California has basically ruled out longer-term natural gas use as an option for back-up power at utility substations during planned outages, but San Francisco-based Pacific Gas and Electric Co. (PG&E) still plans to rely on the fossil fuel when necessary.

California wildfires

A virtual workshop held Tuesday by the California Public Utilities Commission (CPUC) and California Energy Commission (CEC) provided an overview of alternatives to diesel generation to back up generation when public safety power shutoffs are required.

PG&E executives also described wildfire mitigation plans as a series of new fires burned across the state. PG&E’s Jason Regan, director of electric transmission and emergency management, said the utility has identified the most recent peak loads on each of its nearly 1,000 substations, including in high-risk fire areas, which make up more than half of the service territory.

Regarding back-up generation, Regan said “anything is potentially an option. It is a matter of our ability to scale it to our vendors, partners and regulations.” 

PG&E looks at where gas sources are available to truck in, including liquefied natural gas (LNG) and compressed natural gas (CNG), if a pipeline source is more than 20 miles away.

“When you look at it as an option, you have to look at available land needed to support the CNG or LNG, and you also have other requirements imposed by communities. For this year we are not focusing on a natural gas, or LNG or CNG solution, but I would note that we have about 8 MW of natural gas-fired power in our temporary generation fleet for 2020.”

Unlike the last two fire seasons, PG&E this year has “ample opportunity” to provide back-up power solutions with temporary generation at key substations. All 62 substations now equipped with temporary generation were shut down because of fires last year.

“There is a potential natural gas option in those areas if that is a solution needed to meet the challenges,” Regan said.

PG&E Senior Vice President Fong Wan, who heads energy policy and procurement, outlined plans for 470 MW of temporary generation at selected substations this year followed by a two-year effort to install permanent generation at some of them.

“In 2021, we’re looking to build a completely non-fossil fuel portfolio,” said Wan. PG&E’s power mix is 33% renewables, with solar and lithium batteries now 10% of what they cost 10 years ago. “I’m very optimistic that with the market’s help, we can build a clean solution for the future.”

CPUC President Marybel Batjer said the workshop was “exciting, important, and long-awaited” and she appreciated technology providers and stakeholders for “their willingness to come and problem solve and share their expertise.” CEC Chairman David Hochschild said last week’s rolling blackouts underscored the need for a resilient and reliable grid. In addition, replacing diesel is important as it creates harmful emissions. “This is something that from a health perspective, we are focused on and will be holding a workshop around the research needs specifically.”