The largest geothermal field in the world, universally known as The Geysers, has been in commercial operation for over 50 years.  The field covers some 30 square miles in the Mayacamas Mountains of Sonoma and Lake counties in Northern California. Among the handful of geothermal providers at The Geysers, the Northern California Power Agency (NCPA) stands out for its environmental stewardship and innovation. NCPA has integrated several green technologies into one of the most sophisticated and unique renewable energy systems in the world.


In 1997, NCPA was one of the pioneers who created the world’s first geothermal-injection system to recharge the production wells at the Geysers. Since steam extracted from the Geysers is not naturally replenished by groundwater, a supplementary source of water is needed. NCPA contracted with Lake County Sanitation District to take their treated wastewater effluent and—utilizing two 1-megawatt solar installations— pump it more than 26 miles for injection into the geothermal reservoir, dramatically extending the life of this clean, base-load resource. Had NCPA not acted, the Geysers facilities would have ceased production in 2013. Instead, this critical base-load renewable resource will continue to generate clean, reliable power for decades to come.

NCPA at the Geysers