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A Practical Geothermal Database for California and Nevada

Client: The San Francisco Public Utilities Commission on Behalf of the California Energy Commission
Date: 2004 (for full Phase I report please click here)
Date: 2006 (for full Phase II report please click here)

Project Goals

As part of a larger project to evaluate the potential of all renewable energy sources for the state, the California Energy Commission requested a thorough and realistic assessment of megawatt capacity of geothermal fields in California and western Nevada. The primary objective of the project was to quantify geothermal resources in terms of their minimum and most-likely generation capacity, the estimated costs ($/MW) associated with producing this power, including the costs of resource development, power plant construction and transmission interconnection. Assembling this information presented a number of significant challenges including gathering and rationalizing a vast array of disparate data, assembling proprietary information from private organizations, and creating an overarching methodology for cataloguing, analyzing and presenting the findings.

The GeothermEx Approach

One of the most significant contributions of the PIER Report to the geothermal community is the methodology and framework the GeothermEx team created for assessing geothermal costs per megawatt. The GeothermEx framework synthesizes complex data from highly disparate resources into an easy to understand set of defensible cost and production assessments. This groundbreaking approach signifies the first time all relevant information about geothermal power production has been assembled in a single, coherent source for such a large area.

The team began by articulating the phases any given geothermal project undergoes, from reconnaissance exploration through to power production. Costs were assigned to each phase of exploration and development, enabling a consistent model for evaluating per-megawatt costs. This framework was applied to more than 80 fields in the target area. The study concluded that the available geothermal capacity available represents a significant opportunity for commercial development to meet the needs of the California electricity market.


The GeothermEx PIER report has become a primary document for developers, financiers, and government planners in California and western Nevada. The uses of the GeothermEx PIER report have included: 1) supporting California state officials as they plan transmission initiatives 2) assisting municipal-owned and investor-owned utilities in their efforts to cost-effectively open new geothermal areas for energy production; and, perhaps most significantly 3) providing the GeothermEx PIER Geothermal Database, a powerful resource that offers characteristics of 155 separate geothermal projects at 83 resource areas. Together, the PIER Report and Database offer planners, utilities and the entire geothermal industry a methodology and informational baseline for better understanding current and future geothermal energy production.

For full Phase I report please click here

For full Phase II report please click here