Talk:Capacity credit

Timescale?

As you know GB wind can vary a lot from year to year. Is the term ever used on an annual timescale? Chidgk1 (talk) 06:45, 7 April 2022 (UTC)

Where to find numbers?

I am interested in electricity in Turkey but have not yet been able to find any numbers. So I wonder if the numbers are usually confidential and not published? Chidgk1 (talk) 07:04, 7 April 2022 (UTC)

Relationship to capacity market?

If related could Electricity_market#Capacity_market be linked both ways to show relationship? Chidgk1 (talk) 07:26, 7 April 2022 (UTC)

• Thank you! Yes, it would be useful to link both. Firm power is the typical product traded on the capacity markets, so the notions are directly related. --Викидим (talk) 19:25, 7 April 2022 (UTC)

Don't thank me as I leave it to someone who knows more than me. I only know about electricity in Turkey and as I have not managed to find any numbers I guess capacity credits are not used here and we don' have a capacity market, so I guess our "capacity mechanism" payments are just decided by politicians. Page 13 of https://www.shura.org.tr/wp-content/uploads/2020/05/raporweb_ENG-.pdf says little about the " capacity market" and the footnote on page 7 implies it is not a market. Chidgk1 (talk) 06:56, 9 April 2022 (UTC)

Asiaban et al.

The quality of this article is atrocious. It is left in the list of sources temporarily, for its list of references. If you are going to edit, please do not use it as a direct source. --Викидим (talk) 06:23, 9 April 2022 (UTC)

Similar concepts

Should be added to the definition, redirects created: Capacity value (synonym), ELCC (Effective load carrying capability). --Викидим (talk) 08:14, 10 April 2022 (UTC)

• Also the Equivalent firm capacity, EFC. --Викидим (talk) 17:59, 13 April 2022 (UTC)

Low numbers

@Chidgk1:Due to the nature of the electricity planning (for the worst case), the capacity credit numbers for renewables are inevitably low at high penetrations (sun goes down and wind dies down simultaneously over the large territory, making all the plants useless simultaneously). The 5% number is for Germany regions with 50% wind penetration, but the photovoltaics case is even funnier at 1-2% expected contribution to the reliability. So the humanity will have to either (1) figure out the energy storage, or (2) keep almost all the fossil fuel plants on standby indefinitely, or (3) get used to the occasional lack of electricity. For the avoidance of doubt, as a techie I believe in #1, as a cool-headed citizen I fully expect #2 (and associated Germany-style high prices for electricity), but due to too many starry eyes in the electorates I am somewhat afraid of #3. --Викидим (talk) 17:59, 13 April 2022 (UTC)

@Викидим:I understand your general point but surely a 2008 cite is too old? I mean the German grid must have been improved since then. By the way for some of the other cites you can spot harv errors with https://en.wikipedia.org/wiki/User:Trappist_the_monk/HarvErrors Chidgk1 (talk) 08:51, 14 April 2022 (UTC)

• Thanks! (1) The works themselves predict that the capacity credit only goes down with the increased penetration, so it is hard to expect the new numbers to be any better. The 2021 work [1] apparently gives very low CCs (way worse than 5%) for European data up to 2019. I did not finish the reading of it yet, so I will delay adding it to the article, but is seems the things are really that bad nowadays. (2) I think that I have checked the sfn's manually (by clicking on them). Which ones give the errors? --Викидим (talk) 10:28, 14 April 2022 (UTC)

Yes that paper has the advantage of being more up to date and free to read, so the 2008 cite could be deleted I guess? I am not an expert but as you say all the capacity credits they calculate for France are around "4% for onshore and 7% for offshore at the national scale". But should not the real calculation be done on the scale of the synchronized grid and aggregate solar and wind? For example now Ukraine has been synced I wonder how often a dunkelflaute would cover the whole of the ENTSO-E area? Also other links such as to Britain. Presumably some kind of mathematical model could take account of international links? Chidgk1 (talk) 11:45, 14 April 2022 (UTC)

• More bad numbers: Australia wind power CC predicted at 7% at 10 % penetration (30% at zero penetration, see Fig. 8). --Викидим (talk) 00:29, 21 June 2022 (UTC)

  Yes but that cite is from 2016 when battery storage was more expensive than today Chidgk1 (talk) 08:48, 21 June 2022 (UTC)

  • Hard to argue with that, and I have reflected in the article the fact that in California at least, a combination of use solar > to charge the batteries > then use batteries in the late afternoon > to wait for wind to pick up, will give wind turbines a few extra % of CC by shifting the non-(solar+battery) demand by an hour or so. For now this is a prediction, as so far these theoretically cheap batteries in CA were mostly offline. In few years as the battery storage improves to a usable forced outage rate (pretty much guaranteed, as the problems the facilities keep encountering now are peripheral to the actual technology involved), we will see. --Викидим (talk) 22:04, 22 June 2022 (UTC)

@Chidgk1: You have quoted a completely unrealistic 50% capacity credit based on an article that introduces and discusses a new and completely different from the subject of this article operation credible capacity (and credit). This, very different, number apparently (as it is new and not settled) is related to the dispatch time, essentially, if 1GW was promised one day (or hour) in advance, how much of it can be counted on. Of course, this number will be much higher that the true capacity credit that is related to planning not for a day, but for ten years, and the denominator is the nameplate capacity, not the promised output, 2-hour storage described in the article will of course help with a short planning, but will be useless if the wind dies down for a day (pretty normal event). The actual capacity credit (without "operational") number is still in single digits. Only a couple of weeks ago the hot spell (and power crisis) in Texas had seen wind energy at 8% of the nominal capacity [2], way below the 2021 estimate (already in the article) that now turned out to be much too optimistic - and this is just after a year, not ten years. I will revert the text to the original correct values and citation. --Викидим (talk) 22:52, 20 July 2022 (UTC)

I am a bit confused about the difference - not because your explanation is bad but because the subject is tricky. Perhaps you could add an explanation of the difference in the article - maybe examples would help? Chidgk1 (talk) 05:45, 21 July 2022 (UTC)

I am also confused where your mention of 10 years came from - is there a cite? As you know I mostly write about Turkey so am interested in how this applies here. Hydropower here varies enormously year by year depending on rainfall. So the capacity credit of hydro would be based on the driest month estimated in the next 10 years? Also at the moment peak non-solar demand is late on a summer afternoon. But with the rise in solar PV over the next 10 years we would expect the peak demand on non-solar to move to some time after sunset. Also depends how much water is needed for irrigation and when as water ministry may close valves despite energy ministry wanting them open. So a capacity credit for hydro here in Turkey must be incredibly difficult or impossible to estimate over 10 years don’t you think? Chidgk1 (talk) 06:01, 21 July 2022 (UTC)

• (1) 10 years come from the reliability criteria. The idea of capacity credit is that a VRE plant can replace a smaller-capacity non-VRE plant without the loss of reliability. Quantitative reliability estimates use some reliability index. Frequent choice is the LOLE, with the design goal in the US of 1 day of loss of load in ten years. Therefore, the capacity credit for VRE shall take in the account worst case meteorological phenomena over a very long period of time. (2) Hydroelectric plant is not VRE, as it is a "controllable" source. I do not know the details, but there are some "dry years" limits used to estimate the capacity credit there. (3) I do not know how things are in Turkey, but in some of the warm states of the US (say, California) the current hard time is 4-6PM in summer (PV helped to alleviate early afternoon problem), when the sun is already low, yet the air conditioning is still at the maximum. This is why CC for PV is now 1-2% (50GW has to be built in order to replace 1GW of fossil). --Викидим (talk) 08:16, 21 July 2022 (UTC)

Cite errors

Brand, Stabouli & Zejli 2012. Harv error: link from CITEREFBrandStabouliZejli2012 doesn't point to any citation.

Giebel, Gregor (2005). "Wind Power Has a Capacity Credit" (PDF). Risø National Laboratory. Archived from the original (PDF) on 2009-03-18. Retrieved 2008-10-16. Harv warning: There is no link pointing to this citation. The anchor is named CITEREFGiebel2005.

Amelin, M. (May 2009). "Comparison of Capacity Credit Calculation Methods for Conventional Power Plants and Wind Power". IEEE Transactions on Power Systems. 24 (2): 685–691. doi:10.1109/TPWRS.2009.2016493. eISSN 1558-0679. ISSN 0885-8950. Harv warning: There is no link pointing to this citation. The anchor is named CITEREFAmelin2009.

Voorspools, Kris R.; D'haeseleer, William D. (January 2006). "An analytical formula for the capacity credit of wind power". Renewable Energy. 31 (1): 45–54. doi:10.1016/j.renene.2005.03.017. ISSN 0960-1481. Harv warning: There is no link pointing to this citation. The anchor is named CITEREFVoorspoolsD'haeseleer2006.

Brand, Bernhard; Stambouli, Amine Boudghene; Zejli, Driss (August 2012). "The value of dispatchability of CSP plants in the electricity systems of Morocco and Algeria" (PDF). Energy Policy. 47: 321–331. doi:10.1016/j.enpol.2012.04.073. ISSN 0301-4215. Harv warning: There is no link pointing to this citation. The anchor is named CITEREFBrandStambouliZejli2012.

• Many thanks! --Викидим (talk) 11:30, 14 April 2022 (UTC)
  • Fixed the first (and thus the last). The rest is left hanging on purpose for future article expansions. --Викидим (talk) 20:22, 15 April 2022 (UTC)

    I have deleted the very old unused ones but left the 2021 unused source in case you or anyone else wants to use it Chidgk1 (talk) 14:39, 27 March 2023 (UTC)

2022 GB report

User:Викидим You may find this interesting https://www.nationalgrideso.com/document/273781/download Chidgk1 (talk) 14:46, 27 March 2023 (UTC)

So is “de-rating factor” a synonym of “capacity credit”? Chidgk1 (talk) 16:38, 27 March 2023 (UTC)

This is my understanding, too. Note the language I have used in the table at the end of our article. Викидим (talk) 16:57, 27 March 2023 (UTC)

Do you happen to know the status of this document? It says "we" in the foreword and bears the ESO logo, but only Andy Dobbie is named personally; the actual work was apparently done by AFRY. In any case, thank you! - this provides for some interesting reading, starting with the phrase "The economic viability of the resources was not considered in this study" (I wish my company was working under the same lack of financial constraint). But - finally - at least - someone - is talking about the 2035 zero-emission elephant already in the room. Note again that "hydrogen fuel supplies are always available", so for some reason hydrogen is treated as essentially a fossil fuel, with energy spent producing it considered to be negligible. Still, it is the first known to me acknowledgement of the fact that the battery-only approach at the modern level of technology will simply not work for Europe; the world needs some kind of better storage of energy. All that said, not sure how we can use this presentation in our article. Викидим (talk) 16:55, 27 March 2023 (UTC)

It seems National Grid ESO commissioned it to get the conversation started but are intending to go into more depth themselves.

I just noticed you also wrote Reliability index - I might cite it there instead of here. Chidgk1 (talk) 17:09, 27 March 2023 (UTC)

Yes, a new metric "critically tight periods" has been proposed in this work. It is too new, and almost nobody had picked it up (I saw only one more place, https://www.theccc.org.uk/wp-content/uploads/2023/03/Delivering-a-reliable-decarbonised-power-system.pdf , in a footnote). I would therefore propose to wait to see if this idea gets roots. Викидим (talk) 17:36, 27 March 2023 (UTC)

I would propose to add the article to the list of sources in Dunkelflaute, as this work lists the real-life worst-case events of the low wind in Northern Europe. Викидим (talk) 17:46, 27 March 2023 (UTC)