# Design Boosts Chances for Air-Powered Motorcycle

Mathematical modeling shows viability of a motorcycle that could run on compressed air. Karen Hopkin reports

### Listen to this Podcast

Die-hard advocates of alternate energy might fantasize about cars that could one day run on water. But scientists in India have gone a step further. They’ve mathematically modeled an engine that should allow a motorcycle to run on air—compressed air, that is. Their design is described in the Journal of Renewable and Sustainable Energy. [Bharat Raj Singh and Onkar Singh, http://bit.ly/bFd3dO]

The hunt is on for alternatives to fossil fuels. Internal combustion engines convert the energy in gasoline’s molecular bonds into motion. But what if there were another way to make engine parts move?

Scientists in India were thinking of a well-directed wind. And after crunching the numbers on pressure and flow, they’ve concluded that a tank of compressed air could generate enough power to run a motorcycle for up to 40 minutes. The air would spin a turbine, which would then get things rolling.

Of course they’d need to design a tank that could store enough air to fuel a long haul. Current cylinders would need changing or charging after about 20 miles. Which would still cover a lot of commutes and trips to the grocery store.

And you’d still need to get air in the tank in a green way. Maybe a solar-powered, geothermal, wind-driven compressor?

—Karen Hopkin

[The above text is an exact transcript of this podcast.]

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1. 1. fixerdave 12:57 AM 7/6/10

> ...And you’d still need to get air in the tank in a green way. Maybe a solar-powered, geothermal, wind-driven compressor?

I was thinking this very thing for my shop. I always find it annoying to run my big compressor to fill the air tanks I have. I use air tools so infrequently, the tanks usually bleed off more air than I actually wind up using.
Why can't I get a small solar panel, throw it on the roof, and run it through a capacitive starting circuit. Just let the cap charge up to a set voltage then switch on a cheap little disposable 12vdc compressor. It would probably only run for a few seconds... then let it repeat, on, and on, and on. Pift, pift, pift, it would slowly fill the air tank, day after day. Unless I was into a big project that used lots of air, say sandblasting, it would probably negate my need to run the big compressor at all.
At that point, why would I care if it was only 1 or 2% efficient? The input is basically free, and if I burn out the compressor after a year or starting 100 times a day, they're less than \$20 bucks new - cheaper if you garage sale.

I wouldn't mind some more efficient air motors as well. It always amazes me to see that honking big compressor motor that can't even keep up with some little air tool that's not doing a whole lot of work. If we had a cheap way to compress the air and more efficient motors then compressed air might make for a decent storage medium.

2. 2. simon 04:42 AM 7/6/10

This is a very interesting idea, I have a way of charging the tanks using free energy, its an idea that i have been working on for a couple of years. Its a simple system that can be used to provide a power source at a "filling" station where a number fo these bikes can be charged very cheaply with only maintaince costs of the equipment would be added. the units are simple in their operation and can once built run automaticly on free energy, pollution is nill (ignoring the build) Te idea can be used in a number of ways, to provide compressed air or generate electricity for free. I have often wondered what to do with my idea as I dont have the finances or the contacts to take it further.

Simon Willis

3. 3. bloomingdedalus 05:56 AM 7/6/10

You'd probably be better off with Li+ batteries.

4. 4. JamesDavis 07:32 AM 7/6/10

That is a good idea India has and it can be implemented into American cars by simply putting a tank of air in the car that would hit a turbine to charge a back-up battery when you are not around a charging station. It seems though America looks for excuses instead of solutions.

5. 5. zero 08:21 AM 7/6/10

The idea has been around for a while, from memory high pressure fiberglass or lightweight composite was used for the tank. I think the original idea was for pushbikes but could be applied to super light cars.
Compressed air is a great way to store energy, i read about storing high pressure air from either excess green sources or the "excess" power from power stations at night. Another idea was to cut huge tunnels into suitable rocks under cities to store huge amounts of compressed air as back up green energy. It would appear the simple idea went nowhere. Surprise, surprise.

6. 6. spectralguy55 08:33 AM 7/6/10

Well, yes, the problem isn't ever really the energy IN the vehicle, but getting the energy there. Whether it is batteries that power the vehicle, or fuel cells, or whatever, you can easily posit an energy source that, once in the vehicle, is capable of powering it for some distance. Fossil fuels have simply been the most convenient way to deal with that problem, thanks to its energy density, stability, etc. But, a renewable energy source external to the vehicle other than an oil or natural gas well somewhere, with the whole infrastructure necessary to back the postulated external source is the real problem. Even with compressed air, most of the schemes likely to be proposed will entail electrical generation by some means, with the attendant loss of energy through transmission and storage. But, a windmill? I have my doubts. I don't know of anyone's calculations showing that we can make more than a relatively minor dent in our energy needs using windmills. And windmills have a host of drawbacks, ecologically. Take the studies that have shown that windmills kill birds, for example. I hope someone thinks carefully about other aspects of "green living" into account. What about the long-term effects on the rotation of our planet? (Yes, windmills represent a source of drag that will slow the rotation, and if you want to see a global warming problem, start calculating the effects of a longer day, with its longer heating and cooling periods. It is a VERY long-term problem, but one we have no real idea how to fix, and so I don't want to start drawing it any closer.) Part of the problem we humans have created for ourselves is due to the fact that we have never really thought of long-term issues. And part of the reason for that is that we've only recently started understand what the long-term effects of many technologies may be. So, though a compressed air motorcycle may be interesting, I think we need to talk more about those very-long-term issues ... and soon.

7. 7. David N'Gog 08:45 AM 7/6/10

All technologies need to start somewhere... but... with a range of 20 miles this is highly limited just to areas of high population densities... and then only to individuals (not families) and then... only for purely commuting reasons... and only for individuals who will not use it for pleasure/travelling.

As a new technology will no doubt be more costly than it's benefits.

It is very much a niche market- which will inhibit filling stations.

Maybe this will work in the crowded cities of Asia where this "niche" may be more mainstream- I can't see this ever taking off in the west though.

8. 8. dbtinc 09:15 AM 7/6/10

Save gas, fart in a jar ...

9. 9. jtdwyer 12:33 PM 7/6/10

Well, I watched some program on TV yesterday where two Brits rebuilt an old moped with two scuba tanks and I think a refrigerator compressor. It was intended to serve as an island delivery vehicle for a bakery, I think. The also interviewed someone at a small auto manufacturing plant developing a lightweight car. Looks like there's little need for engineering research.

10. 10. jtdwyer in reply to jtdwyer 01:00 PM 7/6/10

BTW, the delivery bike used an electric compressor at the home base to continually fill a large air tank. The bike could recharge from these tanks in just a few seconds and be on its way, unlike recharging directly from a compressor or recharging a battery from generator, which usually requires a significant amount of time.

The bike motors were actually two chain linked refrigerator compressors I think. Of course, weight is not a critical issue in refrigerator design, so the bike design could be optimized for weight. The other critical design factor is the safety of compressed air tanks in a collision: explosion of ~30x compressed air tanks can produce a lot of collateral damage.

11. 11. frgough 08:50 PM 7/6/10

More evidence again at just how fantastic an energy storage medium gasoline is. Fortunately, those of us with brains continue to realize that carbon dioxide is plant fertilizer and not a deadly toxin, and so use our IC engines without guilt.

12. 12. Mekhong Kurt in reply to spectralguy55 01:26 AM 7/7/10

spectralguy55, you may be interested in knowing that sometime recently -- unfortunately, I didn't bookmark the sources -- at least one new study showed that the bird-kill from wind turbines is insignificant. As I recall, it said something like 10,000 or so birds are killed annually in window collisions -- far more than the study found resulting from birds flying into wind turbines.

That's not to say that more can't be done to make the turbines safer for birds, particularly when turbines are located in migratory routes, and more particularly when they're located in unique such routes. (This applies to butterflies as well, by the way.)

There are good reasons to do our very best to protect wildlife. Like many of us, I don't enjoy seeing any living thing suffer, especially needlessly. (That's why I don't enjoy hunting, though I will eat, say, a venison steak -- but before I do, I want to know two points: (1.) that it was a "clean kill," and, (2.) that every edible part of the deer will in fact be eaten by people, and such meat as unsuitable for human consumption will be used to feed pet dogs, or barring that, used in a compost pile, perhaps. . Hypocritical? -- I hope not.)

Can wind turbines reliably fill air tanks? No, not if consistent, steady filling is required. Neither can solar power. Geothermal could, but it's limited in terms of availability in many places -- but folks in Iceland are in luck!

I'm neither a scientist nor engineer (though an enthusiastic supporter of just about anything green), and I've long had a question requiring air-powered engines, a question for which I've not come across an answer: is the power leveled out to some extent? I'm not even sure how to frame the question. Let me put it this way: if I were to be offered the chance to drive 20 miles, as mentioned in this article, would I be able to cruise in a reasonable range that 20 miles, or would I start out at normal cruise speed for the type of road (street versus motorway, for instance) and gradually slow until I was moving at a mere crawl by the time I had depleted the air tank? Or is that just a stupid question in the first place? (I hope I didn't amply prove my own stupidity. Ignorance I don't mind; stupidity is another matter entirely! :-)

13. 13. Mekhong Kurt in reply to frgough 01:37 AM 7/7/10

Indeed, gasoline is a superb energy source in terms of its energy density -- that's beyond dispute. And indeed, CO2 is "plant fertilizer," as you put it.

Now, if there was just some way to get rid of all the *other* crap that comes spewing out of tailpipes polluting not only the atmosphere but our water and soil, such as particulate matter. Anyway, all those byproducts that do "wonders" to increase, for instance, respiratory diseases.

I live in central Bangkok, which is pretty polluted, most noticeably in its air pollution. There are days when the weather forecasters assure us that in meteorological terms, the skies are clear. However, on rare days when that's the report, one *still* can barely make out the Sun due to the extremely dense air pollution. This is gaining real traction with people in the Health Ministry whose task it is to focus on reducing respiratory diseases.

It's nice to be able to drive a vehicle using an IC engine guilt-free of contributing to the reduction of health of others. Wish I could manage it.

14. 14. Mekhong Kurt in reply to David N'Gog 02:11 AM 7/7/10

Dave N'Gog, you mention Asian cities, and as an American long resident in Asia (first in China, the past 16 years in Thailand), you're correct that vehicles such as this can work in Asian cities. (and elsewhere, but I'll come back to that shortly.)

That this could work and work well is well-demonstrated by the rapid uptake of electric bicycles in China. It was about a year ago, as I recall, that I read that some 30 million were already on the road in China, with sales rising, the sales curve steepening practically by the day. An air-powered bicycle offers the obvious benefit of quick "refueling" time compared to recharging a battery, plus batteries are environmentally unfriendly. I bet if an air-powered bicycle were to become available at a price competitive with electric ones were to hit the Chinese market, it would take off quickly. That's particularly true in light of the Chinese government's strong commitment to developing alternative energy sources; I would imagine it would provide the necessary infrastructure. (I assume the compressors to fill up tires aren't suitable for refilling an air tank meant to propel even a bicycle, though I don't know that for a fact.)

The possible places for the deployment of such vehicles goes outside the major cities. Our concept of "rural" in the US is somewhat different than it is in places such as China. In some rather vast regions of China, "rural" is merely relative, i.e., in comparison to the country's major cities, such as Shanghai, Beijing, and Guangzhou (formerly "Canton). That is, an area where one travels 5-6 kilometers, on average, between villages (themselves sometimes far larger than what we think of as a "village") is considered rural. But such vehicles could easily be used in such areas.

Sure, there are places where they wouldn't be very useful, if at all. For instance, great swaths of provinces such as Inner Mongolia and Xinjiang are desert, with *any* outposts of human civilization few and far between. Having traveled by train (years ago) from Hohhot, Inner Mongolia to Yingchuan, Ningxia Autonomous Region, a straight-line distance of well over 300 miles, in mostly utter emptiness, I can attest to that. In one particularly desolate stretch that took us several hours to transverse, the sole sign that humans indeed were to be found there was the camel bearing two Mongolians waiting for our train to pass so they could cross the tracks!

Get tens of millions of Chinese on air-bikes, and we're talking fairly serious stuff.

15. 15. vagnry 03:25 PM 7/7/10

French companies, eg http://www.mdi.lu/english/produits.php

have worked on compressed air vehicles for something like 10 years.

The advantage is quick refill, as an old scuba diver I know, that it takes far less time to fill a tank with compressed air than charging a battery

16. 16. the Gaul 04:30 PM 7/7/10

frgough, more like you use your gasoline-powered internal combustion engines without intelligence or wisdom.

17. 17. jerryd 09:48 PM 7/7/10

Most of you and the authors that are for air power vehicles are dumb as a box of rocks. Air is very ineff storage not to mention the equipment for 3k PSI is expensive. Nor are they quick to recharge unless you use 6k psi tanks, making the whole thing less eff, more costly. I doubt they will go 20 miles without pedal assistance. We have plenty of experience in this in trolley and mining and both gave way a century ago to far more eff electric power.

Recently they tried to do regen in trucks but gave that up too. Generally you can't get more than a couple mile range with air.

But it's easy, cheap with E bikes with 40+ mile range and they can be recharged in 15 minutes to 80% charged. We have been doing that for decades. I do it all the times I need it with my E -Mc, EV's.

On the same energy an air unit can go, an EV unit can go 6-10x's farther.

Air power is a scam!! Deal with it. Plus one has to be licensed to fill such tanks as they are very dangerous.

18. 18. Quinn the Eskimo 01:25 AM 7/8/10

I'm left with two questions; well, actually more, but two will suffice:

1. What to do when the "tank" eventually ruptures at 4,000 psi or higher, eh? Duck

2. What to do when we've compressed *all* the air? What you gonna breathe then, eh?

19. 19. mike cook 05:47 AM 7/8/10

It sure isn't going to sound as cool as a Harley.

20. 20. jerryd in reply to frgough 04:55 PM 7/13/10

frgroug wrote,
More evidence again at just how fantastic an energy storage medium gasoline is. Fortunately, those of us with brains continue to realize that carbon dioxide is plant fertilizer and not a deadly toxin, and so use our IC engines without guilt.

Jerryd replies,
You mean you don't feel guilty for killing 5,000 US soldiers and 150,000 wounded ones for your oil in our oil wars?

How about spending \$400B in imported oil which supports Iran, Russia, oil dictators and terrorists?

How about the \$2T now spent in these wars your kids will have to pay off?

Maybe you and many others need to think about this and the corporate welfare state it supports? Personally I think it's treasonous thinking like you do..

21. 21. billwald 09:15 PM 10/9/10

Spin a turbine? Like dozens of air powered drill motors operating in every block? Might work fine in the land of the deaf.

I propose a nation wide compressed air pipe line pumped up to maybe 200 PSI. As I recall steam river boats and steam tractors ran around 150 psi. A two foot dia. line would have about 3 cu ft per running foot, say 7,000 cubic feet per mile times 3,000 from seattle to New York. 21,000,000 cubic feet of storage. Solar and wind farms all along the route could be paid to pump into the pipe and generating stations in cities and towns could use nice, quiet reciprocating engines to turn electric generators.

22. 22. excel 09:44 PM 10/28/10

Imagine an air tank to install on a motorbike? Seems bulky to me. Perhaps this would be more appropriate on large vehicles.

23. 23. Forthdimension in reply to David N'Gog 06:55 PM 4/3/12

I don't understand how the idea of using compressed air to power a motor would not be cost effective from every single youtube video I've seen makes vehicles very cheap and the motors are actually based on fluid pumps such as a vane pump. The technology is not complicated and has been around for at least 25 years. Filling stations can easily be set in parking garages using solar or wind energy and the person talking about earths rotational drag is a bafoon windmills do not pose a threat anymore than old growth trees or mountain ranges.

24. 24. Forthdimension in reply to frgough 07:15 PM 4/3/12

Yes co2 is plant food but everything produces co2 we as humans produce co2 as well as animals the heavy equipment and other vehicle we use daily. The question is are we creating too much for the the pants to convert that co2 into clean fresh oxygen that we need and is it really having that much effect on the climate change. I'm a mechanic and an automobile enthusiast I believe that we should hold onto the past innovations as well as create new. I think like every other blue collar American "Can this be done better and cheaper?".

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