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If We Ever Get Sustained Fusion Reactions...Then What?


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5 hours ago, magnemoe said:

Breeder reactors create plutonium.

And its amount is limited wby the uranium amount above.
Pu is just cooked U.

5 hours ago, magnemoe said:

Now worrying about scarcity issues of raw materials 100 year into the future is  just stupid,

Yes, like worrying about forests in Medieval England or Spain. They'll grow again, nothing to worry about.

5 hours ago, magnemoe said:

Fix our problems short term and leave the next generation more tools and power to fix our problems :) Coal was once the fuel who stopped deforestation, back in 1700 it was very environmental friendly. 

The problem is that unlike construction materials which can be refurbished, all fuels are limited. They once appeared and will once disappear, they don't reappear. 

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On 11/22/2020 at 11:05 PM, kerbiloid said:

Yes, like worrying about forests in Medieval England or Spain. They'll grow again, nothing to worry about.

Oddly enough, the only reason the forests in Medieval England recovered enough to keep building watermills and a medieval industrial revolution going was the Black Death.  Not enough demand for wood for a generation.  Yew trees aren't extinct, although we must have gotten lucky as it takes hundreds of years for them to grow (they are typically grown as shrubbery.  Getting to tree size takes a loooong time).

The amounts of uranium needed for  breeder reactors is trivial.  If you are worried about running out of fuel, thorium is even less limited (although it *requires* plutonium instead of creating it.  So presumably you would need a few breeder reactors to go with your thorium reactors).

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10 minutes ago, wumpus said:

Oddly enough, the only reason the forests in Medieval England recovered enough to keep building watermills and a medieval industrial revolution going was the Black Death.  Not enough demand for wood for a generation. 

 

So what is 'recovering' now that we are in COVID?

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On 11/21/2020 at 6:44 AM, kerbiloid said:

Googling "world supply of ..."

So, thorium is not an option.

***

And for better dramatism:

http://www.daretothink.org/numbers-not-adjectives/how-long-will-our-supplies-of-uranium-and-thorium-last/

If you read that article, it points out that, assuming a world population of 10bln using British standard of living for 2009(because they have those numbers, but they round them up 25% for convenience), we have enough uranium and thorium in the united states to power the world for 100,000 years with a fuel cost portion of the energy at $0.0004 /kwh  (@$3000/kg)  (ignoring all other sources of power such as solar or oil)

Unless you look at harvesting Uranium  from seawater, which gives us another 64,000 years(ignoring the fact that uranium in seawater is currently in a state of equilibrium, suggesting that there are available deposits to re-dissolve and presumably in-flowing sediment from rivers and streams that will replace much of what we take out, letting the natural leaching of rain water slowly collect those 2.8ppm of uranium in the crust for us without strip-mining the whole planet)

On 11/21/2020 at 6:44 AM, kerbiloid said:

Thorium:

3.5 mln t of world supply

U:
5.5 mln t of found world supply
~10  mln t of missed but wannabe found
4 500 mln t of dissolved in water.

So, a couple of centuries on mined uranium and several millenia on the fished one.
That's all. After that - no U, no Th, no coal, no oil, no gas, and even dry manure looks somewhat unfriendly.
 

umm, this page: https://www.world-nuclear.org/information-library/current-and-future-generation/thorium.aspx from 2017 claims that there is 6.3 mln tons available at $80/kg.  Your article above found a study from 1969 that said 3B short tons(2.7B metric tons) should be recoverable @$500/kg($~3000/kg today)(not including sea-water extraction as it was from 1969)

On 11/21/2020 at 11:52 PM, kerbiloid said:

This figures how much supply is available without "kids are clever, they'll invemt something".

Known and presumably yet missed deposits in concentrations reasonable for chemical extraction.

Thorium is by order(s) of magnitude less common, so it's just a little bonus.
You can rework all Th into U-233, but also you can rework U-238 into Pu-239 for fast neutrons reactors, so Th addition is negligible,

And it's always easier to refine deuterium from seawater than uranium from the crust.

According to this: https://en.wikipedia.org/wiki/Thorium-based_nuclear_power

Thorium is 3x as abundant as uranium in the earth's crust. 

Currently the cost of disposing of the unneeded thorium from rare earth mines is why we don't produce niobium in the US, as thorium is classified as a nuclear waste and makes such mining cost prohibitive compared to China.

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19 hours ago, Spacescifi said:

 

So what is 'recovering' now that we are in COVID?

Probably nothing; the Black Death wiped out 30%-60% of Europe's population in 3 Successive waves. This massive decrease in population was the source of the "Recovery", COVID-19 while serious wouldn't achieve such massive death tolls even if allowed to burn throughout the entire population without any precautions. That's assuming it didn't mutate into some more lethal strain, which isn't an assumption I'd feel confident making.

More interesting is the knock-on effects on Travel, Business and many other things that people have realized can be done cheaper and easier remotely. I can't predict the future, but if there's a shift towards more of the mundane things being done remotely (Business meetings, Staffing, even more people working remote permanently) you might see a corresponding decrease in emissions. But it's unlikely to come close to the Black Death.

And honestly, we have all the tools we need to recover. We shouldn't be counting on a Plague to force us to....

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On 11/23/2020 at 5:05 AM, kerbiloid said:

And its amount is limited wby the uranium amount above.
Pu is just cooked U.

Yes, like worrying about forests in Medieval England or Spain. They'll grow again, nothing to worry about.

The problem is that unlike construction materials which can be refurbished, all fuels are limited. They once appeared and will once disappear, they don't reappear. 

Well forests tend to grow back with some exceptions like if the topsoil wash away or the forest grew then the climate was warmer or wetter than now.
The reasons why the large forests has not return is that we uses the land for farms. 
Interesting its more forests today than 100 years ago as many marginal areas who was farmed back then are not now as they are not economical or practical with modern farming. 

Remember that little of the uranium is used. The US don't reprocess uranium, in part this is an political decision who don't make even less sense now, but other part is probably cost as in mining more uranium works just as well so why bother.  

And we are not running out of fuel, we have way more coal and probably more oil than we can use because of the environment impact.  
Much the same with uranium, nobody will mine uranium from an mine who cost  for a ton is twice as high as the marked price even if fuel is an small part of the cost operating an nuclear plant. 

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On 11/24/2020 at 12:17 PM, Spacescifi said:

So what is 'recovering' now that we are in COVID?

Telecommuting.  It was possible earlier, but getting proven now.   Nothing is really "not being destroyed by Covid-19", but a few things are in trouble.  Theaters (especially live performances, although I can't imagine that film theaters are doing any better), office buildings, support for office buildings,  restaurants, schools (more the buildings, buses, and other "in person" infrastructure, not the teachers and students).

One thing to note is that the logistic chain for trees is [well was in the middle ages] relatively trivial: a woodsman cuts down a tree.  If you need charcoal probably someone else turns it into charcoal.  Finally somebody hauls it to where it needs to be (possibly stopping by a mill to turn it to lumber).

Oil and gas require extreme long term investment, and don't "shut down" easily.  Oil has only limited competition, electric transportation is in its infancy and is unlikely to be effected by Covid.  Natural gas has real competition (especially for high dollar peak electrical use) in solar and wind.  I suspect that wind turbine production can ramp down and ramp back up again relatively easily.  Solar production uses fabs not unlike (low tech) silicon chips, so they might just run continuously and stockpile the panels (or more likely demand will increase, especially if residential use increases and they keep the offices cooled anyway).  In any event, any changes to the supply of oil and gas won't change at all (if Saudi is on the verge of running dry, that might be a huge political thing, but it isn't a real change in supply).  The whole expensive logistic chain is what to watch.

Edited by wumpus
include thoughts about energy
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