User Rank
Re: Air is free
JamesCAnder   11/7/2012 4:09:33 PM
Nothing is free. Compressing gases takes a lot of energy. The potential inside a pressure vessel is not that great compared to a lithium battery. I worked on a defense contract to develop personal power storage systems. I considered compressed air, but later found it to be cumbersome. (The joule to volume of compress air was enormous.) Even with hydrogen, I could not get the vessel size down. Let's hope they have more minds on the job to make it useful. I

I did see a car once that used a compressed hydraulic cylinder for acceleration. Every time the car stopped, it would add to the hydraulic energy. It seemed like an interesting way to go.


User Rank
Air is free
datometer   11/7/2012 1:55:22 PM
Yup, you have to compress the air, but there is a lot of it. It should be pretty easy to compress air using wind/waves/solar/etc.

No fracking/drilling and refineries needed.


I bet the cooling property could be used benefically too. Like for air conditioning or keeping the moving components cool.

User Rank
Re: The perpetual motion machine-?
MKsteel   11/7/2012 8:18:40 AM
You have a good point there. The air motor runs off compressed air, but where does the compressed air come from? There has to be a compressor to charge the tank in the first place, which is where your concern for missing energy in the equation is right on the mark. Its the same thing as an electric car, you STILL have to charge the battery in the first place -- its just that in this case the battery is tank of compressed air. I can see that this would have to be limited to small vehicles though and short ranged ones at that, you have to have access to a compressor that can put of hundreds of psi of air. Air tanks, any pressure tank, is bulky and heavy. Even CNG powered vehicles are limited by the volume of the tanks available today -- and there you are using chemical energy to run an IC engine; with and air motor you are using only stored mechanical energy.That is why some vehicles use compressed air in regenerative braking, it is energy that can be "cheaply" harvested for short term reuse (with the inevitable thermodynamic losses, of course). But as a main driver, the loss of chemical energy makes me dubious until they explain the compression source.

Either way you look at it, only part of the system is expained and it is "zero emissions" only if you ignore the energy supplied to the system from outside. Like any electric vehicle, a compressed air vehicle, needs electricity to run a compressor to store the air. Flywheels are another example of the same kind of energy storage (admittedly without the friction losses slowing a flywheel).

William K.
User Rank
Compressed air powers hybrid engine
William K.   11/6/2012 8:43:53 PM
There is a very fundamental loss in the use of compressed air, which is that part of the workm done in compressing the air results in a temperature rise, that is, compressing air not only raises the pressure, but also the temperature. Then, as heat is lost and the air temperature drops, there is less energy to be recovered. That is a basic and fundamental problem inherant in the use of compressed air. Using a very well insukated tank helps a bit, but the air still cools eventually, and that power iand energy are lost. So u8sing an IC-engine to drive a compressor may have some advantages, the losses through cooling of the hot air are certainly not to be ignored. On the other side, recovering braking energy through compressed air, where the stored energy will be used right away, might make a lot of sense.

User Rank
Stanley Steamer II
Island_Al   11/6/2012 11:00:41 AM
This Freescale motor is an idea I have pondered for some time, but I'm not certain of why they use an electric motor.  A two cylinder compressed air engine will operate without any type of starter or a transmission.  Our ICEs require an optimum RPM for fuel efficiency.  Why not marry the two?  The ICE would run only to supply compressed air to a tank, the power train would run from the compressed air tank.  The ICE would either operate at full power or be off and would be sized for whatever the maximum speed requirement of the vehicle may be.  I fear I am missing something here.

Then again I'm only a professional electronics guy for the most part, but do tinker with mechanics from time to time.

Also I too use a 40KVA 400Hz 3 phase inverter at work.  It weighs about 1600-1800 pounds!  So 40kva in such a small package?  I would love to see their design.


Charles Murray
User Rank
Re: Compact power
Charles Murray   11/5/2012 7:18:44 PM
I don't have the power stats for this engine, Naperlou, but I do know that the big issue with compressed air engines in general is energy density (less than a lead-acid battery and about one-fifth that of a lithium-ion battery). So we're again back to the energy density issue.  

User Rank
Re: Compact power
tekochip   11/5/2012 12:45:15 PM
I've seen compressed air engines used on city and school busses as a
regenerative braking power assist.  The system compressed air while the vehicle
was braking and then used the compressed air to assist acceleration.

User Rank
The perpetual motion machine-?
JimT@Future-Product-Innovations   11/5/2012 12:35:17 PM
Wow. Putting aside any pragmatic issues (weight, power, efficiency, etc.) this appears to virtually run on nothing!  The long sought after perpetual motion machine-?  I was hoping to see more about what made it continue to run!  Establish that foundational architecture and those other issues might resolve themselves thru derivative enhancements, over tests and time.  But what a start-!  What keeps it going?

User Rank
Compact power
naperlou   11/5/2012 10:57:02 AM
Chuck, one thing that is pointed out in the video is the small size of the power and control electronics.  I think that the car companies could probably do better than they are doing.  The weight of the electric vehicles available today is still as much as an ICE driven car. 

I do wonder how much power this vehicle can produce.  I could see such a design being used for small utility vehicles. 

Partner Zone
Latest Analysis
A database containing information on over 16,000 tests done on 500 composites and other materials for wind turbine blades is now available free from Sandia National Laboratories.
Imagine being able to illegally download a physical product the same way you can with music and videos. That’s basically what’s happening with 3D printing and digital manufacturing, with huge repercussions in the intellectual property domain.
Our latest Design News Quick Poll reveals that readers are facing serious cyber security challenges.
Ford will be the first automaker to commercially use Alcoa's tough & fast Micromill aluminum alloy process and materials, debuting on several 2016 F-150 truck components. Alcoa will also license its Micromill process and materials technology to Danieli Group.
Even as an increasing number of instrument manufacturers migrate toward modern touch screens, many engineers say they still prefer the tactile feel of knobs and buttons, a new survey says.
Design News Webinar Series
10/1/2015 11:00 a.m. California / 2:00 p.m. New York
9/10/2015 11:00 a.m. California / 2:00 p.m. New York
10/20/2015 8:00 a.m. California / 11:00 a.m. New York
11/10/2015 11:00 a.m. California / 2:00 p.m. New York
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Oct 19 - 23, Embedded System Design Techniques™ - Driver Design Patterns and the Internet
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7

Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Sponsored Content

Technology Marketplace

Copyright © 2015 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service