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Hidden cost of nukes: intermittency

by Jerome a Paris Sat Apr 7th, 2012 at 08:18:18 AM EST

EDF Says Fires at Penly Nuclear Reactor Extinguished

Electricite de France SA, the biggest operator of nuclear reactors, said two fires were put out in their early stages at its Penly plant in Normandy. (...) data on the website of Reseau de Transport d’Electricite, the French grid operator, showed that EDF halted the 1,330-megawatt reactor at 12:20 p.m. local time. There are two reactors at the site in northern France. Penly-1 was generating normally this morning, according to the latest data available.

I'm flagging this item not to point out the danger of nuclear plants, but to point out a specific cost usually ignored: that of intermittency of nuclear. As the extract above notes, 1.3 GW brutally disappeared from the grid, and it could have been double that if the other reactor had had to be cut off. The grid had to be able to deal with such an incident, which meant it had to find another 1.3GW available on short notice - in fact, the grid must be able to deal with the unexpected drop of any large plant - and by their very nature, nuclear plants are very large.

When you consider that the Gravelines power plant has 5.7 GW of installed capacity, you realize that the grid needs to have at all times the ability to deal with the brutal interruption of that level of capacity, should any event take the site down altogether. While rare and usually benign, events which temporally take down a nuclear plant do happen once in a while and thus impose a permanent cost on the power system which must be over-designed in order to cope with such a possibility.

And when you look at how grid costs are calculated, you see that they are proportional to the maximum load a generator can put into the system - and thus these costs fall, logically, on the largest coal and nuclear plants.

Which means, in practice, that intermittency of nuclear is costlier than intermittency of wind...


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What has been, is or would be the longest period of becalmed winds that might impact an entire field of wind turbines?

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Sat Apr 7th, 2012 at 09:43:38 AM EST
the question is how you define "an entire field of wind turbines" - i.e. how big is the system that needs to be balanced, or what kind of connections do you have to other areas (with different wind patterns) that you can rely on?

The larger the system, the easier it is to deal with local events, and the larger "local" can be.

Wind power

by Jerome a Paris (etg@eurotrib.com) on Sat Apr 7th, 2012 at 10:52:43 AM EST
[ Parent ]
Also, the "outfall" of wind is predictable to a reasonably high degree over wide areas, even two days out, so there is little chance of an unplanned shock to the system.

Conversely, when grid planners know a strong wind is coming, the "balancing" plants can be more efficiently cycled.

"Life shrinks or expands in proportion to one's courage." - Anaïs Nin

by Crazy Horse on Sat Apr 7th, 2012 at 12:04:12 PM EST
[ Parent ]
I was referring to individual offshore installations, such as in the North Sea, the coasts of France and the Netherlands or to large onshore wind farms, the power from which is aggregated into a given tie point to the grid. It did happen recently that a large portion of the windmills in West Texas were substantially becalmed. I am sure that a forthcoming answer is possible.

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Sat Apr 7th, 2012 at 01:06:10 PM EST
[ Parent ]
I often miss answers that are in the subject line. :-)

"It is not necessary to have hope in order to persevere."
by ARGeezer (ARGeezer a in a circle eurotrib daught com) on Sat Apr 7th, 2012 at 01:31:28 PM EST
[ Parent ]
According to the Claverton Group Why was Dinorwic Built? the pumped storage at Dinorwic was probably built specifically to accommodate a sudden outage at Sizewell B, the biggest of UK's fleet.

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by ChrisCook (cojockathotmaildotcom) on Sat Apr 7th, 2012 at 10:22:18 AM EST
Are we not talking about two different kinds of intermittency here? Both types require a level of redundant capacity within the system to make good any production loss at any given windfarm/nuclear site.

However wind-farm outage occurs regularly during calm periods whereas nuclear shut-downs are exceptional events. The capital costs of providing redundant capacity to provide cover for the loss of a GW of wind or nuclear capacity will be similar.  However the ongoing production cost of replacing 1 GW of wind energy on a regular basis will be a lot more than the occasional loss of 1 GW of nuclear energy.

It is a valid point, however, to point our that no production system is without its downtime (planned, unplanned, predictable or not) and that they thus all require a level of overcapacity within the system to guarantee 100% supply/demand balancing at all times.

Intermittancy is not limited to windfarms, and their generally more diffuse connections to the grid may make that easier to provide for than losing one giant nuclear plant at one point in the grid.

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by Frank Schnittger (mail Frankschnittger at hot male dotty communists) on Sat Apr 7th, 2012 at 03:13:30 PM EST
Depends on what back-up you have got. In Sweden with 40% of electricity from hydro everything is handled by adjusting the flow in the dams. So barring exceptional circumstances (lots of nuclear down, cold winter, low water levels at the same time (which has happened too much lately)) the total amount of variation should be the important factor. And as I have presented elsewhere on ET, wind, hydro and nuclear in Sweden has about the same yearly variations.

I would like to see numbers from day-to-day variation for a country with decent amounts of wind and nuclear (and other types as well if possible) so that we could crunch the numbers once and for all.

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by A swedish kind of death on Sat Apr 7th, 2012 at 03:40:03 PM EST
[ Parent ]
MW and MWh are two completely different issues.

The argument against wind is that it provides no standby MW - which is true as far as it goes - but the fact that nuke MWs can go down as well means that you need MW backup for these MWs as well.

Your argument is about MWh, and this one does not stand up to scrutiny. Wind provides MWh of the same value as other sources, and if it's not there, you won't burn more gas because of it - it's the other way round: when wind is there, you burn less gas (or require less draw on hydro resources).

The whole thing about putting wind into the system is that the hard question is not what to do when wind is not there (the answer being: we'll do what we did before there was wind), but what to do when there is wind (i.e. can you switch off the rest). And the ironic thing is that, under current market mechanism, the "other" producers cannot complain as wind does not need priority dispatch - it is actually the lowest marginal cost producer and will always be dispatched in priority to others even under current market rules. So others get dispatched less and make less money.

Then you get into arguments from utilities which say that they won't provide mid-load services as they are less profitable if there is too much wind, which is a systemic issue, i.e. a political one in that they are de facto complaining about the market system which used to favor them and no longer does...

They do not have my sympathy.

In other words: either you think on a systemic basis, in which case wind (which is cheaper on a long term basis) should be naturally integrated into the system, or you think on a market basis, and then the marginal producers should not be complain about being priced out on a marginal basis.

Wind power

by Jerome a Paris (etg@eurotrib.com) on Sat Apr 7th, 2012 at 04:12:25 PM EST
[ Parent ]


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