Urine powered emergency light

Technically speaking, this is an emergency lightsource that has the dry components of a simple zinc carbon cell. To activate it you add salty water, either as a mixture of salt and water, sea water or urine, and the liquid acts as the electrolyte allowing the cell to operate.

The unit is not powered by water. It is powered by the gradual dissolving of the zinc block. The water is just the electrolyte, and once the zinc has degraded the unit will stop working.

The main feature of this light is that when it is stored dry then it can last for a very long time.

If needed, the partially used unit can be emptied, rinsed, dried and kept in storage again.

This light came from AliExpress. Here's an affiliate link if you want one:-
https://s.click.aliexpress.com/e/_c3OsDCub