Intense heat coupled with this summer’s early and active fire season likely will increase the need for public safety power shutoffs (PSPS) this year, according to utilities presenting at a California Public Utilities Commission workshop Aug. 7-8.  

Southern California Edison COO Jill Anderson spoke about the “relentless heat waves” and “months of wildfires” that have hit the state this summer. 

“We’ve been setting records, certainly in SCE’s service area and other places, and all of that for us is a reminder of how critical it is that we are ready with all the tools at our disposal to make sure that we can be managing and responding to extreme weather,” Anderson said. “We know that one of those tools — what we consider a last resort tool — is PSPS.”

PSPS allow utilities to temporarily shut off power in certain areas to reduce the risk of fires caused by electric infrastructure. Several utilities, including SCE, Pacific Gas and Electric, PacifiCorp, and San Diego Gas and Electric, discussed the summer forecast in their service territories, PSPS predictions, and methods of implementing and preventing power shutoff events.

The transition to the La Niña weather pattern, associated with decreased rainfall in California, could extend high fire danger conditions later into fall and winter and increase the number of PSPS events, the utilities noted.  

“We’re concerned about the La Niña weather pattern because it historically correlates with more offshore wind days and also less precipitation, and these are not good markers for PSPS,” said Tom Brady, principal manager of business resiliency at SCE.  

But that correlation isn’t always the case, Brady noted. In some instances, meteorologists have seen rains come early during La Niña weather patterns. Climate change also could weaken the relationship between La Niña and precipitation in Southern California, Brady said.

The utilities highlighted that above-normal precipitation this past winter and in the past few years contributed to the vegetation growth that is fueling wildfires across the state. 

“August fuel levels are now at critical levels, and any moisture benefit from 2024 has mainly elapsed,” Brady said. “We’re in PSPS season, and in fact, we’re activated today for a small event with localized impacts on the border of Kern and Los Angeles counties. We can begin to expect larger events to begin occurring when weather patterns shift and we have more widespread high winds across our service territory.” 

PG&E painted a similar picture, highlighting extreme weather conditions that have increased the likelihood of PSPS events.

Scott Strenfel, PG&E senior director of meteorology operations and fire science, said historically high temperatures have rapidly dried the fuels and “set the stage for what’s already been a very challenging fire season.”

“It is more probable than not that this will be a more active PSPS season compared to the last two years, just because of the danger of fuel,” Strenfel said. “But all of that is going to depend on how many wind events we get and the timing of rainfall that could occur before or after those dry wind events that we get from the northeast.”

Conditions are similar in SDG&E’s service territory, with hot temperatures, increased vegetation and high fire risk.  

“It’s certainly not the forecast that a lot of us want to see going into the fall, but it is one that our situational awareness is very focused on, and we’re very prepared,” said Brian D’Agostino, vice president of wildfire and climate science at SDG&E.  

‘Positive Trend’

The utilities all highlighted ways they’ve worked to prevent PSPS events through system hardening, undergrounding, sectionalizing devices and transmission switches, and using cameras and weather stations.  

In 2023, SDG&E completed 72 miles of undergrounding, trimmed and removed 13,000 trees, conducted 15,000 drone inspections, implemented 60 miles of covered conductors and more. In 2024, the utility aims to implement 40 more miles of covered conductors, 125 miles of undergrounding, trimming and removing 11,000 more trees, and conducting 17,000 detailed asset inspections.  

PG&E completed 664 miles of undergrounding between 2019 and 2023, hardened 1,664 miles of power lines, and installed 602 cameras and 1,424 weather stations. The utility plans to underground 250 more miles, harden 280 more miles, enable the use of AI for the cameras and continue to optimize the weather stations.  

PacifiCorp has made similar progress, replacing over 95 miles of bare conductor with insulated covered conductor in 2023, undergrounding five miles of line, upgrading more than 35 reclosers, relays and circuit breakers, and installing over 4,000 non-expulsion fuses. The utility also implemented the FireSight model to identify areas of heightened fire risk, which led it to identify a new high fire-risk area. In total, high fire-threat districts encompass approximately 1,700 overhead line miles and 54% of PacifiCorp’s territory in California.  

SCE implemented about 5,900 miles of covered conductor and 26 miles of undergrounding, trimmed or removed over 2 million trees, installed or replaced over 14,200 fast-acting fuses and 160 remote-controlled sectionalizing devices, and conducted over 1 million equipment inspections.  

The utilities also highlighted the importance of artificial intelligence and machine learning in their modeling, forecasting and preparedness for PSPS events. For example, SDG&E is using machine learning at each of its 222 weather stations to train AI models to predict exactly which areas could experience a shutoff, allowing the utility to more accurately target notifications.  

SDG&E also relies on three primary AI-based tools to enhance its PSPS response: gridded AI-based fuel models that provide a holistic look at fuel moisture content, machine learning wind gust models and AI smoke detection. The utilities also rely on enhanced powerline safety settings (EPSS), which allows powerlines to automatically turn off power within one-tenth of a second.  

PG&E relies on outage and ignition probability weather models, as well as a fire potential index, to calculate the need for PSPS.  

CPUC President Alice Reynolds expressed optimism despite predictions for increased PSPS events.  

“I’m really pleased to see the progress that has been made on PSPS events over the last several years,” Reynolds said, noting that PSPS customer notifications across all utilities declined from 5.8 million in 2019 to about 500,000 in 2023.  

“There’s a positive trend for the number of customers that have been de-energized … so clearly significant improvements,” Reynolds said.