New Types of Hybrid Engines Proposed

From Instapundit, news of two new types of hybrid engines that may be used for cars:

First, a system that uses "waste" energy to compress air, then uses the compressed air to help drive the engine when power is needed:

Scuderi, based in West Springfield, Massachusetts, has altered the way the internal combustion engine operates to convert kinetic energy into the potential energy of high-pressure air. It splits the four parts of the internal combustion cycle across two cylinders synchronized on the same crankshaft. One cylinder handles the air intake and compression part of the cycle, pumping compressed air via a crossover passage into the second cylinder. The crossover contains the fuel-injection system, and combustion and exhaust are handled in the second cylinder.

Upsides, avoids the heavy metal and rare-earth requirements and the weight for the batteries for conventional hybrids.  Downsides?  Compressed air can be a danger on it's own , and does impose a weight requirement as well for it's containment.  I would guess it's less than the batteries for a conventional hybrid, though. 

The second system is kind of interesting, using a fly wheel to store the "waste" energy and give it back when needed:

Across the Atlantic, a team that formerly worked for the Renault Formula 1 team has adapted its motorsport-developed flywheel system for use with conventional vehicles. The team has formed a company, Flybrid Systems, to commercialize the technology, and has teamed up with Jaguar Land Rover to trial the Flybrid technology that was originally developed as the kinetic energy recovery system (KERS) used in Formula 1 racing to provide a boost during racing. But while most KERS systems work by using a flywheel to charge an onboard battery or supercapacitor, Flybrid uses a gearbox system to transfer kinetic energy directly to and from the wheels.

Flybrid cars transfer energy via either a continuously variable transmission or a less complex three-gear system, which allows 15 different gear ratios on a standard five-gear model. "There are always efficiency losses when you convert energy," explains Flybrid's technical director, Doug Cross. "This system eliminates those losses, making it far more efficient."

The flywheel weighs five kilograms and is made from carbon fiber wrapped around a steel core. Because it is so light, it has to spin fast—at 60,000 rpm—which means that its rim is traveling at supersonic speeds. As a result, it has to operate in a vacuum, and Flybrid has developed special seals so that the wheel can be fully enclosed inside a safety container in case of a crash. At top speed, the flywheel can store 540 kilojoules of energy, which is sufficient to accelerate an average-sized automobile from a standing start to 48 kilometers per hour.

Upside, light, stores a lot of energy, no dirty metals or expensive rare earth, downside?  That's a lot of kinetic energy sitting there if something goes wrong.

Sound interesting.  I remember as a kid (OK, maybe a young adult), an article in Scientific American on the potential to use fly wheels as the source of energy for cars.  If I have located the right reference (R.F. Post, S.F. Post, Flywheels. Scientific American, Dec. 1973) it appears to have been in 1973.  Anyway, IIRC, the main outstanding problem at the time was materials able to withstand the forces involved, and bearings able to function without much frictional loss.  We've had lots of advances in materials since then, so maybe the technology is ripe at last.  

The other anecdote I would relay relates to the power retained in a spinning weight.  Back when Georgia and I were in Grad School, she worked in a Biochem lab where they made heavy use of preparational ultracentrifuges, that spun at speeds similar to the flywheels proposed above.  One night, a centrifuge rotor failed, and essentially exploded.  It was contained by metal walls in the centrifuge, but someone in the lab at the time said it sounded like standing next to a car crash.