Robots powered by human waste might sound kind of nasty, but what if there really were a more practical use for our pee than flushing it down the toilet? Researchers in the UK have come up with a way to use urine to power a heart-like pump that creates enough energy to fuel a small robot. As NBC News noted, “one man’s waste is another bot’s energy drink.”

The robotic “heart” is really a system of tubes, modeled after the human heart, attached to a fuel cell where microbes eat away at compounds in the pee to create energy. The microbial fuel cell can then convert that energy into electricity to power the robot.

“The project is all about generating electricity from waste material,” Ioannis Ieropoulos, a researcher at the Bristol Robotics Laboratory in the UK, said in a video interview from the University of the West of England. “In other words, turning waste into something really, really useful.”

According to Science World Report, every time electricity is made inside the fuel cell, creating heat, it causes the pump to compress. This causes the fluid to shoot through an outlet, allowing the liquid to be delivered to the robot’s fuel cells. When the artificial muscles cool, they return to their resting state. The robotic “heart” pumps every 3.5 seconds. It does this for about half a minute, then stops. Three hours later, the heartbeat is triggered again.

“The artificial heartbeat is mechanically simpler than a conventional electric motor-driven pump by virtue of the fact that it employs artificial muscle fibers to create the pumping action, rather than an electric motor, which is by comparison a more complex mechanical assembly,” study author Peter Walters from the University of the West of England said in a statement.

According to the study, published in the journal Bioinspiration and Biomimetics, previous tests of the device have shown that the robotic heart can power small robots, called “EcoBots,” using energy derived from organic matter.  Scientists have already powered the robots using dead flies, rotten fruits and vegetables, wastewater and sludge.

“We speculate that in the future, urine-powered EcoBots could perform environmental monitoring tasks such as measuring temperature, humidity and air quality,” Walters said. “A number of EcoBots could also function as a mobile, distributed sensor network.”

He continued: "In the city environment, they could re-charge using urine from urinals in public lavatories. In rural environments, liquid waste effluent could be collected from farms."

Unfortunately, the power generated by human pee won’t be enough to run something like a Roomba. Instead, the robotic heart would be suitable for low-power tasks, such as environmental sensors that record things like atmospheric conditions for hours on end and need to stay online at all times. 

Here’s a video uploaded to YouTube from the University of the West England, Bristol, about the pee-powered robots.