From the Globe Environmental Desk

San Francisco Supervisor Ross Mirkarimi has introduced legislation that would make it mandatory for at least 50 percent of the city’s energy to be solar or wind generated.
   Mirkarimi, co-sponsor of the bill, captured national attention last month when he pushed through a bill to make San Francisco the first city in the nation to ban plastic bags.
    If approved by the full Board of Supervisors in May, the ordinance will be the first effort to implement a state law passed in 2002 that allows communities to withdraw from purchasing power from private providers, such as PG&E, and become a buying coop known as a community choice aggregator.
    The legislation calls for constructing wind, solar and efficiency projects with the goal of meeting over 50 percent of the city’s overall electricity demands through renewable resources by 2020.
    “As long as this nation is disproportionately reliant on oil and fossil fuel technology, we stand vulnerable. San Francisco needs to mount a smart, energetic counterattack designed to protect our environment and safeguard against energy market fiascoes,” said Mirkarimi.
    The state’s Community Choice bill passed with help from Paul Fenn of Local Power. Fenn was also the main co-author and negotiator for the new San Francisco ordinance, introduced by supervisors Mirkarimi and Tom Ammiano. The implementation plan was strenuously debated and re-written to reach its current form.
    The newest science on global warming shows that all industrial countries like the U.S. will need to cut carbon-dioxide emissions by up to 90 percent in the next 20 to 25 years in order to avoid a global catastrophic climate collapse, according to bill supporters.