From the Sacramento Bee:

The city plans eventually to have at least 51 percent of its electricity supplied by renewable sources of energy -- compared to about 13 percent for PG&E today. Those new sources could include a wind farm in Solano County, geothermal power from the desert, solar panels in the city's sunny southeast section and even wave power supplied by the Pacific Ocean.

A much more aggressive energy efficiency program would also play a role.

City officials and analysts believe that San Francisco can dramatically boost its use of renewable energy and still get its power for less than residents are paying now. One big reason: municipal bonds. The city can borrow money with low, tax-free interest rates not available to the private utilities.

That cheap money might be able to jumpstart renewable energy projects that otherwise would never get off the ground. Most such projects have high upfront costs and then fairly minimal costs to operate.

This is a plan Greenpeace, the Sierra Club and other groups have been pushing for a while. It's called "Community Choice Aggregation".