State of Telecom Industry in Pakistan

Technology Review reports about an interesting concept in development: a cell phone that never needs recharging. Nokia says it’s developing technology that could draw enough power from ambient radio waves to keep a cell-phone handset topped up. The target for the prototype is to harvest up to 50 milliwatts of power–enough to slowly recharge a phone that is switched off. Current prototypes can harvest 3 to 5 milliwatts.

Ambient electromagnetic radiation–emitted from Wi-Fi transmitters, cell-phone antennas, TV masts, and other sources–could be converted into enough electrical current to keep a battery topped up, says Markku Rouvala, a researcher from the Nokia Research Centre, in Cambridge, U.K.

The Nokia device will work on the same principles as a crystal radio set or radio frequency identification (RFID) tag: by converting electromagnetic waves into an electrical signal. This requires two passive circuits. “Even if you are only getting microwatts, you can still harvest energy, provided your circuit is not using more power than it’s receiving,” Rouvala says.

To increase the amount of power that can be harvested and the range at which it works, Nokia is focusing on harvesting many different frequencies. “It needs a wideband receiver,” says Rouvala, to capture signals from between 500 megahertz and 10 gigahertz–a range that encompasses many different radio communication signals.

Historically, energy-harvesting technologies have only been found in niche markets, powering wireless sensors and RFID tags in particular. If Nokia’s claims stand up, then it could push energy harvesting into mainstream consumer devices.