Just like sunlight, water also can generate eco-friendly electrical power such as the following eco-friendly water powered clock.
The hydro powered clock comes with three water powered batteries that consists of special alloys. Once immersed in water, the batteries can activate the carbon particles to generate electricity for the LCD clock. It means that you just need to refill the three water powered batteries instead of changing batteries. And moreover, after refilled, the batteries can offer about two to three months of use.
The water powered clock is priced at $7.99 USD. If you the eco-friendly gadget, jump to perpetual kid and grab one.
By the way, here is another water powered clock.