If you don’t have any batteries, but you have plenty of soil, then you’ll like this mud powered digital clock. Using nothing but damp soil and 2 different metals, the current that’s created is enough to power a digital clock. The clock is designed as an educational eco toy, helping kids to learn a little about the chemistry of batteries.
The kit uses copper and zinc to create a flow of electrons, which is the current that drives the low voltage digital display. Admitedly, the clock won’t serve much practical purpose, but I’m sure we’ll see more mud-powered clocks in the future. The mud clock is available from Maplin for just £9.99.