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The Geysers more resemble the Altamont Pass wind farm than a monolithic solar field in the Mojave Desert. Wells and small power plants are distributed over a vast area seemingly at random, often located miles apart and connected by rough dirt roads, looking like industrial blemishes on the natural environment. Rocky outcroppings, scrublands, and forests of manzanita, madrone, oak, and pine are dispersed across the steep terrain, seemingly as naturally as the day they were discovered — if you can overlook the network of power lines; bare, winding roads; and eighty miles of above-ground steam pipelines.
Within the next few years, Calpine plans to add a few more specks to the landscape, albeit in the busier southeastern portion of The Geysers (the majority of a ten-square-mile section in the northern part of the property has yet to be developed). The company received approval in November to build a pair of 49-megawatt plants, but is holding off on breaking ground until it can secure long-term power-purchase agreements for both.
Meanwhile, a Reno-based company, Ram Power Corporation, is expected to complete a new 25-megawatt plant at The Geysers by the end of next year, which will be the first plant built there since 1989. Together, the new projects will nudge the field's total power production above 1,000 megawatts.
That's a far cry, however, from the more than 2,000 megawatts it was once capable of generating. Instead, current production is limited to less than half that, with most plants running at 50 percent capacity.
The reason why is a cautionary tale for geothermal developers everywhere. Beginning in the early 1980s, before Calpine bought a stake in its first plant, The Geysers experienced something of a land rush. Developers scrambled to snatch up drilling sites, build power plants, and tap into The Geysers' massive underground steam reservoir, heated by a shallow field of magma.
By the end of the decade, the boom had gone bust. Geothermal plants function by drawing steam from the earth and running it through a turbine to produce electricity. However, steam flow at The Geysers had dramatically decreased, and investigations revealed that the underground reservoir was not recharging itself with surface water as quickly as believed.
At the same time, plant operators were returning only about 20 percent of extracted water to the reservoir, with the remainder evaporating away. In other words, the earth was still generating heat, but the medium needed to convert it to power was missing, reducing the field's production and threatening its long-term viability. "They were drawing so much fluid out of the reservoir that the pressure started dropping like a stone," said Bill Powers, a San Diego-based energy expert who advocates for clean power.
The answer, naturally, was more water. In 1997 came a 29-mile, $45 million pipeline from the Lake County Sanitation District, delivering 8 million gallons of highly treated wastewater every day (a volume that has since declined). And in 2003, a second pipeline followed, this one 40 miles long and delivering approximately 14 million gallons per day from the City of Santa Rosa. The water sources, which are used to replenish The Geysers' naturally occurring underground reservoir, remain essential to operations. Without them, the field could suffer a second, even more severe blow.
But the water may not be available forever. During a recent tour of The Geysers, Calpine Director of Engineering Tim Conant said that while the 25-year contract with Lake County is likely to be extended when it expires in 2022, the Santa Rosa water, guaranteed through 2038, might be less of a sure thing. As the city and surrounding area grows, and as uses for treated and recycled water increase, there's a chance that Santa Rosa may eventually want to keep some or all of its water.
Either way, Powers has concerns about the long-term prospects for power production at The Geysers. "It's basically on a form of life support," he said. "The Geysers couldn't be further from sustainable. ... It's somewhat of a stunner to hear how short-sighted it is." He has a similar critique for California's second-largest geothermal complex, located on the Salton Sea in Southern California, where he suggests a similar crash could be looming.
His solution for both, which he outlines in a March report on the future of clean-energy production in the region called Bay Area Smart Energy 2020, is to retrofit geothermal power plants with a modern cooling system that will reduce water losses, gradually improve reservoir pressure deep inside the earth, and offer the opportunity to extract more steam from the ground — up to 300 megawatts more at The Geysers, Powers estimates. The significant up-front cost would be repaid over time by increased energy production.
But Calpine doesn't have any such plans, said Seperas. Instead, the company is adjusting to the new reality by reducing turbine sizes to increase efficiency at today's flow levels. And with its water sources fixed for at least the next 26 years, Calpine is more intent on developing the next wave of geothermal power plants, known as enhanced geothermal systems, or EGS. In 2008, the company began a partnership with the US Department of Energy to build a $12 million EGS demonstration project at The Geysers. If successful, it could lead geothermal's transition from stepchild to savior.
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