"Reinvent the Toilet Challenge": Solar-powered toilet ready for India debut

CU-Boulder postdoctoral researcher Tesfayohanes Yakob, left, and research engineer Dana Haushulz are shown here with a novel solar-thermal toilet developed by a team led by CU-Boulder Professor Karl Linden as part of the Bill & Melinda Gates Foundation's "Reinvent the Toilet Challenge" to improve sanitation and hygiene in developing countries. 

Credit: University of Colorado Boulder

A revolutionary University of Colorado Boulder toilet fueled by the sun that is being developed to help some of the 2.5 billion people around the world lacking safe and sustainable sanitation will be unveiled in India this month.

Dana Haushulz

The self-contained, waterless toilet, designed and built using a $777,000 grant from the Bill & Melinda Gates Foundation, has the capability of heating human waste to a high enough temperature to sterilize human waste and create biochar.

Biochar is a highly porous charcoal, said project principal investigator Karl Linden, professor of environmental engineering.

The biochar has a one-two punch in that it can be used to both increase crop yields and sequester carbon dioxide, a greenhouse gas.

The project is part of the Gates Foundation's "Reinvent the Toilet Challenge," an effort to develop a next-generation toilet that can be used to disinfect liquid and solid waste while generating useful end products, both in developing and developed nations, said Linden.

Since the 2012 grant, Linden and his CU-Boulder team have received an additional $1 million from the Gates Foundation for the project, which includes a team of more than a dozen faculty, research professionals and students, many working full time on the effort.

Tesfayohanes Yakob

According to the Gates Foundation, the awards recognize researchers who are developing ways to manage human waste that will help improve the health and lives of people around the world.

Unsafe methods to capture and treat human waste result in serious health problems and death – food and water tainted with pathogens from fecal matter results in the deaths of roughly 700,000 children each year.

Linden's team is one of 16 around the world funded by the Gates "Reinvent the Toilet Challenge" since 2011.

All have shipped their inventions to Delhi, where they will be on display March 20-22 for scientists, engineers and dignitaries.

Construction

Karl Linden

The CU-Boulder invention consists of eight parabolic mirrors that focus concentrated sunlight to a spot no larger than a postage stamp on a quartz-glass rod connected to eight bundles of fiber-optic cables, each consisting of thousands of intertwined, fused fibers, said Karl Linden.

The energy generated by the sun and transferred to the fiber-optic cable system, similar in some ways to a data transmission line, can heat up the reaction chamber to over 600 degrees Fahrenheit to treat the waste material, disinfect pathogens in both feces and urine, and produce char.