Why would anyone ever want to carry around a two pound battery pack that uses disposable batteries to charge their MacBook Air, which barely weighs more than that by itself? There are reasons, and they may even be good reasons.

A flywheel battery is a system that stores electricity as kinetic energy, in the form of a a wheel that spins at tens of thousands of RPM. Made of carbon fiber and levitated in a vacuum using magnetic bearings, hundreds of flywheels are about to join the power grid in New York.

By converting some of the wires inside memory chips into carbon nanotubes, researchers say that they could boost the battery life of cell phones and laptops and other mobile electronics by a factor of 100.

Some gadgets still require you to use AA batteries, like a Wii or Xbox 360 controller or a cheap digital camera. Wouldn't it be handy to not have to pop rechargeable batteries into a charger and wait for it to juice up? A new battery design concept would eliminate the wait time by letting you wind up the battery to recharge it.