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Mining the seas for energy
by MARK ST.J. COUHIG
Pacific Northwest National Laboratory has a new task in hand: testing prototype materials that could turn the world’s oceans into a vast uranium mine.
Don’t get nervous.
The uranium is already there — an estimated 4.5 billion tons of it. But the oceans are vast: the uranium is present at just 3 parts per billion.
The trick is extracting it in sufficient amounts to make the process economically feasible.
The payoff, too, could be vast: enough uranium to potentially fuel the world’s nuclear power plants for 6,500 years.
Sequim researchers are working with their colleagues at Oak Ridge National Laboratory to develop a new material — an “adsorbent” — to make the process more efficient and more cost-competitive.
The latest American-made materials take advantage of earlier work done in Japan.
The technology Japanese researchers pioneered uses long mats of braided plastic fibers embedded with uranium-absorbent amidoxime to capture trace amounts of uranium in the ocean. The mats are placed 200 meters underwater to soak up uranium before being brought to the surface.
They are then washed in an acidic solution that captures the radioactive metal for future refinement.
To make this process more economical, U.S. researchers use plastic fibers with 10 times more surface area than the Japanese design, allowing for a greater degree of absorption.
PNNL tested the adsorbent materials using filtered seawater from Sequim Bay, with initial tests showing the Oak Ridge adsorbent can soak up more than twice the uranium of the Japanese material.
The new design cuts the cost of extracting uranium from seawater from $1,232 to $660 per kilogram.
The results were presented at the fall meeting of the American Chemical Society, which ran Aug. 19-23 in Philadelphia.
ORNL chemical engineer Costas Tsouris presented the research team’s findings, while Sequim PNNL chemical oceanographer Gary Gill presented a poster on the PNNL testing program.
Gill said the work is all part of a larger effort by the Department of Energy to find new sources of nuclear fuel.
Gill said the Japanese have been very cooperative. “They even shared some of their materials so we could test it.”
Currently the lab is completing its second year in the three-year project. “If (DOE has) met their goals, they’ll probably extend it for another three years,” Gill said.
That may be sufficient time to provide “proof of concept,” he said. But commercial applications are still far off. “Maybe five or 10 years,” he said.
Reach Mark Couhig at email@example.com.