Current notebook computers offer a unique method for generating energy. Simply opening the computer may supply power. However, this one action needs to provide power for the entire session; otherwise, users would be forced to flap their computers open and closed. From some simple empirical tests, the maximum force that a user may reasonably expect to exert when opening a notebook computer is
Assuming a maximum of 0.5 m of swing when opening the computer,
of power would be available for a 10 minute session. For an hour's use, the available power drops to 12 mW. For most current applications, these power rates are inadequate.
Figure:
Power from body-centered sources. Total power
for each action is included in parentheses.