Engineering On The Edge

If you’ve visited the Bill & Melinda Gates Foundation website lately, you know exactly where the Microsoft founder’s mind has been: the toilet.

The CalTech solar toilet. Image: Gates Foundation

In July, the Gates Foundation rolled out its Reinvent the Toilet Challenge, an international effort to bring alternative sanitation technology to the developing world. Improper sanitation and waste disposal lead to millions of deaths each year, with the lack of suitable toilets leading to the spread of disease and fouled drinking water. The Gates Foundation has tasked teams of engineers and scientists with developing low-cost, sustainable toilets that don’t require electricity, running water, or a sewer hook up, and that can operate on 5 cents per day or less.

The first grants were announced in July, and grantees unveiled their prototypes at an August “Reinvent the Toilet Fair” in Seattle. The winning team from CalTech took the top prize of $100,000 for their solar-powered latrine that converts waste into hydrogen and electricity. The concept marries engineering with biology and chemistry.

The CalTech entry, developed by lead engineer and professor Michael Hoffman, uses a photovoltaic or solar panel to convert sunlight into enough energy to power an electrochemical reactor that Hoffmann designed to break down water and human waste  into hydrogen gas. The gas is then stored in hydrogen fuel cells to provide a backup energy source for nighttime operation. The current model would cost around $2,000 to produce, but that figure would drop in a mass production scenario.

You can see a video demonstration of the unit below:

Source: Bill & Melinda Gates Foundation