# How much electricity could be generated by a person's stomach acid?

Motorola has a device that is powered by stomach acid. Given that a battery consumes the electrolyte as it generates a charge, how much power could be generated using a device such as this? Let's assume the electrodes are large enough that the electrolyte is the limiting factor in this reaction. Would the body just generate more acid to compensate? Would there be any physiological side-effects from using such a battery?

• Sounds like one for Randall from xkcd
– sehe
Nov 29, 2013 at 22:02
• The acid isn't the relevant consumable, the electrode is. Nov 29, 2013 at 23:55
• @sehe I was thinking the same thing, although this one may not have enough physic for him. Nov 30, 2013 at 2:13
• @Aesin In my understanding both the electrodes and the acid are consumed. Let's assume we have large enough electrodes so that the acid is the limiting factor. Dec 2, 2013 at 14:04

The electricity generate depends mainly from the electrodes. This is the same misconception of lemons battery. In fact the energy of every battery comes from the metals and not from the acid use as electrolyte, as you can't generate energy from lemon juice but from the different potential between copper and zinc coin so you can't generate energy from a stomach acid but with it. However $HCl$ is not used normally for battery so I think you could not produce a big amount of energy even if you ingest very big electrodes.