Flywheels have been around for many decades. Why wasn't a flywheel Hybrid mass produced years ago?

Since the flywheel is rather light, why not couple it with a battery (to extend range without the ICE running) and make it an extendable range AWD plug-in hybrid.

If you click back further into the archived GCC posts on this topic you'll see that Volvo has been working on the KERS-based hybrid since 2009. Moreover, that's from public releases -- likely they've been tinkering in labs well before that.

The electrical solutions have gotten quite a bit more emphasis for a number of good reasons: power electronics have made huge leaps outside of automotive applications, electric energy storage supports auxiliaries (e.g., HVAC) more readily for start/stop environments, etc.

Further, the long goal of zero propulsion system emissions frankly gets more near-term attention than perhaps it should (the perfect as enemy of the good). This causes external funding and subsidy sources such as the US ATVM program and ZEV credits to be focused around electric (or H2 FCV) and practical, effective measures like flywheel KERS are orphans. (I would add that there is a tremendous "emotional" appeal to driving electric. Although my Leaf is a sensible car only because of a confluence of personal circumstances that fit VERY few people's lives, even doubters are stunned at the smooth, comfortable, quiet and seamless rush of power this odd little car provides. You can fall in love with the EV ride pretty quickly. That's why people are able to convince themselves that 600kg of battery in the Tesla Model S is "disruptive" and "visionary" when it is in fact mostly just a cool and lovely engineering stunt.)

Finally, you can't ignore the industrialization factor. High-speed carbon fiber flywheels and hermetic vacuum chambers do not have the giant industrial base of Lithium chemistry batteries, high-power IGCTs, etc., so the parallel activities of cost optimization present additional challenges. The target production cost for this addition to the car is USD1600 (2009 economics), or somewhere less than USD2000 today. Considering the low weight of the module (flywheel + coupling + gear reduction under 75kg) and the relatively minor packaging challenge to fit it to the rear axle, it is a very interesting solution. When you further consider there are no cold-weather operability or other thermal management hurdles, no public infrastructure heroism needed, a very benign failure mode, and relative transparency to the operator, your next question really has to be: "when can I get one?"

Thanks guys. I agree. This really seems like the sub-$1000, sub 100kg (with rear drive assembly), zero rare earths, solution to mass hybridization.

Peter_XX
Flywheels compete with supercapacitors (or small, specialized packs of batteries that have characteristics that match up with hybrid usage).

Herman,
You're also confusing issues for electric cars with things flywheels will deal with. There is no point in talking about the weight of the Tesla pack or your Leaf. The comparison here is whether 20kg of ultracaps (or 10kg of A123 cells like they were using in F1 from 2010-2013) plus something like a 18kg Yasa-250 motor is better from a total life cycle perspective compared to the flywheel and its components.

Toyota didn't put batteries in the MILLIONS of hybrids because they like spending extra money. If flywheels were better, then they would have used them. If something has changed then it may be worth revisiting. But I doubt Toyota spends extra $$$ building each car because they've got some secret love affair with batteries.

If Volvo has found something cheaper and better in some way, then I'm sure the world will beat a path to their door.

Dollared,
Nobody is using flywheels in production yet either. Some F1 teams were using supercaps in their hybrid last year (notably Red Bull) and Toyota was using them in their Hybrid in LMP1 while Audi was using a flywheel in their LMP1 car.

So I think my statements are correct because nobody is using either supercaps or flywheels in production yet but both are being used in experimental cars and racing.

Production hybrids are still using batteries.

Thanks, T2, for a rational view. I'll have to think about much of what you said -- good points. I would openly disagree with one: "With an EV handling large amounts of regenerated power suddenly is never a problem". It's "never a problem" because when the battery can't accept the power, there's no regeneration. When the battery is fully charged, too cold, or too hot, it doesn't accept the regen and the brakes do the work. I spent plenty of time with only one or two battery bars this winter and frequently saw no regen lights until things warmed up. Simply rejecting the regeneration from the flywheel when, for example, the system senses skidding doesn't seem too difficult.

Dollared,
I just found a reference that Mazda is shipping some supercaps starting this July. It's not using the kinetic side for propulsion, but rather excess energy from braking for running other electric components in the car. They are claiming a 10% improvement from this system and that it's total weight is just 9.3kg. I assume it can be that light as it's not including any kind of motor or transmission.
http://articles.sae.org/11845/

One more slightly OT note about efforts to achieve efficiency without significant electrical energy storage/conversion in a SAE article...

I did not see this speech referenced in February's GCC archives, so forgive me if I'm way late to the table. CARB member Dr. Daniel Sperling spoke to the 2014 SAE Hybrid & EV Symposium at the February meeting in La Jolla. In my mind the key message in his speech was this:

"[W]ith the possible exception of full-size trucks, meeting the 54.5-mpg fleet target will not be an overly difficult task, most experts believe. Because of the comparatively high cost of batteries, traction motors, power control, and charging systems, it would take an estimated outlay of $150 billion to achieve rough cost parity with conventional ICE vehicles by 2025, according to a University of California-Davis analysis cited by Dr. Sperling. The cost of both types won’t likely converge until 2050, he said, when production scale and systems innovations for plug-ins are realized."

This isn't some Exxon guy speaking -- he is a card-carrying CARB exec and ZEV supporter. Clearly, the industry will seek non-electric solutions if they are reasonably effective, and some of them seem to be promising.

Thanks Herman. I shouldn't be making comments when I'm running between meetings at work and not taking the time to read through what people are really saying and making sure my responses are thought out.
I like GCC because it's usually a civil place to ask questions or throw out some ideas. I avoid sites where everyone is spewing vile so I don't want to make it bad here.
In response to your original post, you're absolutely right that the money/investment in the tech follows political goals very often rather than the best potential technology.

Toyota and BMW will probably use new ultra caps instead. Are those two making a mistake?