Here is a cool kit that lets you build and experiment with your own fuel cell. The MudWatt Core Kit relies on microbes found in mud. You can track the growth of your electric bacteria colony with the blinker circuit and mobile app. Simply experiment with different types of dirt to see what works best.
MudWatt comes with 2 carbon felt electrodes, gloves, LED blinker board, instructions, and an app. Another cool educational kit for kids.