Legislators in the State of California passed a bill that would require energy companies to generate 33% of their capacity from renewable sources by 2020. Both legislative houses have voted for the bill and the ball is now in Governor Jerry Brown’s court.

The bill would raise the bar from the state’s current target of 20% by 2010. Brown has not taken a position on the issue, but his election platform in 2010 included setting a more aggressive renewable-energy target, according to the Los Angeles Times.

If the mandate becomes law, energy prices in the state – where they are already some of the highest in the US – may go up, resulting in higher operating cost for its large data center industry.

Many of the state’s utilities have to buy renewable energy from other producers and make future power purchase agreements with them for lack of their own capacity to generate enough electricity from renewable sources.

In its latest report on compliance with the existing Renewables Portfolio Standard, PG&E, one of the largest utilities in California and one of two utilities serving Silicon Valley, said it would be able to comply with the 20% mandate. Its compliance, however, would depend on multiple factors outside its control.

Since the utility would have to buy renewable energy from other producers to comply, its compliance would depend on those producers’ ability to overcome "financing, permitting and transmission obstacles." PG&E has made a number of agreements with independent producers to purchase renewable power from them.

Another potential obstacle the utility cited was state utility regulators’ recently imposed limit on utilities’ ability to trade renewable energy credits associated with some generation capacity outside of the state. This limit, PG&E maintained, constrained its ability to create a "compliance buffer" in case some of its near-term renewable projects fail.

PG&E representatives did not respond to a request for comment in time for publication.

In 2010, 18% of total retail electricity the state’s three largest utilities (including PG&E) served came from renewable sources, according to the California Public Utilities Commission. PG&E managed to make 17.7% of its portfolio renewable, Southern California Edison reported 19.4%, and San Diego Gas and Electric reported 11.9%.