Are you looking for a novelty clock ?
You can try the Eco-Friendly Water-Powered Clock from Bedol.
The clock does not need any batteries and any electricity. Just need water and salt !! Cause, it is powered by water and a pinch of salt. The electrodes inside the clock use energy from water for powering.
The entire device has 4 inches high and 3 1/2 inches wide.
So, you don’t need to buy batery anmore.
Thats mean you can help saving energy for the earth.