US company M2E Power has come up with a handy answer to all those CO2 emissions being belted out by mobile phone chargers - it has invented a rechargeable phone battery that works on kinetic energy alone.

Kinetic energy is electricity generated by natural motion like when moving your hands, for example. Seiko's Kinetic watches already work on this principle.

M2E Power also says its charger can extended the battery life of devices by between three and seven times compared to a standard mobile, M2E Power said.

The materials needed to develop this new type of battery are already available, and not that much more expensive than today's lithium-ion batteries, Regan Warner-Rowe, M2E's licensing and business manager, told ZDNet. The batteries also use 30 to 40 per cent less heavy metals.

The aim is to develop a device incorporating the self-charging generator/battery and sell it directly to consumers, an M2E spokesperson said. The development process is likely to take at least two years, so it will probably take until 2010 until we see the first mobiles with mini-generators included.