Sustainable power generation at The Geysers is possible today because of two large-scale recycled water partnerships with Lake County and the City of Santa Rosa. Together, these projects provide up to 20 million gallons of reclaimed water daily for injection into The Geysers reservoir. The vast amount of naturally occurring heat in reservoir rocks efficiently converts the water into steam, supplementing the production of original reservoir steam for power generation.
Throughout the 1970s and 1980s, more steam was produced from The Geysers reservoir than was replaced. By 1989, accelerated development had caused severe steam pressure decreases in the reservoir, resulting in lower steam production rates. This decline threatened the future sustainability of Geysers power generation.
To sustain reservoir pressure and steam production, The Geysers needed a large, reliable supply of water that could be used to augment injection.
At the same time, community growth like many areas in California, had strained its public infrastructure. In the 1980’s the Lake County Sanitation District was providing sewer service to many communities and cities in the County and was struggling with its wastewater treatment systems, deficient storage and was facing disposal capacity issues. These deficiencies resulted in a State order for upgrades to treatment processes and a mandate to find a sustainable, long-term solution to dispose of the County’s wastewater.
Finding environmentally acceptable and affordable solutions was not easy, and Lake County spent years evaluating alternative options, including expanded agricultural irrigation and created wetlands. Lake County’s neighbors in Yolo County had also taken notice because one alternative being considered was a discharge into Cache Creek.
In 1990 a collaborative effort between geothermal operators at The Geysers, Lake County and the California Energy Commission identified Lake County wastewater from the southeast regional collection system as the preferred source of water.
Construction of the Southeast Geysers Effluent Pipeline (SEGEP) began in 1995 and delivery of recycled water to The Geysers commenced in 1997. The original 29-mile pipeline, now lengthened to 40 miles to include additional nearby communities is now delivering approximately 8 million gallons of recycled water daily to The Geysers.
Today, representing a model of strategically using water recycling to address other local environmental problems, the South East Geysers Effluent Pipeline collects effluent from a total of four treatment plants serving 22,000 people and 360 businesses in ten Lake County communities. This represents 85% of all effluent produced in the County.
For Lake County, the most important environmental beneficiary is Clear Lake. It dominates the life of the local region in economic and environmental terms. For years, Clear Lake water quality suffered from hydraulic overloading of wastewater systems that annually discharged millions of gallons of treated and untreated sewage into the Lake. This problem has been addressed by South East Geysers Effluent Pipeline, resulting in valuable water quality improvements for drinking water systems that use Lake water, and for the wildlife and recreation values of the Lake that are key to the local economy. In this way, the recycling system is protecting the outflow of Clear Lake to Cache Creek, which serves downstream domestic, agricultural, and recreation uses in Yolo County and the Sacramento Valley.
At The Geysers, since the start of the South East Geysers Effluent Pipeline, both Calpine and Northern California Power Agency have noticed lower amounts of naturally occurring non-condensable gases normally found in its steam.
With SEGEP steam emitting less gases costs are down and heavy truck traffic on local roads are reduced, also helping the region enjoy better air quality. This pipeline system is significantly increasing steam reserves in the southeast portion of The Geysers helping to extend reservoir life and sustainable power generation.
At present, the system is estimated to be supporting approximately 77 megawatts of generating capacity that would otherwise be unavailable if recycled water was conventionally disposed. Moreover, maintaining The Geysers is a critical renewable source to stabilize California’s electric grid because of its baseload generation character. And, through its reduction in carbon emissions, The Geysers is performing a significant role in addressing climate change.
The success of SEGEP injection in maintaining reservoir pressure provided momentum for a similar recycled partnership between Calpine and the City of Santa Rosa on the Santa Rosa Geysers Recharge Project (SRGRP).
In the 1980s and 1990s, the City of Santa Rosa struggled to keep pace with increased flows into the Laguna Treatment Plant and comply with increased restrictions on its discharges into the Russian River. The Geysers Recharge Project was an unlikely solution to the recycled water problems the city faced but turned out to be an efficient and environmentally friendly solution.
The $220 million project was completed in 2003 following seven years of planning and design and three years of construction. For over two decades this project continues to benefit the region by delivering recycled water from Santa Rosa Water’s Laguna Treatment Plant, through the 41-mile-long pipeline, to recharge Calpine’s geothermal steamfields at The Geysers helping increase clean energy produced. This partnership produces enough clean and renewable electricity to power 100,000 homes in the North Bay. In addition to using the region’s recycled water to produce clean power, the project also protects the Russian River by almost entirely reducing discharges to the waterway.
For over 20 years, SRGRP has continued to delivery approximately 11 million gallons per day of recycled water to replenish The Geysers’ geothermal reservoir providing The City of Santa Rosa a weather independent discharge solution.
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ADDITIONAL CONTENT FROM PROVIDED FILES
6.1.1
Recharging the System
Throughout the 1970s and 1980s, there were multiple operators at The Geysers and vastly more steam was produced from The Geysers reservoir than was replaced. By 1989, accelerated development had caused severe steam pressure decreases in the reservoir, resulting in lower steam production rates. This decline threatened the future sustainability of The Geysers.
The Water Story
Sustainable power generation at The Geysers is possible today because of two large scale recycled water partnerships with Lake County and the City of Santa Rosa and its regional partners. Together, these projects provide approximately 20 million gallons of reclaimed water daily for injection into The Geysers reservoir. The vast amount of heat in reservoir rocks efficiently converts the water into steam and supplements the production of original reservoir steam to power plants at The Geysers.
1. Residential and commercial recycled water is collected from communities
2. The recycled water is treated.
3. Recycled water is pumped to the top of the Mayacamas mountain range and flows from there to The Geysers.
4. Water is injected into wells to maintain the underground supply of steam.
5. Steam piped from production wells powers generators to make electricity.
6. Electricity from The Geysers ties into California’s power grid.
In order to sustain reservoir pressure and steam production, The Geysers needed a large, reliable supply of water that could be used to augment injection. In 1990 a collaborative effort between Geysers operators, Lake County and the California Energy Commission identified Lake County wastewater from the southeast regional collection system as the preferred source of water.
This project, known as the Southeast Geysers Effluent Pipeline (SEGEP), was supported by the Geysers operators (Calpine, NCPA and Unocal) and a host of federal, state and county agencies. SEGEP construction began in 1995 and delivery of wastewater to The Geysers commenced in October 1997. The original 29-mile pipeline, now lengthened to 40 miles to include effluent from additional communities in the Clear Lake area, delivers approximately 9 million gallons per day of secondary treated wastewater for injection into The Geysers Reservoir.
The success of SEGEP injection in maintaining reservoir pressure provided momentum for a similar project to bring tertiary treated effluent from the Santa Rosa area to The Geysers. In 2004, the City of Santa Rosa and Calpine Corporation partnered on constructing a 42-mile pipeline which became known at the Santa Rosa Geysers Recharge Project (SRGRP). Since 2007 SRGRP has delivered approximately 11 million gallons per day of tertiary treated wastewater to replenish The Geysers’ geothermal reservoir.
6.1.2
A Win-Win for the Environment
Lake County and the City of Santa Rosa benefit from injection projects at The Geysers by having a reliable, environmentally responsible method of disposing of waste effluent. In addition, stable electrical generation at The Geysers provides continuing income for Lake and Sonoma Counties, where Calpine is the single largest taxpayer.
Today The Geysers generates approximately 850 MW of renewable, clean, reliable, base load power. The success of SEGEP and SRGRP injection in stabilizing production insures that green energy will flow from The Geysers for many years to come.
Calpine is completing a 25 MW expansion project at The Geysers. Recent extreme heat events attributed to the impacts of climate change highlighted the importance of California adequately planning to ensure sufficient generation during peak periods. To address imminent supply shortages, the California Energy Commission highlighted a range of incremental upgrades at existing facilities that could increase their capacities. The North Geysers Incremental Development (“NGID”) will help meet that mid-term reliability need for the California electricity system.
Currently, with 13 power plants in operation at The Geysers, Calpine Corporation reliably supports California with up to 725 megawatts of clean, geothermal energy every hour of every day. The NGID project expands Calpine’s operations by drilling eleven new production and two new injection wells within the Northern portion of The Geysers resource. Utilizing existing steam field infrastructure, the wells will be drilled on four well pads with piping to transfer the superheated steam to nearby operating geothermal power plants to increase overall output.
Constructed under a project labor agreement, the NGID is a multi-year project that Calpine will bring on-line in phases, anticipated to be completed by June 2026. 65 years in operation, geothermal from The Geysers is a proven consistent source of renewable energy and the NGID project is the next step in Calpine’s sustainable management approach of the resource while adding to the many community and environmental benefits to the local region.
6.1.3
The pipes running along roads at The Geysers serve several functions.
The smallest pipes are used to pump water into the injection wells.
Pipes of 20 and 24 inches carry treated recycled water to The Geysers for injection into the steam reservoir.
Large 30-inch pipes carry steam from the production wells to the power plants.