Gov. Jerry Brown signed SB 100 on Monday, requiring California to use 100 percent renewable electricity -- like solar, wind, hydropower and geothermal -- by 2045.
While Brown acknowledged reaching a goal of entirely clean electric power will be difficult, he also said the measure "is sending a message to California and to the world."
The governor appears to revel in challenging the Trump administration's stance on climate science and energy, calling out "Trump's insanity" when new EPA rules for coal power were announced last month.