ModeLabs designed three concept phones that use renewable energy to recharge the handsets.

The renewable energy discussion on portable devices is an important issue for extending the battery life of the more and more complex and demanding devices. It would be great if phones would just recharge themselves because I walk around with them.
Portable solar chargers are the only commercial solution I saw so far.

The ModeLabs YoYo (photo) is worn around the neck. In this way, it can make use of solar and kinetic energy thanks to its photovoltaic cells and its pendulum located on the rear side. This hybrid energy concept allows the mobile to continuously recharge itself.
The Runaway concept (first photo below) is designed of active sports. The mobile phone would convert its own movements into energy.

The last design is called U-Turn. ModeLabs integrates an azerty keypad to simplify emailing for professionals that are on-the-move. It recovers energy from the opening and closing of the keypad to recharge its batteries.

ModeLabs is known for developing mobile phones for brands like Levi's, MTV or Elite.
Via ModeLabs.