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The Makers of This Solar-Powered Technology Want to Eliminate a Global Sanitation Issue

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A new piece of technology is aiming to offer an innovative solution to an age-old problem. And it's nothing to pooh-pooh.

For the 2.5 billion people in the world with no access to modern sanitation and at risk for all sorts of related public health challenges, human waste is a big problem. From loss of life due to disease to medical bills and other costs, the World Bank estimates the annual worldwide cost of poor sanitation at about $260 billion.

And as it turns out, the situation in India is especially foul. An estimated 640 million people in India regularly defecate in the open, producing 72,000 tons of human waste each day.

With this issue top-of-mind, a group of researchers has used technology to develop an unconventional solution to this rather stinky problem. The team at the University of Colorado Boulder used a grant from the Bill and Melinda Gates Foundation to fund their creation of the self-contained, waterless toilet, which was unveiled last month at the Reinvent the Toilet Challenge event in New Delhi, India.

No water, you say? The toilet uses fiber optic cables -- the same things that likely carry your cable television signal -- to sanitize human waste.

Still not clear? Eight parabolic mirrors on the device capture sunlight and focus it on a small spot on a quartz glass rod. From there, the solar energy is transferred to eight bundles of fiber optic cables, which can produce a total of about 700 watts of energy that is used in the reaction chamber where the waste is treated.

The toilet has two main collection vessels: one for fecal matter and one for urine and hand wash water. Each vessel has two chambers -- one for collection and one for reaction -- which are rotated on a simple carousel system. The power from the concentrated sunlight heats the fecal reaction chamber to between 392 and 1,112 degrees Fahrenheit and the liquids chamber to between 140 and 158 degrees Fahrenheit. This disinfects the waste and turns it into something called biochar, a highly porous charcoal which can then be used as fuel or fertilizer.

According to Karl Linden, professor of environmental engineering at CU-Boulder and the project's principal investigator, the biochar has a one-two punch in that it can be used to increase crop yields and sequester carbon dioxide, a greenhouse gas. “Biochar is a valuable material,” Linden said in an announcement. “It has good water holding capacity and it can be used in agricultural areas to hold in nutrients and bring more stability to the soils.” Soil which has been mixed with biochar can hold more water and increase the availability of nutrients to plants.

While the idea of using sunlight to sterilize objects and waste isn't new, the use of fiber optic cables to bring that concentrated solar power to a location where it can be used is unique. Linden points out that it is a truly interdisciplinary project as well, bringing together chemical engineers for heat transfer and solar energy work, environmental engineers for waste treatment and stabilization, mechanical engineers to build actuators and moving parts and electrical engineers to design control systems.

The Gates Foundation also funded trips for the team at CU-Boulder to travel to Switzerland, South Africa and North Carolina to collaborate with other researchers. “It is one thing to do research," Linden said, "and another to screw on nuts and bolts and make something that can make a difference." With so many brilliant minds working tirelessly on the issue of sanitation, they are well on their way to doing so.

What crazy apps and gadgets have you come across lately? Let us know by emailing us at or by telling us in the comments below.

Katherine Gray

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Katherine Gray is a freelance writer, photographer and desktop publisher based in western Maryland.