Thursday, November 16, 2006

Wireless Power

Listen to the text-to-speech Robo-Podcast


You've got a cell phone, a wireless laptop and maybe a Blackberry. You are the very picture of a wirelessly connected person on the go - until your batteries run down.

Wouldn't it be great if you could recharge all your electronics without having to plug into a charger?

A group of physicists from MIT thinks so too. They're proposing a design for a wireless power transmission system that could make power cables and battery chargers things of the past. What's more, the researchers believe the power source could run buses or possibly even nano-robots tooling around inside your body.

Marin Soljacic and his MIT colleagues presented their idea at the Industrial Physics Forum meeting going on this week in San Francisco. It created quite a stir in the press, leading to stories in major newspapers and dozens of techy websites.

The system Soljacic is proposing doesn't broadcast power the way an antenna does. Radiating energy out to space would be wasteful. Instead, a power source creates a short range oscillating electric field. Properly tuned circuits that are within range of the source suck up some of the energy. If there are no electronics to charge or power nearby, then most of the unused energy returns to the source.

As an incurable early adopter, and electronics junky, I can't wait to get the system in my house. The only problem is, I don't think it will work.

Soljacic 's idea is based on old established science, well within the grasp of nineteenth century electronics wizards like Marconi, Edison and Tesla. There's no reason that the system, if it's feasible, couldn't have been built over a hundred years ago. Soljacic has suggested that it's an idea whose time has come only with the advent of wireless communications.

But I'm not buying it. I'm sure my great grandmother would have appreciated a cordless vacuum back in 1910.

So, despite the fact that I would give my eye-teeth for wireless power, I'm not going to hold my breath.

One problem is likely to be the inefficiency of wireless power. Even Soljacic 's calculations show that the best you could get is 60% efficiency. I'd bet Tesla and Edison gave it a shot and found that it's much worse in real world conditions. Of course it might make a nice combination power source and space heater, after all the wasted energy has to go somewhere. I'm guessing it goes into heating the room.

On the other hand Soljacic may be onto something. If I'm wrong, and his wireless power works, I'll be first in line at Walmart to pick one up.

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