Another thing to try, is using a magnesium electrode, in the earth or in a pot of dirt going to the body. The magnesium releases electrons as it ever so slowly erodes in moist dirt. I know this for a fact since I power a watch on water using magnesium 99% pure as the negative electrode and copper as the positive electrode. The electrodes go in water and the digital watch runs for many months. After so many months I change the water if I notice the display a bit dim. Ive read any metal will release electrons but have found no greater current from a metal then from pure magnesium metal so far.