This post, part of a series we're running all about electric cars, was written by Christopher Lampton from HowStuffWorks.com.
If you own a rechargeable electric toothbrush, you may have noticed something odd. When you place it in its base, there's no electric plug visible, just a smooth plastic stand that holds the smooth plastic toothbrush handle so it doesn't fall over while waiting for your next brushing. And yet the moment the toothbrush and holder come together – indeed, the moment they come within even a fraction of an inch of one another – a light flashes on the toothbrush and the battery inside it starts to recharge. Somehow electricity is passed from the stand to the toothbrush without wires or physical contact.
How is this possible? The electric toothbrush recharges itself through a method known as electromagnetic induction, in which an electric current in one wire causes an electric current to start flowing in a nearby wire. Energy actually travels wirelessly through the small amount of space between one wire and the other. Electric toothbrush makers aren't the only ones using this technology for battery recharging. The new Palm Pre cell phone comes with an optional recharging pad called the Touchstone. Just place the phone on top of the pad and it'll begin recharging immediately. And though the Touchstone itself has to plug into a conventional electric outlet, the phone just has to sit there, recharging itself without wires. Such wireless recharging systems are slower than wired rechargers and usually only work over short distances, but Fujitsu has recently announced a wireless recharging technology with greater power and efficiency than any other system developed to date.
With all this electricity in the air, so to speak, it seems inevitable that someone would be working on a way to recharge electric cars without the need for wires or plugs. And so they are. Evatran has announced a wireless electric car recharging tower that should be commercially available by April 2011. It consists of an adapter that attaches to your electric car's built-in charging unit and a tower that you place in your garage. Park the car over a pad next to the tower and the battery immediately starts recharging, without wires, plugs or any effort on the part of the owner (other than installing the tower itself). Evatran calls their system "proximity charging."
Automakers have also taken heed of this technology. At the moment, Nissan seems to be the company with the most invested in developing a wirelessly rechargeable electric car, with plans to have one on the market possibly as early as 2011 (though the technology does not seem to be incorporated into the first generation of the new Nissan LEAF). When these zero emission vehicles (ZEVs) are parked on top of a wireless recharging pad that can be embedded in the floor of a garage or in a parking lot, they automatically charge while their owners are off doing something else. Ultimately, Nissan would like to see these recharging pads embedded in the road itself, so that highways would have designated recharging lanes that would allow electric cars to recharge while being driven. Detectors in the roadway would identify the car and send the bill for the electricity to its owner. If this works, it may never again be necessary to stop at a fueling station, at least as long you don't wander too far from an electrified lane. Embedding rechargers in the highway won't happen anytime soon, though, and Nissan admits that there's a great deal of research and planning still to be done before on-the-go recharging will be a reality.