Interesting write up from Mark Valentine on his “steam battery” he writes –
A few months ago, Forrest M. Mims III, the editor of The Citizen Scientist, received an inquiry from an upper-level physics student that led to a brief (or perhaps not so brief) account of how I discovered the “Steam Battery.” Essentially, this is an arrangement that produces a voltage across a sample of black ESD (Electro Static Discharge) foam when human breath is applied to one side of it.
After I gave my account, I began thinking about well-documented effects that behave similarly to the steam battery. The most prominent is the “hot-point-probe” effect I suggested previously in the “Backscatter” column, in which a p-type or n-type silicon wafer generates a current between two probes when one is hot, and the other is cold. It’s similar to the Seebeck effect, but a bit more complicated, since the current can flow in either direction depending on the type of wafer.
Steam battery – breath power calculator – Link.