Gov. Jerry Brown signed SB 100 Monday, completing the legislative effort to transition California to fossil-fuel-free electricity.

The law, which calls for 60 percent renewable energy by 2030 and 100 percent carbon-free energy by 2045, makes California the largest jurisdiction to legally commit to clean energy. Brown signed it as leaders from around the world are heading to San Francisco for a Global Climate Action Summit this week intended to rally efforts to stop climate change.

California already has laws on the books requiring a reduction in overall greenhouse gas emissions. SB 100, if successful, will eliminate them from the electricity sector; long-term success requires cleaning up transportation and industrial processes, each of which now produce more emissions than the state's electrical generation.

To address other areas of the economy, Governor Brown also announced an executive order today directing California to achieve carbon neutrality by 2045 and to be net greenhouse gas negative thereafter. The order will require the Golden State to undertake additional decarbonization efforts, such as capturing and sequestering carbon in soil and building materials. Brown said that a regional electricity grid will also be necessary to meet these goals. A bill authorizing regionalization failed in the state legislature last month.

“California is committed to doing whatever is necessary to meet the existential threat of climate change,” Brown said at the signing, according to the L.A. Times. “And yes, it is an existential threat. No matter what the naysayers may say, it is a real, present danger to California and to the people of the world.”

The 100 percent goal follows years of careful preparation, in which California asked its utilities for increasing quantities of wind and solar power, and deployed grid batteries large and small to store electricity for times of need.

As of last year, California got 29 percent of its power from renewables. Another 9 percent came from nuclear and 15 percent from large hydropower; both of those count as carbon-free, but the last remaining nuclear plant is slated to retire by 2025. Natural gas provided 34 percent of California’s electricity.

The law stipulates that the renewables share must double by 2030. The harder task, though, will be weaning the state off the gas plants that have flexibly balanced out the fluctuations of wind and solar generation.

California utilities have deployed lithium-ion batteries to provide local capacity when traditional grid resources were stretched thin. PG&E is building a massive 300-megawatt battery to compensate for several gas plant retirements. A highly renewable system, however, will require much greater storage capacity, not to mention resources that can shift energy across weeks and months.

The text of the law leaves considerable leeway in how the state meets the requirement, defining the goal but not the means. That will provide a compelling market opportunity for businesses to improve upon today's grid technologies and perhaps invent new ones.

Whether California can achieve this goal without spending a great deal of extra money remains to be seen. Whatever innovations the state comes up with, though, are likely to trickle out to other markets, shaping the decarbonization process elsewhere in the world.

More coverage of SB 100 and its implications: