This Water Powered H2O clock is as simple as it comes; it has no alarms, no stopwatch and backlight. However it is powered by water instead of battery, just remove the two transparent tubes, fill them with water and it will come to life. The clock will work for about 2 months until it needs a refill. It might come in handy in case of emergency. The Water Powered H2O Clock is available from Select Solar for £6.