PG&E preps for potential power shut-offs |

PG&E preps for potential power shut-offs


Utility transmission can be a challenge even during ideal conditions because of a number of variables.

That’s especially true during wildfire season.

Fire season can lead to Public Safety Power Shut-offs — periods when PG&E decides if it needs to cut power in order to avoid catastrophic conditions that could be set off by the weather.

Conditions warranting a PSPS event include hot temperatures, low humidity and lots of dry ground vegetation. There is no formula for when a PSPS event might occur. However, PG&E does not take the action lightly, but acts to prevent a catastrophe, said Megan McFarland, PG&E spokesperson, this past spring.

One way to avoid loss of power as well as property is the deployment of specialized portable generation systems. These generators have a reputation of generating excessive noise and exhaust, as they are powered by diesel fuel that’s stored at the Brunswick Substation in the Glenbrook Basin. Yet the generators help to prevent blackouts during summer when power lines in the valley are overheating. Additionally, running the generators is part of PG&E’s plan to add power to the system.

PG&E strategically deploys mobile generators across its service area during emergencies and PSPS events to avoid outages and keep the power on for thousands of customers, said Paul Doherty, PG&E marketing and communications representative. These generators maintain connection to the grid through substation distribution sites.

“In 2020, temporary generation, plus an expanded network of enhanced weather technology, along with installation, isolates the grid into smaller segments,” said Doherty. “It enables PG&E to keep the power on for hundreds of thousands of customers.”


These were the residents who would have lost power during comparable weather events during 2019. And because of the tech advancements, PG&E was able to remove more than 800,000 from the scope of the 2020 PSPS events. This is equivalent to a reduction in size of each PSPS event of last year by 55%, Doherty said.

“For 2021, PG&E has reserved approximately 185 megawatts (power for 65,000 homes) of temporary generation to again be used at substations which had the highest probability of experiencing a PSPS event,” Doherty said.

Also, PG&E has already from time to time used temporary generators interconnected at the Brunswick Substation to support a transformer bank replacement. Banked transformers are tied together through secondary electrical mains and are supplied by the same primary feeder. They can reduce lamp flicker caused by starting motors, as well as decrease the amount of power required, and produce better average voltage along a secondary line and have greater flexibility for power load growth.

“The trigger for using the temporary generators is when temperatures exceed more than 100 degrees, which is to ensure grid reliability during the transformer bank replacement,” said Doherty. “This has been in use for approximately seven weeks when temperatures surpassed this threshold.”

The generators are California Air Resource Board certified and are registered under the state’s Portable Equipment Registration Program.

“Additionally, PG&E strove to ensure the mobile diesel generators reserved are capable of operating on a type of renewable diesel in the form of hydrogenated vegetable oil,” said Doherty.

This means that the combustion of this type of a fuel typically results in lower life cycle emissions of greenhouse gases and other air pollutants verses a fossil diesel fuel.

William Roller is a staff writer with The Union. He can be reached at

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