207. URANIUM FROM SEAWATER (PART 1)
Lately, we've been hearing a lot of the "peak uranium" soundbite: "if we turn to uranium, it too will peak in 30 years." This isn't true, and to see why, I'm going to walk you through the most elegant and beautiful mining technique ever invented: recovering uranium from seawater.
This feat has actually been accomplished by Takanobu Sugo and his colleagues at the Japan Atomic Energy Research Institute (JAERI).
To begin, the group fabricates a material called the "adsorbent" which can selectively soak up uranium. This material begins as a nonwoven fabric made primarily of polyethylene. Molecules called amidoxime groups are attached to this fabric by a process called "graft polymerization" (which apparently involves irradiating the polyethylene with a high energy electron beam). Each pair of attached amidoxime groups can "grab" a single heavy metal ion.
This material has an amazing capacity to soak up uranium (as well as other valuable metals like vanadium, cobalt and titanium). Bench tests show it can hold an amazing 500g of heavy metals per kg of absorbent. It can also be washed with alkali, and reused. Here's an abstract of the JAERI group's most recent experiment (2003):
The total amount of uranium dissolved in seawater at a uniform concentration of 3 mg U/m3 in the world's oceans is 4.5 billion tons. An adsorption method using polymeric adsorbents capable of specifically recovering uranium from seawater is reported to be economically feasible. A uranium-specific nonwoven fabric was used as the adsorbent packed in an adsorption cage 16 m2 in cross-sectional area and 16 cm in height. We submerged three adsorption cages in the Pacific Ocean at a depth of 20 m at 7 km offshore of Japan. The three adsorption cages consisted of stacks of 52 000 sheets of the uranium-specific non-woven fabric with a total mass of 350 kg. The total amount of uranium recovered by the nonwoven fabric was >1 kg in terms of yellow cake during a total submersion time of 240 days in the ocean.SourceThis is what one of these adsorption cages looks like:
So if you want to collect tons of yellow cake, instead of just kilograms, you just need to string 300 of the cages together and hang them in the ocean. Sugo illustrates three possibilities (from the top): suspension from a floating platform, dangling under a bridge, or stringing with buoys (like a trot line):
The technique reminds me of Asian seaweed farms:
It's a beautiful low-tech approach... almost agricultural. And it's hard to imagine any cleaner method of "mining". No tailings, no scarring of the landscape. In fact, it would clean the ocean rather than pollute it.
You can even take it a step further. The following shows an idea for synergetic wind farming and aquaculture, but we could just as well imagine hanging adsorbent cages, and hoisting them with wind power (click to enlarge):
*Part 2 of this article is located here: 208. URANIUM FROM SEAWATER (PART 2)
-- by JD
posted by JD @ 3:00 AM
18 comments
18 Comments:
Yes, but what will you do in a million years after peak uranium?
:+)
The problem with debunking doomer scenarios, is that they may start to believe you and take matters into their own hands, as in "The Twelfth Monkey." These people badly want to see widespread doom and gloom.
JD:
You need to understand that most of the uraniums are not useful nuclear fuels. There are U238 and U235. You need U235, which is one part of 137 part of total Uranium.
They harvested 1 kg of Uranium in terms of yellow cake. Of these, there is maybe 7 gram of the useful U235. That, at the cost of 350 kg of specially made material and one years of operation of the facility. You have got to wonder whether that 7 gram of U235 would give you back enough energy to pay back the energy cost of manufacturing the special material and the operation of the facility. So, ah ha, EROEI gets in your way again.
The earth does not lack Uranium, which is more abundant than even the lead. But the earth lacks economically mineable uranium. Uranium from the sea water may not be economical, in terms of EROEI.
Quantoken
Another way of considering it is consider how much uranium, the U235 kind, the world currently consumes per year in nuclear power plants. My estimate is above ten thousand tons per year.
But let's be very conservative. Let say we only use one thousand ton. Which is way too conservative. To harvest 100 ton of U235 per year, use the Japanese device which harvests 7 grams per 350 kilogram speciality material. A simple calculation shows you need 5x10^10 kilogram of those materials, averaging 8 kilogram per person. Which does not seem to be something you can ramp up in scale.
schinkenpilze wrote:
can you plz open a disussion forum, for non doomers ...
i have enough of discussions with doomers without technical knowledge
or anyone knows a good forum ?
We already got one. It's very nice.
http://groups.google.com/group/Peak-Oil-Debunked
Wildwell: Thanks for the information source. My original estimate used 1000 ton uranium. Now it looks the world currently use 70,000 ton per year. 70 time more than my conservative estimate. And if nuclear electric power should replace all fossil fuel electric power, you need 5 times more uranium. That's 350 times my original estimate. So each person on the earth needs to have 8 kg * 350 = 2.8 ton of that special material that absorbs uranium. An impossible goal to reach.
Roland:
Keep day dreaming with the Flying Windmill, but they can not be built.
Those floating units, tethered to the ground and generating 20 megawatts each, are just some huge kites. There is indeed strong constant air flow high up in the air. Let's borrow Einstein's idea and change our reference frame so we move at the same speed as the air flow at 30000 feet high. What we see?
What we see is the air is not flowing, it is at rest. The ground is moving at a very fast speed, almost like highway speed. Let's say 30 meters per second, relative to the air. And a tether, tied to the ground, drags the huge kite so it moves forward with the ground. The dragging force of the tether provides a Newton mechanical work per meter of distance moved. And part of that energy provided by the dragging force is converted into electricity energy and sent down the tether.
Let's assume 100% efficiency. The horizental dragging force on the tether would then need to provide enough power to generate 20 megawatts. Since the moving speed is 30 meter per second. Divide 20 megawatts by 30 m/s. The horizental component of the dragging force would have to be 0.667 mega newton, or 68 metric ton of weight.
The tether itself will have height, too! A tether capable of supporting 68 ton is quite thick. The weigh of the tether would probably be much more than the kite can support without falling down.
energyspin:
Information source URL, please. I am skeptical to the accuracy of your data, but not knowing your source I can not comment.
As for the new method that the Japanese invented, you forget to count in the energy required to manufacture the speciality material used to absorb uranium from sea water. If you count that in the net EROEI is less than one. Since this method is claimed to be the most economical of all that retrieve uranium from sea water, it means other method must have an even lower EROEI.
Einstein's refrigerator
No moving parts. Low energy(?)
Invented by Einstein and Szilard 70 years ago.
http://en.wikipedia.org/wiki/Einstein_refrigerator
Roland:
I wish you had not talked about flying a huge Helium ballon 30000 feet above in the air, and tethered to the ground. The wind there blows at near Hurricane Katrina speed. A helium ballon of that size does not stand a chance to survive a single second under that condition!!!
Also keep in mind the earth do not have a natural source of helium, other than the minuscule few helium atoms generated by natural radioactive decay, and trapped in underground natural gas fields, and mined out together with natural gas.
And so as the world natural gas production peaks, which is happening now, so does the helium production!!! Even if helium production does not peak. The current production rate barely provided enough helium ballons to children in American shopping malls. You do not have nearly enough helium to float that many huge wind mill kites. Remember each one needs to support nearly a hundred ton of weight of the kite and the tether!!! What volume of a helium ballon is needed to provide enough air buoyant force to support 100 ton? At 30000 feet, one cubic meter of helium ballon volume provides less than 10 ounces of buoyant force.
And of course, with the wind blowing at more than 30 meters per second, the ballon will result in several hundred time more horizental dragging force, than the vertical buoyant force. Which of course means you need many times stronger and many times heavier tether cable to tie the ballon down, and even bigger ballon to support the heavier tether.
Roland:
I wish you had not talked about flying a huge Helium ballon 30000 feet above in the air, and tethered to the ground. The wind there blows at near Hurricane Katrina speed. A helium ballon of that size does not stand a chance to survive a single second under that condition!!!
Also keep in mind the earth do not have a natural source of helium, other than the minuscule few helium atoms generated by natural radioactive decay, and trapped in underground natural gas fields, and mined out together with natural gas.
And so as the world natural gas production peaks, which is happening now, so does the helium production!!! Even if helium production does not peak. The current production rate barely provided enough helium ballons to children in American shopping malls. You do not have nearly enough helium to float that many huge wind mill kites. Remember each one needs to support nearly a hundred ton of weight of the kite and the tether!!! What volume of a helium ballon is needed to provide enough air buoyant force to support 100 ton? At 30000 feet, one cubic meter of helium ballon volume provides less than 10 ounces of buoyant force.
And of course, with the wind blowing at more than 30 meters per second, the ballon will result in several hundred time more horizental dragging force, than the vertical buoyant force. Which of course means you need many times stronger and many times heavier tether cable to tie the ballon down, and even bigger ballon to support the heavier tether.
As for the new method that the Japanese invented, you forget to count in the energy required to manufacture the speciality material used to absorb uranium from sea water. If you count that in the net EROEI is less than one.
This is simply false. The polyamidoxime material soaks up about 1% by mass uranium. If burned in a conventional thermal reactor, a kilogram of uranium yields about 700 gigajoules of thermal energy. This more than 100x the heat of combustion of 100 kilograms of plastic. Moreover, the plastic adsorber can be reused many times.
Economic studies show that the cost of the adsorber (and its extraction/regeneration treatment) is a small fraction of the cost of the seawater uranium process. The dominant cost is the cost of the support structure that suspends the cages. Even this is tolerable, if uranium rises to a few times the current spot market price.
If this really works, why isn't it being used for gold, which is also dissolved in seawater?
The concentration of gold in seawater is much lower than that of uranium. Uranyl ions are rather soluble when complexed with bicarbonate ions.
the world will always have energy, it can just get a bit more expensive than it is now, even though right now it is overpriced due to speculation.
There isn't going to be a doomsday without energy.
With breeder reactors and uranium and thorium from the earth's crust and then from seawater, there is enough electricity to last a billion years.
When oil runs out our transport needs will be supplied by battery vehicles powered by nuclear.
Airplanes are a bit tougher to replace with batteries.. but they are irrelevant in the grand scheme.
dommsdayers eat shit. you will not run out of juice anyday soon. but it might get a bit more expensive. but since we live in a post industrial society, not even that little extra cost matters.
hold on ... we'll use batteries in place of oil.
What are batteries made out of?
Quantokens mass computation were interesting but false.
They used 350kg polymeric for 240 days to extract 1 kg uranium.
In 365 days they would get 1.5kg.
Current uranium comsumption is approx. 70 million kg. Then you need
70e6/1.5*350kg = 16.3e9 kg device material, approx. 2.5kg/man on earth.
If uranium power generation would be increased by factor 5, these are 17.5kg/man on earth.
If additionally uranium breeding technology would be applied, the weight will be reduced by (theoretically) a factor of 100.
Anyway you cut it, there will not be enough resources to match the growth of world population. When will population control become a reality? If not you better get with renewable energy and recycling. And for all the advocates of big families with religous justification, God only made the planet so big and made you smart enough to know it.
The calculations of the previous anonymous user are incorrect.
The process was improved and now yields 1gU3O8/kg adsobent in ~10days. The adsorbent can be reused ~20times.
1 atom of U235 yields ~250MeV in a typical lightwater reactor, so the EROI is easily in the green because the adsorbent consist mainly of polyethylene.
Hey Ren,
Sorry to inform you, but unlike many other websites, this one is not a beachhead for doomer spam. You've been censored, asswipe. Have a nice day.
JD
Using electron beam to irradiate the absorption material, and then arranging cages in extensive sea areas, waiting a year, recovering few kg Uranium, out of which 8% U235 will be used in powerplants? Economically viable alternative to current 20 USD per barrel instantaneous oil production???
This makes no financial sense and no EROEI sense.
Sure, as some people commented, there are always alternatives to oil such as breeder and thorium fission, but messing up practical approaches with fairytales like this post helps to ensure that what needs to get done will not get done before a crisis!
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