A hermetically-sealed 40,000 rpm, 1 kWh, 135 kW, graphite composite flywheel has been developed at CEM. The unit with integral motor/generator is installed in a Houston-Metro transit bus. It utilizes a 5-axis levitation system with permanent magnet bias homopolar magnetic bearings. The thrust bearing is integral with one radial bearing. This flywheel was successfully built and road-tested in a bus.