California would set a goal of phasing out all fossil fuels from the state's electricity sector by 2045 under legislation signed by Gov. Jerry Brown.
Brown signed the measure Monday as he prepares to host a summit in San Francisco of climate change leaders from around the world later this week.
He has positioned California as a global leader in the effort to reduce greenhouse gas emissions.
The renewable energy measure also would require California's utilities to generate 60 percent of their energy from wind, solar and other specific renewable sources by 2030. That's 10 percent higher than the current mandate.
The state would then aim to use only carbon-free sources to generate electricity by 2045. It's merely a goal, with no mandate or penalty for falling short.