CAISO Says SONGS Shutdown Means Reliability Risks for Southern California This Summer

The California Independent System Operator (CAISO) said on May 6 that the continuing shutdown of the San Onofre Nuclear Generating Station (SONGS) heightens reliability concerns for areas of Southern California this summer.

The two-unit plant north of San Diego has been idle for almost 18 months after leaks and excessive wear were discovered in the plant’s steam generators early last year. Southern California Edison, the plant operator, is currently waiting on a response from the Nuclear Regulatory Commission to its request to run Unit 2 at 70% power this summer. For planning purposes, CAISO said it is assuming SONGS will be unavailable.

Last summer, two gas-fired units at the Huntington Beach Power Plant were brought out of retirement to provide replacement power. Those units are no longer available because their emissions permits have been sold and transferred to another plant. Instead, they are being converted to synchronous condensers to provide voltage support.

CAISO said the absences of SONGS and the Huntington Beach units, as well as reduced hydroelectric generation as a result of an ongoing drought, mean reliability risks to southern Orange and San Diego counties are “marginally more challenging” this summer, but still within planning standards. Several new combined cycle plants in the Los Angeles area that came online recently have eased pressure further north.

Still, reserve margins in Southern California could drop as low as 6% during high peak demand, though this is expected to be above the 3% level at which service interruptions could occur. CAISO cautioned, however, that under these conditions, any unexpected events such as plant outages or transmission limitations due to summer wildfires could challenge grid reliability.

System-wide, CAISO expects peak demand to reach 47,413 MW this summer, which is 738 MW more than last year. The all-time record peak demand was 50,270 MW in 2006.

Sources: POWERnews, CAISO

—Thomas W. Overton, JD, Gas Technology Editor (@thomas_overton)

NOTE: This story was originally published on May 7