LOS ANGELES - A bill that would power up California's already ambitious effort to shift to cleaner, renewable energy has cleared the state legislature, but it was uncertain if Governor Arnold Schwarzenegger would sign it.

Schwarzenegger, who supports the more aggressive requirements in the measure, is under pressure from interests such as small energy producers and local utility districts to veto the bill.

The plan, passed by the state Senate late on Friday, would require California's utility companies to get one-third of their electricity from solar, wind and other alternative energy sources by 2020.

The state has embarked on the most ambitious U.S. effort to switch to more environmentally friendly energy production. But it is struggling to meet its current goal of sourcing 20 percent of its electricity from renewable sources by 2010.

Senate Bill 14 would lift the existing renewable energy sourcing requirement and boost the 2020 goal to 33 percent.

It also would limit the amount of out-of-state renewable power sold in California, a move meant to keep jobs in the nation's most populous state as it grapples with dwindling revenue and high unemployment.

Schwarzenegger has 30 days to act on the legislation, which was written by Senator Joe Simitian. His district includes Silicon Valley -- the famed technology hub that gave birth to companies like Web search company Google Inc and computer maker Hewlett-Packard Co.

Electricity generation accounts for 32 percent of California's gross carbon dioxide emissions. Emissions from the electricity sector are increasing twice as fast as emissions from any other sector, including transportation, state officials say.

California's three largest utilities, Pacific Gas and Electric, Edison International's Southern California Edison and San Diego Gas & Electric, produced just 13 percent of their power from renewables last year.

The state, which is the world's eighth-largest economy, is a huge market for companies like Tempe, Arizona-based First Solar and San Jose, California-based SunPower Corp.

Lawmakers also passed Senate Bill 32, which would expand California's feed-in tariff -- a form of government incentive -- for solar power projects. The governor has 30 days to veto or sign this legislation.

The bill would increase the size of the eligible projects to 3 megawatts from 1.5 megawatts.

(Additional reporting by Laura Isensee in Los Angeles and Peter Henderson in San Francisco; Editing by Xavier Briand)