Progress in sea uranium extraction
Extracting uranium from seawater is closer to becoming an economic reality which could guarantee the future of nuclear power, scientists say.
The world's oceans hold at least four billion tons of the precious metal. But for the past four decades, the goal of mining seawater for uranium has remained a dream because of the technical difficulties and high cost.
A report presented to a scientific meeting showed that fast progress is being made towards turning the oceans into a uranium reservoir.
Improvements to the extraction technology have almost halved production costs from around 560 dollars (£355) per pound of uranium to 300 dollars (£190).
Dr Robin Rogers, from the University of Alabama, told the annual meeting of the American Chemical Society in Philadelphia: "Estimates indicate that the oceans are a mother lode of uranium, with far more uranium dissolved in seawater than in all the known terrestrial deposits that can be mined.
"The difficulty has always been that the concentration is just very, very low, making the cost of extraction high. But we are gaining on that challenge."
The standard extraction technique, developed in Japan, uses mats of braided plastic fibres embedded with compounds that capture uranium atoms.
Each mat is 50 to 100 yards long and suspended 100 to 200 yards under the water. After being brought back to the surface, the mats are rinsed with a mild acid solution to recover the uranium. They are then dunked in the water again in a process that can be repeated several times.
The new work involves making cheaper and more efficient versions of the mats and the compounds that latch onto uranium.
A team led by Dr Rogers is exploring the use of waste shrimp shells from the seafood industry to produce a biodegradable mat material.