Ever hear of a green battery? Scientists are always trying to discover clean energy sources to reduce pollution. Here's a way to power your battery-operated digital clock and help save the environment at the same time [source: Environmentally Safe Potato-Powered Clock].

You'll need the following items:

  • Two potatoes
  • Two short pieces of heavy copper wire
  • Two galvanized nails
  • Three alligator clip leads (wires with alligator clips on each end)
  • An LED clock that uses either a single 1- or 2-volt button-type battery, or a single 1.2- to 1.5-volt standard battery

Got everything? Let's make that potato clock:

  1. Remove the battery from the clock, taking note of which way the plus (+) and a minus (-) sides of the battery face.
  2. Number the potatoes "1" and "2" with a marker.
  3. Insert a galvanized nail in each potato.
  4. Insert a copper wire into each potato, positioning them as far a possible from the nails.
  5. Connect an alligator clip lead between the copper wire in potato 1 and the plus (+) terminal of the clock's battery compartment. Don't let the alligator clip touch any other metal parts in the compartment.
  6. Connect another alligator clip lead between the copper wire in potato 2 and the minus (-) terminal of the clock's battery compartment. Use the same precaution as in Step 5.
  7. Connect the remaining alligator clip lead between the nail in potato 1 and the copper wire in potato 2 [source: How to Make a Potato Clock].
  8. Set the clock and have a great time!

If the clock doesn't work, try the following:

  • Carefully check that all wires are connected correctly and firmly.
  • Try reversing the two clip leads on the clock's battery terminals.
  • Try another clock or use different potatoes.
  • Make sure the galvanized nails are really galvanized (ask at the hardware store).
  • Check that all wires, clip leads and battery terminals are clean. Remove any dirt with sandpaper.