SEATTLE - These aren't your typical loos. One uses microwave energy to transform human waste into electricity. Another captures urine and uses it for flushing. And still another turns excrement into charcoal.
They are part of a Bill & Melinda Gates Foundation competition to reinvent the toilet for the 2.6 billion people around the world who don't have access to modern sanitation.
Scientists from around the world have taken up the challenge and the foundation planned to announced Tuesday which projects would be getting more money to take their ideas from the lab to cities.
Local entrepreneurs will use the new technology to turn pollution into cash.
To pass the foundation's threshold for the world's next toilet, it must operate without water, electricity or a septic system, not discharge pollutants, preferably capture energy or other resources and operate at a cost of 5 cents a day.
The United Nations estimates disease caused by unsafe sanitation results in half the hospitalizations in the developing world. About 1.5 million children die each year from diarrheal disease.
Scientists believe most of these deaths could be prevented with proper sanitation, along with safe drinking water and improved hygiene.
The foundation expects to field test its first prototypes within three years.
Most of the prototypes on display this week in the open courtyard of the foundation's Seattle headquarters turn solid waste into energy. This is both a practical and pragmatic solution to the solid waste puzzle, said Carl Hensman, program officer for the foundation's water, sanitation and hygiene team.
The roughly $42 million project started just about a year ago and Hensman said they decided to hold a toilet fair this week to show how far the scientists have gotten in that time. Among those scheduled to attend the toilet fair were government ministers from African nations, utility workers and potential financial partners like UNICEF and Oxfam.