With the advancement in technology, mankind is discovering more uses for waste matter.

If researchers have their way, then human pee could power future environmental robots. Researchers are now exploring this option and are looking at building bots that are powered by artificial hearts that use urine to pump it instead of blood.

Peter Walters, an industrial designer at the University of the West of England, and his colleagues at the University of Bristol have created four generations of EcoBots in the past 10 years. Previous generations of these robots were fueled by dead flies, rotten produce, waste water and sludge.

The device which Walters and his colleagues have created imitates the squeezing action of the human heart and is used to pump urine into a microbial fuel cell. This can in turn power robots who will convert the waste into electricity. 

"In the future, we hope the robots might be used in city environments for remote sensing," where they will help in monitoring pollution, per Walters. "It could refuel from public lavatories, or urinals." 

The robotic heart pumps for 30 seconds (every 3.5 seconds) and then rests. Post 3 hours the heartbeat is triggered again. The urine goes into a fuel cell where microbes eat through the energy-rich compounds. This in turn generates electricity which powers the robot. 

The "muscles" of the artificial heart are made of a titanium-nickel alloy which can shape shift. The material is capable of expanding when electricity passes via it. Once cooled, it shrinks back to the original shape and can squeeze a chamber that is full of fluid like a real heart. 

Since it may not be possible to extract much energy from human pee, this mechanism will not work for most robots.  However, the urine-powered bots may be useful for tasks that do not require much movement like measuring gas levels. 

"We don't extract a huge amount of energy from the urine," acknowledged Walters.