The Problems: Batteries are difficult to dispose of and contain harmful heavy-metal compounds that may leach into the soil.
The Solution: Again with the urine. This time, at least it's your own. Scientists in Singapore have figured out a way to harness human urine to create a chemical reaction that powers a rudimentary battery. Add a drop of pee to an assembly of copper chloride, magnesium and copper, and voila — it produces as much power as a AA battery. Scientist hope the small rigs can be used for medical applications like disposable at-home testing kits, but they caution more development is still needed.
Eco Craziness 2/5. Human urine is certainly not in short supply, and this could eventually lead to cheap, ultra-portable medical tests ready at a moment's notice — as long as you're properly hydrated.