Palo Alto officials will consider upgrading the city's transmission lines and seek new power sources after a fatal plane crash damaged three transmission lines bringing electricity to the city -- leaving residents and businesses without power for most of Wednesday.
The plane, a twin-engine Cessna that carried three Tesla employees, hit a transmission line and tower near Beech Street in East Palo Alto and damaged two 115 kilovolt lines that were bring electricity to the city from the Ravenswood substation, located across the Dumbarton Bridge. Both lines were damaged when the plane crashed into the transmission tower shortly before 8 a.m.
Under normal circumstances, the city would still receive power from a third transmission line, which stretched between wooden poles about 30 feet away from the damaged PG&E tower. But the third line, which carries power from the Cooley Landing substation in East Palo Alto, faltered after it was hit with a piece of debris, according to Tomm Marshall, assistant director of the city's Utilities Department.
Palo Alto utility officials called Wednesday's accident "the perfect storm" when it came to disrupting the city's power supply. All 28,000 or so Palo Alto customers lost power and didn't get it back until about 6 p.m.
Utility officials told the Weekly that the problem wasn't a shortage of transmission lines. The Cooley line takes a different route than the two Ravenswood lines, said Russ Kamiyama, who manages the city's electric operations. The problem is that all three lines were sharing the same corridor near the PG&E transmission tower. So when the plane crash damaged the infrastructure along the corridor, all three lines were damaged.
"The reason it took so long to restore power is because the accident happened at this point in the corridor," Kamiyama said.
PG&E officials repaired the Cooley line by about 5:30 p.m. Wednesday, restoring power to the entire city. The company was completing its repairs on the other two lines Thursday, Marshall said.
Marshall called Wednesday's plane crash a "freak accident" and said it's extremely unlikely for all three lines to be affected by the same event, particularly given the separation between the Ravenswood lines and the Cooley line.
Still, he said the department plans to consider possible upgrades and changes to the city's transmission system.
The Utilities Department has conducted at least two studies in the last few years examining major changes to the transmission lines, Marshall said.
One study explored installing a new transformer at Stanford Linear Accelerator Center (SLAC) in Menlo Park and transmitting power from SLAC to the Stanford Research Park in Palo Alto.
Marshall said the new transformer would create another redundancy in the city's power system and allow the city to transfer energy to a different parts of Palo Alto. But the project would cost about $45 million and would require the city to obtain permission from the U.S. Department of Energy, which would operate the new transformer.
So far, the Department of Energy has not been supportive the city's plan. But Marshall said the city plans to continue its discussions with federal officials.
"The plan is still there -- it hasn't been abandoned," Marshall said.
The department has also considered converting the city's existing 115kV lines to 230kV lines -- a conversion that Marshall said would save the city about $1 million a year. Palo Alto currently has to pay a fee to PG&E for using power lines with less than 230kV -- a fee that would no longer be charged if the conversion is made. The new lines would be installed underground, where they would be less exposed, Marshall said.
The conversion to 230kV lines would cost the Utilities Department about $200 million, but would also bring in long-term savings and improve the reliability of the city's power system, Marshall said.
"There are significant savings that we can make with a 230kV connection," Marshall said. "We're going to go back and consider the economical ways that this could be done."
While some residents voiced frustration about the extended blackout, Palo Alto utility officials said there was little they could have done to speed up the process of restoring power given that the tower and the lines are operated by PG&E.
But Marshall and Kamiyama both said PG&E responded quickly, given the magnitude of the damage and the amount of debris. Marshall noted that the company had to bring in cranes and other heavy equipment to remove debris from the crash site.
"From my point of view, I think they responded very quickly," Marshall said. "We were very lucky that they had local crews here who were able to respond immediately."