Connect with us

Hi, what are you looking for?



Solar-Powered Toilet That Can Turn Waste Into Biochar

A toilet that can transform human waste into biochar, powered by nothing but the sun, has been developed by researchers at the University of Colorado Boulder.

The new technology was designed to address some of the sanitation issues that are common in many developing countries — and thereby help to protect local water supplies, and limit the spread of waterborne illnesses and diseases.

Image Credit: UC Boulder

Image Credit: UC Boulder

The self-contained unit works by using the energy of the sun, concentrated by eight parabolic mirrors, to heat up a quartz-glass rod that’s connected to eight bundles of fiber-optic cables, which then heat up the reaction chamber. The temperature in this chamber can reach over 600 degrees Fahrenheit — hot enough to sterilize human waste and produce biochar.

This new system was built and designed as part of the Gates Foundation’s “Reinvent the Toilet Challenge” using a $777,000 grant from the Bill & Melinda Gates Foundation. The ‘challenge’ was created as a means of developing solutions to the problems associated with human waste pollution. For example, more than 700,000 children die every year as the result of exposure to food and water tainted with pathogens from fecal matter. A cheap, effective means of dealing with human waste could go a long way towards limiting those numbers.

As far as the other side of this equation — for those that don’t know, ‘biochar’ is the term used to describe charcoal when it’s used for a number of specific purposes, such as a soil amendment. The researchers note that the widespread use of biochar could be used to both boost crop yields and to sequester carbon dioxide.

“Biochar is a valuable material,” stated researcher Karl Linden. “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. A soil mixture containing 10% biochar can hold up to 50% more water and increase the availability of plant nutrients. Additionally, the biochar can be burned as charcoal and provides energy comparable to that of commercial charcoal.”

The University of Colorado — Boulder provides more:

Tests have shown that each of the eight fiber-optic cables can produce between 80 and 90 watts of energy, meaning the whole system can deliver up to 700 watts of energy into the reaction chamber, said Linden. In late December, tests at CU-Boulder showed the solar energy directed into the reaction chamber could easily boil water and effectively carbonize solid waste.

While the current toilet has been created to serve four to six people a day, a larger facility that could serve several households simultaneously is under design with the target of meeting a cost level of five cents a day per user set by the Gates Foundation.

The CU-Boulder team is now applying for phase two of the Gates Foundation Reinvent the Toilet grant to develop a field-worthy system to deploy in a developing country based on their current design, and assess other technologies that may enhance the toilet system, including the use of high-temperature fluids that can collect, retain and deliver heat.

Interesting technology, though I do have questions about how likely it is to enter widespread use.

What do you think?

Appreciate CleanTechnica’s originality? Consider becoming a CleanTechnica member, supporter, or ambassador — or a patron on Patreon.
Have a tip for CleanTechnica, want to advertise, or want to suggest a guest for our CleanTech Talk podcast? Contact us here.

New Podcast: How NVIDIA Is Bringing Autonomy To Automakers

Written By

James Ayre's background is predominantly in geopolitics and history, but he has an obsessive interest in pretty much everything. After an early life spent in the Imperial Free City of Dortmund, James followed the river Ruhr to Cofbuokheim, where he attended the University of Astnide. And where he also briefly considered entering the coal mining business. He currently writes for a living, on a broad variety of subjects, ranging from science, to politics, to military history, to renewable energy.


#1 most loved electric vehicle, solar energy, and battery news & analysis site in the world.


Support our work today!


Power CleanTechnica: $3/Month

Tesla News Solar News EV News Data Reports


EV Sales Charts, Graphs, & Stats


Our Electric Car Driver Report

30 Electric Car Benefits

Tesla Model 3 Video

Renewable Energy 101 In Depth

solar power facts

Tesla News

EV Reviews

Home Efficiency

You May Also Like


In the United States only about 1.3 percent of all vehicles sold last year were battery powered. And about 90 percent of those sales...


In the second half of this CleanTech Talk interview, Michael Barnard sits down with Paul Werbos, Ph.D. Co-Director of the Center for Intelligent Optimization and Networks,...

Autonomous Vehicles

Researchers around the world on hard at work finding new ways to make Lidar sensors that are compact, scalable, and affordable. Toshiba may be...


When an electric vehicle (EV) comes off the road, what happens to the vehicle battery? The fate of the lithium-ion batteries in electric vehicles...

Copyright © 2021 CleanTechnica. The content produced by this site is for entertainment purposes only. Opinions and comments published on this site may not be sanctioned by and do not necessarily represent the views of CleanTechnica, its owners, sponsors, affiliates, or subsidiaries.