Innovative solar-powered toilet set to be unveiled in India

A toilet that's fueled by sun is set to be unveiled in India this month.

The self-contained, waterless toilet, designed and built using a 777,000-dollar-grant from the Bill and Melinda Gates Foundation, has the capability of heating human waste to a high enough temperature to sterilize human waste and create biochar, 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 team led by project principal investigator Karl Linden, professor of environmental engineering, University of Colorado Boulder, is one of 16 around the world funded by the Gates "Reinvent the Toilet Challenge" since 2011.

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 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.

Linden said that biochar is a valuable material, which has good water holding capacity and can be used in agricultural areas to hold in nutrients and bring more stability to the soils.

A soil mixture containing 10 percent biochar can hold up to 50 percent more water and increase the availability of plant nutrients, he said. Additionally, the biochar can be burned as charcoal and provides energy comparable to that of commercial charcoal.