Flywheel Spin Mass Storage

Energy storage as spinning disc at high speed, 200 000rpm, similar to a jet turbine rotation rates, vertical axis magnetic leviation on a stick, a vertical axis wind or water turbine is easy to incorporate into the design. Solar concentrator (fresnell) can be a mass disc, at r=100m, giving same energy density, S=30kWh/kg. Centrifugal force design equation is a_rad = 4*pi^2*f^2*r, so larger disc with same total specific energy has less radial acceleration force.