Future of Nuclear Energy

The Future of Nuclear Energy Could Be Seawater Uranium

Under the sea, there's a world filled with uranium. Now, just to get it out.

By David Grossman

Usually if you want to get uranium, you're going to have to do some mining. However, a new study out of Stanford suggests an unusual and potentially major source of uranium in the future: seawater.

Scientists have long known that trace elements of uranium exist in seawater, which covers approximately seventy percent of the Earth's surface in case you forgot the exact, impressive percentage. Furthermore, since 1983 scientists have been aware of an extraction method. Uranium dissolved in seawater combines chemically with oxygen to form uranyl ions that poses a positive charge. From there, if you dip plastic fibers containing a compound called amidoxime into seawater, you can extract these uranyl ions.

So why aren't there uranium mines dotting the oceans? Cost and effectiveness. "Concentrations are tiny, on the order of a single grain of salt dissolved in a liter of water," said Yi Cui, a Stanford materials scientist and co-author of a paper in Nature Energy. Many, many urayl ions would be needed to run a power station.

The questions—which Cui and his co-authors, including Stephen Chu, fresh from a stint running the Department of Energy aim to answer—are threefold: How much uranyl sticks to the fibers? How quickly can ions be captured? How many times can the fibers be reused?

Their solution? To create a conductive hybrid fiber incorporating carbon and amidoxime. The conductivity of the fiber is key. By sending electrical pulses down the fiber, the properties of the hybrid fiber are altered so that more uranyl ions can be collected. Testing proved the construction had merit. When electrified in California's scenic Half Moon Bay, the Stanford fiber was able to capture three times as much uranyl during an 11-hour test.

Of course, it's more than access to uranium that is holding back nuclear power. Incidents like Fukushima still weigh large in the public's mind. The general state of nuclear power in America is slow, over-budget, and economically untenable. Issues of nuclear waste remain political flashpoints. But Chu believes that these issues can be either be worked on in parallel or be eased by greater access to uranium.

"For much of this century," he says in a press statement, "some fraction of our electricity will need to come from sources that we can turn on and off. I believe nuclear power should be part of that mix, and assuring access to uranium is part of the solution to carbon-free energy."