Tuesday, June 23, 2009

Self rechargeable battery from Nokia soon

Nokia is in the process of developing a battery which can recharge itself when the phone has been kept on the standby mode. This technology will end the worries of the people, as the standby mode is always referred as a curse to the planet, reports the Guardian.

"A new prototype charging system from the company is able to power itself on nothing more than ambient radio waves- the weak TV, radio and mobile phone signals that permanently surround us. The power harvested is small but it is almost enough to power a mobile in standby mode indefinitely without ever needing to plug it into the mains," said Markku Rouvala, one of the researchers who have developed the device at the Nokia Research Centre in Cambridge, U.K.

The Oyster cards used by the commuters in London are of the same phenomenon, powering themselves from radio waves emitted by the reader devices as they are swiped. And similarly old crystal radio sets and more recently modern radio frequency identification (RFID) tags, which are increasingly used in shipping and as antitheft devices, are powered wholly by radio waves.

"The Nokia's prototype instead of harvesting tiny amounts of power (a few microwatts) from dedicated transmitters, it is able to collect relatively large amounts of discarded power around a thousand times more, even from miles away. Individually the energy available in each of these signals is miniscule. But by harvesting radio waves across a wide range of frequencies it all adds up," said Rouvala.

Similar kind of wireless transfer of energy was first demonstrated by Nikola Tesla in 1893, who was so taken up with the idea that he had attempted to build an intercontinental transmission tower to send power through wireless across the Atlantic. The antenna and the receiver circuit of Nokia are designed to pick up a wide range of frequencies - from 500 megahertz to 10 gigahertz - and convert the electromagnetic waves into an electrical current, as the second circuit is designed to feed this current to the battery to recharge it.

This will ensure that these circuits use less power than the amount that is being received,. Till now, the researchers have been able to harvest up to five milliwatts. Nokia's short-term goal is to get in excess of 20 milliwatts, which is enough power to keep a phone in standby mode indefinitely without having to recharge it. But this would not be enough to actually use the phone to make or receive a call. The hope is to be able to get as much as 50 milliwatts, which would be sufficient to slowly recharge the battery.

"Radio frequency power falls off exponentially with distance," said Steve Beeby, an expert in harvesting ambient energy at the University of Southampton. "It would be a remarkable achievement," Beeby added.


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