Toilets are a waste.

They are also simply out of reach for 2.6 billion people in developing nations, says the United Nations Children's Fund (UNICEF). That's how folks who use no-tech alternatives like buckets or holes in the ground. Such lack of sanitation leads to typhoid, cholera, dysentery, and other diseases.

So last summer the Bill and Melinda Gates Foundation spread $3 million in grants among eight research teams in North America, Asia, Africa and Europe, reports the Scientific American. This challenge is part of Gates' pledge last summer to spend $42 million to reinvent the toilet.

The teams were given these guidelines: come up with a toilet alternative that doesn't need plumbed water, a sewer system, electricity and will cost 5 cents or less per user daily to build and maintain.

The teams delivered.

The Dutch team's idea uses microwaves to turn human waste into carbon monoxide and hydrogen that in turn could become fuel stacks to generate electricity.

The British team is working on a way to turn waste into bio-charcoal.

The Canadian team dehydrates the stuff by running it between rollers over smolders.

The U.S. team proposed a solar powered toilet that converts waste into hydrogen for fuel cells.

The foundation also wanted teams to include an "inspirational element" to their designs to get people to want to use these newfangled toilets. Frank Rijsberman, director of the initiative, told Scientific American that the ultimate design would be so desirable, it would be like the "iPad of sanitation," he said.

An iPad-like toilet funded by the founder of Microsoft. What more could a full digestive system want?