[permaculture] This Black Sponge Isn't Dirty, It's Making Cheap, Solar-Powered Drinking Water | Co.Exist | ideas + impact

Lawrence London lfljvenaura at gmail.com
Mon Aug 4 15:30:00 EDT 2014

This Black Sponge Isn't Dirty, It's Making Cheap, Solar-Powered Drinking
Water | Co.Exist | ideas + impact

A new sponge-like system could be an alternative to expensive water
desalination plants.

n drought-stricken California, a giant billion-dollar desalination plant
<http://carlsbaddesal.com/> is now under construction, and 15 others are
proposed along the coast. While the plants could help provide desperately
needed water, the current technology has at least two major problems: it
uses a lot of energy <http://www.fastcoexist.com/explore/energy>, and it's
very expensive. An alternative now in the early stages of development at MIT
<http://www.fastcoexist.com/organization/mit> might help.

The new technology looks a little like a sponge. A black material, made
from graphite and filled with tiny holes, floats on top of water, soaking
up sunlight. As the material heats up, it heats up a small area of water
around it, and a layer of foam at the bottom keeps everything hot. The
water starts to turn into steam that could be used for everything from
drinking water to sterilization in places off the grid.

"The most exciting thing is it's simple," says Gang Chen, head of the
mechanical engineering department at MIT. "You could even hand-build this.
It could be done with a simple manufacturing process
<http://www.fastcoexist.com/explore/manufacturing-process>--and that can
lead to lower cost."

Unlike a typical large-scale desalination plant, which has to be hooked up
to huge amounts of electricity
<http://www.fastcoexist.com/explore/electricity>, the new technology is so
efficient that it could in theory be used anywhere around the world,
relying solely on the sun.

The system could also be used to generate ultra-efficient, cheap solar
thermal power. Right now, large solar thermal plants--like the enormous
Solana Generating Station in Arizona, which sprawls over three square
miles--make electricity
<http://www.fastcoexist.com/explore/make-electricity> by using a expensive
system of mirrors that track sunlight throughout the day. MIT's technology
may someday be able to generate that same power without all of the extra
equipment <http://www.fastcoexist.com/explore/extra-equipment>.

The next step for researchers will be figuring out whether it makes sense
to focus on desalination first, or renewable energy
<http://www.fastcoexist.com/explore/renewable-energy>, and then working on
the details of the design.

Will it be ready soon enough for places like California to potentially
avoid investing billions more in energy-hungry desalination plants
<http://www.fastcoexist.com/explore/energy-hungry-desalination-plants>? "In
terms of really taking this into a commercial system, it's hard to put a
timeframe on the technology," Chen says. "But overall the principle is
simple enough . . . it really depends on whether we decide it's
desalination or power we should pursue. That will happen in the next year
or two."

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