permaculture

[Lawrence London <lfljvenaura@gmail.com>]

Environment / Ocean
http://discovermagazine.com/2004/oct/hydrates-hydrates-everywhere
Hydrates, Hydrates Everywhere
A geophysicist revisits a provocatively simple—and previously
unworkable—process for extracting freshwater from the sea
by David Wolman, Photography by Adam Friedberg
>From the October 2004 issue; published online October 1, 2004

"Something strange is brewing inside a former ice-cream factory on
Florida’s Gulf Coast. There, in a small marine laboratory, stands a
clear tube, 6 feet high and 8 inches in diameter, filled with ordinary
seawater from the mouth of Tampa Bay. The only sound is the hum of a
high-pressure water pump. Ethane, a hydrocarbon gas, is fed into the
bottom of the tube. Within minutes tiny crystal shards float to the
surface. To the untrained eye they look like bubbles, but the
magnified picture on a nearby video monitor shows an icelike
consistency. “At first we thought it was dust or something,” says
Sarah Holman, a chemical engineer. “Now we know it’s hydrate, and it’s
forming almost immediately.” Gradually, larger masses begin to form. A
layer of frosty material gathers at the top of the tank, like salt on
the rim of a giant margarita. As more and more accumulates, it begins
to look like an Italian ice slowly filling the top of the tank.

This is the first step in what could be a revolution in wringing
freshwater from the sea. When hydrates form, even in the ocean, salt
is excluded from the crystalline structure. Melt the hydrate and it
separates into distilled water and gas. Build a large enough
structure—say, a tube a thousand feet or longer on the shore or in the
sea itself—and you could provide freshwater for an increasingly arid
planet, which could quite literally change the world. That is exactly
the result Marine Desalination Systems founder Michael Max is gunning
for."