After more than 25 years leading Farallon Capital Management, Thomas Steyer is ready to launch into the next phase of his career. But he remains coy about what exactly he plans to do — perhaps because he plans to do a lot.

For the past few years, Steyer, an avid Democrat, has led a not-so-secret double life as a political power broker, education activist and energy policy commentator. The native New Yorker’s passion for his adopted home state of California burns so brightly that several of Farallon’s investors have speculated that he might run for office someday. But Steyer, who was a featured speaker at the Democratic National Convention in September in Charlotte, North Carolina, disavows any grand political ambitions — though that’s not to say he eschews a good dustup. Borrowing a saying from a friend, former secretary of State George Shultz, he says, “Democracy is not a spectator sport.”

The self-made billionaire is certainly much more than a citizen spectator. Steyer first ventured into California politics in 2010, when he cochaired and helped fund the campaign against a statewide ballot measure known as Proposition 23 that was supported by oil companies keen to roll back California’s greenhouse-gas emissions law. In 2012 he helped design Proposition 39, a ballot measure that sought to close a corporate tax loophole that had allowed out-of-state companies to choose how they calculated income taxes on their sales in California. Steyer spent $32.3 million of his own money to help bankroll the measure, which passed with a 61 percent “yes” vote in November.

Thanks to Steyer’s efforts, “39,” as it is known colloquially, is expected to raise $1 billion a year for the state, half of it slated to fund energy efficiency and clean-energy redevelopment projects in California schools and other public buildings for the next five years. The effort will not only provide much-needed construction jobs in California but also advance one of the causes closest to Steyer’s heart: energy conservation. A pragmatist to the core, Steyer is clear-eyed about the need to achieve greater energy independence by tapping into the U.S.’s vast shale oil and natural-gas reserves — hydraulic fracturing, he concedes, is here to stay — but he’s intent on encouraging responsible fracking and putting more resources behind new technologies to combat global warming.