Many alternative energy sources have been suggested as a replacement for oil; wind, solar or biofuel just to name a few. Now another can be added to the list: urine.
Whilst abundant worldwide, this waste liquid is not the most obvious choice for weaning the world off oil. To extract urine’s energy Gerardine Botte of Ohio University employed a process called electrolysis which uses an electric current to break up molecules. The resulting hydrogen can then be put to work as a clean source of energy.
Electrolysis has already been used to create hydrogen from water, but this requires quite a lot of energy. Botte turned to urine as a way of improving efficiency. Although urine is 95% water much of the remaining 5% is urea, a chemical compound which has four hydrogen atoms per molecule. This is twice the number found in water molecules, and the atoms are less tightly bonded so extracting the hydrogen from urea instead of water requires about a third of the energy.
Originally the research team used “synthetic” urine made by dissolving urea in water, but the process works equally as well with the genuine article. Working with human urine requires special clearance, which held up the publication of their research, says Botte.
The team are now looking at the long-term feasibility of urine hydrolysis, as well as the potential for scaling it up to industrial levels. Botte believes that existing sewage plants could be put to work generating energy, as well as cleaning up waste. “We do not need to reinvent the wheel as there are already electrolysers being used in different applications,” she says.