg (40'ish pounds) and are considered somewhat cumbersome.

Im not sure I would fancy having my legs either side of a metal cylinder at 400 Bar in a crash either.

I also understand that having 11.4 kWh worth of batteries between your legs in a crash is not deterrent enough to not desire a Zero SR. Firefighters are known to carry compressed air tanks in extremely hazardous situations, just saying.

Sorry but I just don't think your arguments are interesting - they remind me too much of non-arguments against electrical drive.


I think temperature control of the released air is a might be an issue. If I'm not mistaken the air-pressured car from Peugeot dehydrates the air to prevent icing. Maybe using regular scuba tanks would be impossible/impracticable below 10 degrees (C) or so. I also thing using regular scuba tanks would make regenerative braking impossible. Maybe it could have a special mini tank for storing braking energy, but it may not be worth the gain or extra weight/cost/complication.

Thing is, this technology has potential to cost much much less cutting the cost of batteries. A low cost dirt-bike or commute.

[Tudor]

I think it is very different if you use a steel or aluminum Tank. As much as I know the fire service has carbon fiber tank with higher pressure as scuba.

I think the fire fighter tank is carbon for heat resistance and weight reduction, obviously at a higher cost. Ideally the air-bike would take either, not relying on one specific dimension or type. This would open up to very inexpensive array of extra tanks. Or you would line up the low-end to come with a steel tank and the exclusive version with a carbon

The air idea is nice but I don't believe the 100km range. A Prototype 2011 and nothing happen than gives the idea it was not so successful.

Yeah, the 100 km is very unspecific. But a prototype can always be made more efficient, or you can have it take twin tanks or whatever. Or stay content with a, say 60km true range. I also wonder what happened to it, given the simple construction involved one would think it would be further developed.

BTH When I was young I had an Air-driven toy car 25cm long. You fill it with an (hand) air pump and it was really nice how it was accelerating.

Hehe cool, my daughter has a balloon-driven plastic car about that size which is quite cool.

[Justin Andrews]

I also understand that having 11.4 kWh worth of batteries between your legs in a crash is not deterrent enough to not desire a Zero SR. Firefighters are known to carry compressed air tanks in extremely hazardous situations, just saying.

I rather sit on a tank which *might* catch fire and scold my nads before I decide to drop the bike and walk away, than sit on a bike with a tank pressurised at 4000PSI. 

I have a horrible feeling that I'd not be able to outrun the blast radius of the air tank going up...


Plus the efficiency of the best air powered vehicles is just horrible, about that of a poor efficiency ICE engine, I went electric to move towards a more efficient use of power than petrol.
While the energy storage of air is also very low (worse than that of lead acid batteries), as already pointed out.

Finally, and by far the most important, to me. Is that I can (and have) walked into my bike dealership, and bought an electric bike. Frankly until air power hits the marketplace, its not worth me considering it as anything more than vapourware. Its like Lithium-Air batteries in that regard.

[BSDThw]

I think for a dirt bike on a race course it my be an easier system as electronic. You don't have the pollution/water/dust problems and the shock at electronic components... You can easy change the tank and tanks will be cheaper as separate batteries. The tanks need little service and can be used after years. You can recycle it easy... 

As a developer in the electronic area I know how difficult it can be to built a shock proved board.

[Tudor]

Plus the efficiency of the best air powered vehicles is just horrible, about that of a poor efficiency ICE engine, I went electric to move towards a more efficient use of power than petrol.
While the energy storage of air is also very low (worse than that of lead acid batteries), as already pointed out.

The efficiency related to environmental impact is great, as is efficiency related to cost. Indeed efficiency in terms of weight and volume is poor, as are batteries compared to gas so its not a deal breaker.

I rather sit on a tank which *might* catch fire /../ not be able to outrun the blast radius of the air tank going up...

You emphasize might in the burning battery scenario but not for the air tank blowing up? Biased?

Frankly until air power hits the marketplace, its not worth me considering it as anything more than vapourware. Its like Lithium-Air batteries in that regard.

The vapourware is indeed a deal breaker, I cant argue with that. I just which it wasn't, and I'm curious why it is. Seems to me it have a lot of potentials as a cheap low-end bike.

I'm sure both the founder of Zero and Brammo was tired to death of hearing exact the same arguments over and over again when talking about their ideas of an electric motorcycle.

No range, no performance, explosion-prone, novelty, in-effective etc..
well they changed all that with research and product iteration. A 2008 Zero is a novelty compared to any 2013 model, or even 2012 for that matter.

Again I'm surprised to hear the very same arguments being used against electric in favor of IC-engines. I did not expect to find that kind of rhetorics in this forums.

[NoiseBoy]

Maybe if you had a pair of cylinders at very high pressure. Up until recently I was shooting match air rifle regularly so had a scuba tank to refill the small cylinder on the gun.  It was rated to 300 Bar and i believe they pressure test cylinders to double their rating, so maybe you could get a laboratory grade cylinder that is up over 600 Bar?  Two of those would you give you a similar amount of energy to a Zero X.

But then you have more problems, where are you going to get a compressor capable of working at those pressures, how much would it cost and who has space to keep it?  If you take the cost of even a normal compressor like one they use for SCUBA your bike isnt looking so cheap.  Refilling a standard tank locally costs £12-15.  More expensive than a tank of fuel!

[NoiseBoy]

Tudor; Given that this forum is populated by people who are obvious open to alternative energy solutions for transport. Does it tell you something that the response to air power has been so negative.

Don't get me wrong, I have nothing against it and if it can work then that is fantastic, bring it on.  However everything I have seen so far tells me its unlikely to succeed.

[Justin Andrews]

Tudor; Given that this forum is populated by people who are obvious open to alternative energy solutions for transport. Does it tell you something that the response to air power has been so negative.

Don't get me wrong, I have nothing against it and if it can work then that is fantastic, bring it on.  However everything I have seen so far tells me its unlikely to succeed.

As soon as I can see an air-powered motorcycle that can do 80 miles per charge, and the charge costs about £1, then I'd start getting more interested.
Right now I've seen very little to indicate that air powered vehicles can do more than a dozen miles on a tank.

filing a standard tank locally costs £12-15

Its been a while, but from what I remember those compressors do not scrub all the mosisture out of the air either? Air power requires a very low mosture content to stop the internals of the engine icing up.

Tudor:
As for bias, I'm not *that* biased, I've worked with compressed air and experienced a (small scale RC battery) lithium fire. Lithium fires develop quite slowly (but oh do they burn bright when they get going) while compressed air explosions develop quickly indeed. Simply put I feel you can walk away from one much more easily than the other.