This is something i've been thinking about a while. Concerning things like gym's and everyday devices.
There are generators out there, such as on the bicycle, or at the gym where the machines should be able to generate energy instead of them draining energy on the machines or lights.
What im looking into abit is to find some kind of energygenerator either such as a kinetik engine to physicaly work to make energy to re-charge my laptop, or to put together a heat-based charger such as the watches that work on body heat.
Altho i havn't yet found out how to do either. Most interested in the kind where workout will generate energy. That would be a good incitaement to get into shape.