Caltech Team Develops Solar Powered Toilet
This might be the last place you'd expect solar power to change your life. | Photo: Epsos.de/Flickr/Creative Commons License
More than two and a half billion people on the planet lack access to
sanitary facilities, and the resulting contamination of drinking water
is responsible for one of the leading causes of deaths among the worlds
infants and children. But a team of Caltech engineers, with funding from
Bill and Melinda Gates, may have a partial solution to the problem --
and the whole thing runs on solar power.
Dehydration from diarrhea is the second
largest cause of global infant mortality, after respiratory ailments,
and 88% of life-threatening diarrhea worldwide is caused by drinking
contaminated water. A child somewhere in the world dies from drinking
impure water every 30 seconds.
In the developed world we can go about our bodily functions without
thinking: we have fresh water piped into our (often wasteful) flush
toilets, which then take the resulting waste away so that it can,
theoretically, be treated and made less harmful. Though our system is
far from perfect, and has significant pollution effects of its own, it
has made possible a revolution in public health: hardly anyone in the
industrial world dies of waterborne diseases anymore.
But much of the world has access to neither fresh water nor a safe
sewage system, and the Bill and Melinda Gates Foundation, through its "Reinventing the Toilet"
program, is trying to create off-the-grid ways for people to answer the
Call of Nature without polluting that nature, or their neighbors'
drinking water. The Gates Foundation has raised an engineering
challenge: can we build a toilet that doesn't require a sewer hookup, a
water source, or grid power, and costs five cents a day or less to
operate, but which doesn't pollute the air or water?
A team from Caltech just won a challenge held as part of that
campaign with its solar-powered toilet. Engineer MIchael Hoffman and his
colleagues took their design to the Gates Foundations' "Reinvent the
Toilet Fair," held this week in Seattle, and walked away with the
$100,000 prize for the best design.
The Caltech design uses a photovoltaic panel to generate energy,
stored in batteries, to power an electrostatic unit that purifies
liquids drawn from a small septic tank. The unit produces hydrogen as it
cleans the water, potentially a supplementary source of toilet power on
cloudy days or at night. The unit also purifies the solid waste which
can then be used as biofuel or fertilizer. (Keep reading...
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