Keyboards will continue to be a major interface for computers into the next decade [Starner et al, 1995]. As such, typing may provide a useful source of energy. On a one-handed chording keyboard (HandyKey's Twiddler), it is necessary to apply 130 grams of pressure in order to depress a key the required 1 mm for it to register. Thus,
is necessary to type. Assuming a moderately skilled typist (40 wpm), and taking into account multiple keystroke combinations, an average of
of power is generated. A fast QWERTY typist (90 wpm) depresses 7.5 keys per second. A typical keyboard requires 40-50 grams of pressure to depress a key the 0.5 cm necessary to register a keystroke (measured on a DEC PC 433 DX LP). Thus, a QWERTY typist may generate
of power. Unfortunately, neither method provides enough continuous power to sustain a portable computer, especially since the user would not be continuously typing on the keyboard. However, there may be enough energy in each keystroke for each key to ``announce'' its character to a nearby receiver [Hawley, 1995]. For example, the keyboard may have a permanent magnet in its base. Each key would then have an embedded coil that would generate a current when the key was moved. Another possibility is to use PVDF which bends at each keystroke to generate energy (again, 11% efficiency). Thus, a wearable, wireless keyboard may be possible.