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Solar toilet gets backing from leading plumbing firm

A team of Caltech researchers have been developing a solar-powered toilet for years, and now have backing from global plumbing giant Kohler.

In August 2012, environmental science professor Michael Hoffmann and his colleagues won the Bill and Melinda Gates Foundation’s Reinventing the Toilet Challenge, which aims to tackle the problem of sanitation for the 2.5 billion people around the world without access to sanitary toilets.

The Caltech team’s toilet can safely dispose of human waste for just five cents per user per day, without a septic system or an outside water source.

This toilet uses PV solar to power an electrochemical reactor, which breaks down water and human waste into fertilizer and hydrogen. The hydrogen can be stored as energy in fuel cells and the treated water can be reused to flush the toilet or for irrigation.

Graduate student Clement Cid with the Caltech team's solar-powered toilet. Credit: Caltech

Graduate student Clement Cid with the Caltech team’s solar-powered toilet. Credit: Caltech

The team have used the Reinventing the Toilet Challenge grant money to keep developing the system, and now have support from one of the world’s leading plumbing and bathroom product companies. Kohler will provide the Caltech team with design expertise and plumbing products, as well as technical support when the system is trialled in India.

“I am thrilled to have the support of Kohler Co. as we move forward with the Gates Foundation to provide better sanitation options in the developing world,” says Michael Hoffmann, Caltech’s James Irvine Professor of Environmental Science.

“It is exciting and certainly an honor for us to work with the Caltech team, who are true pioneers of their time,” says Rob Zimmerman, Kohler Co. sustainability marketing manager.

“Kohler is known for pioneering innovative products and helping to advance technology, and through the Gates Foundation challenge, we get the opportunity to support others in their efforts to push traditional systems to a new level.”


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