Tetra Tech certified greenhouse gas (GHG) emissions of one hydroelectric development project and two geothermal power plants that have been registered with the California Climate Action Registry. The hydroelectric project, located in three counties on a major river in northern California, has the capacity to generate 250 megawatts of power. The two geothermal power plants and the associated steam field are part of the Geysers Known Geothermal Resource Area in the Mayacamas Mountain Range, 75 miles north of San Francisco.

These facilities reported six GHGs associated with operations, including carbon dioxide (CO₂), methane (CH₄), nitrous oxide (NO), hydrofluorocarbons (HFCs), perfluorocarbons (PFCs), and sulfur hexafluoride (SF₆). Certification involved inventorying, reviewing, and comparing emissions data and documenting the findings in a report. Tetra Tech completed the following tasks to certify the registered emissions:

• Conducted site visits for first-year certification
• Completed an analysis of the GHG emissions that evaluates whether the reporting program is consistent with the registry’s General Reporting Protocol and Power Utility Protocol
• Prepared and submitted a certification report and certification opinion
• Discussed the certification report and opinion with the Northern California Power Agency
• Completed the certification form in the registry’s database

Tetra Tech is certifying the emissions from these facilities through reporting years 2006, 2007, and 2008.

Highlights:

• Certified hydroelectric and geothermal facilities emissions
• Certified plant emissions under the Registry
• Resolved issues of fugitive emissions compared to process emissions