Solar
Sponge
Submitted by
Aravind K.A. (A6429713001)
Generating steam is enormously useful. Much of the
world's energy actually comes from steam--coal power plants heat up water to
produce water vapour, which turns turbines to generate electricity. A new
technology creates steam by harnessing solar energy, using a relatively cheap
sponge-like material, and it does it with greater efficiency that ever
previously achieved, according to a study.
The researchers don't claim the device could
be used to create electricity, at least not yet. But it could relatively easily
be scaled up to make fresh water out of salt water via distillation, for
example, or to sterilize medical or food-processing equipment in areas of the
world where electricity is hard to come by, said MIT researcher Hadi
Ghasemi .
The spongy device is made of graphite on top,
with carbon foam on the bottom. The graphite is highly porous and fractured, a
crown of flakes, created by putting the material in a microwave oven
and allowing bubbles to come to the surface and burst, in a way "just
like popcorn," the researchers said. Graphite absorbs the sun's
rays and heats up. This creates a pressure differential that sucks water from
the bottom into the top, where it vaporizes. This sponge converts 85 percent of
the solar energy in sunlight it absorbs into heat, the authors wrote in
the study, which is extremely efficient.
Current methods to create steam involve
heating liquids or using a system of mirrors to concentrate sunlight, which are
both more expensive and inefficient--whereas the graphite and carbon used in
this sponge are relatively easy to get your hands on, the scientists
said.
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