All you have to do to keep the clock ticking is change the water every six months. It uses "the latest electrochemical technology" to power the digital display with water and there are no emissions or waste. Shaped like cans, the clocks are available in four colours.
It's not an alarm - water obviously isn't that powerful yet, but it does look quite cute and displays the time on the digital panel at that front. Pair it up with Efergy's showtime water-use monitor as a green present for the eco-warrier in your life.
Even better, get GreenStamp's water-powered clock making kit and let your green friend experiment with what liquids make the clock run. A good one for kids.SOURCE