Citroen debuts air-hybrid system. Going into production soon.

"Although it sounds massively complicated and exceedingly strange, Hybrid Air, in fact, isn’t very complex. Here’s how it works: A planetary gearbox is sandwiched between the gasoline engine and a hydraulic motor. The hydraulic motor is powered by—you guessed it—a hydraulic pump that’s also located under the C3′s small hood. As for what powers the hydraulic pump, well, this is where the “Air” part of Hybrid Air comes in. The prototype C3 features a pair of tanks, one mounted longitudinally down the middle of the car and another “low-pressure” unit sitting transversely behind the rear axle. The rear tank stores compressed air, which can be piped into the central tank or, more appropriately, chamber, which is initially filled with hydraulic fluid. During acceleration, the air (which likely inflates a bladder within the main tank) is released, forcing the fluid through the hydraulic pump and into the motor, driving the wheels. Although Citroën doesn’t specify, there most likely is a reservoir tank where the hydraulic fluid is stored after it cycles through the motor.

"Like most other hybrids, the Citroën has a regenerative braking system to capture energy that would normally be lost during deceleration. Unlike gas-electric hybrids, which recharge their batteries via an electric motor/generator, the C3′s hydraulic motor, when turned by the drive wheels, draws hydraulic fluid out of the reservoir tank and pumps it back into the main tank. (Hydraulic motors are essentially pumps; simply switch its output to its input—in this case, the drive wheels—and it turns into a pump.) As hydraulic fluid is forced into the chamber—the fluid is not compressible—the displaced air in the system is compressed into the rear tank where it is stored until needed again. A prototype hydraulic-hybrid delivery truck cooked up by UPS, the EPA, and several truck makers here in the U.S. operates similarly; during acceleration an engine powers a hydraulic pump that turns two motors mounted in series, but on deceleration the motors turn the pump, forcing fluid against a nitrogen-filled bladder and pressurizing it; later, the pressurized fluid is released back into the system to drive the motors during acceleration.

"Besides the unique method by which the Citroën’s gas-engine-augmenting hydraulic motor receives its energy, the relationship between the motor and the engine is like that in any gas-electric hybrid. This means that at higher speeds, the gas engine does most of the motivation. At lower speeds (less than 43 mph) or taking off from a stop, the system punts accelerative duties to the hydraulic motor, unless there isn’t a sufficient amount of compressed air, at which point the gas engine either takes over or aids the motor. The engine and hydraulic motor can each power the front wheels individually, or combine forces to move the C3, depending on what the car’s computer deems necessary."

Not a new idea - Tata have been talking about putting it into production "imminently" for several years. The technology is licenced off a Luxembourg company, who've been punting it for ages.
http://www.mdi.lu/english/

Basically, it's just a normal hybrid, but instead of using electricity as an interim storage measure, it uses compressed air. Somehow, it conveniently ignores the fact that compressed air is a massively inefficient storage medium compared to batteries. I'm not sure I'm happy sharing my car with a 3,500psi air tank, either...

Erm...I saw this in Top Gear I think a couple of months ago and thought minor accident but squifs the car a bit and boom up goes the tank.....

Presumably people thought the same about petrol back in the day ... "I'm not happy about sharing my car with eight gallons of highly flammable liquid!" and so on. And compressed air may be inefficient as a storage medium, but it doesn't present the same disposal problems as batteries do. All new technology has to start somewhere. I like this.

Very true. Especially the more exotic chemistries which provide much better energy density. (Best not to ask Boeing about those, though...)

These are running around South of France
http://www.jolon.com/air-powered-car/

Lots of interesting stuff should affect the motor industry (& other industries) in the coming years. eg super-powered battery breakthrough claimed by US team.

Mate
Electric powered Pony that is the way to go
6 Volt!

3 km range that should get us to the pub!

4 x AA batteries?



So long as there's no traffic at the bottom of the hill.

Here's a natty idea!

Toyota Camatte57 concept unveiled at a TOY show!