The Bill and Melinda Gates Foundation is on a mission to improve human sanitation, particularly in areas of the world that don't have a reliable water supply. Much of that effort is about reinventing the toilet but the foundation has also challenged scientists to find ways to turn human waste into something useful.

Enter Bristol Robotics Laboratory in Bristol, England. Scientists there have developed technology that converts human urine into electricity that can be used to powered a smartphone, as spotted by the Register's Jasper Hamill.

The scientists have demonstrated their wee-powered battery charging a smartphone. They've been awarded a grant from Bill Gates' foundation to develop the tech further.

Here's how it works:

That little round thing is called a Microbial Fuel Cell. Inside of it is are micro-organisms that take the urine, break it down and output electricity.

Here's another look at the heart of the fuel cell, the part filled with microorganisms.

The full system involves piping the urine through a tube ...

... into a series of fuel cell converters, each of which houses that microbial. In addition to creating electricity, the unit expels a broken down version of the urine, (into those bottles) which make it safer to dispose of, the scientists say.

The scientists say the biggest challenge is to string enough of these converters together to provide a useful level of electric output.

Looking at it work in the lab is pretty gross. But we can imagine such a system deployed in sanitation plants worldwide, letting us create electricity as we sanitize.

The project gives new meaning to the term "human powered."

Here's the full video where the scientist explains the process in detail: