Cal-ISO wind generation spikes on windstorm; oversupply curtailments climb

Strong California winds that led to multiple weather warnings across the region pushed up wind generation to a seven-month high and increased renewable curtailments from oversupply as power prices dipped to the lowest level in two months.

Wind-powered generation Jan. 19 reached as high as 16.4% of the total fuel mix, a seven-month high, to be the third most used fuel behind thermal and imports, according to California Independent System Operator data. Meanwhile, solar generation slipped to 7.5% of the mix and thermal generation dropped to 22.6%, a more than six-month low.

Wind generation has averaged 5.4% of the fuel mix so far this month, the highest January average, according to ISO data.

The rise in lower-cost wind generation pulled down power prices. The SP15 on-peak day-ahead locational marginal price dipped to $25.12/MWh Jan. 17 as on-peak real-time LMP fell to $16.50/MWh, both were two-month lows.

Renewable curtailment changes

There are two types of curtailments. Systemwide curtailments occur when there is an oversupply, while localized curtailments occur when the amount of power from one transmission point to another point is controlled for congestion management.

While total wind and solar generation curtailments so far in January are lower compared to a year ago, curtailments from oversupply jumped significantly Jan. 17, according to ISO data.

Cumulative systemwide curtailments were 2,309 MWh for Jan. 1-16 and jumped to 4,915 MWh Jan. 17, according to ISO data.

"The increase on the 17th was largely system curtailments of solar generation due to weak loads (it was a Sunday) during the peak solar output hours," said Morris Greenberg, North American power analytics senior manager at S&P Global Platts.

ISO peakload reached 25.027 GW Jan. 17, the lowest level so far this month, according to ISO data.

Cal-ISO did not reply to a request for comment.

Windy weather warnings

Many parts of the region were under high wind warnings with gusts as high as 80 mph expected earlier this week. A high wind warning means a hazardous high wind event is expected or occurring, according to the US National Weather Service.

Some areas were also under red flag warnings as critical fire weather conditions are either occurring now or will shortly, according to NWS. A combination of strong winds and low relative humidity can contribute to extreme fire behavior.

In 2020, 9,917 fires burned 4,257,863 acres across California resulting in 33 fatalities, according to the California Department of Forestry and Fire Protection. So far in 2021, 161 fires have burned 876 acres.

"While wildfires are a natural part of California's landscape, the fire season in California and across the West is starting earlier and ending later each year. Climate change is considered a key driver of this trend," according to CAL FIRE. "Warmer spring and summer temperatures, reduced snowpack, and earlier spring snowmelt create longer and more intense dry seasons that increase moisture stress on vegetation and make forests more susceptible to severe wildfire."

Utility outages

Public Safety Power Shutoffs by utilities are approved by state regulators as an important safety tool to mitigate fire risk during dangerous weather conditions.

Pacific Gas and Electric Company initiated a targeted Public Safety Power Shutoff early Jan. 19 for about 5,000 customers in seven counties, according to PG&E. Service has been restored to all the customers affected by the PSPS, except for those in areas where circuits sustained wind damage. Those repairs are ongoing.

More than 371,000 PG&E customers had interruptions in electric service due to the windstorm and 93% had power restored by early Jan. 21, according to a company news release.

"The damage we have found from this windstorm has been monumental, but we are committed and have a relentless focus on to doing the job until all of our customers are restored," Sumeet Singh, PG&E's interim president, said in the news release.

Southern California Edison reported 1,559 customers without power as of 2:15pm CT Jan. 21, representing less than 1% of customers. In comparison, 42,671 customers were without power midday Jan. 19 with another 259,844 customers under consideration for power shutoffs.

The Los Angeles Department of Water and Power reported Jan. 19 that the high winds and red flag conditions resulted in extended power outages.