Another battery type

[user removed]

Green Car Congress: Audi R18 e-tron quattro: diesel hybrid Le Mans racer with electric flywheel energy storage

regards
Mech

[skeeterb]

Back when i was in CC, I was looking at old back issues of Popular Mechanics, and saw and article about flywheel powered vehicles. I forgot the issue number but it's been around for a long time, but just really hasn't seen common use.

[RunningStrong]

And the wonderful bit is a CF flywheel's failure scenario is that it turns into a giant carbon brush of de-laminated layers.

As opposed to a metal flywheel that separates into 3 approximately equal missiles.

[puddleglum]

It's definitely not a new idea, but it's interesting to see someone is going to try to make it work again. I remember reading the article in Popular Mechanics or Mechanics Illustrated as well. They fitted a Pinto with a flywheel and drove something like 50miles at 50mph, if memory serves. I always wondered what undisclosed problems kept the concept from going forward. I think that using it in a hybrid makes good sense and the technology is so much better now.

[skeeterb]

Yeah, use the motor to charge up the flywheel and use the momentum from the flywheel to drive the vehicle. That would REALLY save on the battery packs of an EV or hybrid.

[RunningStrong]

Originally Posted by puddleglum

It's definitely not a new idea, but it's interesting to see someone is going to try to make it work again. I remember reading the article in Popular Mechanics or Mechanics Illustrated as well. They fitted a Pinto with a flywheel and drove something like 50miles at 50mph, if memory serves. I always wondered what undisclosed problems kept the concept from going forward. I think that using it in a hybrid makes good sense and the technology is so much better now.

The big issue is friction. Lightweight flywheels need to work at 10s of thousands of RPM to be viable. The friction involved in such rotation in a moving vehicle is difficult to overcome with just bearings and lubricant alone. So you need vacuums and magnets, all the more complicated, all the more expensive.

[Ken Fry]

Originally Posted by RunningStrong

. So you need vacuums and magnets, all the more complicated, all the more expensive.

Yes. A few Formula One cars used the Flybrid system for a while. Added about $100,000 to the cost of the car (and the system stored less energy than the standard Prius battery does). Flywheels have had some success in uninterruptable power supplies, but in vehicles, the weight/energy storage/cost just doesn't work.

In a vehicle, the bearings must be ultra low friction but also ultra strong to withstand the precession forces associated with handling and ride motions.

[puddleglum]

Originally Posted by RunningStrong

The big issue is friction. Lightweight flywheels need to work at 10s of thousands of RPM to be viable. The friction involved in such rotation in a moving vehicle is difficult to overcome with just bearings and lubricant alone. So you need vacuums and magnets, all the more complicated, all the more expensive.

I'm quite sure that the flywheel in the Pinto was running in a vacuum and had magnetic bearings. I'm sure the up front cost would be very high and I'm also guessing that any hard acceleration would kill it pretty quick. Still, it should virtually last forever with almost no maintenance. There have been many seemingly great ideas that, for whatever reason haven't made it into the hands of the general public. I'm assuming flywheel energy storage is just another one.

[RunningStrong]

Originally Posted by puddleglum

I'm quite sure that the flywheel in the Pinto was running in a vacuum and had magnetic bearings. I'm sure the up front cost would be very high and I'm also guessing that any hard acceleration would kill it pretty quick. Still, it should virtually last forever with almost no maintenance. There have been many seemingly great ideas that, for whatever reason haven't made it into the hands of the general public. I'm assuming flywheel energy storage is just another one.

It's probably because batteries had more potential, with plenty of room for improvement in energy density.

It was probably felt there was a reasonable limit to how big and how fast you could make a flywheel, and that would quickly be met.

[Ken Fry]

Originally Posted by puddleglum

There have been many seemingly great ideas that, for whatever reason haven't made it into the hands of the general public. I'm assuming flywheel energy storage is just another one.

Flywheel storage is, of course, used in every engine (and most dramatically in singles) to carry the engine through the exhaust, intake, and compression strokes. So the idea has not died out, it has just found the niches where it works economically.

The UPS market is one where there could be continued growth in flywheel application. Grid load leveling is another potential market. However, batteries are much more economical as a storage method right now. (I could not possibly consider flywheel storage as a serious competitive technology as part of my plug-in hybrid... it would triple the cost of the car.) Flywheels are already at a very high level of development, so no one is forecasting a large drop in price ($/kilowatt-hour storage). Batteries are, however, expected to drop in price to about 1/3 their current price.

LithiumX batteries in cars can be expected to last about 10 years, which for that market is acceptable life. In a home installation, however, it would be nice to have longer life, so a flywheel system to store solar and wind energy from a home installation (for later use in the home or for use by others via the grid) could have some appeal, even if the system costs twice as much as a battery system.

In vehicles, a flywheel's tendency to maintain its orientation in space is potentially problematic (because the instantaneous bearing loads can be so high over bumps etc.) However, if Lit Motors is successful, they will translate this potential problem into an asset.