Man & Machine tried to say something about "natural bio-electricity," but the only electricity in a human body is in the nerves, and that would have trouble powering an LED, let alone a high-powered cyberlimb or computer chip.

Batteries have the shortcoming of running out of stored power after a while. That's not a problem for low-demand devices like cybereyes or headware, but cyberlimbs can demand hundreds of watts of output to match natural muscle performance. You'd need an impressive battery to power a cyberleg for a marathon or long march.

Which leads me to my perennial suggestion for cybernetic power sources: a fuel cell or other chemical power system that taps blood sugar and dissolved oxygen to generate electricity. Excess power (generated during sleep or desk jockeying) can be stored in a battery to meet peak demands. Recharging is easy: just eat normally.

crap, i swear i looked

That's exactly what man & machine imples.

Would you quote that bit of M&M at me, or at least give a page number, please? I might be thinking of something else.