New frontiers of science: how to produce electricity from pee

The solution to the energy crisis could also be in the pee: a new study on the decomposition of urea

That of producing electricity from pee seems to be a long-standing dream for part of the scientific community. At the beginning of the new millennium, attempts were made to break down urine by harnessing the activity of certain bacteria, while in 2013 a research team at the Bristol Robotics Laboratory tried to charge a cell phone using only the energy produced by pee.

A revolutionary new study has just been published in Nature that seems to confirm the original intuition: perhaps it really is possible to produce electricity from pee.

A catalyst for pee

Pee is a waste product of our bodies, and those of most animals. Mammalian urine contains urea, a compound rich in potential energy that can be used to produce a flow of electrons, and therefore an electric current.

The current is produced when urea is broken down into nitrogen and carbon dioxide, a step made extremely complex by the decay of the molecule: six electrons are produced that are very difficult to control, an operation that tends to absorb more energy than that produced.

A new study by the Universities of Anhui and Hefei in China and the University of Adelaide sheds new light on the long-cherished prospect of producing electricity from the breakdown of urea molecules.

To do so, a special nickel and iron-based catalyst has been developed, which together appear to be able to "fence" the six rebel atoms resulting from molecular decay.

Technically, the scientists explain, nickel facilitates the transformation of urea into carbon dioxide and ammonia; once broken down, the iron atoms each pick up two ammonia molecules, going on to form nitrogen gas and using the electrons in the ammonia to generate an electric current.

Clean energy and environmental friendliness

As researchers close to Chen's team explain, "urea is abundant in all the world's wastewater, and it could be used to power fuel cells as an alternative energy," says Yao Zheng.

It has long been known that urine can be used to produce hydrogen through the action of electrolysers, but efforts to produce energy from pee have always yielded less than satisfactory results in terms of efficiency.

Often, we said, the energy required to control the process of decaying urea molecules far exceeds that produced. As Shizhang Qiao, director of the Adelaide Materials Center, says, "We tried to improve existing catalysts, which tend to have poor performance."

An improvement on what has already been discussed and studied in recent years, then. The new catalyst, based on nickel ferrocyanide, seems to be succeeding: the process of catalyzing urea is much faster and more efficient than all other systems tested.

"We have shown for the first time," says Zheng, "that there is a much more efficient catalyzation process that can reduce the input energy and produce more hydrogen than any other existing catalyst."

In addition to its ability to produce clean energy, the new catalyst is also capable of cleaning wastewater of the immense amounts of urea it contains, according to the Chinese and Australian researchers who published the study.