4 ms·

Roughly 3-4 times as abundant as Uranium, according to http://www-pub.iaea.org/MTCD/publications/PDF/TE_1450_web.pdf http://www-pub.iaea.org/MTCD/publications/P

Roughly 3-4 times as abundant as Uranium, according to http://www-pub.iaea.org/MTCD/publications/PDF/TE_1450_web.pdf http://www-pub.iaea.org/MTCD/publications/PDF/TE_1450_web.pd.... To give you an idea on how much energy could be produced with this: A rough estimate shows that if all our current electric energy demand would be satisfied with Uranium, the reserves would run out in roughly 10 years. See http://johncarlosbaez.wordpress.com/2010/09/03/how-long-would-uranium-last/ http://johncarlosbaez.wordpress.com/2010/09/03/how-long-woul....

eloff 12y ago
This estimate doesn't seem to account for enrichment. For every KG of uranium mined, you get a much lower ratio of enriched fuel.
- rwcarlsen 12y ago
  It shouldn't account for enrichment because thorium is a fertile material (not fissile) just like uranium 238 (99.3% of all uranium). Unenrichced uranium can be used in breeder type reactors just like unenriched thorium.
Tuna-Fish 12y ago
> rough estimate shows that if all our current electric energy demand would be satisfied with Uranium, the reserves would run out in roughly 10 years. While strictly correct, this is extremely misleading. Current resources would be exhausted in a decade, but resources are defined as the known deposits extractable under current market prices. Should we actually start using a lot of uranium, the price would spike, which would lead to a lot more deposits becoming economically available. This has almost no effect on the cost of nuclear power, as the cost of the raw uranium isn't a large part of the cost of producing power. The end game there is when the price rises sufficiently for extraction from seawater becoming profitable. The world's seas have ~1000 times more uranium than conventional ground-based resources. Nuclear fuels will not run out in this millennium.
- orbifold 12y ago
  The total known ground resources are estimated to be roughly seven times larger than the current mining reserves. So this gives you at most a factor of ten. Of course there are other unrealistic assumptions in those estimates. Realistically you would use other sources of electric energy for instance. I don't now if the Thorium reserves are roughly four times larger than the current Uranium reserves or four times larger than the amount of Uranium that could feasibly be extracted from the ground. In any case, both are only a solution for the near future, that is the next 50-100 years or so. With current technology it would not make sense to extract Uranium from the Ocean, its concentration is $10^{-9}$, it can be commercially extracted from rocks with $10^{-4}$ concentration. It does not possible to filter huge amounts of seawater for such insignificant quantities of Uranium.
- venomsnake 12y ago
  How about energy return on energy investment. You have to vaporize a lot of water (of course you will have all those gold, iron, rare metals "waste" which will help the economic case).
  - maxerickson 12y ago
    Research has focused on other methods: http://en.wikipedia.org/wiki/Uranium_mining#Recovery_from_seawater http://en.wikipedia.org/wiki/Uranium_mining#Recovery_from_se...
DennisP 12y ago
That estimate for uranium assumes conventional reactors, which fission U-235. That's 0.7% of natural uranium. For a real comparison, you should look at fast reactors, which use the rest of the uranium. That takes your estimate up to about a thousand years. But the estimate is looking at economically recoverable reserves, and if the same ore produces a hundred times as much energy, a lot more becomes economically recoverable. Thorium would be 3-4 times more abundant than that. (But if seawater extraction works out, uranium will have the advantage again.)
Aardwolf 12y ago
If it's 3-4 times bigger than the Uranium, and Uranium will last us 10 more years - Thorium would last us 30-40 years. What to do after that? If there ever appears a new intelligent civilization millions of years after humanity, they'll be very disappointed to be on an Earth without any Uranium or Thorium!
- Tuna-Fish 12y ago
  See my post: https://news.ycombinator.com/item?id=8036690 https://news.ycombinator.com/item?id=8036690 Uranium will simply not run out. The "10 years" figure stems entirely from misunderstanding what the word "reserve" means in mining. Also, there is 3-4 times more natural thorium than natural uranium. Of natural uranium only 0.7% is U-235, which is useful in a traditional reactor. Breeders can use all of it. Thorium reactors are all breeders. Assuming only resources extractable at current market prices, using uranium breeders the reserves would last ~1400 years and the thorium reserves would last ~5k years.

eloff 12y ago

This estimate doesn't seem to account for enrichment. For every KG of uranium mined, you get a much lower ratio of enriched fuel.

rwcarlsen 12y ago
It shouldn't account for enrichment because thorium is a fertile material (not fissile) just like uranium 238 (99.3% of all uranium). Unenrichced uranium can be used in breeder type reactors just like unenriched thorium.

Tuna-Fish 12y ago

> rough estimate shows that if all our current electric energy demand would be satisfied with Uranium, the reserves would run out in roughly 10 years. While strictly correct, this is extremely misleading. Current resources would be exhausted in a decade, but resources are defined as the known deposits extractable under current market prices. Should we actually start using a lot of uranium, the price would spike, which would lead to a lot more deposits becoming economically available. This has almost no effect on the cost of nuclear power, as the cost of the raw uranium isn't a large part of the cost of producing power. The end game there is when the price rises sufficiently for extraction from seawater becoming profitable. The world's seas have ~1000 times more uranium than conventional ground-based resources. Nuclear fuels will not run out in this millennium.

orbifold 12y ago
The total known ground resources are estimated to be roughly seven times larger than the current mining reserves. So this gives you at most a factor of ten. Of course there are other unrealistic assumptions in those estimates. Realistically you would use other sources of electric energy for instance. I don't now if the Thorium reserves are roughly four times larger than the current Uranium reserves or four times larger than the amount of Uranium that could feasibly be extracted from the ground. In any case, both are only a solution for the near future, that is the next 50-100 years or so. With current technology it would not make sense to extract Uranium from the Ocean, its concentration is $10^{-9}$, it can be commercially extracted from rocks with $10^{-4}$ concentration. It does not possible to filter huge amounts of seawater for such insignificant quantities of Uranium.
venomsnake 12y ago
How about energy return on energy investment. You have to vaporize a lot of water (of course you will have all those gold, iron, rare metals "waste" which will help the economic case).
- maxerickson 12y ago
  Research has focused on other methods: http://en.wikipedia.org/wiki/Uranium_mining#Recovery_from_seawater http://en.wikipedia.org/wiki/Uranium_mining#Recovery_from_se...

DennisP 12y ago

That estimate for uranium assumes conventional reactors, which fission U-235. That's 0.7% of natural uranium. For a real comparison, you should look at fast reactors, which use the rest of the uranium. That takes your estimate up to about a thousand years. But the estimate is looking at economically recoverable reserves, and if the same ore produces a hundred times as much energy, a lot more becomes economically recoverable. Thorium would be 3-4 times more abundant than that. (But if seawater extraction works out, uranium will have the advantage again.)

Aardwolf 12y ago

If it's 3-4 times bigger than the Uranium, and Uranium will last us 10 more years - Thorium would last us 30-40 years. What to do after that? If there ever appears a new intelligent civilization millions of years after humanity, they'll be very disappointed to be on an Earth without any Uranium or Thorium!

Tuna-Fish 12y ago
See my post: https://news.ycombinator.com/item?id=8036690 https://news.ycombinator.com/item?id=8036690 Uranium will simply not run out. The "10 years" figure stems entirely from misunderstanding what the word "reserve" means in mining. Also, there is 3-4 times more natural thorium than natural uranium. Of natural uranium only 0.7% is U-235, which is useful in a traditional reactor. Breeders can use all of it. Thorium reactors are all breeders. Assuming only resources extractable at current market prices, using uranium breeders the reserves would last ~1400 years and the thorium reserves would last ~5k years.