Tuesday, August 18, 2009

Charging a Cell Phone Without Electricity

Cell phone chargers suck electricity even in standby mode, adding to the "vampire energy" that goes to waste in so many households. Nokia, for one, is doing something about it.

It's doing away with chargers altogether.

A prototype charging system at the Nokia Research Centre in Cambridge, U.K., keeps cell phones juiced up with nothing more than the electromagnetic waves that envelop us constantly. All the stray waves from radios, cell phones, TVs and RFID chips that bounce around unseen -- they'll be put to good use by Nokia's charger.

Goodbye, electricity. Hello, electromagnetic waves.

Nokia claims it can grab the energy from radio waves miles away. If they're really pulling this off, it's pretty amazing. Electromagnetic waves follow the inverse-square law, which means their power (or intensity) is inversely proportional to the square of the distance the waves have traveled from their source. By the time a radio wave has trekked a few miles, its strength has waned considerably (kind of like some humans).

5 milliwatts is all Nokia researchers have been able to draw from the air so far. But they're hopeful of raising that to 20 mW and eventually 50 mW. That would be enough to charge today's cell phones.

The charger-less phone may hit stores in about 3 years. It would be a welcome step toward conquering vampire energy.

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