Damage and revenue loss from the Valley fire will total $30 million to $35 million for Calpine Corp. energy production operations at The Geysers geothermal complex, the company announced Monday.

The estimated toll includes property damage and lost revenue due to reductions in electric power generation.

Facility repairs should be completed within 12 months.

“We believe our insurance program will cover repair and replacement costs as well as our net revenue losses, after deductibles,” the company said in a statement.

The announcement came on the same day that Calpine said all of its employees had returned to work at its facilities in The Geysers, the world’s largest geothermal complex, occupying 45 square miles along the border of Sonoma and Lake counties.

Calpine has about 300 employees and 150 contractors that work in the area. Since the outbreak of the fire, and mandatory evacuations ordered by the state, only essential personnel were operating plants in the complex.

Calpine expects its unmet obligations for electricity delivery will be excused until repairs are completed by reason of “force majeure,” a contract clause that typically removes liability for natural and unavoidable catastrophes.

The company suffered fire damage to cooling towers and other facilities at five of its 14 power plants. The 76,000-acre blaze began Sept. 12 in the nearby Cobb area in Lake County.

Calpine’s facilities at The Geysers currently are producing 540 megawatts, or about three-quarters of its normal operating capacity of 725 megawatts.

Calpine generates about 60 percent of the electricity needs for the North Coast from the Golden Gate Bridge to the Oregon line.

The electricity primarily is sold to PG&E, Sonoma Clean Power and Southern California Edison.

You can reach Staff Writer Robert Digitale at 521-5285 or robert.digitale@pressdemocrat.com. On Twitter @rdigit