Bill Gates Wants To Reinvent The Toilet: Solar Power Wins

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

by Tina Casey, via CleanTechnica

How’d this one slip past us? Last week, the Bill and Melinda Gates Foundation announced the winners of its Reinvent the Toilet Challenge and the top prize went to a souped up, solar-powered model that produces hydrogen and fertilizer. If you’re thinking this sounds like another pricey high-tech green gadget for next-generation McMansions, think again: the aim of the challenge is to kickstart the development of low cost toilets for the 2.5 billion people worldwide who don’t have access to modern sanitary facilities.

U.S. Captures Top Toilet Prize

The top winner was produced by the California Institute of Technology. The Caltech team won a $400,000 grant last year to produce a toilet that can operate without running water, does not discharge into a septic tank, and does not generate pollutants — all for about five cents per user per day.

As the winner of the Reinvent the Toilet challenge, the team gets another $100,000 to fine-tune the device, which is a bit more complicated than your ordinary pot.

When CalTech’s toilet is flushed, the water and waste collect in a small tank called an electrochemical reactor. Powered by solar panels, the reactor breaks down waste into hydrogen gas, water, and solids.

The gas can be used to generate electricity from hydrogen fuel cells; the treated water can be used for irrigation or to flush the toilet; and the solids are rendered into an inert, organic material suitable for use as a fertilizer.

More Goodies from Beyond the Toilet Bowl

Other prize-winning entries came up with designs for toilets that create charcoal and other waste-to-energy products, and capture minerals along with reclaiming water.

All this activity won’t come as a surprise to regular readers of CleanTechnica, where wastewater reclamation is one of our favorite things to talk about. After all, the idea of recovering energy from people going about their daily business is pretty cool, kind of like the Matrix, only not.

In terms of the large-scale municipal sewage treatment plants that dot the landscape, the US is becoming a regular hotbed of sewage resource recovery and sustainable land use (some of those treatment plants cover a lot of acreage). Aside from producing fertilizer and usable water, some of the projects in development or well underway are biogas, biodiesel, bioplastic, solar power, and of course wind power.

We’ve also covered the work of Kartik Chandra, a Columbia University professor who has carved out a name for himself in the wastewater field with a study on reducing greenhouse gas emissions from treatment plants. Chandra has contributed to the development of a system using recovered ammonia to grow bacteria for biofuel, and last summer he received a Gates Foundation grant to produce a low cost municipal wastewater system that generates biodiesel and natural gas for communities in undeveloped areas.

On top of that, the Obama Administration has been getting behind the waste-to-energy trend in agriculture, encouraging dairy farms and other livestock operations to install equipment that generates methane gas and fertilizer from raw manure.

Aside from cutting down on waste disposal costs and reducing environmental hazards, the digesters provide farmers with low-cost energy and a potential new revenue stream. Try that with a lump of coal.

Just sayin’.

Tina Casey specializes in military and corporate sustainability, advanced technology, emerging materials, biofuels, and water and wastewater issues. This piece was originally published at CleanTechnica and reprinted with permission.

4 Responses to Bill Gates Wants To Reinvent The Toilet: Solar Power Wins

  1. Mark Spohr says:

    I’m somewhat confused about this competition which seems to have produced a bunch of very complicated toilets which will be difficult to produce and maintain.
    They also don’t seem to have any advantage over the basic composting toilet design which has been in use for many years and which is simple, reliable and can operate without power or can be solar powered for greater capacity.

  2. Sharolyn Molle says:

    The GYTTE organization in Mexico has used Dry Composting Toilets for years. You can read all about their design, construction, use, and maintenance at Why use water if you don’t have to?

  3. Brooks Bridges says:

    I have a fairly clear memory of Rosalynn Carter describing how grateful people were in some villages to be introduced to the idea of pit toilets and a modicum of privacy. And how much the health of the village improved.

    The design has to take into account people at this level of technology.

    I see, for instance, this system being quickly overwhelmed by a large number of users. Or what about a few users with diarrhea?

  4. Georgiy Potulov says:

    Oh good ole Bill Gates.. Now we know what you think of us “crappers” lol. Does he realize that those toilets are going to be stolen and sold for pieces in 3rd world countries and it ain’t going to help out bank accounts worth shit? Maybe he can invest that 2.5 B on jobs!