This is worth a look (and allow yourself a childish giggle). I found it in New Scientist, with the headline "Pee-powered battery smaller than a credit card". Here's an extract:
The first urine-powered paper battery has been created by physicists in Singapore. The credit-card sized unit could be a useful power source for cheap healthcare test kits for diseases like diabetes, and could even be used in emergency situations to power a cellphone, they say.
Read the whole article here. My favourite line from the article is:
The battery is currently suited for use with disposable devices â€" it is not yet ready to power laptops or iPods.
Now that's a nice mental picture, eh? -cvj