Aaron Kinney for Mercury News:  In the latest sign that a Bay Area renewable energy trend is picking up steam, San Mateo County is taking a close look at buying its own power on the open market, instead of relying on PG&E, in a bid to lower its greenhouse gas emissions.

The county is exploring whether to establish a community choice aggregation program, which allows local governments to create their own energy portfolios that rely more on alternative sources like wind and solar and less on fossil fuels. On Tuesday, the board of supervisors will vote on allocating $300,000 toward a technical study of the proposal.

Marin County pioneered the community choice aggregation model in California. Since launching in 2010, Marin Clean Energy has grown to serve roughly 125,000 customers. The nonprofit claims it delivers more than twice as much renewable energy as PG&E at a slightly reduced cost to consumers.

Sonoma County followed suit last year with Sonoma Clean Power, and numerous jurisdictions are now looking into the model, including Alameda County and the South Bay cities of Cupertino, Mountain View and Sunnyvale.