Despite all the auto-tech brain-power in this world, fully electronic brakes-
which would replace brake fluid with lighter, quicker wires and motors-have yet to arrive. The long-standing obstacle: Industry-standard 12-volt electrical systems can´t drive a motor powerful enough to stop a two-ton sedan. The prototype Electronic Wedge Brake, by German company Siemens, solves this problem by tapping the vehicle´s own energy to slow itself down. Electric motors  drive screwjacks  that move a corrugated outer plate  fore and aft in plane with the rotor . Trapped between that surface and an opposing corrugated plate  are several small rollers . When the outer plate moves, it wedges the rollers between ridges in the opposing surfaces, driving the inner plate and brake pad  into the rotor. The spinning rotor pulls the pad in its direction until the rollers are so tightly sandwiched that they stop the wheel. Look for Wedge brakes on your 2009-model car.
Five amazing, clean technologies that will set us free, in this month's energy-focused issue. Also: how to build a better bomb detector, the robotic toys that are raising your children, a human catapult, the world's smallest arcade, and much more.