Koenigseggs hybrid tech

[Greg_D]

I read with great interest in this months evo about Koenigsegg developing a technology whereby instead of using regenerative braking to turn a generator to create electricity for a heavy battery (lots of waste heat/noise and friction making it fundamentally inefficient, not to mention lugging heavy batteries round 100% of the time) they use cylinder deactivation to turn the whole engine into an air pump under braking that fills a carbon fibre tank with compressed air that is then reintroduced as boost to the engine at low revs or to power an electric motor for city driving (i may have imagined that last bit)

No noticeable extra weight for significant gains, surely this is a much more elegant solution than existing hybrid power trains?

I'm interested in other people's opinions on this. Is there something i am missing or is this a trick that the large OEMs have all missed?

[Grenoble]

As I understand it, compressed air has some disadvatages.

1) not much energy can be stored compared to a battery or fast spinning flywheel
2) if they go bang...
3) you still have an inefficiency in compressing the air and releasing it

[hairykrishna]

I think Peugeot are working on a compressed air hybrid.

t's got disadvantages of it's own; energy density of the storage is rubbish, even at massive pressures and it's pretty inefficient.

[Roo]

hairykrishna said:

I think Peugeot are working on a compressed air hybrid.

http://www.autocar.co.uk/car-news/green-cars/peugeot-citroen-unveils-compressed-air-hybrid-tech

[Greg_D]

Grenoble said:

As I understand it, compressed air has some disadvatages.

1) not much energy can be stored compared to a battery or fast spinning flywheel
2) if they go bang...
3) you still have an inefficiency in compressing the air and releasing it

all valid points, but my uneducated response would be
1) possibly, but look at the extra weight that these things dictate, esp battery
2) flywheels are a significantly more terrifying prospect
3) you are merely using the energy and momentum that you have 'paid for' (ie revs) and instead of just turning it all back into heat via the brakes, you are collecting some of it for future reuse.

As a 'light' hybrid, i see it having a number of benefits

[Grenoble]

Agreed but air has a rubbish power density compared to, for example, a battery.

Some serious research here for compressed air cars:

http://iopscience.iop.org/1748-9326/4/4/044011/

As a hybrid technology, the science still applies. Koenigsegg will have some smart engineers, I guess they are looking at way of getting through emissions rather than actually wanting hybrid tech.