GeoZone | Sonoma Clean Power


Sonoma Clean Power is partnering with Sonoma and Mendocino counties in exploring opportunities to accelerate local geothermal development. Our region is home to a world-class geothermal resource at the Geysers. An increasing penetration of intermittent renewables, ambitious environmental targets, and retirement of nuclear and natural gas plants are creating an increasing need for more geothermal power. The Geothermal Opportunity Zone (GeoZone) was created to provide the framework for a public-private partnership between member counties, SCP as a power off-taker, and geothermal technology and development companies to pursue incremental geothermal development in our region. The GeoZone endeavors to host novel technologies that increase the compatibility of geothermal development with the values of the community. The ultimate objective of the GeoZone is to build 500 MW of incremental local geothermal capacity. Initial deployments will likelyrequiregrant fundingto remain competitive, but at-scale the GeoZone offers to promise of providing a long-term, sustainable, and affordable source of reliable clean energy.

Private Partner Solicitation

Sonoma Clean Power is issuing a Request for Information (RFI) to select geothermal technology and development companies to partner in pursuing the objectives of the GeoZone. Responses to this solicitation will be due April 29, 2022. Links to documents, events, and other material for the solicitation are included below.The questions and answers document will be regularly updated during the solicitation process.

< Request for Information >< Webinar Calendar Invite>< Questions & Answers from Respondents >

Geothermal Power

The earth has a constantly-regenerating source of heat that is transferred from the core to areas near the surface by conduction and the flow of magma underground. There are areas in the world where magma exists particularly close to the surface and significantly elevated subsurface temperatures. This condition is particularly pronounced in our region, where a thermal anomaly exists that is associated with the Clear Lake Volcanic Field. Power is produced by using geothermally heated rock to transfer heat to the fluid that is produced through wellbores. At the Geysers today, produced steam is expanded through a turbine that spins to generate electricity. Other geothermal technologies exist today that exchange heat between the produced fluid and generate power using a separate fluid and power cycle. These systems allow the development of resources with lower temperatures than the Geysers and limit geologic emissions and water usage.

Supply Portfolio

Since starting service in 2014, geothermal has constituted a significant portion of Sonoma Clean Power’ssupply portfolio. Sonoma Clean Powercurrently contracts for 50 MW from the Geysers that provides clean and reliable energy to ourportfolio and serves an essential role in powering the100% local renewable 24/7 premium energy product EverGreen.In 2021,California regulators recognized the importance of geothermal energy in meeting state climate goals and ordered the procurement of 1,000 MW of incremental baseload renewable capacity by 2026. The constant generation output of geothermal resources is especially important given the planned retirement of the Diablo Canyon nuclear plantand upcoming retirement of natural gas plants.By 2045, the California Public Utilities Commission expects the California supply portfolio will need to include over 1,500 MWof new geothermal resources. Given the lack of recent new development in our region, near-term increases to geothermal capacity are expected to come from Nevada imports or development inCalifornia’sImperial Valley. Long-term, the GeoZone’s objective is toenable our region to substantially contribute to the state’s need for more geothermal.

Currently, the Geysers generations around 750 MW of the state’s 1,600 MW of geothermal capacity. Importantly, the state is relying on current geothermal capacity to be sustained. Identifying opportunities to increase the resilience, efficiency, and longevity of current regional resources is a core objective of the GeoZone.

Public Engagement

Sonoma Clean Power partnered with Sonoma and Mendocino Counties in forming the GeoZone with the objective of facilitating early and effective engagement of local stakeholders in the development strategy of new geothermal in our region. Validating the compatibility of geothermal power projects with community values will greatly increase the chance of the GeoZone’s success.If you have questions or input on the GeoZone, please contact us at