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PostPosted: Sep 26, 2014 11:20 am 
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Ida-Russkie wrote:


I'm not sure what part of the mobile equipment you think is electric, but from what I am seeing these are hybrid diesel electric driven machines (serial hybrid, diesel generator making power for electric motor traction). Or am I missing some power cable somewhere??


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PostPosted: Sep 26, 2014 11:24 am 
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E Ireland wrote:
Also if we optimise for carbon emission wouldn't we expend more energy in the centrifuges to push the enrichment of the tails fraction as low as possible?
That would reduce mining and conversion/deconversion emissions.


Quite correct. But I'm not assuming this. I suspect there is already a big push toward lower tails assay going on right now because all operating plants are now centrifuge plants which are low energy and operation cost (in fact shutting them down or throttling often wears down the centrifuges). This move toward lower tails will be enforced by the advent of laser enrichment which will very likely become very significant in this timeframe (60 years into the future). I actually think we may see an upward trend in energy consumption with lasers for this reason, they may end up using 2-4x more than centrifuges but its still 10+x lower than diffusion. But that's just speculation of yours truly.


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PostPosted: Sep 26, 2014 11:36 am 
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Cyril R wrote:
I'm not sure what part of the mobile equipment you think is electric, but from what I am seeing these are hybrid diesel electric driven machines (serial hybrid, diesel generator making power for electric motor traction). Or am I missing some power cable somewhere??


Some very heavy equipment like the mighty Bagger 288 can be switched to grid electricity.

There are also trolleybus esque systems for mining lorries to climb out of pit mines now.

I think there might be a power cable visible in that caterpillar video.


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PostPosted: Sep 26, 2014 12:32 pm 
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Well, the heavy mobile equipment is just one part of the energy usage at the mine. Typically a mill is included, if that is electric and nuclear powered then huge savings are possible even if the mobile equipment is diesel powered. Similarly if the chemicals used are produced with nuclear electric or nuclear heat then very substantial savings would be possible.

But, there is a more important point to be made here. The fuel used in the mine is less than 1/1000th the fuel used to generate electricity with coal. So, honestly how the mine is powered isn't important. Its important that we have a lifecycle emission of 1 gram CO2 per kWh or thereabouts. Versus 1000 grams CO2/kWh for coal. We tackle 99.9% of the emissions by going nuclear even if the nuclear fuel cycle is powered by fossil fuels. That to me is the main point.

Now I could use some feedback on the LCA. I've been conjuring up a lot of numbers and I would like to know if things are sane within a factor of say 2. One item I've omitted is transport energy. It appears trivial for uranium but may be significant for iron ore, steel, and sand, gravel and cement.


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PostPosted: Sep 26, 2014 5:54 pm 
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Location: Idaho Falls, Idaho
http://www.youtube.com/watch?v=JdTHQIWYb5g

Note this shovel is dragging a mining power cable. In this post you see the portable power poles clearer. If they can set up trolley lines they will use electric trolley trucks. These have been been around a long time. Why pay for diesel, and those engines use a bunch, when you can use electric power?


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PostPosted: Sep 27, 2014 3:21 pm 
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Very interesting topic, good work Cyril.

I have not looked in details at your calculations but I guess this topic will be useful in further discussion with nuclear opponents. A lot of them say that EROI of nuclear is very low. They also say that mining cycle, decommissioning and waste management are underestimated both in energy consumption and in CO2 emissions.

But if the EROI of the ESBWR is really around 200, and CO2 emissions around 1 gram/kWh, that is quite impressive and should silence the nuclear opponents on these points.

Sadly we won't have ESBWR in France, I will maybe try to do the same estimation for the EPR someday, I guess the results will be lower for the EPR considering the design, but I hope they will be in the same order of magnitude.


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PostPosted: Sep 27, 2014 4:57 pm 
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Thanks Fab. We should consider that this is still a work-in-progress, no doubt there are some other energy inputs to be considered. In case of decommissioning it seems hard to come up with an energy figure that is higher than the energy reduction from using all that steel in steel recycling.

EPR should do about the same as ESBWR. One interesting finding is that construction energy isn't big. Much more important is efficiency of the plant and in using uranium. EPR does very good here, bit better than ESBWR even.


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PostPosted: Sep 27, 2014 9:10 pm 
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This makes me wonder how things like ocean-extraction of Uranium do in carbon terms.
Since they would potentially eliminate the dominant carbon dioxide source in the entire system.
(The new extractants are very good really).


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PostPosted: Sep 28, 2014 2:17 am 
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E Ireland wrote:
This makes me wonder how things like ocean-extraction of Uranium do in carbon terms.
Since they would potentially eliminate the dominant carbon dioxide source in the entire system.
(The new extractants are very good really).


Well lets take a look. Making the polymer stuff is the big energy intensive step, start with oil plus refining energy use, plus grafting. How energy intensive is this? Lets work with a working guess of 100 GJ/ton. With an achievable 4 kgU/ton absorbent and 20 recycles, we 137,500 ton absorbent to get our 11,000 tonU need, 13,750,000 GJ. This is more energy needed than low ore grade mines of today, but not by a large factor (less than 2). Still we have to add the acid elution step and the energy to recycle the polymer and we still have the conventional step of purification and milling to make yellowcake.

Anyone have a good source on this? The most detailed I have is from Ugo Bardi but he is a doomer who set out with the purpose to show that ocean U mining is no good and made terrible assumptions on multiple energy accounts to get to his purpose.

What's the most recent estimate of yield/ton absorbent and absorbent type? Number of recycles feasible? Are the MOFs still being researched as alternate absorbent?


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PostPosted: Sep 28, 2014 9:27 am 
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Yes MOFs are now the big hope I think.
(I follow this as this was always a field of chemistry I was interested in during my first set of studies).

As to recycles - remember that you still have the polymer backbone after the 20th cycle and it is still usable, if not directly, as the carbon feedstock for the making of new polymers.
You could use an electric arc gassifier to produce syngas and then cycle back to synthetic plastics.
So cost of production drops significantly.


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PostPosted: Sep 28, 2014 11:34 am 
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Quote:
Thanks Fab. We should consider that this is still a work-in-progress, no doubt there are some other energy inputs to be considered. In case of decommissioning it seems hard to come up with an energy figure that is higher than the energy reduction from using all that steel in steel recycling.

EPR should do about the same as ESBWR. One interesting finding is that construction energy isn't big. Much more important is efficiency of the plant and in using uranium. EPR does very good here, bit better than ESBWR even.


Thanks Cyril, indeed the construction's energy constitutes a lower part than I would have expected and the mining energy a bigger part that I would have imagined. That's a good news for the EPR.

That also means that the EROI of an iso-breeder reactor should be great since we don't need enrichment, the mining's requirements are very low (zero in fact for 238U since we already have huge amounts of 238U in stocks) and the waste management's energy requirements are lower. We need reprocessing for an iso-breeder but I guess the energy requirements are low compared to energy requirements mining for a classic once-through LWR cycle. Ironically despite a bigger EROI the Sodium Fast Reactor breeders are still more costly than classic LWRs, EROI isn't that important in the energy's cost of an energy's producer system.

ESBWR is really the best solution available now to make electricity. What a waste that western populations are so afraid of nuclear energy. A big state financed program with ESBWRs builded in series and the problem of energy transition for electricity is solved in less than 20 years for the entire 21th century (since I imagine that service life of ESBWRs will be extended to 80 years, there is still the problem of natural uranium requirements but if seawater's uranium can really be a realistic solution, that's great).


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PostPosted: Sep 28, 2014 12:30 pm 
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E Ireland wrote:
Yes MOFs are now the big hope I think.
(I follow this as this was always a field of chemistry I was interested in during my first set of studies).

As to recycles - remember that you still have the polymer backbone after the 20th cycle and it is still usable, if not directly, as the carbon feedstock for the making of new polymers.
You could use an electric arc gassifier to produce syngas and then cycle back to synthetic plastics.
So cost of production drops significantly.


Do you know more about the recycling proces for the grafted polymer? Is it a simple thermal process or maybe more chemical? If the latter then it may not matter much how much recycles you get beyond 20. The recycling energy would start to dominate. I have a feeling that the electronuclear grafting requires the largest energy and that graft vacancies would be lost with whatever recycling process we use. So if we need large energy input for recycling plus new electronuclear grafting each time then those steps would dominate the energy process.

I imagine that acids can be recovered almost completely for liquid exchange processes. But I am not familiar enough with the processes involved to be confident.

In the case of MOF, recycling the metal would be easy but keeping the organic part intact would be hard. The MOF would have to offer superiour recycling energy performance or largely improved uranium yield to be really interesting.


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PostPosted: Sep 28, 2014 12:40 pm 
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fab wrote:
That also means that the EROI of an iso-breeder reactor should be great since we don't need enrichment, the mining's requirements are very low (zero in fact for 238U since we already have huge amounts of 238U in stocks) and the waste management's energy requirements are lower. We need reprocessing for an iso-breeder but I guess the energy requirements are low compared to energy requirements mining for a classic once-through LWR cycle. Ironically despite a bigger EROI the Sodium Fast Reactor breeders are still more costly than classic LWRs, EROI isn't that important in the energy's cost of an energy's producer system.


EROEI is very important economically but the thing is the difference between an EROEI 100 and a EROEI 1000000 source is economically very small. Consider EROEI more to be a condition - it has to be above say 10 to be economically attractive in a modern industrialized world but getting much higher does not improve economics much.

Quote:
ESBWR is really the best solution available now to make electricity. What a waste that western populations are so afraid of nuclear energy. A big state financed program with ESBWRs builded in series and the problem of energy transition for electricity is solved in less than 20 years for the entire 21th century (since I imagine that service life of ESBWRs will be extended to 80 years, there is still the problem of natural uranium requirements but if seawater's uranium can really be a realistic solution, that's great).


Agree ESBWR is technically one of the best wholesale lumps of electricity solution to the big energy problems we face. Apart from the hostile societal and political environment it seems, sadly, that GE is not as firm in pushing ESBWR as say Westinghouse is in selling the AP1000. That's strange because, economically when it comes down to it ESBWR should have an advantage over AP1000 so GE should be in a very competitive position if they were more serious about new build.

Mines are almost certainly not a problem. One of the things with nuclear reactors is, they take long to build and operate long. That's perfect when you are a mining company. You can anticipate new mine build (takes less time than the nuclear plant itself) and the commitments are very long (nuclear plant lasts longer than the mine typically). Plus, the nuclear plant owner will pay almost any price for the uranium because it is a vital component yet makes up only a fraction of the price of generating. For mining companies this type of bargaining position is as good as it gets. Nuclear has a bad rep but so do all mining sectors. The copper mining industry isn't known for being environmentally benign but it hasn't stopped its growth. We need copper.


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PostPosted: Sep 28, 2014 3:46 pm 
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Cyril R wrote:
Agree ESBWR is technically one of the best wholesale lumps of electricity solution to the big energy problems we face. Apart from the hostile societal and political environment it seems, sadly, that GE is not as firm in pushing ESBWR as say Westinghouse is in selling the AP1000. That's strange because, economically when it comes down to it ESBWR should have an advantage over AP1000 so GE should be in a very competitive position if they were more serious about new build.


I have wondered about that too. Somehow, GE appears to be very lukewarm about nuclear energy and its GE-H nuclear division is treated as a stepchild. However, GE and Hitachi are cash rich conglomerates. GE alone has a cash pile of over $ 60 bn. The acquisition of Alstom's energy division, earlier this year, was pocket change for GE. With such a cash pile it is in a much better position than Westinghouse (and its parent Toshiba), as GE can offer more attractive financing options to potential buyers of ESBWRs.

Perhaps they can learn something from the Russians who offer attractive all-inclusive packages for buyers of Rosatom's VVER reactors.


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PostPosted: Sep 29, 2014 5:43 am 
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Forgot to add the CO2 emission from cement calcination step. This appears to be around 0.1 ton/ton concrete equivalent (assume no fly ash benefit), with 276,000 ton concrete it is 27,600 ton CO2.

This increases the CO2 emissions by a whopping 0.04 grams/kWh. Total now up to 1.08 gram/kWh.


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