(Bloomberg News) When Bill Gates ran Microsoft Corp., he determined the fate of programs worth billions of dollars. The co-founder and former chief executive officer of the biggest software maker turned his attention yesterday to toilets.

With 1.5 million children a year dying of diarrhea related to poor sanitation in the developing world, billionaire Gates and his wife Melinda asked their foundation to focus on helping to create a next-generation commode that's suitable for countries with limited access to water and sewage lines, Bloomberg.com's Tech Blog reported.

"The topic we are discussing today can rightly claim to be the most neglected thing in all the things that are done to help the poor," Gates said yesterday at a ceremony to announce the top four projects at his foundation's Reinvent the Toilet Fair in Seattle. "The toilet that was invented 200 years ago, the flush toilet, really hasn't had that many milestone advances."

The Bill & Melinda Gates Foundation gave grants to eight institutions last year to develop low-cost loos that can be operated for 5 cents a day per user, don't require a connection to a sewer or water to flush, and are hygienic and sustainable for the world's poorest populations. The projects are also supposed to look at how the waste can be used to generate energy and recover salt, water and other nutrients.

Potties developed by the organizations that lined up funding last year, plus 27 other related projects built with the foundation's grants, were on display yesterday. The exhibits included fecal substitutes made from miso paste, which is meant to mimic the viscosity of human waste. The foundation purchased 50 gallons of the faux feces for use at the expo.

Solar Loo

Lamenting the lack of innovation in toilet design, Gates invoked Thomas Crapper, the plumbing company founder who helped popularize the modern toilet.

"If Crapper was born today, he'd find the toilet quite familiar," Gates said.

The winning entry went to the California Institute of Technology's solar-powered white ceramic toilet and stainless metal urinal combo. While it looked normal from above, underneath was a septic holding tank that separates solids and liquids before they move on to an electrochemical reactor that disinfects waste and generates hydrogen to be used as fuel.

Second place went to Loughborough University, based in the U.K., whose system is essentially a pressure cooker for human waste.

Biological Charcoal

A long metal tube called a hydrothermal carbonization reactor turns feces into a brown dust called biological charcoal that looks and smells like coffee grounds and can be used as soil or fertilizer. The system also generates clean water from urine and feces, as well as energy by combusting the biological charcoal.