Scientists
today reported progress toward a 40-year-old dream of extracting
uranium for nuclear power from seawater, which holds at least 4 billion
tons of the precious material. They described some of the most promising
technology and an economic analysis showing uranium from the oceans
could help solidify nuclear energy potential as a sustainable
electricity source for the 21st century. Their reports were part of a
symposium at the 244th National Meeting & Exposition of the American
Chemical Society, the world’s largest scientific society, being held
here through Thursday.
“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,” said Robin D. Rogers, Ph.D., who organized the
symposium and presented his own technology. “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.”
Erich
Schneider, Ph.D., another speaker at the symposium, discussed an
economic analysis done for the U.S. Department of Energy (DOE) comparing
seawater extraction of uranium to traditional ore mining. It shows that
DOE-funded technology now can extract about twice as much uranium from
seawater as the first approaches, developed in Japan in the late 1990s.
That
improvement reduces production costs down to around $300 per pound of
uranium, from a cost of $560 per pound using the Japanese technology.
However, extraction from seawater remains about five times more
expensive than uranium mined from the ground.
Schneider
explained, however, that the current goal is not to make seawater
extraction as economical as terrestrial mining. Instead, scientists are
trying to establish uranium from the ocean can act as a sort of
“economic backstop” that will ensure there will be enough uranium to
sustain nuclear power through the 21st century and beyond.
Nuclear
power plants, he noted, are built to operate for 60 years or longer and
involve a huge investment. In 2008, for instance, one energy company in
Florida estimated it would cost more than $14 billion to build a new
two-reactor plant. Before making that kind of outlay, energy companies
want assurance that reasonably priced uranium fuel will be available on a
century-long time frame.
“This
uncertainty around whether there’s enough terrestrial uranium is
impacting the decision-making in the industry, because it’s hard to make
long-term research and development or deployment decisions in the face
of big uncertainties about the resource,” said Schneider. “So if we can
tap into uranium from seawater, we can remove that uncertainty.”
Another
advantage of seawater extraction could be avoiding some of the
environmental costs of extracting uranium ore. Like other kinds of
mining, recovering uranium can produce contaminated wastewater, impact
the environment and have health consequences for miners.
The
Japanese technology uses mats of braided plastic fibers embedded with
compounds designed to capture atoms of uranium. The mats are 50-100
yards long, and suspended 100-200 yards below the surface. When brought
to the surface, the mats get a rinse with a mild acid solution that
captures the uranium for recovery. The mats then go back down in a cycle
that can be repeated several times.
Rogers
said the next steps are to improve both parts of the adsorbent system,
the plastic substrate and the compounds that lock onto uranium. His
research group is testing waste shrimp shells from the seafood industry
to make a biodegradable sorbent material.
Source: American Chemical Society
