BMW Working on Supercapacitor Hybrid
Not quite known for making environmentally responsible vehicles, BMW is nonetheless a believer in the hydrogen future, although their version of that future is slightly different from that of most other carmakers and includes internal combustion engines powered by H2, not fuel cells. But until now, BMW had been pretty quiet about hybrids (except to say that they are undesirable). That may be about to change: BMW is working on a hybrid, but it's not quite like what we're used to."Ours is lighter, faster and more efficient," says Professor Freymann. Super capacitors, power boosted by regenerative braking, replace batteries. "[The super capacitors] are lighter and store less power, but unlike batteries we can use all their power — all 100 percent." So they give a quick, high-power, short-term "fix" to a small electric motor (mated to a conventional gasoline engine), used only for standing-start acceleration. "An electric engine has a lot of torque at low revs — that is its main benefit — so it's ideal for fast initial acceleration. At higher revs, once you've begun to accelerate, nothing can beat an internal combustion engine. Our hybrid approach combines the best characteristics of both engines."
Of course BMW is going to use that technology to make cars that fit within their market, but it would be interesting to see if that kind of supercapacitor hybrid technology could be used in less expensive and more eco-friendly vehicles at a lower cost than full parallel and serial hybrid technologies.
This type of regenerative braking could be coupled with a stop/start system like the new Toyota Vitz (a system that stops the engine instead of letting it idle, immediately restarting it when needed) and thus give many of the benefits of a hybrid but without the stack of batteries and with only one electric motor needed.
(apologies to those who had a heart-attack seeing the BMW logo on TreeHugger - I couldn't help myself)