Better than batteries: the simple flywheel made with modern materials and technology.
via fastcompany.com
The flywheels act much like a regenerative braking systems in hybrid-electric cars powered by batteries. Every time the driver brakes, energy is stored by spinning up the flywheel. Energy is returned to the wheels through a variable mechanical transmission or magnets. Newer systems overcome past problems with efficiency and weight by using vacuum-sealed carbon-fiber discs rotating on low-friction bearings or superconducting magnets. If successful, the devices are expected to achieve 60,000 rpm and put out 80 horsepower, while cutting fuel consumption by 20%…
