How PG&E is using microgrids to further its sustainability and safety goals

Pacific Gas & Electric has placed protecting against wildfires and extreme weather events at the center of its resilience and climate goals since emerging from bankruptcy in 2020. Those measures include an open-ended plan to bury more than 10,000 miles of power lines and a pledge to create a net-zero energy system by 2040.

A crucial element for both plans: Remote and community microgrids that combine renewable power generation with energy storage systems to downplay future risks to the grid. These are small-scale systems that provide power generation and, increasingly, energy storage resources. They can operated or independently or connected to the larger grid to share electricity.

More than $30 billion in liabilities from wildfires linked to its transmission system forced California’s largest utility to declare Chapter 11 in 2019. The decentralized approach it adopted in 2020 serves PG&E’s strategies for improving public safety, shoring up grid availability and accelerating decarbonization, said Carla Peterman, executive vice president, corporate affairs and chief sustainability officer at PG&E. In 2023, the utility reduced its Scope 1 and Scope 2 emissions by 27 percent. 

“There is a real orientation to risk assessment, working through risk, and engaging with customers and communities on how to do that,” Peterman said.

There are about 4,500 microgrid projects planned across the U.S., with about 8.5 gigawatts of capacity in operation, said Elham Akhavan, senior microgrid analyst at research firm Wood Mackenzie. The industry is growing at a rate of about 22 percent annually. Most microgrids are owned by commercial or industrial accounts. PG&E and its counterparts in southern California are leading a shift in thinking among utilities, said Akhavan.

“Conventionally, utilities have seen microgrids as a competitor, now we are seeing that this is shifting toward them recognizing this as a grid modernization tool,” she said. 

Other factors: an aging population vulnerable during power outages and the millions of individuals who work from their home rather than in a commercial office setting.

“This concept of microgrid and local generation is emerging very fast,” Akhavan said.

Source: PG&E

A strategy rooted in safety and resilience concerns

PG&E’s strategy is multi-pronged. It dispatches “remote grids” in areas where other measures to “harden” the grid, such as burying utility lines or installing stronger poles, won’t be as cost-effective, according to Peterman. These systems are placed in high fire-threat areas at the end of long distribution lines. They aren’t connected to the main grid.

PG&E’s first remote, solar-powered grid, installed in 2021 near Yosemite National Park, let the utility replace 1.3 miles of overhead electricity lines, which can spark wildfires during high winds. There are now more than nine remote grids in operation, with 11 more under development; together, they’ll replace 13 miles of overhead lines.

The utility manages 108,000 miles of electric distribution lines, which carry power from substations to consumers, and 18,000 miles of transmission lines, which handle higher voltage loads running between power plants and substations. (It put 364 miles of powerlines underground in 2023.)

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These remote grids are being developed in parallel with PG&E’s two community microgrid programs, which help fund the installation of microgrids that support “vulnerable” communities that don’t typically have access to fossil fuels-free electricity options. Unlike the remote grids, they may or may not be connected to the primary distribution network.

“This is going to be key to our customers having the lowest cost of energy possible,” Peterman said.

PG&E supports two initiatives:

• Community Microgrid Enablement Program, launched April 2021, prioritizes projects with resilience concerns. One of the most prominent examples is the Redwood Coast Airport Microgrid, a solar-plus-storage installation that serves 19 businesses and public agencies.
• Microgrid Incentive Program, started in October 2023, includes $79.2 million in grant money for projects in disadvantaged communities including Native tribes. PG&E received more than 50 applications and plans to award $34 million to approximately a half-dozen projects in October.   

Lessons from Redwood Coast Airport

The Redwood Coast Airport Microgrid, switched on in June 2022, was the first multi-customer “front-of-the-meter” microgrid installed in California. It includes a 2.2 megawatt solar array and a corresponding capacity of energy storage, sited on seven acres of land leased from Humboldt County. The microgrid was funded by several sources, including a $5 million grant from California’s Electric Program Investment Charge (EPIC) initiative and the local Community Choice Energy program, in turn supported by a $6 million loan from the U.S. Department of Agriculture.

Part of the installation is grid-connected, so the owners can sell electricity at wholesale prices. What sold local authorities, however, was the ability for the rural community to keep the airport and the local U.S. Coast Guard station up and running by using the microgrid during outages or grid shutoffs. After an earthquake in December 2022, it kept both operational for nearly 15 hours during a broader grid outage.  

Public funding was crucial to approval of the project, said Cody Roggatz, director of aviation for Humboldt County. The ability to save electricity costs on the hundreds of lights needed to light runways at the airport while serving the businesses there, including rental car agencies and airlines, were also compelling arguments, he said.

“There are a lot of rural airports that have excess, undeveloped lands,” Roggatz said. “There are dozens across the state that could do something similar.” 

Roggatz’s advice for businesses considering a microgrid:

• It takes coordination: At least 10 organizations were involved with the airport project, with Schatz Energy Research Center and the Redwood County Energy Authority handling project management. The buildout started in fall 2020 and was completed in spring 2021. It took another year to formally start operations.
• Understand land-use implications. The airport needed permission from the Federal Aviation Authority before proceeding, and it needed to keep the agency closely briefed. “We had to reset expectations many times,” he said.
• Manage battery reserves closely. The airport microgrid is backed up with diesel generators, which take over after batteries are depleted. The owners manage charge levels carefully, with an eye to the weather, ensuring they’re at 60 percent minimum reserve. Those levels can keep the entire airport up and running for 24 hours in the absence of new solar generation, Roggatz said.