Jason Pretslaf, a senior mechanical engineer for PG&E, shows off the utility’s new Yerba Buena battery energy storage project on Oct. 15, 2013, in
Jason Pretslaf, a senior mechanical engineer for PG&E, shows off the utility's new Yerba Buena battery energy storage project on Oct. 15, 2013, in the hills above Evergreen Valley College in San Jose. The facility is capable of storing up to four megawatts of power. (Karl Mondon/Staff)