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Load-following and intermittency: France

by DoDo Tue Jul 6th, 2010 at 02:25:45 PM EST

Recently on ET, there was discussion on whether nuclear power plants can be operated in a load-following way (peak load), rather than at continuous maximum output (baseload) -- something that would be necessary both in the case of working alongside intermittent renewables (also see Wind power faulted for low prices!), and in the case nuclear energy were to provide most or all of our electricity.

In February, in Load-following and intermittency, I presented a study into the question by IGE/IER from Germany, which answered it with a tentative yes. However, being based on German experience, it was largely hypothetical, with many question marks regarding the practical feasibility of load-following operation. Something describing the experience in the country known to have researched nuclear load-following most, France, was needed.

Here I review such a study, even if its information on operation in France is still rather limited. The study itself concludes in broad terms that load-following operation is technically possible, but won't be widely realised for economic reasons.



Background

The study in question is: Pouret, L. and Nuttall, W.J. (2007) "Can nuclear power be flexible?" Electricity Policy Research Group Working Papers, No.07/10. Cambridge: University of Cambridge. A draft version is available on-line. Hat tip again goes to Jérôme.

Like the EGA/IER study, this one "answers" other studies assuming an inflexibility of nuclear power, too; in this instance, in Britain: they quote the UK government's 2006 Energy Review saying that nuclear power "has the disadvantage that it cannot easily follow peaks and troughs in energy demand".


Technicalities of load-following operation

The most potent way to regulate nuclear power plant output highlighted in the German study was to use the control rods in pressurized water reactors (PWR). Supported by some digging, I questioned whether that would be so easy maintenance-wise: in particular, control rod manipulation leads to uneven power distribution in fuel rods, resulting in stresses. I and rootless2 also questioned whether fatigue from the wear & tear on the control rods themselves in continuous operation can be dismissed.

Well, the Pouret-Nuttall study confirms these concerns and more:

It is important to note that while most reactor types have control rods for reactor shut-down control, these rods are not optimised for controlling flexible reactor power levels... The exclusive use of control rods for output power control would have negative consequences, such as: flux distribution disturbances (see figure below), component materials fatigue, mechanical wear, and adverse impacts on fuel burn up. Many of these difficulties arise for the fact that, for instance, output electrical frequency control involves very many low-amplitude rod movements (up to several hundreds a day), which may limit the lifetime of control rod mechanisms. [3] [References are mostly to Framatome publications]

They go on to describe the factors of temperature inhomogeneities and xenon-135 creation (which enhances said inhomogeneities) in more detail, and mention the influence of such design features as power density and fuel enrichment.

However, there are ways to mitigate these problems, by retrofitting the reactor:

...conventional rods are known as `black rods' indicating their complete absorptive capacity for stopping the passage of fission neutrons. Flexible reactor operations are facilitated through the use of special reactor control rods known as `grey rods'. These rods do not completely absorb the fission neutrons that try to pass through them. For load-following manoeuvres, a clever management of both control rods and soluble boron is found to be optimal [5].

Soluble boron is a neutron absorbing material, which in addition can deal with xenon. From later discussion, it appears that boron has primacy in France at present, and "grey rods" have a full roll-out only with the EPR. For the EPR in mode G (grey rods), they claim the possibility of power output regulation at a speed of up to 2% of total output per minute, between 30% and 100% of total power, and they indicate specifically that such an operation is possible on a daily basis (the assumption that quasi-permanent load-following operation of existing plants won't have adverse maintenance consequences was one of my criticisms of the German study).

A further factor is reactor temperature.

Unlike the case of Gas Cooled Reactors, the relatively low coolant temperature range in PWRs (see table below) limits a plant's thermodynamic efficiency, its thermal stresses, and the fatigue of components.

Again looking into the future, they claim that the EPR has the same temperature in the 60 to 100% range. In their conclusion,

Given these significant improvements, one can therefore state that new build PWRs will offer operational flexibility as good as that of current fossil fuel plants [5].

From which it follows that even the flexibility of nuclear power as practised in France is inferior to fossil fuels. Sadly the study contains no example data or load curves, nor a consideration of exports. They only state in the economy section that

Today, nuclear accounts for more than 80% of French electricity and, therefore, most NPPs have to often operate occasionally at part-load and some plants must be sufficiently flexible to load-follow to ensure grid stability.

If stepped reductions and shutdowns are more commonly used (as elsewhere), it follows that in present practice, the contribution of load-following operation to variability is rather limited.


Economics

Now, the technical aspect is one thing. The other is: will it pay for the owner of the plant? After all, when advocates of nuclear power say that it is cheap, they are thinking of current widespread practice of operation at maximum.

As nuclear power load-following remains a rather uncommon practice, exclusive to a handful of countries, economic information is larely unavailable. Most data on nuclear power plant economics assumes baseload operations.

The analysis starts with the cost structure of different plant types from a French government study:

After a disclaimer about great variability due to uncertain factors and country differences, they state:

Despite such local differences, the cost structure of nuclear power always contains more fixed costs (especially capital costs) than fossil-fuel-based alternatives. This is the essential reason why baseload operation is generally preferred for nuclear power plants. We can safely, albeit perhaps somewhat simplistically, assume from a generating company's perspective, that, given the cost structure of nuclear power, operators would want their NPPs to operate at full-load for as much of the time as possible, in order to maximise income.

With operating hours as the primary factor, the French government study calculated these production price curves (which Pouret-Nuttall include with the disclaimer that this diagram assumes only full shutdowns for nuclear, not load-following):

The discussion so far assumes constant retail prices. However, on our brave new electricity markets, balancing is a separate spot market that can have much higher prices. Still, Pouret-Nuttall say, regarding the UK example:

Prices in the balancing market can ... be very generous, but they are insufficiently high to motivate flexible nuclear generation given its very high fixed costs discussed earlier. As the market evolves and new nuclear power plants come on-line it is not inconceivable that this situation could change and nuclear power might find a role in the balancing market...

Then again, if things aren't left to market forces and nuclear gains a high share due to government policy, load-following becomes a technical necessity. Unfortunately, Pouret-Nuttall can give few numbers or conclusions on the economics of this.

Thus far the discussion considered only the main effect from fixed costs and reduced operating hours. Pouret-Nuttall also mention some of the secondary effects of extra operational costs from load-following:

..secondary effects can arise; for instance, load-following operation may imply an increased use of soluble poison to control the reactor power. In such modes of operation much more water must then be treated and discharged, which might imply extra operating costs at the margin.

There is also the maintenance effect:

In France, NPPs have relatively low availability coefficient (about 80%) [30]. A recent study by EDF (Electricité de France) shows that operating NPPs at their maximum load improves their overall performance. It especially reduces the unscheduled outage coefficient from 3% to 1.8% in four years. This clearly suggests that load-following reduces the availability of NPPs, mainly because of more frequent maintenance (see below). The cost of such a difference of the unscheduled outage coefficient has been estimated at several millions euros [31].

They also state that "no study has yet been undertaken by the French authorities to estimate" the full range of extra maintenance and lifecycle costs. Will load-following accelerate plant aging? Pouret-Nuttall say that this would be sensible to assume, but French authorities claim there is no clear evidence today.

Even if they concede that a very small number of pieces of equipment (control rods drives for instance) may be adversely affected, they still argue that proper designs and load-following procedures ensure the core components are not excessively degraded. Also, there is the possibility that EDF might concentrate load-following operations on just a few NPPs, in an almost sacrificial manner so as to avoid damaging the wider NPP fleet [32].

It is in the economy section that the authors tell about the relevance of exports, but only to state that:

Another method by which NPPs might operate close to the top of the merit order in a given country is to shed surplus nuclear electricity via sales to neighbouring electricity systems. France is a major exporter of nuclear-generated electricity and it would be interesting to study the relationship between electricity exports and NPP operations. Such considerations lie beyond the scope of this paper.

Display:
Could some of our France-based readers find power curves, any power curves, for French electricity production?

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Tue Jul 6th, 2010 at 02:27:10 PM EST
Adding: there is a lot more detail in the Pouret-Nuttall study, on the merit order and other things, go read it all if interested. (25 pages with references.)

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Tue Jul 6th, 2010 at 02:29:22 PM EST
[ Parent ]
can be found here

Wind power
by Jerome a Paris (etg@eurotrib.com) on Wed Jul 7th, 2010 at 05:15:48 AM EST
[ Parent ]
A thousand thanks! Just fom the graphs for today,

(1) the daily variations...

  • of consumption: c. 18 GW;
  • of production: c. 9 GW;
  • of net exports: c. 7 GW, and net exports have an opposed phase to consumption;
  • rest I can't explain after this quick check: 2 GW.

(2) within production, in the order of total power, the daily variations are (in power output as well as in percentage of the daily maximum):
  • nuclear: 2.7 GW (c. 6%);
  • hydro: 4.1 GW (c. 40%);
  • coal: 1.9 GW (c. 70%);
  • gas: 1.3 GW (c. 55%);
  • fuel oil + peak: 0.1 GW (100%).


*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Wed Jul 7th, 2010 at 09:15:57 AM EST
[ Parent ]

If anyone has a better idea how to visualise net exports especially, I'm all ears.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Wed Jul 7th, 2010 at 01:30:07 PM EST
[ Parent ]
gas... and not only gas, but COAL... in order to fulfill export obligations? Am I reading that first graph correctly?

It is rightly acknowledged that people of faith have no monopoly of virtue - Queen Elizabeth II
by eurogreen on Thu Jul 8th, 2010 at 09:31:53 AM EST
[ Parent ]
No. I subtracted exports from total production, so the green line (which shows the highest variability) is more or less equal to domestic consumption in France. Thus the daily variation in coal, gas, as well as exports is needed to give the full daily variation of consumption, because nuclear's variability is nowhere near enough.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Thu Jul 8th, 2010 at 02:03:38 PM EST
[ Parent ]
Here is another attempt to illustrate what I wanted to show. Now I subtracted the minimum of the average daily curves, and stacked only the daily variations for each power mode. This way I could stack the contribution of exports, too.



*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Thu Jul 8th, 2010 at 03:35:11 PM EST
[ Parent ]
The same for the first seven days of July (stronger daily variation, much stronger use of export balancing -- that is in essence the use of Italian, Dutch, Spanish, British coal/gas/hydro for balancing):



*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Thu Jul 8th, 2010 at 03:52:22 PM EST
[ Parent ]
thanks DoDo, nice article. I see I am going to have to have an in-depth talk with an old friend of mine who works at Areva...

Re the economics: and this I think these are general arguments. So what if if the produced kWh price ends up 3 or 4 or even 6 or 7 cents more expensive if
a) fossil power will eventually pay the cost of CO2
b) we consume less electricity (e.g. by being more efficient (something still not high enough on the agenda of energy politics IMO)) and
c) well, I'll gladly pay a few cents more if that means we have less global warming(!).

Especially c) should be something that deserves more attention, many people will pay a premium to drink good wine, eat organically grown food, etc... but there are only few people willing to buy "premium" electricity, although there are some offers out there (at least in Germany).

by crankykarsten (cranky (where?) gmx dot organisation) on Thu Jul 8th, 2010 at 02:34:32 AM EST
There is a basic problem with that argument, tough - which is that the only way to reduce the carbon emissions of the wider economy is to encourage electrification of every aspect of it that can be electrified, and high electricity prices would make that near impossible, as people would simply continue to use fossil fuels instead of electrons. So what we need is a situation where electricity is  

A: Cheap and abundant. - Ideally, cheaper than it is now! Remember, using resistance heaters with clean power is better than having a gas furnace, despite being an insanely wasteful use of electricity, and not everyone can use heat pumps.  
B: carbon free and clean.
C: Demand and supply curves match up somehow without wrecking points A. or B - This means no gas fired peakers, and it means that any energy storage systems you include must cost less than your generating scheme. If you mean to solve it via overbuild and just wasting the surplus power, again, this cost needs counting.

This is a very tall order. In my judgement, it is, in fact, not possible to get there with renewables. A europe wide grid linking wind would still have large variations in output not linked in any way with demand swings.
It might be possible with nuclear and pumped storage, since the maximum storage capacity needed is what you need to cover day/night variation, but this is still going to add some to those costs listed. The ideal solution would, naturally, for the extra electricity consumed in the process of
"Electrify those bits of our economy not currently on the grid" were to fall overwhelmingly during the night, so that we end up with a much, much flatter demand curve. - This, however, would require the wide adoption of, oh, electric cars that do not need recharging during the day in normal use. (if people charge their cars at night + while they are at work, that doesnt help. the battery really needs to last all day in normal use. )

by Thomas on Thu Jul 8th, 2010 at 07:40:55 AM EST
[ Parent ]
Note that this argument assumes ongoing free riding by fossil fuel. If fossil fuel is sold at full economic cost, then there is no need for electricity to be any cheaper than it is today, and it could indeed by a bit more expensive and still represent a substantial savings.

This argument also assumes there is no Connie Mae institution financing the capitalized savings of energy saving capital spending at subsidized terms (where it may be noted that this financial subsidy could easily be provided by a portion of a carbon fee while still recycling a majority of carbon fee payments as social dividend).


I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.

by BruceMcF (agila61 at netscape dot net) on Thu Jul 8th, 2010 at 01:14:07 PM EST
[ Parent ]
Remember, using resistance heaters with clean power is better than having a gas furnace, despite being an insanely wasteful use of electricity, and not everyone can use heat pumps.

In a (part-)nuclear grid, central heating can obviate this requirement.

For that matter, there is no good reason why we have to replace all current uses of fossil fuels with electricity: Heating requirements can be wholly obviated via appropriate architecture, even in Northern Finland in the winter; the need for transportation can be greatly abridged with improved city planning and settlement patterns; shipping can, for all non-perishable commodities, be powered by sail. The only major uses of fossil fuels I can think of off-hand are air travel (which will need to be replaced by trains and ships), industrial heat sources like furnaces and electricity generation for existing electricity demand.

This will kill the suburbs and radically alter the rural areas, of course. But our way of life is negotiable - the laws of physics are not.

- Jake

Friends come and go. Enemies accumulate.

by JakeS (JangoSierra 'at' gmail 'dot' com) on Thu Jul 8th, 2010 at 01:50:00 PM EST
[ Parent ]
Speaking of electrical heating. Both in Sweden and France, electrical heating was advocated by the utilities with the reasoning that this can reduce the nuclear-unfriendly daily variability of demand. However, the two load graphs I posted upthread reflect the snag with this: seasonal change. The graph for the first half year of 2010, which includes a heating season, shows lesser variability in total production minus net exports than the first six days of July graph, corresponding to the season when people don't use heating and generally consume less (less need for lights, less TV watching...). So, in the end, electric heating doesn't reduce balancing capacity requirements at all.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Thu Jul 8th, 2010 at 03:07:47 PM EST
[ Parent ]
At least in Sweden, it was strongly advocated by Vattenfall and was backed by Vattenfalls role as monopoly grid controller. Local utilities that followed Vattenfalls line was rewarded by lower prices on electricity sold to them and higher prices on electricity sold from them. Utilities that did not follow the line was similarly punished. This was regulated in secret treaties (that has expired and are no longer secret) during the period that nuclear power was much debated and a referendum held on abolishment of nuclear power.

Sweden's finest (and perhaps only) collaborative, leftist e-newspaper Synapze.se
by A swedish kind of death on Fri Jul 9th, 2010 at 08:47:19 AM EST
[ Parent ]
The electric heaters are very interesting. I've seen no study on this (but would love to make one), but my hypothesis is that the nuclear overbuild in the 80's in Sweden resulted in an oversupply of power, which had to be used for something. Enter the electric heaters.

What's really interesting is that Swedish power consumption has been pretty flat since 1985 (when the latest nukes came online), but the amount of electrical heating has steadily fallen, after the initial surge in use.

Essentially, the growth in power demand due to economic growth has been hidden by the constant draw-down of electric heaters. Now that that low value-added use of power has more or less been phased out, new generating capacity will be needed to fuel future economic growth.

The idea that the linkage in growth in GDP and power consumption in Sweden has been fundamentally broken, is going to be shown to be an empty shell. This means the projected power surplus of the future will fail to materialise.

Did I mention it would be totally cool to make a study where one can try to falsify this hypothesis? ;)

Peak oil is not an energy crisis. It is a liquid fuel crisis.

by Starvid on Tue Jul 13th, 2010 at 09:31:06 AM EST
[ Parent ]
That would be cool, yes.

If you are interested in trying to make such a study, I would guess this institution might be interested:

Chalmers: Energi och miljö: Fysisk resursteori

På avdelningen för fysisk resursteori bedriver vi tvärvetenskaplig forskning och utbildning inom områden som hållbar utveckling, energisystem i ett klimatperspektiv, industriell ekologi samt komplexa system.


Sweden's finest (and perhaps only) collaborative, leftist e-newspaper Synapze.se
by A swedish kind of death on Tue Jul 13th, 2010 at 10:06:58 AM EST
[ Parent ]
Another study I would be interested in: the pumped hydro potential of Europe. I only have a vague idea of what would be the limiting factors.

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Tue Jul 13th, 2010 at 12:09:30 PM EST
[ Parent ]
... in limiting factors between pumped hydro added to conventional hydro, pumped hydro into an artificial reservoir above a natural reservoir, and modular pumped hydro. The first is limited by conventional hydro capacity and rival reservoir uses, the second in a way parallel to coventional hydro by appropriate sites, the last by minimum efficient scale for economies of scale and availability of sites with sufficiently steep slopes and sufficient height differential between top and bottom reservoir.

I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.
by BruceMcF (agila61 at netscape dot net) on Tue Jul 13th, 2010 at 04:20:09 PM EST
[ Parent ]
A europe wide grid linking wind

I don't think anyone foresees a wind-only renewables future. Other renewables have to mature.

It might be possible with nuclear and pumped storage

With pumped storage, anything is possible.

Question: do you mean only or mostly pumped hydro? If yes, have you ever calculated what the capacity needs of all of the EU translate to in physical parameters?

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Thu Jul 8th, 2010 at 03:00:24 PM EST
[ Parent ]
...
A europe wide grid linking wind would still have large variations in output not linked in any way with demand swings.
... would also be a be a europe wide grid linking traditional hydro, which is eminently dispatchable, a europe wide grid linking run-of-river hydro, which while volatile seasonally is quite predictable on a load balancing time scale, and a europe wide grid linking generating capacity that can be readily fired with biocoal.

And of course, a europe wide grid linking wind would also be a europe wide grid crossing multiple time zones spreading peaks in CSP power availability.

Putting individual sustainable production technologies in 20th century silos will always make the challenges look harder than pooling them into a diverse portfolio.


I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.

by BruceMcF (agila61 at netscape dot net) on Thu Jul 8th, 2010 at 10:56:15 PM EST
[ Parent ]
Re the economics: personally, I think policymakers should move away from free-market mindset as soon and as far as possible. Thus, yes, I personally would not oppose de-carbonising intermediate and peak load at the price of higher production costs.

However, on the technical side, what I came away with after reading these studies (and studying the load data Jérôme linked) was that, while theoretically possible, the technology for daily large-amplitude load-following with nuclear is still in its infancy, just like all the other carbon-free solutions except pumped hydro (pumped air, distributed capacitor, battery or fuel cell storage, large-scale natural balancing). What will actually work, we'll see.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Thu Jul 8th, 2010 at 02:50:37 PM EST
[ Parent ]
I don't think this was the point of your diary, but much of the problem of matching electricity supply to demand can be done by the demand dispatch approach. That is, a rate structure is constructed that encourages demand shedding when the supply is exceeded, and the adjustments are automated by smart grid technology. Because much of the expected demand in the future is to charge batteries of electric cars, and since many of the routine uses of electricity do not require urgent scheduling, it is expected (at least by the American electrical engineers) that demand dispatch will enable much of the migration to 100% sustainable sources. It's discussed in some detail in recent articles in the IEEE Power and Energy Society journals, unfortunately behind a subscription firewall...

http://www.ieee.org/organizations/pes/public/2010/may/index.html

A recent example...

http://www.globenewswire.com/newsroom/news.html?d=195091

by asdf on Fri Jul 9th, 2010 at 11:30:26 PM EST
Why not increase the capacity factor of French nukes and send the power cross channel at night, and use it to power a number of new pumped hydro plants in Scotland and Wales? Like Dinorwig. Half a dozen of those beasties and all the necessary power lines, that's what I call a stimulus package!

Peak oil is not an energy crisis. It is a liquid fuel crisis.
by Starvid on Tue Jul 13th, 2010 at 09:35:09 AM EST
Won't those be needed by Britain already, whether for more wind or new nuclear?

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Tue Jul 13th, 2010 at 12:08:04 PM EST
[ Parent ]
Well yes I suppose, but it seems to me that it makes far more sense to use underutilised French nukes than to build brand new ones in Britain.

Peak oil is not an energy crisis. It is a liquid fuel crisis.
by Starvid on Tue Jul 13th, 2010 at 12:24:01 PM EST
[ Parent ]
Slightly off-topic, but still related.

Does any of the resident specialists have any idea on the EROEI of nukes? I've found a few sources with contradictory information and simply do not know what to believe. The whole economics of nuclear energy is a mystery to me: being such a contentious issue it is very easy to find all kinds of claims with a reasonable degree of factual support...

by t-------------- on Tue Jul 13th, 2010 at 09:58:39 AM EST
This appears to be the state of things regarding EROEI research on nuclear:

The Oil Drum: Net Energy | The Energy Return of Nuclear Power (EROI on the Web-Part 4)

EROI

We have found the information about the EROI of nuclear power to be mostly as disparate, widespread, idiosyncratic, prejudiced and poorly documented as information about the nuclear power industry itself. Much, perhaps most, of the information that is available seems to have been prepared by someone who has made up his or her mind one-way or another (i.e. a large or trivial supplier of net energy) before the analysis is given. As is usually the case, the largest issue is often what the appropriate boundaries of analysis should be. The following diagram, which should be considered conceptually if not necessarily quantitatively appropriate, illustrates the main issues. The diagram indicates from left to right the timeline of a power plant, with the initial negative values ("phase 1") indicating the initial energy costs of plant construction, the large positive value generated over the reactor's lifetime (with a correction for the energy to get/refine the fuel) and phase 3 indicating the energy required for dismantling the plant and sequestering the dangerous by products.



Figure 8 - Lifecycle view of energy costs and production (Leeuwen 2005). The above figure is a general outline of the energy costs and gains lifecycle, but does not accurately reflect the operational lifetime (which is more likely to be around 50 years) or the EROI (which depends on the study looked at).
Click to Enlarge [See linked article for enlarged picture.]

The seemingly most reliable information on EROI is quite old and is summarized in chapter 12 of Hall et al. (1986). Newer information tends to fall into the wildly optimistic camp (high EROI, e.g. 10:1 or more, sometimes wildly more) or the extremely pessimistic (low or even negative EROI) camp (Tyner et al. 1998, Tyner 2002, Fleay 2006 and Caldicamp 2006).

To hazard a guess, phase 3 looks like a likely candidate for diverse interpretations on energy consumption.

Sweden's finest (and perhaps only) collaborative, leftist e-newspaper Synapze.se

by A swedish kind of death on Tue Jul 13th, 2010 at 10:46:16 AM EST
[ Parent ]
Thanks a lot.

I think this is an highly important issue (in the light of peak oil) for which key facts seem to be missing.

Decommissioning seems to be an issue. But, at least until now, countries like France or Sweden seem to have profited a lot from nuclear energy.

by t-------------- on Tue Jul 13th, 2010 at 10:56:35 AM EST
[ Parent ]
Actually, the facts have been worked out, in mindnumbingly exhaustive detail, indirectly - There has been a tonne of studies of the life cycle carbon emissions of nuclear power, some of which are from countries where nuclear power currently make up only a small faction of total energy supply - , and in those countries the carbon emmissions from the nuclear life cycle must logically be a pretty good proxy for the energy consumption of the nuclear energy sector cradle to grave.. and the answer is that it is trivial.
by Thomas on Tue Jul 13th, 2010 at 04:22:09 PM EST
[ Parent ]
-and if you dig into the details of said studies, almost the entirety of the energy consumption is from the enrichment stage, as gaseous diffusion is the method used most widely, with all other steps of the life cycle having very low emissions indeed... and gaseous diffusion is on the way out.
by Thomas on Tue Jul 13th, 2010 at 04:50:53 PM EST
[ Parent ]
This is true. I looked into this exact question for the UK Offshore Valuation a few months ago. There's a graph on my blog[1] which shows the trajectory of EROEIs calculated over time for a number of technologies including nuclear which shows it reducing as time passes.

There is a fair amount of detail and discussion in "Life cycle energy and greenhouse gas emissions of nuclear energy: A review"(Lenzen, 2008). As is pointed out elsewhere, this explains that the rising EROEI is mainly because centrifuge enrichment is more energy efficient than gaseous diffusion.

[1] <a href="http://ococarbon.wordpress.com/2010/05/19/eroei-of-electricity-generation/">http://ococarbon.wordpress.com/2010/05/19/eroei-of-electricity-generation/</a>


www.ococarbon.wordpress.com

by oCo Carbon (jamie[dot]bull[at]oco-carbon[dot]com) on Wed Jul 14th, 2010 at 04:29:03 AM EST
[ Parent ]
Welcome to ET, oCo!

By laying out pros and cons we risk inducing people to join the debate, and losing control of a process that only we fully understand. - Alan Greenspan
by Migeru (migeru at eurotrib dot com) on Wed Jul 14th, 2010 at 05:22:58 AM EST
[ Parent ]
Hello oCo Carbon, and welcome!

Sorry our spam-fighting precautions prevented you from posting a link. You'll be able to from now on.

Your blog post is here for those who want a direct link.

by afew (afew(a in a circle)eurotrib_dot_com) on Wed Jul 14th, 2010 at 05:34:44 AM EST
[ Parent ]
Thanks. Looks like an interesting forum you have here.

www.ococarbon.wordpress.com
by oCo Carbon (jamie[dot]bull[at]oco-carbon[dot]com) on Wed Jul 14th, 2010 at 07:32:30 AM EST
[ Parent ]
How did you find it?

By laying out pros and cons we risk inducing people to join the debate, and losing control of a process that only we fully understand. - Alan Greenspan
by Migeru (migeru at eurotrib dot com) on Wed Jul 14th, 2010 at 08:59:43 AM EST
[ Parent ]
I have a google alert set up for EROEI. I saw Jerome a Paris here and recognised his name from Claverton Energy Group so thought I'd put in my two penn'orth.

www.ococarbon.wordpress.com
by oCo Carbon (jamie[dot]bull[at]oco-carbon[dot]com) on Wed Jul 14th, 2010 at 12:04:28 PM EST
[ Parent ]
The grade dependence of ore-to-fuel is another issue... especially if you want to expand nuclear greatly globally, which may quickly force a move to grades a tenth or hundredth of the present mean. (Related issue: earth volume moved by mining and connected air-water pollution.)

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Tue Jul 13th, 2010 at 12:06:24 PM EST
[ Parent ]

That graph is on the whole extremely misleading. The energy cost of constructing a reactor is measured in days of output, so should be an absolutely tiny dot on the start of that graph, and as for the back end.. Say what? I am not avare of any proposals for waste management that are ongoing energy hogs! A geological repository does not have a bloody electricity bill.
Arrrgh!
The energy consumed by enrichment mining assumed are also way out of wack, but not as obviously full of shit as the rest of the graph.
by Thomas on Tue Jul 13th, 2010 at 01:06:04 PM EST
[ Parent ]
You appear to be attacking the graph on the faulty premises.

The following diagram, which should be considered conceptually if not necessarily quantitatively appropriate, illustrates the main issues.

(My bold)

Thomas:

and as for the back end.. Say what? I am not avare of any proposals for waste management that are ongoing energy hogs! A geological repository does not have a bloody electricity bill.

There is no ongoing energy hog in the graph, if there was one phase 3 would not stop. Phase 3 consists of: waste conditioning, clean-up, cooling in safe storage, dismantling and final disposal. All of which costs energy.

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by A swedish kind of death on Tue Jul 13th, 2010 at 02:02:53 PM EST
[ Parent ]
What is an "energy hog", BTW? (Google doesn't help)

*Lunatic*, n.
One whose delusions are out of fashion.
by DoDo on Tue Jul 13th, 2010 at 02:08:13 PM EST
[ Parent ]
A hog is a domesticated pig. From it springs the word hogging.

Hogging - Wikipedia, the free encyclopedia

Greedily eating something, or taking too much of it: see wikt:hogging

So an energy hog would be something that use (too) much energy.

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by A swedish kind of death on Tue Jul 13th, 2010 at 02:16:19 PM EST
[ Parent ]
The graph is not claiming to be to scale, no, but the scales picked are utterly arbritary and intended to make you conclude that nuclear power is a net energy consumer, and facts be dammed. High grade example of lying through your teeth with pretty pictures.
by Thomas on Tue Jul 13th, 2010 at 04:09:14 PM EST
[ Parent ]
... show a net energy loss, wouldn't it? If it was "intended to show nuclear power is a net energy consumer", showing nuclear as a net energy producer as the schematic actually does would fall a bit short of the intention.

The diagram actually says if you know the figures for each stage, add all the energy gains, minus all the energy costs, the difference is the net energy.


I've been accused of being a Marxist, yet while Harpo's my favourite, it's Groucho I'm always quoting. Odd, that.

by BruceMcF (agila61 at netscape dot net) on Tue Jul 13th, 2010 at 08:09:55 PM EST
[ Parent ]
The energy cost of constructing a reactor is measured in days of output

What do you mean?

I am not avare of any proposals for waste management that are ongoing energy hogs!

To be pedantic, waste has to be transported and treated to; but methinks the disposal energy costs include disposal site construction, concreting-over, and the energy needed by the machines doing the dismantling and collecting the soil...

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Tue Jul 13th, 2010 at 02:06:22 PM EST
[ Parent ]
.. okay here we go. an EPR outputs 1650 megawatts of electricity. This is 1650 x 24 megawatthours of electricity per day. Or to put it into units a bit smaller, 39600000 kwh/day.
If the plant under consideration is replacing coal fired capacity, (815 grams co2/kwh, according to externe)
this works out to 32274 tonnes of CO2 emissions saved per day. an epr clocks in at 180000 tonnes of concrete and steel.. Concrete production emmits some 1.25 tonnes co2 per tonne of concrete, and steel some 2 tonnes of CO2 per tonne of steel, so at a maximum, the embodied CO2 in an epr is some 300000 tonnes. or less than 10 days worth of operations. Make it twenty if we are replacing gas instead of coal, but the carbon from construction does not really amount to squat over the 60 year life of a reactor.
by Thomas on Tue Jul 13th, 2010 at 04:05:55 PM EST
[ Parent ]
I admit- this is not intuitively obvious - the first time I napkinned those numbers, I went "that cant be right", but the facts are that while nuclear power plants cost a heck of a lot of money, the material consumption in construction is quite modest. The bulk of the costs are skilled labor and suppliers taking advantage of the mismatch between the demand from the nuclear rebirth and the sad state of the supply chain industries to gouge like hell.
by Thomas on Tue Jul 13th, 2010 at 04:15:27 PM EST
[ Parent ]
How did you get from from EROEI and measuring in days of output to CO2?

If you originally meant to make the point that the energy input of construction is much less compared to annual production than indicated on the graph, you may have been right. But, being the nitpicker, I have to put the figures right.

This source claims the Olkiluoto 3 EPR is 250,000 m³ concrete (about 600,000 t) and 52,000 t steel. Calculating with 20 GJ/t for steel and 1.6 GJ/m³ for concrete, I get 1.44*10^15 J, or 0.4 TWh. I don't know how to estimate the energy use to move the excavation volume of 450,000 m³ and the energy input of the making and transport of other building materials, but the total is probably not magnitudes higher. Against this stands an annual production of 14 TWh at a high capacity factor of 97%.

Then again, the real question marks still concern the enegy input of making the fuel and decommissioning.

*Lunatic*, n.
One whose delusions are out of fashion.

by DoDo on Wed Jul 14th, 2010 at 05:09:20 AM EST
[ Parent ]
,, or, as I said, ten days. (used carbon instead of energy because I can actually remember those numbers off hand..) Compared to a 60 year operating life, if put into accurate scale the construction phase would literally not show up on the graph. Or rather, it would be a flat line leading up to reactor start. The only aspect of the nuclear fuel cycle which does consume quantities of energy that would actually show up to the human eye in a graph of energy consumption versus output is enrichment - and this is a legacy effect due to the rather horrid inefficiency of gaseous diffusion.
by Thomas on Wed Jul 14th, 2010 at 05:38:27 AM EST
[ Parent ]
Why the hell various sources disagree about how much the EPR weighs tough.. say what? That really should not be a subject of debate. puzzled
by Thomas on Wed Jul 14th, 2010 at 05:41:29 AM EST
[ Parent ]
RE: shutdown.. honestly, given the extensions we are seeing on the current generation of plants, and the extreme focus on longevity / ease of maintainance in the epr design, I would not be shocked if come 2332 O-3 is still in operation on the grounds of "it costs less to keep it running than it does to build another zero-point-energy-tap"
by Thomas on Wed Jul 14th, 2010 at 05:45:37 AM EST
[ Parent ]


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