[caption id="attachment_51143" align="alignright" width="400" caption="The Geysers Power Plant Unit 3"][/caption]
SONOMA COUNTY – Key projects are under way at The Geysers to upgrade existing facilities, test new Enhanced Geothermal System technology and to study the effectiveness of injecting treated wastewater to fracture ultra-hot rock and stimulate greater steam production.
Progress also continues toward the potential addition of two new geothermal power plants.
“Our objective is to sustain current levels of steam and electricity output by responsibly managing the geothermal resource while also planning for the next half century using leading-edge technology,” said Mike Rogers, Senior Vice President, Geothermal Region with Calpine Corporation (NYSE:CPN).
Calpine’s geothermal operations encompass a 29,000-acre, 45-square mile area 75 miles north of San Francisco in portions of Sonoma and Lake counties.
Today, 15 steam-driven power plants produce 725 megawatts (MW) of clean energy representing 20 percent of California’s renewable electricity generation.Two proposed new plants
The Sonoma County Permit and Resource Management Department determined that the two proposed power plants would have no significant effect on the environment and identified the Mitigated Negative Declaration (MND) process as the appropriate permitting path for these facilities.
Last November, the Sonoma County Board of Supervisors unanimously approved land use permits, based on the MND declaration, paving the way for the construction of two new geothermal power plants with capacity to produce up to 49 MW of electricity each. These would be the first new plants to be constructed at The Geysers since 1989.
Before construction could begin, the Northern Sonoma Air Pollution Control District’s air permit process must be completed and Calpine must secure a contract to sell power the plants would produce.
Groundbreaking for the first plant could take place this year, although utilities still need time to review their renewable energy plans and to assess the delivery timeframe and cost of power from these plants. Depending on who purchases the power, a Power Purchase Agreement (PPA) could also require regulatory approval.
The “Wildhorse” plant would be the first to be built, followed by the “Buckeye” plant a few years later.The 50-year plan
Calpine will be working over the next several years to upgrade existing power plants and the steam field extraction process to ensure ongoing production over the next 50 years. Improvements include updating and standardizing control systems to enhance productivity and automate operations.
All but two of the steam turbines originally installed in 1982 will be replaced with more efficient units from the Toshiba Corporation that generate more megawatts using less steam.
Vacuum pumps will also replace steam driven systems, and more injection and production wells and pipelines will be added to help maintain consistent electricity output of six MW hours per year – a rate that has been sustained for over a decade.
With continuous use, The Geysers’ 333 steam wells and 45 injection wells, linked to power plants by an 80-mile network of pipes and 69 miles of injection water lines, has resulted in a decline in overall steam pressure.
“We are examining alternative techniques, such as using high efficiency turbines that use less steam,” Mr. Rogers said. “But our options do not end here.”Enhanced geothermal system
In a collaborative program with the U.S. Department of Energy, Lawrence Berkeley National Labs and the U.S. Geological Survey, Calpine has drilled two experimental wells as part of an Enhanced Geothermal System demonstration project at The Geysers.