Potato can be used to generate electricity. Potato juice contains many water soluble chemicals that may cause a chemical reaction with one or both of our electrodes. So we may get some electricity from that.
Here is a small example where Potato is used as battery to power an alarm clock. Potato can converts chemical energy into electric energy by spontaneous electron transfer. As the experiment describes, the potato acts as a sort of buffer between the zinc ions and copper ions allowing the electron transfer to take place over the copper wires of the circuit, which channels the energy in the clock.