The idea of using photovoltaics to recharge a mobile phone on the go comes as no surprise these days. But what about other renewable power sources? While wave and tidal power probably won't be of much use, wind is a possibility. Lo and behold, students at the Department of Industrial Design at Indian Institute of Technology, Delhi have come up with a small (pocket-sized), inexpensive (Rs 200, or about $4-$5), wind turbine that can be used to recharge phones. With sufficient airflow, it can put out about 4 watts -- not an enormous amount of energy, but sufficient trickle-charge a phone or power an LED lamp.

One of the paradigm-shifting aspects of wind and solar is that, for small uses, power generation can happen just about anywhere. This pairs up nicely with the proliferation of small, network-enabled gadgets. Power should be as accessible as communications. If the cost of relatively-efficient solar and micro-wind turbines can be brought down sufficiently, we may be heading towards a world where any structure or piece of equipment expected to be outside in the sun and wind for extended periods of time have minor power generation features.

(WorldChanging contributor Ethan Zuckerman adds this alternative phone energy source:)

Slightly more expensive, but now commercially available is the Sidewinder cellphone charger, which uses a small hand crank to power cellphones. At $25, the product appears to be designed for travelling executives, not developing world users, but the concept could be adopted by developing world engineers and customized for local needs. Motorola is offering a similar product, Free Charge, designed in collaboration with FreePlay, well known for their work making wind-up radios and flashlights. Unfortunately, Free Charge will set you back at least $70, making it unlikely to have a major impact for developing world users.