[ExI] Could Thorium solve our energy problem?

[Brent Neal]

On 10 Jul, 2010, at 14:54, Max More wrote:

> So far as I've been able to determine so far, it does sound like John's number of 85 TJ per *KG* is right -- *if* you can burn all the thorium. There seems to be agreement that, while you can use only a small fraction (0.7%) of natural uranium in a reactor, you can use all of the thorium. With fast breeder reactors, the situation seems even better.


Max -
It is 85 TJ/kg - my first number was indeed incorrect. The subsequent calculation that I made on depletion was not, though (I just bobbled the transfer from my spreadsheet, where I had 0.085 EJ/ton - I did all my calculations in EJ.)  And while you're right about the doubling period, remember, we're also talking about cumulative use. By 2500, thus, I estimate that we'll have consumed ~48.5 million exajoules since 1980, with an annual consumption of about 3 million exajoules.  While that is well within even conservative estimates of the number of joules available from thorium, its still linear vs. power law. Its just that the power law is pretty tame - 1.8 % :)

I think you're right: we aren't far off in our opinions - we're just niggling over details, as is so often the case with deep subjects! The conclusion that I try to convey to the lay audiences that I speak to about the subject is twofold: 1) We can't rely on any one source of energy. In addition to the guaranteed depletion or surpassing of the global budget (in the case of renewables) there is also the inherent risk of a monoculture.  And, 2) that if you believe, as I do, that human culture (or transhuman culture, such as it may be) will continue for thousands of years, that we will be forced to either leave the surface of the planet for resource extraction or see a collapse of civilization.

On 10 Jul, 2010, at 10:28, John Clark wrote:

> There is no way you could get complete uranium fission with the pressurized light water reactors we use today,

Yes, that's correct. I also stated that you can use uranium in a molten salt reactor, where the conversion efficiency is identical to that of thorium.  You are conflating molten salt reactors with thorium. There is no technical reason why this has to be the case.

> Although it would be more economical to mine high quality ore that can approach 50% Thorium content first, if at random you picked one cubic meter of rock anywhere in the Earth's crust you would find about 12 grams of Thorium in it. if placed in a liquid Thorium reactor 12 grams would produce the energy equivalent of 37 tons of coal, enough to power one person's western middle class lifestyle for about a decade. 


This is true. You are however neglecting to account for the energy needed to extract said thorium (a common layperson mistake, which leads to people believing things like corn based ethanol are good ideas) in your computation.  If the energy return is less than 10:1, then you are still disadvantaged relative to solar, geothermal, etc.  And CSP has a EROEI of as much as 100:1, depending on which solar plant you're talking about and whether its trough-based or tower-based, etc.


On 10 Jul, 2010, at 17:23, samantha wrote:

> So, are there any current commercial molten salt thorium reactor projects in the US?  If not, why not?  How much does say a 300 MW plant cost to build?  Which billionaires can we recruit or which energy companies?  

There are not, unfortunately, any serious attempts currently underway in the US. The Indians are actively researching it, largely due to their large domestic supply of thorium.  Last I researched it, there was a small group that was attempting to design and/or build a modern reactor in the US, but I do not believe they have the funding to build.  One advantage of the molten salt reactor is that it can be built with a much smaller footprint than a LWR.  Unfortunately, the key drawback is the NRC. The only two designs licensed to be built and operated in the US are the GE and Westinghouse LWR designs. The level of politics required to gain that license is certainly Herculean. 

My chief efforts in this regard have been to discuss MSRs with influencers in South Carolina, where they are very interested in expanding nuclear power (due to the presence of the Savannah River National Lab.)  Alas, for most of these people nuclear = uranium, and no amount of data seems to be able to convince them.  I'm attending the Innoventure Alternative Energy conference next week in Spartanburg, SC, where I'm hoping to talk to a different set of people on the subject. Since my boss is one of the conference organizers,  I hope that I'll be able to talk to a different, more technical, group of influencers.

B


--
Brent Neal, Ph.D.
http://brentn.freeshell.org
<brentn at freeshell.org>