A number of gas-fired and solar power additions have come online in recent months in California, mitigating the impact of the permanent shutdown by Southern California Edison (SCE) of the San Onofre nuclear plant.
A net total of 3,243 MW of additional generation is expected to enter commercial operation by June 1 2014, with 2,258 MW in the SP26 region and 985 MW in NP26, said a summer 2014 assessment report released May 9 by the California Independent System Operator.
This 3,243 MW comes from 3,555 MW of new generation that went into commercial operation since last summer, the retirement of 650 MW of power generation at Dynegy’s Morro Bay plant, and an additional 338 MW that is expected to become commercial operation by June 1, 2014.
Of the 3,243 MW, 61 percent is solar, 32 percent is natural gas-fired, and 7 percent is in other categories. This will help to offset the anticipated hydroelectric derate total in 2014, which is caused by a widespread drought in recent months in California.
As a result of the drought, and based on discussions held with Pacific Gas and Electric and Southern California Edison, the two largest hydro capacity owner/operators in the ISO, the ISO has determined that a hydro derate in the amount of 1,370 MW (normal scenario) to 1,669 MW (extreme scenario) should be applied to the net qualifying capacity of 7,666 MW.
There is only 44 MW of Net Qualifying Capacity (NQC) hydro generation located in San Diego and Orange Counties and the majority of this generation is pumped storage. Consequently, drought conditions will have little impact on local resource adequacy in the San Diego and Orange County areas.
A less obvious impact of the drought relates to the fact that thermal power plants need water to run. Among the 260 thermal power plants greater than 20 MW, three facilities in Northern California totaling 1,150 MW have been identified to be at risk of having water supply curtailments. The ISO said it will work with state and local agencies to monitor these facilities through the summer. Water supplies to thermal generation will likely be of a greater concern in 2015 if the current drought continues.
Generation in the ISO balancing authority is primarily fueled by natural gas (60.8 percent), followed by 22.0 percent renewables portfolio standard (RPS) resources, 12.5 percent large hydro, 3.5 percent nuclear and a small amount of oil and coal. Although San Onofre Units 2 and 3, totaling 2,246 MW, were retired in June 2013, they were excluded in 2013 summer resources and outages calculation.
In major moves lately in terms of capacity:
- Contra Costa Units 6 and 7 totaling 674 MW were replaced in May 2013 with the 800-MW Marsh Landing Generation Station Units 1-4.
- Huntington Beach Units 3 and 4 were converted to synchronous condensers in December 2012.
- Morro Bay Units 3 and 4 were retired on Feb. 5.
A total of 14,330 MW renewable commercial operation generations were composed of 41.5 percent wind, 31.1 percent solar, 11.0 percent geothermal, 8.9 percent small hydro, 4.8 percent biomass, and 2.9 percent biogas. Maximum wind generation reached 4,268 MW on June 23, 2013. Maximum solar generation reached 2,893 MW on Dec. 26, 2013.
Because California has a relatively large share of natural gas generation, a potential shortage of natural gas could create reliability issues on the power grid, the report noted. Greater fuel diversity through integration of renewable resources is helping to mitigate this risk.
The report noted how a number of oil- and gas-fired plants are impacted by new rules restricting once-through cooling (OTC). Of 17,792 MW OTC units affected by the regulations, 5,036 MW of these units are in compliance. The remaining 10,517 MW will be required to repower or retire by the end of 2020, many by the end of 2017. Compliance for the Diablo Canyon (2,240 MW) plant is subject to a pending study by a Water Board Review Committee for Nuclear Fueled Power Plants.
A list in the report said that out of compliance with OTC regulations right now are plants/units that include: NRG Energy, El Segundo Unit 3 (335 MW) and Unit 4 (335 MW); NRG Energy, Ormond Beach 1-2 (1,516 MW); and Dynegy, Moss Landing 1-2 (1,020 MW) and Moss Landing 6-7 (1,500 MW).
In compliance are plants/units that include: AES Corp., Huntington Beach 3-4 (452 MW); Dynegy, Morro Bay 3-4 (650 MW); and NRG Energy, Contra Costa 6-7 (674 MW). A moot point is that the retired San Onofre 2 and 3 are also in compliance.
The permanent retirement of the San Onofre Nuclear Generating Station (SONGS) was announced in June 2013. This further validated the steps taken in 2012 to prepare the system for the summer of 2013 in anticipation of SONGS not returning to service. Those steps consisted of complete several transmission and voltage support enhancements in the LA Basin area, including:
- Conversion of Huntington Beach Units 3 and 4 to synchronous condensers to provide voltage support in the vicinity of SONGS.
- Installation of additional reactive support devices near SONGS. SCE installed 80 MVAR capacitors at each of the Santiago and Johanna substations and two 80 MVAR capacitors at the Viejo substation.
- SCE reconfigured the Barre-Ellis 220 kV lines from the existing two circuits to four.
While additional approved mitigations are expected to begin coming into service for the summer of 2015, no additional transmission measures are available for the summer of 2014, the report said. With continued modest load growth, local reliability conditions in the south Orange and San Diego counties are likely to be marginally more “challenging” this summer compared to last summer, the report added.