San Francisco Chronicle: Backers of a state ballot initiative to require a significant boost in renewable energy used by all utilities in California can begin collecting signatures, the secretary of state announced Monday. The proposed Solar and Clean Energy Initiative would require all utilities to generate 20 percent of their power from renewable sources by 2010, increasing to 40 percent by 2020 and 50 percent by 2025. Current state law requires Pacific Gas and Electric Co. and other investor-owned …