Bill and Melinda Gates want you to build them a new toilet

"That's strange," you might be thinking. "Surely the Gates can afford the very best that the wide world of toilets has to offer." And you'd be right — but that still wouldn't make their toilet that much better than anyone else's. In fact, odds are high that the Gates' toilet is probably pretty similar to your toilet, my toilet, and just about everyone else's toilet. Everyone, that is, besides the estimated 1.1 billion people worldwide who have no toilets at all.

See, the basic water-flush design of the toilet and its connection to a sewage or septic system has actually been around since the late 18th century; and from a functional standpoint not a lot about this concept has changed. But for much of the world, especially where fresh water and sanitation are major issues, our outdated toilet technology is utterly impractical. We need toilets that work in parts of the world without sewage systems and running water — and that can transform waste into energy, clean water, and nutrients.

That's why the Gates want a new toilet, and are offering millions of dollars to people building one.

To achieve this, the Gates posed their Reinvent the Toilet Challenge:

The Water, Sanitation & Hygiene program of the Bill & Melinda Gates Foundation recently challenged 22 universities to submit proposals for how to invent a waterless, hygienic toilet that is safe and affordable for people in the developing world and doesn't have to be connected to a sewer. Eight universities were awarded grants to "reinvent the toilet."

Here are the eight universities and scientists awarded grants to reinvent the ancient technology of the toilet, and the innovative ways they're aiming to do so, as described in the WSH: Reinvent the Toilet Challenge Fact Sheet:

1. A toilet that produces biological charcoal, minerals, and clean water
Professor M. Sohail of Loughborough University and his team propose to develop a toilet to transform feces into a highly energetic combustible through a process combining hydrothermal carbonization of fecal sludge followed by combustion. The process will be powered by the heat generated during the combustion phase and will recover water and salt from feces and urine.

2. Turning the toilet into an electricity generator for local use
Professor Georgios Stefanidis and his team at Delft University of Technology propose to develop a toilet system that will apply microwave technology to transform human waste into electricity. The waste will be gasified using plasma, which is created by microwaves in tailor-made equipment. This process will yield syngas, a mixture of carbon monoxide (CO) and hydrogen (H2). The syngas will then be fed to a solid oxide fuel cell stack for electricity generation. This toilet system will be able to serve single households or groups of households.

3. A urine-diverting toilet that recovers clean water on site
Professor Tove Larsen of the Swiss Federal Institute of
Aquatic Science and Technology and Dr. Harald Gründl of the industrial design company EOOS propose to design and construct a functional model of a urine-diverting toilet that recovers water and is user-friendly, attractive, hygienic, and provides water for cleansing.

4. A community bathroom block that mineralizes human waste and recovers clean water, nutrients, and energy
Professor Christopher Buckley and his team at the University of Kwazulu-Natal propose to design, prototype, and evaluate a toilet system that can safely dispose of pollutants and recover valuable materials such as water and carbon dioxide from urine in community bathroom blocks.

5. A community scale biochar production plant fed by human waste
Brian Von Herzen of the Climate Foundation and Professor Reginald Mitchell of Stanford University in Palo Alto, California, propose to design, build, and test a self- contained system that pyrolyzes (decomposes organic material at high temperatures without oxygen) human waste into a type of biological charcoal (biochar) that is used for carbon capture and storage. The system will be able to process two tons of human waste daily at a facility located in the slums of Nairobi.

6. A toilet that uses mechanical dehydration and smoldering of feces to recover resources and energy
Professor Yu-Ling Cheng and her team from the University of Toronto Department of Chemical Engineering and Applied Chemistry propose to develop a technology for treating solid waste streams through mechanical dehydration and smoldering that will sanitize feces within 24 hours. They also intend to develop a method for sanitizing urine through membrane filtration and ultra- violet disinfection. Their third area of research will be on user-centric design to determine a preferred interface that creates demand to use the toilet technology.

7. A solar-powered toilet that generates hydrogen and electricity for local use
Professor Michael Hoffman of the California Institute of Technology proposes to design a self-contained, solar-powered domestic toilet and wastewater treatment system. The solar panel will convert the sun's rays into enough energy to power an electrochemical reactor that Hoffmann designed to break down water and human waste into hydrogen gas. The gas can then be stored in hydrogen fuel cells to provide a backup energy source for nighttime operation or for use under low-sunlight conditions.

8. A pneumatic flushing urine-diversion dehydration toilet
Professor How Yong Ng and his team at the National University of Singapore propose to research the development of a decentralized modified pneumatic flushing urine-diversion dehydration community toilet block for five to six households with separate collection and treatment of urine and feces to recover water and nutrients. The toilet system will recover energy from feces combustion and clean water from advance adsorption desalination.

You can read more about the Reinvent the Toilet Challenge and the Water, Sanitation, and Hygiene Program over at The Gates Foundation.