[1] numbers for fossil fuels only
[2] for all-regions/all-years 2000-2050,
[3] contracting globally to near-zero by 2050 and
[4] converging to equal per capita globally by 2020

http://mbf.cc/A59e [it'll be there for 28 days only]

Use Acrobat ‘tools’ ’select and zoom’ then ‘pan and zoom’ to get big-picture and detailed numbers as-above simultaneously . . .

C&C can be shown this way at any rates specified.

It is my impression that something like this is now the next step.

But this runs, *politically*, contrary to many CSP advocates who believe that CSP can handle “virtually” all generation. You see the problem.

There is a sodium-molten salt storage system in California. There was also a nasty, dirty fire caused by this. But, assuming they get it worked out, the idea of a limited-peak lowers the cost.

Just keep in mind: for all the heat storage used, it’s an overall hit on MW output during the peak solar period of the day. So, for every hour you store heat, you take away an hour of producing power.

Thus, a 5 hour CSP plant that produces 100MW, for this period, you knock off, say, 2 hours then you are not producing for that period of time, saving it for later. You get into a cost-factor, and a pretty big one, when doing this. It has to be done, obviously.

Pump storage has limited capacity potential if there is not hydro to retrofit.

David

“Solar can provide peak load [demand] with a few hours of storage…”

Yes, I agree with this 100 %.

Wind can meet off peak load demand quite adequately.

There is a predictable minimum (base load) demand which is there all day, every day.

Some people (me excluded) argue that this must be met by the supply of real base load power, which can provide this amount of electricity (no more, no less) all day, every day. They argue further that supplying this sort of electricity can be done very cheaply. Normally coal and nuclear are seen as the technologies appropriate for this role. Gas seems to be able to do this but at greater cost. Gas is also dispatchable – which coal and nuclear seem not to be.

The argument above is wrong because if sufficient stored energy ( pumped hydro or molten salt) is available and electricity can be produced from that stored energy at a cost lower than from coal or nuclear it is the appropriate [base load]energy source.

“Why do you want solar to have enough storage for base load [as opposed to peak and off peak load]?”

I want wind or solar or any other CO2 free electricity source (or at a push low CO2 gas) to replace high CO2 sources. This can be done if energy from these intermittent sources can be stored. Currently wind and pumped water are the best proven and costed combination of energy and storage to meet this need. If CSP with pumped water or CSP with molten salt prove to be cheaper than wind with pumped water then that combination should be used. In practice of course both energy sources will have more and less favourable locations and therefore rising costs – which would imply using both wind and CSP from the appropriate lowest cost sources.

Kind regards,

David Murray

I think solar thermal with storage is already operating in Spain at Andasol 1 and there are plans to increase it considerably in subsequent stages. It was designed (as was the Californian facility you referred to) to overcome the variations in sunlight within one day and transfer power to the high late afternoon/early evening periods of demand. They were not designed to be the real base load you refer to.

Solar thermal can be designed to replicate real base load, i.e. all day (which it has done as per above) and everyday. The only problem to achieve ‘everyday’ is to store potential energy in some form (including molten salt) for more than a few hours. The current well tried and costed way to store potential energy is pumped hydro.

Less well tried or costed is the storage of molten salt for more than a few hours. I don’t know what the cost of storage would be, and how it would increase with the time stored. I note that the people you spoke to were of the opinion that the cost would be “high”.

Sandia labs (in October 2006) at http://www.sandia.gov/Renewable_Energy/solarthermal/NSTTF/salt.htm comment on this way of storing heat. Cherry picking from that short document their third and final paragraph reads:

“The uniqueness of this solar system is in de-coupling the collection of solar energy from producing power, electricity can be generated in periods of inclement weather or even at night using the stored thermal energy in the hot salt tank. The tanks are well insulated and can store energy for UP TO A WEEK [My emphasis]. As an example of their size, tanks that provide enough thermal storage to power a 100-megawatt turbine for four hours would be about 30 feet tall and 80 feet in diameter. Studies show that the two-tank storage system could have AN ANNUAL EFFICIENCY OF 99 PERCENT. [Again my emphasis, but I am not sure I know what this 99 percent means – heat in to heat out?]”

Kind regards,

David Murray

At a recent solar conference here, I asked them why “only 7 hours”. The answer: it’d cost too much to make it run for the 20 hours over peak MW rating…they’d have to build it out too much.

I asked if there was “anyway it could?”. The answer” yes, “give us the ‘federal support’ and we can do it, but even we think that would be too much to ask”.

The idea that you can economically build out renewables like solar thermal and wind cheaply enough…for base load…which is all day, everyday, at a minimum of the system’s load, with renewables is proven false by the planners/ISOs etc in very pro-renewable countries like Denmark and Spain: they have no plans to eliminate on demand power, period. Thus they both build natural gas plants as part of their ‘renewable’ programs.

David

and thanks for posting it in this column (much easier to read).

I’m not sure I clearly understand your question. If you’re asking, can you get bomb material out of an IFR, the answer is no, not without a dedicated IFR-to-warhead factory, ie. a PUREX plant (to chemically separate the U and Pu) as well as an enrichment facility, to isotopically enrich your U or Pu. In the Hannum et al. paper I reference above, they write:

Possession of a plant for isotopic separation, centrifuge or otherwise, would be ipso facto evidence of intention to proliferate.

If you load with pure uranium, depleted, natural or enriched, you will breed plutonium, both Pu-239 and Pu-240, as well as an amount of higher transuranics (actinides). If you load with some mixture of uranium, plutonium, and other actinides, same thing.

If you want to make a weapon you’d load with uranium and short cycle the reactor, as Barry says, to avoid buildup of the higher atomic weight products. The product would include U-235, U-238, Pu-239, Pu-240, and higher actinides in decreasing proportion. The proportions of heavier nuclei depend on how long you’ve cooked your rod. And while brief neutron irradiation will give you a favourable Pu-239/Pu-240 ratio, there’s a much lower total Pu concentration, which means to get a decent yield, you’re going to have to run your reactor in serious breeding mode. Not ideal for power, and hard to hide, since you’ll be refueling like crazy.

This mixture is not weaponizable. You first need to chemically extract the U and Pu (a PUREX operation). The U or Pu you wind up with is likewise not weaponizable. For that you need an enrichment facility for either U or Pu, depending on the flavour of bomb you want. If you’re using fast reactor product, it will be plutonium flavoured.

Weapons grade plutonium contains at least 93% Pu-239. Reactor grade plutonium less than 82%. So you need enrichment.

Its been suggested that reactor grade Pu could be used in a bomb (Carson 1990). This paper was convincingly critiqued by Marsh and Stanford (Bombs, Reprocessing, and Reactor Grade Plutonium). The Carson paper, despite its shortcomings, does include a good list of the practical difficulties a would be bomb maker would face. They’re both worth reading.

So, to make your bomb from an IFR, you want to run short fuel load cycles (presumably easily detected). You need to divert the underdone rods. You then need to separate the Pu in a PUREX plant, which you’ve somehow built in secret. You then need to take that Pu and enrich it in another secret facility. Don’t get me started on how hard that is. Having recovered your Pu-239 you can then start your weapons programme.

If you have that capability, I think you’d be better off just starting with natural uranium. Its easier to get hold of, and you don’t have to do that jiggery pokery with the reactor. Also, I think a U-235 bomb is probably easier for a first time bomb maker due to less of a problem with preignition, leading to a fizzle.

Marsh and Stanford write:

The terrorist threat from reactor-grade plutonium has been greatly exaggerated by the argument that what is theoretically possible to do, can be done by subnational groups.

I think this is a really important point to bear in mind in any discussion of what it might be possible to do with the reactor fuel cycle.

One question that strikes me is whether it is possible to withdraw and replace fuel rods in an IFR core without shutting the reactor down. It would certainly be possible to design the reactor that way, and would make refueling very detectable. But you presumably need some backup generation capacity during refueling. Where does that backup come from? Alternatively, if you can do live refueling, I suppose it would be easier to do brief irradiation of rods sequentially, although it would take a long time to cook enough Pu.

So a simple question – can an IFR refuel without powering down? If not, do we need backup?

I assume the regular intended use of spiked fuel means that the minor actinides created (in the process you describe above) provide possibly a lower level of proliferation protection?

Is there feasible way or realistic risk that the these minor actinides might be worked around or produced in less quantity in order to produce a usable weapon?

[Again the answer to this question should not necessarily slow deployment of IFT in countries with existing reactors.]

Finally, (A slight diversion), Can the radioactive gases in Gen III reactors be captured and prevent atmospheric venting (as described for IFR by Blees).

John, nice find on that Hannum et al 2004 paper. I’d read their Sci Amer version, but this one is far more detailed on some aspects, which is really useful.

Its good to know that IFR is not worse than regular PUREX. I gather that IFR might make proliferation harder than most existing nuclear facilities.

But I actually meant can you use uranium without the actinides? Just plain unspiked uranium? Can you use this to get around IFRs regular intended radioactive protection and make usable Plutonium?

If proliferation were possible, it wouldn’t necessarily mean limiting IFR to countries with existing reactors (like Australia), but would be useful to consider (and plan for) how wide spread it might go. I.e how distributed would Hans Blix allow IFR to go?

Good graphic, taah!

The IFR (or LFTR, etc.) allows dismantling all reprocessing facilities. With that done, civilian nuclear power is pretty much decoupled from weapons development.

I just came across an interesting paper on pyroprocessing by Hannum, Marsh and Stanford which discusses the proliferation aspects. I also found a nice graphic of the pyroprocessing modules in an IFR which might help. There’s nothing there doing any isotopic separation.

That paper comes from Gerald Marsh’s website – lots more good stuff there on fuel processing and proliferation – I think I’ve found my bedtime reading. And check out his physics section to see what a hairy chested physicist this guy is.

E.g. If proliferation became a barrier to public acceptance of IFR, concerned scientist could be invited to the existing IFR and challenged to make plutoium or weapons material.