Toilet wins prize with solar power
Gretchen Vogel | ScienceNOW
A solar-powered toilet that turns urine and feces into hydrogen and electricity has won a $100,000 first prize in the Reinvent the Toilet Challenge sponsored by the Bill & Melinda Gates Foundation.
The prize was announced Tuesday at the foundation’s Reinvent the Toilet Fair in Seattle. The event, which ended Wednesday, showcased dozens of projects that aim to create an inexpensive and eco-friendly alternative to the flush toilet. Researchers used more than 50 gallons of soy-based synthetic feces to demonstrate their prototypes during the two-day fair.
The flush toilet is convenient and hygienic, but the technology has its drawbacks: It uses clean water to flush away a potential source of nutrients and energy, and it’s prohibitively expensive for many of the estimated 2.6 billion people who lack access to sanitation.
The Gates Foundation launched its toilet challenge a year ago, funding eight projects that aimed to invent a toilet that could be operated for 5 cents per user per day while recovering salt, water, nutrients, and energy.
The winning design, developed by Michael Hoffmann of the California Institute of Technology in Pasadena and his colleagues, uses solar power to run an electrochemical reactor that breaks down human waste to produce hydrogen gas. The gas can be stored and used to run the reactor at night or on cloudy days.
Tove Larsen of the aquatic research institute Eawag in Dübendorf, Switzerland, Harald Gründl of the design firm EOOS in Vienna, Austria, and their colleagues won a special $40,000 prize “for their outstanding design of a toilet user interface.”
That prize was a last-minute addition, says Carl Hensman, program officer for water, sanitation, and hygiene at the foundation.
The design uses a foot pump that helps recycle water, and it features a clear tube that allows the user to see the clean water refill the tank – what the team calls the toilet’s entertainment factor.
: from Journal Gazette