Nuclear power is looked upon as a replacement for fossil fuels in the future. To increase the share of nuclear power in the total power mix, extracting uranium from seawater has to graduate into a reality from the level of an idea.
It is exciting as an idea but at the practical side is hamstrung by many challenges including the low yield of uranium from seawater.
However, scientists are working on a rapid breakthrough in the process, in the hope that it will open up a new source of clean energy and help many power-starved counties to access nuclear power even if they lack uranium mines at home.
Uranium In Seawater
Seawater has a moderate presence of uranium. According to estimates, uranium atoms constitute 3.3 parts per billion or 3.3 micrograms per liter.
"Concentrations are tiny, on the order of a single grain of salt dissolved in a liter of water," said Yi Cui, a materials scientist, and co-author.
The paper has been published in Nature Energy.
Steven Chu, co-author of the paper also noted that there is more promise from nuclear power as a clean energy source.
Globally, nuclear power constitutes 13 percent of all electricity produced and its share in the U.S is 20 percent.
Innovation In Extraction
In the sea water related extraction, Stanford researchers made significant progress by developing conductive hybrid amidoxime fibers that are advanced in leaching uranyl ions from water.
Uranyl ions carrying positive charge are formed by the reaction of uranium in the seawater with oxygen. They are extracted by inserting plastic fibers containing amidoxime into seawater for making the uranyl ions stick on it.
Once the fibers are saturated, chemical treatment of the plastic follows to release uranyl for use in reactors after due refinement.
Three factors are crucial to the success: volume of uranyl sticking to the fibers, the speed with which ions are captured and frequency of reuse allowed by the fibers.
The researchers were able to induce more efficiency on all fronts: capacity, capture rate, and reuse. The conductive hybrid fiber comprising carbon and amidoxime with improved capacity has been the turning point in the innovation by Stanford team.
The efficiency of Stanford's amidoxime-carbon hybrid fibers is well illustrated by the comparable performance with common place amidoxime fibers.
The saturation capacity differs in both fibers. Amidoxime-carbon hybrid fibers can collect nine times more uranyl than the ordinary amidoxime fibers.
It was further proved in a long drawn test conducted with Half Moon Bay seawater. The test showed the innovated fibers of Stanford capturing three times more uranyl with a lifespan higher than the standard amidoxime fibers.
Chong Liu who supervised the lab tests said more steps are needed on reactor safety and waste disposal issues even while stepping up research on uranium extraction from sea water.
"We have a lot of work to do still but these are big steps toward practicality," added Liu.
Given nuclear energy's low carbon footprint is a perennial attraction, extracting uranium from seawater on a commercial basis will be imperative and open up an era of cleaner, cheaper, and affordable power to all countries.
The progress in extracting uranium in big quantities in a limited time will make nuclear power a broad component of the carbon-free energy of the future.
Among renewable energy forms, the wind and solar energy are contributing to the reduction of carbon emissions and their operating costs are also plunging. But the flexibility of nuclear power in meeting any peaking demand without carbon emissions makes it an all time choice.
Currently, uranium resources are restricted to Kazakhstan, Canada, and Australia with some small mines existing in other countries.