For more than a decade now, three power companies and one community in California have received awards for their outstanding environmental performance from the use of geothermal power. Here's a timeline of their award-winning performance.

1990

Pacific Gas & Electric Company received California's first Air Pollution Reduction Award for minimizing hydrogen sulfide emissions at The Geysers.

1990-2004

Lake County—home to five of The Geysers power plants—has been the only California air district to attain all the state ambient air quality standards for more than a decade.

1991

The California State Assembly passed a resolution commending the Mammoth Pacific on the start-up of two of its geothermal power facilities in Mono County, recognizing its use of clean energy without "environmentally damaging emissions."

2000-2004

For four consecutive years, Mammoth Pacific received from the California Department of Conservation an award for its outstanding environmental record at its Mono County geothermal facilities.

2002-2003

Calpine Corporation—for its geothermal operations at The Geysers—received environmental and safety performance awards from the California Department of Conservation, which praised the company for air quality improvement and pollution prevention.

2003

Mammoth Pacific, for its Mono County geothermal facilities, received the Governor's Environmental and Economic Leadership Award, which recognizes the use of innovative technologies to improve environmental quality and protect public health and safety.

2004

For its geothermal operations at The Geysers, Calpine Corporation received the Clean Air Award for Technology Development from the American Lung Associations of the Bay Area.