Intel on Friday said it is researching technology to harvest free energy from the environment, which could lead to devices such as mobile phones running for indefinite periods without recharging. The company is working on tiny sensors that can capture energy from sources such as sunlight and body heat. In the future, such energy could be used to power personal electronic devices such as cell phones. There are already watches available that are powered by body heat, as well as prototype smartphones with display screens that double as solar cells, said Justin Rattner, chief technology officer at Intel, during a press event. Intel is also looking at powering a mobile phone by harvesting the energy the user generates by moving the phone's trackball. The radiation of cell phone or TV signals might also be used to power devices.Intel Hopes to Bring Free Energy to Mobile Devices - PC World
yeah, kinentic (shaking), termal (heat changes), baromatic (air pressure changes), wireless electricty (radio), radiant energy (solar), using the buttons/wheels/balls and why not also use case pressure.
Besides from radio each of those on their own may not provide sufficent power the sum of the parts should be capible of extending battery life by a serious amound.
The phone makers have always improved efficency by small bits at a time.
Soon we will all be wearing propeller hats.