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, and currently supplies over 5% of the state’s electricity needs, and generates an amount of electricity equivalent to more than 60% of the electrical needs of the entire northern coastal region, stretching from San Francisco to Oregon. 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 a number of green technologies into one of the most sophisticated and unique renewable energy systems in the world.
In 1997, NCPA created the world’s first, wastewater 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 26 miles for injection down deep into the geothermal reservoir, dramatically extending the life of this clean, base-load resource. Had NCPA not taken action, 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.