238:
same time and in the same way - and the chance of a system stress during low wind condition increases, the capacity credit of a VRE plant decreases. Greater geographical diversity of the VRE installations improves the capacity credit value, assuming a grid that can carry all necessary load. Increasing the penetration of one VRE resource also can result in increasing the CC for another one, e.g., in
California, increase in solar capacity, with a low incremental CC, expected to be 8% in 2023 and dropping to 6% by 2026, helps shifting the peak demand from other sources later into the evening, when the wind is stronger, therefore the CC of the wind power is expected to increase from 14% to 22% within the same period. A 2020 study of ELCC by California utilities recommends even more pessimistic values for photovoltaics: by 2030 the ELCC of solar will become "nearly zero". The
193:) compares the additional power of a new plant to that of a conventional power plant and directly represents the amount of the conventional generating capacity which can be replaced by a VRE plant while keeping the value of the risk index. A similar metrics, comparing the plant contribution to that of a perfect always-available-at-full-capacity plant is called an
237:
For very low penetrations (few percent), when the chance of the system actually being forced to rely on the VRE at peak times is negligible, the CC of a VRE plant is close to its capacity factor. For high penetrations, due to the fact that the weather tends to affect all plants of similar type at the
229:
is zero regardless of its CF (under this scenario all existing conventional power plants would have to be retained after the solar installation is added). More generally, the CC is low when the times of the day (or seasons) for the peak load do not correlate well with times of high energy production.
61:) power plant can typically provide the electricity at full power as long as it has a sufficient amount of fuel and is operational, therefore the capacity credit of such a plant is close to 100%; it is exactly 100% for some definitions of the capacity credit (see below). The output of a
65:(VRE) plant depends on the state of an uncontrolled natural resource (usually the sun or wind), therefore a mechanically and electrically sound VRE plant might not be able to generate at the rated capacity (neither at the nameplate, nor at the
853:
884:
242:
orders of 2021 and 2023 intend to add by 2035 additional renewable generation capacity with NQC of 15.5 GW and nameplate capacity of 85 GW, implying planned NQC for renewables (a combination of solar and wind), combined with
712:
269:, the solar contribution to the system adequacy is small and is primarily due to scenarios when the use of solar allows to keep the battery storage fully charged until later in the evening. The
614:
181:
73:
a system with weather-dependent generation can reliably provide. For example, with a low, but realistic (cf. Ensslin et al.) wind power capacity credit of 5%, 20
124:). For a dispatchable plant, QC is self-assessed and might go as high as the maximum power of the unit. For wind and solar, QC is based on an ELCC modeling; for
799:
258:
strongest in the winter. This results in a relatively low CC for such potential wind power locations: for example in Texas a predicted average for
254:
In some areas peak demand is driven by air conditioning and occurs on summer afternoons and evenings, while the wind is strongest at night, with
895:
875:
622:
239:
832:
745:
24:
936:
997:
77:(GW) worth of wind power needs to be added to the system in order to permanently retire a 1 GW fossil fuel plant while keeping the
100:) defines the capacity value as the extra load that can be added to the system once the plant is added without degrading a chosen
864:
148:) is similar to QC, except it takes into account the connection of the generator to the grid, for large generating plants,
849:
270:
221:(CF): in a not very probable scenario, if the riskiest time for the power system is after sunset, the capacity credit for
53:
which can be relied upon at a given time (typically during system stress), frequently expressed as a percentage of the
78:
807:
2008 IEEE Power and Energy
Society General Meeting - Conversion and Delivery of Electrical Energy in the 21st Century
763:
1016:
204:
percentile of peak-period availability defines the capacity value by calculating the capacity at chosen worst-case
854:"De-rating Factor Methodology for Renewables Participation in the Capacity Market: Consultation Response Summary"
69:
level) when needed, so its CC is much lower than 100%. The capacity credit is useful for a rough estimate of the
62:
105:
58:
230:
Ensslin et al. report wind CC values ranging from 40% down to 5%, with values dropping off with increased
906:
Long-Term
Resource Adequacy in Wholesale Electricity Markets with Significant Intermittent Renewables
904:
798:
Ensslin, Cornel; Milligan, Michael; Holttinen, Hannele; O'Malley, Mark; Keane, Andrew (July 2008),
883:
Kevin Carden; Alex Krasny
Dombrowsky; Arne Olson; Aaron Burdick; Louis Linden (August 31, 2021).
838:
751:
592:
54:
46:
977:
993:
964:
828:
786:
764:"The value of dispatchability of CSP plants in the electricity systems of Morocco and Algeria"
741:
244:
113:
101:
697:"Comparing Capacity Credit Calculations for Wind: A Case Study in Texas (NREL/TP-5C00-80486)"
985:
956:
913:
818:
810:
778:
731:
723:
713:"Simplified methods for renewable generation capacity credit calculation: A critical review"
151:
137:
374:
248:
218:
66:
17:
926:"Determining the Capacity Value of Wind: An Updated Survey of Methods and Implementation"
226:
615:"CPUC Augments Historic Clean Energy Procurement Goals To Ensure Electric Reliability"
1010:
266:
255:
129:
951:
Garver, L. (August 1966). "Effective Load
Carrying Capability of Generating Units".
755:
842:
429:
427:
425:
423:
259:
125:
989:
978:"Load Control and Management of Systems with Thermal Power, Hydro Power, and Wind"
782:
222:
208:(say, 5th lowest) of the power distribution during the times of the peak demand.
50:
925:
800:"Current methods to calculate capacity credit of wind power, IEA collaboration"
696:
231:
205:
133:
70:
968:
960:
814:
790:
727:
762:
Brand, Bernhard; Stambouli, Amine
Boudghene; Zejli, Driss (August 2012).
291:
109:
74:
535:
533:
386:
384:
823:
736:
433:
917:
695:
Jorgenson, Jennie; Awara, Sarah; Stephen, Gord; Mai, Trieu (2021).
273:
in 2019 suggested planning for the following EFC-based de-rating:
108:). Unlike the dimensionless CC, ELCC is expressed in power units (
984:. Vol. 4. John Wiley & Sons, Ltd. pp. 2201–2212.
591:
Carden, Kevin; Krasny
Dombrowsky, Alex; Winkler, Chase (2020).
885:"Incremental ELCC Study for Mid-Term Reliability Procurement"
357:
355:
353:
351:
89:
There are a few similar definitions of the capacity credit:
654:
642:
539:
414:
390:
448:
446:
444:
442:
154:
562:
560:
402:
175:
23:"ELCC" redirects here. For a Canadian church, see
953:IEEE Transactions on Power Apparatus and Systems
183:; ELCC metrics was introduced by Garver in 1966.
361:
217:The capacity credit can be much lower than the
924:Milligan, Michael; Porter, Kevin (June 2008).
711:Dent, C J; Keane, A; Bialek, J W (July 2010),
277:Indicative de-rating factors in Great Britain
865:"2020 Qualifying Capacity Methodology Manual"
678:
666:
551:
524:
8:
822:
735:
153:
912:, National Bureau of Economic Research,
275:
347:
896:California Public Utilities Commission
876:California Public Utilities Commission
623:California Public Utilities Commission
512:
240:California Public Utilities Commission
593:"2020 Joint IOU ELCC Study, Report 1"
452:
247:, batteries, long-term storage, and
140:, the history of production is used.
25:Evangelical Lutheran Church of Canada
7:
937:National Renewable Energy Laboratory
704:National Renewable Energy Laboratory
578:
566:
500:
488:
476:
464:
262:is 13% and for offshore wind is 7%.
112:). California regulators, in their
116:calculations, use different term,
94:effective load carrying capability
14:
403:Brand, Stambouli & Zejli 2012
982:Handbook of Clean Energy Systems
375:"Resource adequacy in the 2030s"
187:equivalent conventional capacity
1:
990:10.1002/9781118991978.hces094
903:Wolak, Frank A. (July 2021),
362:Dent, Keane & Bialek 2010
783:10.1016/j.enpol.2012.04.073
79:electrical grid reliability
1033:
613:CPUC (February 23, 2023).
22:
15:
63:variable renewable energy
45:) is the fraction of the
961:10.1109/TPAS.1966.291652
815:10.1109/PES.2008.4596006
728:10.1109/PES.2010.5589606
720:IEEE PES General Meeting
195:equivalent firm capacity
106:loss of load probability
16:Not to be confused with
976:Söder, Lennart (2015).
955:. PAS-85 (8): 910–919.
142:Net qualifying capacity
809:, IEEE, pp. 1–3,
722:, IEEE, pp. 1–8,
232:wind power penetration
177:
176:{\displaystyle NQC=QC}
655:Jorgenson et al. 2021
643:Jorgenson et al. 2021
540:Jorgenson et al. 2021
415:Jorgenson et al. 2021
391:Jorgenson et al. 2021
251:to be 15.5/85 = 18%.
178:
852:(25 February 2019).
152:
434:Ensslin et al. 2008
278:
118:qualifying capacity
81:at the same level.
850:National Grid, ESO
679:National Grid 2019
667:National Grid 2019
552:National Grid 2019
525:National Grid 2019
276:
173:
57:. A conventional (
55:nameplate capacity
47:installed capacity
1017:Power engineering
834:978-1-4244-1905-0
747:978-1-4244-6549-1
491:, pp. 15–16.
479:, pp. 13–14.
339:
338:
271:National Grid ESO
114:resource adequacy
102:reliability index
1024:
1003:
972:
947:
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878:. November 2020.
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225:without coupled
182:
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138:geothermal power
43:de-rating factor
1032:
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1023:
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1021:
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892:www.cpuc.ca.gov
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455:, p. 2209.
451:
440:
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417:, pp. 1–2.
413:
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401:
397:
389:
382:
373:
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368:
360:
349:
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249:demand response
219:capacity factor
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150:
149:
87:
67:capacity factor
31:Capacity credit
28:
21:
18:Capacity factor
12:
11:
5:
1030:
1028:
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1019:
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1004:
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973:
948:
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918:10.3386/w29033
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39:capacity value
13:
10:
9:
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999:9781118991978
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949:
938:
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771:Energy Policy
765:
760:
757:
753:
749:
743:
738:
733:
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725:
721:
714:
709:
706:. Golden, CO.
705:
698:
693:
692:
688:
680:
675:
672:
668:
663:
660:
657:, p. 21.
656:
651:
648:
644:
639:
636:
624:
620:
616:
609:
606:
594:
587:
584:
581:, p. 10.
580:
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568:
563:
561:
557:
554:, p. 16.
553:
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541:
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521:
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467:, p. 12.
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288:Offshore wind
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267:Great Britain
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256:offshore wind
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170:
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147:
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130:biomass power
127:
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115:
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107:
104:(usually the
103:
99:
95:
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84:
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68:
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48:
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40:
36:
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26:
19:
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940:. Retrieved
932:
905:
891:
871:
806:
774:
770:
719:
703:
681:, p. 3.
674:
669:, p. 6.
662:
650:
645:, p. 7.
638:
626:. Retrieved
618:
608:
598:10 September
596:. Retrieved
586:
574:
569:, p. 9.
547:
542:, p. 6.
527:, p. 4.
520:
508:
503:, p. 7.
496:
484:
472:
460:
436:, p. 3.
410:
398:
393:, p. 1.
369:
285:Onshore wind
264:
260:onshore wind
253:
236:
216:
198:
194:
190:
186:
145:
141:
126:cogeneration
121:
117:
97:
93:
88:
59:dispatchable
42:
38:
34:
30:
29:
872:cpuc.ca.gov
777:: 321–331.
619:cpuc.ca.gov
513:Garver 1966
223:solar power
85:Definitions
51:power plant
824:10197/3213
737:10197/3209
453:Söder 2015
342:References
245:geothermal
206:percentile
134:hydropower
71:firm power
969:0018-9510
791:0301-4215
579:CPUC 2021
567:CPUC 2021
501:CPUC 2020
489:CPUC 2020
477:CPUC 2020
465:CPUC 2020
326:2023/2024
312:2022/2023
298:2020/2021
110:megawatts
75:gigawatts
1011:Category
942:11 April
933:nrel.gov
756:28954479
628:12 April
292:Solar PV
843:4650836
689:Sources
37:, also
996:
967:
841:
831:
789:
754:
744:
213:Values
136:, and
929:(PDF)
910:(PDF)
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868:(PDF)
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839:S2CID
803:(PDF)
767:(PDF)
752:S2CID
716:(PDF)
700:(PDF)
335:1.2%
332:12.1%
321:1.2%
318:12.9%
307:1.2%
304:14.7%
49:of a
994:ISBN
965:ISSN
944:2023
829:ISBN
787:ISSN
742:ISBN
630:2023
600:2022
329:8.2%
315:8.4%
301:9.0%
282:Year
98:ELCC
986:doi
957:doi
914:doi
819:hdl
811:doi
779:doi
732:hdl
724:doi
265:In
199:EFC
197:or
191:ECC
146:NQC
41:or
1013::
992:.
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894:.
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