When we think of renewable energy we mostly think of power from the sky such as solar and wind. And when we think of what we should phase out, we picture underground sources such as coal, oil, and fossil gas. However, one underground power source is relatively benign and counts toward California’s renewable energy goals – geothermal.

 Sonoma County is home to the world’s largest electricity-generating geothermal power resource. A very rare convergence of factors creates The Geysers: enough porous rock at a hot enough temperature that is close enough to the surface with a plentiful water supply to create steam.

 Although The Geysers are right in the Mayacamas Mountains, in the past very little of the electricity that Sonoma County customers purchased was from The Geysers. That is changing. Sonoma Clean Power has contracted for electricity from Calpine Corporation, operators of most of The Geysers. Sonoma Clean Power customers can now select EverGreen, electricity that is 100 percent local geothermal power. For customers that select Sonoma Clean Power’s basic service called “CleanStart,” the electricity mix includes about 15 percent Geysers power.

 Many supported Sonoma Clean Power because they expected it would catalyze the development of new local renewable energy generation. Sonoma Clean Power’s purchase of Geysers power does help catalyze new renewable energy. Every megawatt of Geysers power enables the installation of 3 to 5 megawatts of intermittent power like solar and wind. Industry rules specify a ratio of “baseload” power to intermittent power in a given area to protect customers from blackouts. Geysers power is baseload, meaning it runs around the clock. As distributed solar installation increases in the county, this renewable baseload power will become even more important to the stability and resilience of our local grid. And as the EverGreen program grows, Sonoma Clean Power will purchase more power from The Geysers.

 In addition to the environmental benefits of geothermal, there are numerous associated economic benefits with having geothermal generation in our community such as good paying jobs, property taxes and royalties.

Information about EverGreen, CleanStart, and Sonoma Clean Power is available at www.sonomacleanpower.org.


Woody Hastings, is the Renewable Energy Implementation Manager for the Climate Protection Campaign. He can be reached at woody@climateprotection.org, 707-525-1665 x117.