Uranium in sea water 'could be used as nuclear fuel'

[Ed Barrow]

Experts estimate that the oceans contain billions of tons of uranium that could be used in nuclear power stations. So far, however, it has proved too difficult to extract. A US team is now developing special chemicals that can ''grab'' uranium ions - electrically charged molecules - from seawater. Currently uranium is extracted from scarce solid ores such as uraninite.

Dr Orion Berryman, a member of the Scripps Research Institute team from La Jolla, California, said: ''There is about 4.5 billion tons of dissolved uranium in the ocean. This is nearly 1,000 times more than the terrestrial uranium sources in the western world.

''Our work addresses the challenges of uranium extraction from a unique perspective - isolating the uranium atom from its native environment through encapsulation.''

The scientists are creating ''ligands'' - chemicals that bind to specific molecules - with a high affinity for uranium. The hope is that the research will lead to economical ways of extracting uranium from the oceans.

Seawater contains uranium at a concentration of just 0.003 parts-per-million, compared with 20,000 parts-per-million in high-grade uranium ore. However the volume of the world's oceans is so huge that seawater could still provide almost limitless amounts of the precious metal, say the scientists.


http://www.telegraph.co.uk/earth/energy/7809011/Uranium-in-sea-water-could-be-used-as-nuclear-fuel.html

[bananas]

1. Wind over sea water 'could be used as wind power'

http://www.treehugger.com/files/2009/09/surface-area-required-to-power-the-whole-world-with-solar-power-wind.php

[bananas]

2. Sunlight over sea water 'could be used as solar power'

http://www.treehugger.com/files/2009/09/surface-area-required-to-power-the-whole-world-with-solar-power-wind.php

[Dogmudgeon]

4. Chocolate syrup over bananas 'could be used as a Banana Split'

(Well, a different kind of bananas.)

Come on, admit it. You laughed.

--d!

[petronius]

3. Of course it could - if it wasn't dissolved in sea water

And the gold in the oceans would make us all rich, and the dissolved titanium would provide an endless supply of lightweight backpacking gear. Just gotta get it out... :)

Interesting study though, it'll be great if they can make it work.

[NNadir]

6. You are confusing several issues. First of all the expense of titanium has nothing to do with...

the availability of ore. Like aluminum ore, it is widely distributed and is in fact one of the largest single inorganic chemicals used in industry, all mined from highly concentrated ores.

Almost all of the white paint on Earth contains significant titanium dioxide.

The expense of titanium metal has to do with the process of reducing it, which involves chlorination, distillation, and heating in a batch retort for several days with an active metal, usually calcium. This is an expensive process and almost all currently available industrial quantities of titanium metal and titanium metal products have been produced in this way.

In the next several years, better processes are likely to be commercialized, resulting in cheap titanium metal. I recently wrote about that here:

http://www.democraticunderground.com/discuss/duboard.php?az=view_all&address=115x249984">Electrowinning of Titanium Metal in Molten Salts.

The idea of recovering uranium and gold from seawater is not new. Nobel Laureate and strange bird Fritz Haber worked extensively on gold recovery from sea water in the early 20th century.

The Japanese (and others) have written many papers on the technology of uranium recovery from seawater. A notable series is in Ind. Chem. Eng. Res.

Although gold can be isolated from sea water, the expense of the process is not justified by the price of gold.

The same situation is true of uranium. The Japanese have piloted aldoxime resin based recovery of uranium from sea water and have obtained kg quantities. However for the process - which is interestingly driven to overcome the Gibbs Free energy using solar energy, inasmuch as the process is driven by ocean currents - is more expensive than mining uranium from land formations. It can be shown the aldoxime resin process can recover enough uranium from intake pipes on cooling towers (ocean based) to recover about 1/4 as much uranium as they consume.

It can also be shown that the recovery of uranium from sea water becomes economic at a price of about $200/kg, prices that have not been seen.

It should be said that energy content of uranium already mined could support the energy demand of the world for centuries in a breeder situation. This is triply true if the thorium that has already been mined for the lanthanide content of ores (and then dumped) is used for the fuel.

[petronius]

7. Thank you, that is very interesting, but I think you took my post a bit more seriously

than it was intended. Really I was making a joke about the somewhat obvious nature of a portion of the article cited in the OP - randomly picking a few other things that are present in sea water which would be nice to extract if there was an economical way to do so. (I did read your earlier post, by the way - perhaps that's why titanium was floating around in my mind.)

So, I'm going to have to reject your implication that I'm confused... :)

[bananas]

5. The energy density of uranium in seawater is about 0.1kWh/ton

which means that to run a 100-watt lightbulb for an hour would require processing 1 ton of seawater.
To power your 100-watt lightbulb continuously would require continuously processing 1 ton/hour of seawater.
Unfortunately, it appears that it would take more energy to process that much seawater than you would get out of it.

For comparison, a ton of coal (2000 pounds) would power the light bulb for 2 years:

http://en.wikipedia.org/wiki/Coal

It takes 438 kg (966 lb) of coal to power a 100 W lightbulb for one year

http://www.mdpi.com/2071-1050/2/4/980/pdf

Extracting Minerals from Seawater: An Energy Analysis

<snip>

The energy involved in desalination by reverse osmosis is normally reported as in the order
of 2–4 kWh/ton. A recent study <21> reports a “state of the art” value of 2.5 kWh/ton. For uranium
separation, membranes cannot have a too different value of the permeability and, therefore, the energy
needed cannot be too different. On this basis, we can calculate the EROEI of the process. Consider that
the present worldwide production of nuclear energy is about 2.5 × 103 TWh (terawatt-hour) per year
<7> and that we need to process 2 × 1013 tons of water per year (see Table 2) to produce a sufficient
amount of uranium. Therefore, the “energy density” of seawater in terms of energy that can be
produced by the present nuclear technology is about 0.1 kWh/ton. If we need 2.5 kWh/ton for
extraction then the EROEI is less than 0.1 and the process has no practical interest as a source of fuel
for fission plants. This result agrees with previous estimations based on different considerations that
led to the same conclusion <9>.

The second possible strategy of extraction is to drop the membrane into the sea and wait for
currents or thermal diffusion to bring the uranium to the adsorbing sites. This method avoids the
energy cost of pumping. Yet, it is also a less efficient way to use the membrane. As a consequence, we
need a larger mass of membranes, a larger infrastructure, and we need to move the membranes in and
out of the sea, all of which incurs energy costs.

We can examine the feasibility of the process using an order of magnitude estimate.

<snip>