Ker's Type Flywheel

This technology has seem limited use in Formula 1 as well as in buses for public transportation.

Not sure if Formula 1 counts as real world...but buses should.

Kinetic energy recovery systems in Formula 1 racing even has its own Wiki.

I agree that Formula 1 may not be considered "real world" but it is a terrific development platform.

Porsche have been toying with the idea of using KERS but nothing concrete yet.

I wouldn't hold my breath waiting for Porsche to roll out any cars equipped with concrete KERS installed.

Concrete doesn't have the material properties needed to build a compact low mass high energy storage KERS system.

I read about a kinetic energy system that used flywheels for energy storage.The flywheel was composed of a wound rotor made of carbon,kevlar,and nylon fibers,the most expensive being used in the highest stree areas,and the cheaper one in the lower stress positions.This was about 25+ years ago.They had to be installed in pairs in vehicles to neutralize the gyro effect of the flywheel,with the flywheels rotating in opposite directions.At the time, they claimed that 2 units weighing less than 20 pounds could replace a small 4 cylinder car motor.Never saw anything in the marketplace though.I heard some larger units were being used in buses.The name Ballard seems to stick in my memory of these.The problem at the time was the energy required to suspend the shaft with magnetic bearings when the car was on a bumpy surface.Now with superconductor bearings, who knows where the technology will go?

Superconductors introduce a whole lot of added engineering problems. Predominantly the cryogenics required will prevent superconductor bearings from being used for the near future. I realize that research is being done now for many good reasons on superconductor bearings used in stationary flywheels. I do not expect this to ever happen with a moving flywheel. A counter rotating flywheel assembly will produce no net gyroscopic forces outside the assembly but these forces will still happen at the bearing point for each flywheel.

Gyrobus was operating in the 1940s.

By now magnetic bearings (mainly the active types) have progressed to the point where they can be used on large machinery. I assume this means they could be used on high energy flywheel (Kevlar shroud???), but these are not for thrust bearing. That requires a different technology. I suppose if the rotor is mounted with horizontal axis, the thrust is minimal (vacuum chamber for rotor), with energy coupled in/out by electromagnetism.

I am looking for someone with information/experience with electrodynamic magnetic bearings. These incorporate permanent magnet with conducting sleeve (all mounted on the shaft). Eddy current generate opposing field when displacement off center occurs. Still require thrust bearing. In small equipment this can be a point-plane bearing, I suppose.

I suppose air stone bearings might be of use, but the problem there is keeping the air out of the flywheel compartment, I would think.

Interesting how this has popped up again. I knew a guy who worked on high speed, low mass flywheels about fifteen years ago. (The company was small and got bought out, possibly by Volvo.) He was pretty excited about the potential of these flywheels. Their research indicated that these flywheels might be better suited to long trips at fairly constant speed (such as long haul trucking, which could be why Volvo got interested). Bearings definitely were a concern, and (of course) containment housings. He felt that the key to success with these flywheels was high r.p.m. / low mass. He was working at 100,000 r.p.m. and higher, but Volvo may have found success at a lower speed. He admitted that they were experiencing some wild windage effects at those high speeds, as well as gyroscopic effects.