CarTalk.com Blogs Car Info Our Show Deals Mechanics Files Vehicle Donation

Hybrid Cars powered by compressed air

I heard about a car transmission that included a compressed air capability to aid in getting the car moving initially, accelerating, etc., saving gas. This story was around about the same time that hybrid cars were first being developed.

The story was the transmission would only add an additional $600 to the price of a car, it added only a little more weight to the car, the energy recaptured while braking or decelerating was around 70% as opposed to 30% for electric cars, and it dramatically improved gas mileage especially in the city.

What ever happened to that idea? I can’t find anything on it now.

Dan

There are a lot of ideas that sound wonderful in theory but never get past the concept stage because of unforeseen problems or limitations. Here are just two that I recall from the past:

At one point–probably about 30 years ago–Nissan announced that they had developed a Freon-based propulsion system for cars, and that this system was so economical that it would eventually supplant the ICE. I don’t recall the exact details of how this system worked, but apparently it never got past the concept/press release stage, as far as I can tell.

I can recall an article in either Popular Science or Popular Mechanics (I read both as a child), back in the '60s, that illustrated and described how a massive horizontal flywheel underneath heavy trucks would essentially store energy while the truck was moving, and allow it to operate in urban conditions with much greater efficiency and with much lower fuel costs. Have you ever heard of this being actually used?

I’m waiting for 2015 when Doc Brown returns from the future with his Mr. Fusion-powered DeLorean. Great Scott!

VDC

I read a while back that Porsche incorporated a flywheel into one of their race cars. Whether or not it was practical I can’t say.

Ed B.

This is my favorite recent ‘hybrid’ (depending on the horse breeds on the treadmill):

Lest we think the OP complete crazy. Ford tried it.

http://www.epa.gov/otaq/technology/420f04019.pdf

and so did UPS.

There are a lot of reasons it didn’t pan out.

You’re right, compressed air has been tested and touted for decades, lots in the last 10 years. Makes a lot more sense than horses!

@Texases - The only question I have is…

What happens to the horse manure??? But I like it…Ingenious.

@VDCDriver - The flywheel technology for storing energy ran into a lot of problems. It’s being looked at again. The problem was the wheel had to get up to about 100k rpms in order for it to be usable. At that speed…it would sometimes break apart. And when this happened…it would send pieces of metal flying up to several hundred feet away. If a battery explodes…it won’t kill you (unless your face is right over it when it explodes). This thing could kill you if you were 100’ away.

Last I read…they had some new materials that were more stable…and if there was a problem…it would basically break into very small lightweight pieces that wouldn’t go far and not hurt anyone. But not too many companies are working on this.

The thing to always remember when reading these new ideas is that they generally do not create energy, only store it. And the source from which it comes to them, the source from which they draw the energy they store, is the gasoline. Even the flywheel in only storing energy that the engine (gas) created in the first place. And there is always a loss in converting energy. In the case of the flywheel, the loss would be bearing friction and heat loss. A flywheel will return much of its inertial energy to the vehicle, but cannot return more than it acquired from the gas burned to get it spinning.

The ideas that conserve energy, like those that reduce weight, drag, or combustion losses, are the ones that interest me. These include improved manufacturing technologies (including casting), better materials technologies such as polymers to replace metals, technologies to improve the fuel’s combustability (like direct injection), and even things to reduce losses due to reciprocating masses (like lighter reciprocating parts, and even a rotating ball-valve system that I saw once to replace valvetrains).

If you want a laugh, google ‘compressed air car’, LOTS of them, just none in production. I got a kick out of the 2008 article promising one would be on sale in the US by 2010:

“which runs to 35mph entirely on air, or uses a trickle of petrol to heat and compress more air to reach higher speeds up to 90mph. It’ll cost next to nothing to run (how do 30,000km service intervals sound?), have a range of up to 1000 miles, and retail for well under US$20,000”

From our Indian friends at Tata Motors, of course!

Must have been written by some marketing guy. Now all the engineering guys have to do is figure out how to create enough energy to accelerate and move a vehicle those speeds out of air!

Oh! Wait! I’ve got it! Sails!

The fundamental problem with compressed air is that it just doesn’t contain enough energy per pound or per cubic foot to power a car any useful distance.

It does if you unfurl the sails!
Of course going under overpassess is a problem…

The flywheel system was used pre WWII in a Swiss urban bus system . The bus would have the flywheel run up to speed at each end of its run and the system was quiet and workable but only useful for short runs .

Here’s a good recent summary of the status of air cars. Not too promising.

It’s all a matter of perspective. Imagine if you will, that the first means of mechanical transportation had been fueled by unobtanium. Personal vehicles traveled at speeds of 200mph and only required re-fueling every 6 months. Unfortunately, as the affordability and therefore popularity of personal transportation grew, the supply of unobtanium was nearing exhaustion and the price was spiraling out of control. Not to mention the environmental issues associated with the widespread use of unobtanium. Then some people come along and propose we use gasoline as an alternative fuel instead. Are you out of your mind?!? I can only go 100 mph and I have to refuel every week!?! What a bunch of loons to suggest such a thing!

Compared to a horse, an air powered car that goes 35mph and needs to be “re-fueled” every 25 miles is a pretty good bargain. Compared to the current gas powered automobile, it seems primitive and backward. But that may be where we are headed.

It’ll never fly. You simply cannot get around the problem of the amount of energy needed to make the car usable.

TT, the latter part of the 19th century and the very early part of the 20h century are repleat with various modes of powering vehicles. The most popular until the Model T was steam. Gasoline simply won out because it contains the energy density needed to make a vehicle usable with reasonable energy storage needs (a simple gas tank). At this time gasoline is still the best alternative overall.

As was unobtanium until it wasn’t the “best” option anymore. :wink: Obviously no one is talking about today. Times change. My point is, just like the carefree days of easily modifying your ride are coming to a close, we may need to adjust our expectations about what constitutes an acceptable level of vehicle performance in the future.

There are lots of variations on the hybrid theme out there. Many work exceptionally well in the lab. Usually, like the turbine motor, practicality rears it’s ugly head and it ends up being too expensive, unreliable or both. You do see many exotics in special applications in the military where tax dollars trump everything when it comes to , too expensive.

For example, the military has used nuclear power hybrid technology for years and the miniaturization of the plant has made it possible to make this a power sourse for cars using electric drive motors. Imagine Never having to refuel your car for the entire time you own it. The registration, licensing, purchasing and inspection costs of such an animal makes buying gas seem pretty cheap though…