Flywheel energy storage

Hi,

this is my very first post on any forum. I am posting this because I am looking for a particular product I was desperately trying to find.

I need a compact flywheel energy storage system for a vehicle application. The ratings I need: about 1 to 2 kWh of energy, 50 to 100 kW of power. The best match I found so far was the Porsche GT3R Flywheel with a power of 180 kW and 375 Wh energy. Using 4 or 5 such flywheels would give me the energy I need. The system would weight then about 300 kg. I believe a single compact flywheel with less power but more energy storage would give me a much better energy density. But I have yet to find such a wheel. My question therefore: Has anybody any information for what I am searching?

Thanks a lot