I don't really understand what it said, but it look not really like the system of flybrid system Ltd's....

http://www.williamshybridpower.com/technology/

Yeah apparently Williams are the only team to use a flywheel rather than a battery for their KERS system.

so, there must be 3 but not 2 style of KERS?

Define style. There are over 300 styles if you define style loosely enough, or 1 if your a bit tight with the definition.♠

Is Renault use Flybrid System Ltd's system?