Uranium is not the only element/mineral of interest that is dissolved in seawater. Research has been done on this stuff before. I'm glad it's being done, but unfortunately this will remain unviable when compared to open-pit or underground mining (even accounting for the risk of depending on foreign suppliers + transportation costs of importing).

The biggest reserves are in Canada and Australia, not really countries we have to worry about cutting off supply anytime soon. We have bigger strategic mineral concerns (REMs and China)

Cool tech, won't leave the lab. Just like the billion "metal-ion/air/water" batteries that get shilled non-stop.

>> The biggest reserves are in Canada and Australia, not really countries we have to worry about cutting off supply anytime soon.

Unless you are Iran. North Korea. Or anyone else currently not able to buy uranium from Canada.

Uranium is quite common, if you don't care too much about cost. If you own a house with a suburban lot, the top meter of soil in your yard probably contains several kilograms of uranium.

>> the top meter of soil in your yard probably contains several kilograms of uranium.

No. That is way way off. Grams ... more likely milligrams and even that sounds too much.

According to [1], "the normal concentration of uranium in soil is 300 μg/kg to 11.7 mg/kg." According to [2], the density of topsoil ranges from 1,100 to 2,500 kg/m^3. One acre is about 4,000 m^2, so a conservative estimate is that there is about 1.3 kg of uranium in 1 meter of top soil on a 1 acre lot. (4000 m^3 * 1100 kg/m^3 * 3x10^-7). That's just the low end - taking the midway point for both yields over 40kg (4000 m^3 * 1800 kg/m^3 * 6 mg/kg).

[1] https://en.wikipedia.org/wiki/Uranium_in_the_environment

[2] https://structx.com/Soil_Properties_002.html

  on a 1 acre lot

Not many of us have all of an acre lot for our homes.

According to [1], 2 billion people are subsistence farmers with under 5 hectares. The population adjusted average seems to be around a quarter of a hectare (~0.6 acres) per person (which sounds low to me, as someone who has grown my own food without automation).

10^9 == many of us. Unless your definition of "us" is hacker news readers.

[1] https://en.wikipedia.org/wiki/Subsistence_agriculture

Do the math. Average crustal abundance of U is around 3 ppm.

for a house in my neighbourhood I'd guess ~100 mg

Several milligrams or kilograms?

According to Wikipedia(https://en.wikipedia.org/wiki/Uranium_in_the_environment):

"According to the United Nations Scientific Committee on the Effects of Atomic Radiation the normal concentration of uranium in soil is 300 μg/kg to 11.7 mg/kg."

So let's say 5mg/kg. 200kg of soil per gram. How much area do you need to make 200kg of soil if you're going down 1m? I'd guess not much...

So I think OP is wrong and it's more like 'several grams'.

According to this[1] the weight for 1 cubic meter of dry soil is 1200kg, so 6 grams of uranium per cubic meter.

Looking at average suburban lot sizes, they seem to be about 7200 sqft , which is about 668m^2.

Which gives 668m^3 which gives about 4kg of uranium shockingly.

[1] https://www.reference.com/science/much-cubic-meter-soil-weig...

I thought the numbers from wikipedia looked a little shaky, maybe. I couldn't find those specific numbers in the reference UN PDF.

Google says soil concentration of Uranium is like 3ppm. But, if you do the math, 668 x 1200 x 1000 x (1/1000000) = 802g for every ppm. 3ppm Uranium would be 2.4kg by this number.

Lead is at like 15-40ppm (https://ag.umass.edu/soil-plant-nutrient-testing-laboratory/... ), so between 12 and 32 kg of lead in everyone's back yard?

I first thought that OP estimate was way off, but from your numbers he may be right! If you only need 200 tons of soil for 1kg of Ur, that's not much.

A cubic meter of soil is ~2 tons, maybe more, which means you only need a 10m by 10m square to get 1kg of Ur if you go 1m deep. Wow.

I think getting to enriched uranium is the hard bit.

Also, now your property is a large hole.

I think uranium at that concentration would qualify your lot as a Superfund site. It's a toxic heavy metal and that's a lot. Your numbers might be off by a zero or two.

As others have pointed out here, no, I was not off. It's a bit of a shocker to realize how much U is out there. There's a reason one should test your basement for radon before you buy a house.

But, since people don't mine uranium randomly, one may assume that your back yard doesn't have enough to be price-competitive with modern mines.

Of course. The point is that if a nation wants to make nuclear weapons, keeping them away from uranium is a nonstarter. Uranium is everywhere, if you're willing to pay to extract it (in this case, by piling up the dirt and leaching the uranium using a bicarbonate solution).

Fun fact: if the uranium and thorium in an average crustal rock were totally fissioned (using breeder reactors), the rock would produce about 20x the heat energy of burning the same mass of coal.

I don't think the idea is that it's meant to be competitive against extraction on land. What it does do is expand the potential uranium supply to make nuclear power viable as a global power supply on the order of hundreds of thousands of years at least.

It also gives a path to nuclear power and weapons for counties with no uranium deposits.

Is obtaining the uranium really the bottleneck?

It's a bottleneck, if you don't get past it, you're done. Uranium as far as I know, is a heavily regulated material. You can't buy nuclear reactor level amounts of refined uranium without the blessing of the states that control the supply. There are a LOT more problems after that though.

> The biggest reserves are in Canada and Australia, not really countries we have to worry about cutting off supply anytime soon.

Perhaps not maliciously, but might those countries hypothetically shut down those mines for environmental reasons?

Things change, US itself has changed. Why do you expect Canada to lick the boot of Trump if they get the treatment they get today ? Why does one expect that an uranium cartel will not be formed the moment that it gains significant market adoption?

Related:

Nuclear Power Worldwide: Development Plans in Newcomer Countries Negligible

* An analysis of current decommissioning and new construction projects reveals a downward trend in nuclear power worldwide

* Only four newcomer countries are currently constructing nuclear power plants and all are plagued by financial difficulties and delays

* An econometric analysis suggests that countries classified as potential newcomers tend to be less democratic

* On the supply side, the dominant driving force is the geopolitical interests of countries that export nuclear power

* Within the relevant international organizations, Germany should work to ensure that no support is given to the construction of nuclear power plants in newcomer countries

https://www.diw.de/documents/publikationen/73/diw_01.c.74261...

Aluminum is 1000 times more abundant in seawater than (edit)uranium. Lithium is about 60 times as abundant. With uranium at $32/lb, aluminum at $0.75/lb and lithium at $6/lb it seems that aluminum and lithium would reach commercial viability first.

Magnesium has already made it with significant production coming from seawater.

I don't think your first sentence says what you think it does...

The price of aluminum reflects the price of the energy needed to reduce it to the metallic form. Extracting from seawater would still need to pay this price.

“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 of a paper in Nature Energy. “But the oceans are so vast that if we can extract these trace amounts cost effectively, the supply would be endless.”

That's a lot more uranium than I would have guessed. According to the top few google results, it's about 3 milligrams per cubic meter.

Great, now can anyone build a reactor that will be cheaper than solar + batteries?

Problems like these make me think of jetpacks or flying cars. It turns out that the future isn't what we thought it would be from the sci-fi ideas of the mid 20th century. It's a lot cooler in some ways, and far far more boring in others. (I want my jetpack)

No, because the cost of uranium wasn't the reason nuclear power is expensive (and anyway, this doesn't reduce the uranium price, since conventional mines are cheaper still.)

For anyone who hasn't seen these yet: https://www.youtube.com/watch?v=_VPvKl6ezyc

Also see: https://www.youtube.com/watch?v=EAJM5L9hhBs

These are incredible and I hadn't seen them, thank you!

I'd rather have a teleporter than a jetpack. Jetpacks are loud and smelly. I'd rather just beam somewhere instantaneously, and go on with my day.

Or your clone goes on with their day.

Those lacking in imagination should be sure to watch The Prestige in order to have it imagined on their behalf.

An instance of you.

> How to extract uranium from seawater for nuclear power

“Concentrations are tiny, on the order of a single grain of salt dissolved in a liter of water”

This sounds way to much, I can boil a litre of water in the kitchen and have a grain of Uranium?

From Yahoo answers

Grain of Salt - 2.25 mg (.00008 ounces).

Uranium - 3 micrograms per liter (0.00000045 ounces per gallon)

Yahoo answers didn't have how much energy 3 micrograms of Uranium can create.

I'd guess if we could get a way to extract it with an algae or something, the energy(sunlight) it uses would be better off stored and burned.

Going based on numbers from Wikipedia, U-235 is good for 83.14 TJ/kg, but that isotope only has a natural abundance of 0.72%. So 3 micrograms of uranium in the natural proportions would get you around 1800 J ignoring any contribution from other isotopes (ie. you're not using a breeder reactor). That means your uranium extraction method needs to be very energy efficient indeed.

Oh yeah, you pretty much have to use breeder reactors to use seawater uranium. That has been the plan all along, e.g. Cohen 83: http://large.stanford.edu/publications/coal/references/docs/...

Anyone who comes with Thorium reactor, India will gladly supply their Thorium for your power requirement provided you give them working Thorium reactor.

Illinois EnergyProf just did a video on Thorium power. I enjoyed it.

https://youtu.be/5zJ7fuRPmxc

thats a lot of water to pump. I notice they don't mention a cost: spot price for U remains low, and renewables cheaper.

Who said anything about pumping water? As far as I can tell, this is meant to be a passive collection system.

How does one enforce nuclear non-proliferation if any country can extract uranium from seawater?

Uranium enrichment to a suitable level is a seriously involved industrial process that requires thousands of supersonic centrifuges to do at scale. This is not something that flies under the radar easily. It's also very energy intensive to run those centrifuges, so it's difficult to conceal.

Illinois EnergyProf has a video I enjoyed on uranium enrichment.

https://youtu.be/z8mUCBG49N8

Getting Uranium is not particularly hard anyway. The difficult bit is enriching it to weapons grade.

Article from 2017. Also not very informative IMHO about how this process actually works