Mayor Ed Lee on Thursday set a new goal for San Francisco — that at least 50 percent of the city’s electricity come from renewable sources by 2020. That’s 10 years ahead of the target the state has set for itself.

“At a time when the federal government is rolling back environmental regulations, we are pushing forward in San Francisco, setting one of the most ambitious clean energy targets of any major city in the U.S.,” Lee said.

San Francisco now funnels electricity through four services: Pacific Gas and Electric Co., CleanPowerSF, Hetch Hetchy Power and direct access providers, where large buildings buy energy from third parties. A total of 44 percent comes from renewable sources, so the city needs an increase of six percentage points to meet its goal.

The city will receive the bulk of that energy through CleanPowerSF, the city-run green energy program that began in May after years of political gridlock and resistance from PG&E. About 40 percent of the electricity provided by the program already comes from renewable sources and will continue to increase. The current mix is 5 percent higher than the original goal of 35 percent, and 10 percent more renewable than energy provided by PG&E. By 2019, CleanPowerSF is projected to provide 400 megawatts of power — enough electricity to power 320,000 homes and businesses.

The program works much like a buyers club for energy. The city purchases electricity for residents, while PG&E delivers that energy on its electrical grid. CleanPowerSF is operating at 60 megawatts and provides electricity to 75,000 residents and businesses. More San Francisco neighborhoods will be auto-enrolled over the next three years.

“That’s a big undertaking,” said Barbara Hale, assistant general manager for power at the San Francisco Public Utilities Commission. “While going from 40 to 50 percent doesn’t sound like a big number, the volume we are applying that percentage to is different. It’s a big change in number of customers. But we don’t expect the extra energy is going to be difficult to get.”

City officials have paralleled their climate goals with the state, which seeks to drop to 1990 carbon dioxide emission levels by 2020. San Francisco had set a goal to reduce the levels by 25 percent by 2017, which was achieved in 2015, despite a burgeoning economy and growing population. The city seeks to achieve a 40 percent reduction by 2025.

“San Francisco is a city that rehearses the future,” said Debbie Raphael, director of the San Francisco Department of the Environment. “We are trying to be even bolder than the state of California.”

Back to Gallery SF’s green energy goal is a decade ahead of target 3 1 of 3 Photo: Michael Macor, The Chronicle 2 of 3 Photo: Michael Macor, The Chronicle 3 of 3 Photo: Michael Macor / The Chronicle





As state and local policy drive the market, the renewable energy economy has flourished. Local green energy programs are up and running in Sonoma and Marin, and prices have dropped. The state Energy Commission estimates that almost 25 percent of electricity came from renewable sources in 2014.

With the growing market comes lower prices and more realistic goals. Seeking to increase renewable power in the city by six percentage points is achievable, said Alice Kaswan, an environmental law professor at the University of San Francisco School of Law, who has studied renewable energy issues.

“The key question is whether they are talking about generating that amount of renewables or purchasing it,” she said. “There’s a lot of renewable energy being developed in the state. My sense is that, if all they are committing to is purchasing power supplied in that way, it is a very feasible and realistic goal.”

The city should be able to meet the goal, if not surpass it, said Mark Jacobson, a professor of civil and environmental engineering at Stanford University and director of its Atmosphere and Energy Program.

“There is so much solar, in particular, and wind as well, available in Northern California to the city, in addition to rooftop solar space available, and many companies chomping at the bit to install the renewables,” Jacobson said. “The cost, job and health benefit of such a transition is so large that the city would be remiss not to take this opportunity.”

Raphael of the environment department also sees forces aligning in favor of clean energy.

“We’ve got a public and business community that wants renewable energy and a city determined to procure renewable energy,” Raphael said. “We have this perfect storm that allows us to beat our goals. That’s what is so exciting.”

The city hopes to have 100 percent renewable energy by 2030. But while political gridlock over CleanPowerSF has passed, battles between the city and PG&E persist. A recent complaint by the company seeks to force the city to upgrade buildings that receive Hetch Hetchy hydropower through PG&E’s transmission lines at a cost of $600 million. City officials maintain it’s an attempt by PG&E to maintain its monopoly. It could take years for the Federal Energy Regulatory Commission to issue a ruling.

Lizzie Johnson is a San Francisco Chronicle staff writer. Email: ljohnson@sfchronicle.com Twitter: @LizzieJohnsonnn