University of Colorado–Boulder scientists, including Tesfayohanes Yakob (left) and Dana Haushulz (right), have fabricated a novel solar-thermal toilet that doesn’t need water and can generate useful biochar. Credit: University of Colorado.
Everyone poops. Thankfully, sanitation systems have done wonders to carefully separate wastes from our everyday lives in most developed parts of the world. “Plumbing has made an extraordinary but little recognized contribution to human health,” states the World Plumbing Council’s website.
But nearly 2.5 billion people around the world still don’t have access to adequate sanitation, according to the Bill & Melinda Gates Foundation. That lack of sanitation is a big problem for both public health and the environment.
To address these global concerns, the Gates Foundation initiated a “Reinvent the Toilet Challenge” in 2011, with the goal of developing toilets that don’t rely upon water, sewer, or electrical system connections. The idea is to invent a system that can be implemented simply and feasibly, without relying upon developed infrastructure. Read more about the challenge here (pdf).
Using funds from a Reinvent the Toilet Challenge grant, a team of scientists at the University of Colorado–Boulder built a self-contained, waterless porcelain princess that harnesses the power of the sun to sterilize and reuse human wastes.
The interdisciplinary team includes chemical, environmental, mechanical, and electrical engineers and is led by environmental engineering professor Karl Linden. As he explains in the press release, “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. 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.”
The char he refers to is biochar, and is one of the interesting perks of this solar-powered throne. In addition to providing a sanitary means to contain and disinfect human waste, the commode turns that waste into a porous charcoal material that has fertilizing capabilities.
“Biochar is a valuable material,” Linden says in the press release. “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.” Mixing just a small amount of biochar into the soil can drastically increase water-holding capabilities, leading to increased crop yields. Biochar also can be burned as fuel, helping to solve other environmental problems as well.
The system collects solar energy and transfers it to the commode with fiber-optic cables. Linden says that the fiber-optic cables can each produce about 80–90W of energy, for a total energy output of 700W to the reaction vessel. The team has tested the system and shown that it can collect enough energy to “easily boil water and effectively carbonize solid waste.”