ENERGY SPECIAL Charge your phone using renewable 'urine-tricity'

Waste not, want not, the saying goes, and researchers at the Bristol Robotics Laboratory are turning something we all produce - urine - into clean electricity, or 'urine-tricity'.

It sounds outlandish, but earlier this year, at the Reinvent the Toilet Fair in New Delhi, India - co-hosted by the Indian Department of Biotechnology and the Bill and Melinda Gates Foundation - the team exhibited a functional urinal that was able to charge a phone using just urine, a world first.

"It's very simple. The down pipe from the urinal goes straight into the box which contains the microbial fuel cells, it's as simple as that," Yannis Ieropoulos, professor and director of the Bristol BioEnergy Center at the Bristol Robotics Laboratory, told CNBC.com in a phone interview. The Bristol Robotics Laboratory is a collaboration between the University of the West of England and the University of Bristol.

"There is no pumping, no kind of clever filters or membranes in place: it is the urine going straight down the pipe and into the microbial fuel cells," he added.

The microbial fuel cells - or MFCs - Ieropoulos refers to contain live, naturally occurring microorganisms. These feed on the urine and produce electrons as a respiratory by-product. Electrodes in the MFCs facilitate the transfer of these electrons and create current when connected via a circuit.

The project Ieropoulos has been leading has received funding from, among others, the Bill and Melinda Gates Foundation.

Together with his team, he is now looking at ways of implementing the technology in the developing world, where the lack of both adequate sanitation and reliable energy supplies presents a huge challenge. 

Worldwide, more than six trillion liters of urine are produced every single year, making it an abundant, renewable resource with vast amounts of potential.

"The Gates Foundation is facilitating and also financing collaboration with manufacturers, with mass producing companies that can help us take what we have in the lab and put it in the real world through the market," Ieropoulos said.

"The Gates Foundation is primarily interested in the developing world and improving people's quality of life... this is where we're being pushed to deliver." Current options being looked at include putting microbial fuel cells behind a pit latrine.

Read More Sunny side up: World's staggering solar plants 

As well as helping communities in the developing world, Ieropoulos sees no reason why 'urine-tricity' cannot be used in wealthier societies. "In the modern world... we use the toilet, we flush it, that's it. That doesn't have to change," he said.

"What we are saying is that the microbial fuel cells can be retrofitted to any existing toilet in any infrastructure and just take the flushed waste... and get electricity from it as it goes down the drain," he added.

"We're talking about urine simply because we haven't done experiments with faeces. There are groups out there which are looking to faeces, and believe me, there's a whole toilet world out there."

What is Ieropoulos' ultimate aim?

"Utilizing waste to generate useful energy and at the same time improve quality of life through sanitation."

By Anmar Frangoul | Special to CNBC.com | CNBC – 6 hours ago