California Governor Jerry Brown Signs Bill for Carbon-Free Power by 2045

California Governor Jerry Brown signed legislation that would require all of the state’s electricity to come from carbon-free sources by 2045, marking the biggest step yet in his fight against global warming.

The measure, passed last month by the legislature, will eliminate the reliance on fossil fuels to power homes, businesses and factories in the world’s fifth-largest economy, accelerating a shift already under way. The state currently gets about 44 percent of its power from renewables and hydropower.

“California is committed to doing whatever is necessary to meet the existential threat of climate change,” Brown said before he signed the bill in Sacramento. “California has been doing stuff that the rest of the world is hoping to get to one day.”

Brown’s announcement comes ahead of a climate summit he is hosting this week in San Francisco that will draw local governments, businesses and investors from around the world. The California governor has taken on the mantle of leading the U.S. effort to combat climate change as President Donald Trump has sought to roll back environmental regulations and support coal-fired power plants. Brown is also fighting the Trump Administration’s effort to deny California’s authority to set its own, more stringent auto-pollution standards.

Earlier this year, California became the first U.S. state to mandate solar rooftop panels on almost all new homes. It would be the second state to require 100 percent carbon-free power after Hawaii.

The move would accelerate a shift already underway to wind and solar but hinges on a big bet — that battery costs will plunge, allowing for a transition away from the natural gas plants that provide about a third of California’s electricity. The measure, sponsored by state Senator Kevin De Leon, requires the state to get 60 percent of its power from renewable energy by 2030, up from a target of 50 percent by the same deadline.

Proponents of the bill say solar and wind energy already compete in price with fossil fuels and that costs are expected to decline further. But they also note that the measure allows for a mix of clean-energy resources, including large hydroelectric dams.

Opponents — including the state’s investor-owned utilities run by PG&E Corp., Edison International and Sempra Energy — raised concerns that the requirement would increase electricity costs. California would need to install more than 200 times as much energy-storage capacity than it has now to make up for the loss of gas plants, according to the Clean Air Task Force, a Boston-based energy-policy nonprofit.