The Potrero Power Plant, a longtime source of pollution and health concerns for residents of San Francisco’s southeastern neighborhoods, is slated for partial closure once the Trans Bay Cable begins transmitting electricity into the city.
The Trans Bay Cable is an undersea cord that will transmit 400 megawatts of power underneath the San Francisco Bay from power plants in the Pittsburg / Antioch area. Last we heard, from a January article  in the San Francisco Examiner, the project was running a full month ahead of schedule.
From the Examiner update:
“The cable was scheduled to become operational in March. However, the $505 million project is moving ahead of schedule, according to PJ Johnston, a spokesman for the joint venture that’s financing and installing the cable. The planned date to switch on the cable is now Feb. 1, according to Johnston.”
Well, Feb. 1 came and went. March came and went. Now, it’s April – and the Potrero Power Plant is still going strong, its telltale plume issuing from the tall brick smokestack.
We called PJ Johnston, the spokesperson, for another update. “We’re still testing,” he explained. “We’re going to be testing at least into the next month or longer. We’re working with the [California Independent System Operator] to determine a commercial operation date.”
The construction of the Trans Bay Cable and the converter stations were completed last year; and the system was energized in December; Johnston noted.
"We won’t speculate on a latest start date," he responded after being asked when, at the very latest, it would go into service.
That elusive date is key, because that’s when the city can kiss the primary unit of its only remaining power plant goodbye. Unit 3, which accounts for the lion’s share of harmful emissions, will no longer be required to operate by the California Independent System Operator (Cal-ISO) once the alternative source is in place, clearing a major obstacle that stood in the way of the plant’s closure for years. Three smaller diesel-fired units at the plant will remain in service until a Pacific Gas & Electric Co. cabling project is finished later this year, but they’ll run far less frequently than the workhorse Unit 3, according to Cal-ISO spokesperson Gregg Fishman.
“We had heard March too,” Fishman commented. He confirmed that “the large unit at Potrero will no longer be needed,” once the cable comes online, and referred us to Johnston for more information. In an accord  reached with City Attorney Dennis Herrera last year, Mirant -- the company that owns the Potrero plant -- agreed that it would shutter the plant once the Cal-ISO gives the nod.
When the cable comes online and Unit 3 finally does become history, the air quality in San Francisco’s Bayview Hunter’s Point neighborhood is sure to improve. Yet as the Guardian has noted  in the past, there are environmental justice questions surrounding a project that essentially shifts the pollution impact of the city’s energy needs from one low-income community to a similar neighborhood, farther away.