The NoPoPo (which apparently stands for No Pollution Power) battery has a shelf-life of 10 years and requires only a dropper-full (supplied) of pee to kick start it into life.
The batteries, which are designed for emergency use, are available in both AA and AAA sizes.
The basic principle is that a mixture of magnesium and carbon reacts when mixed with a urine to produce, in the case of the AA battery, up to 500 milliamp-hours (mAh) of life.
And the battery can be recharged this way for about five times – although it produces slightly less power with each charging.
They are available in the US from The Japan Trend Shop where two sets of three batteries will cost you $59.