A geothermal generating plant at The Geysers
About a month ago, I wrote, in “California’s Next Big Thing,” about the pleasure of exploring this multifaceted state and enjoying vineyards, wineries, cheese makers and locally grown delights – from almonds and avocadoes to pistachios, garlic and a near-infinite selection of fruits and vegetables. I concluded, tongue firmly in cheek and with photos to “prove” my assertion, that “the next big thing” in California agriculture would be “marshmallow farms.” (Check out the link above.)
A couple of weeks after I wrote that, Sandra and I took another Wine Country drive, this one to an area we’d barely begun to explore – Lake County, just north of Sonoma and Napa valleys. There, outside Middletown, we found something that would be a cool addition to the bucket list of every resident and visitor whose interests include clean, green energy.
What we discovered was the visitor center of The Geysers, the single largest generator of geothermal electric power not in California, nor in the United States, but on Planet Earth. Right here in our own backyard!
An easy 90-mile (145-km) drive north of San Francisco and just 33 miles northeast of Santa Rosa, The Geysers’ 327 steam wells produce enough energy to generate about 6 million MWh (megawatt hours) of electricity a year. That’s nearly 10 percent of all of California’s renewable electricity and 48 percent of all the geothermal power in the entire United States. To see it from another perspective, it’s enough clean, renewable electrical energy to power a city the size of San Francisco.
If you’re reading this online in the North Bay (Marin, Sonoma, Napa and Solano counties), the chances are that a significant portion of the electricity running your computer or recharging your handheld device is generated by this clean, infinitely renewable, base-load-reliable* natural resource powered by the Earth’s incandescent interior.
The geothermal field that The Geysers exploits covers some 45 square miles (115 sq km) in the secluded corner of the state that sits atop a “hot spot” that underlies the Mayacamas Mountains where Sonoma, Napa, Lake and Mendocino counties come together. What makes this resource so accessible is that it’s above an area where the Earth’s shifting tectonic plates push magma relatively close to the surface and where the rock is exceptionally permeable, which allows superheated water in its fissures to be brought to the surface as steam.
People have known about this resource since long before Mexicans and Americans settled the area. Native Americans took advantage of steam escaping from the ground to heat sweat lodges. Today, if you travel just 17 miles south of Middletown along scenic (but hilly and twisty) Route 29 to Calistoga, you can enjoy some of California’s best hot-spring relaxation, including resorts featuring mud baths.
Just outside Calistoga you can also find a man-made geyser – actually an old well that was drilled inadvertently into hot groundwater – which erupts anywhere from every 5-15 minutes in winter to every 25-55 minutes in summer. (The more frequent winter eruptions are probably related to seasonal rains.) Despite its name, Geyserville, 24 miles northwest of Calistoga along Route 128, is better known for wineries than for hot, fountaining water.
The Geysers’ visitor center is well worth a detour from a wine-tasting expedition or mud-bathing adventure. Open Wednesday through Saturday, 11:30 a.m. to 5 p.m., its attractive, user-friendly, interactive exhibits invite people to, among much else:
• learn how geothermal power is related to volcanoes and earthquakes
• explore the planet’s geothermal potential
• compare geothermal with other renewable sources of energy
• peer inside a geothermal power plant
• see what it takes to drill through 8,000 feet of rock (yes, about a mile and a half)
• learn about injecting recycled water into subterranean rock to recharge steam wells
So next time you’re exploring Wine Country, think about putting down your glass, “going underground” for a while, and discovering what lies beneath all those vines.
* Not all sources of renewable energy are equally reliable. Solar panels can’t generate power at night and are less effective on cloudy days. Windmills are of no use when the wind dies down. That’s why these sources of renewable energy are usually backed up by a connection to the power grid, most of whose electricity comes from fossil-fueled generating plants. To enjoy the benefits of electrical power 24/7/365, most parts of the world still rely heavily on fossil fuels.
However, just like fossil fuels, two sources of clean, renewable energy can be relied upon around the clock, all year long – hydropower and geothermal power. Unfortunately, not all geographical locations are lucky enough to have hydro or geothermal power in their backyard. Wine Country, however, is blessed with a great geothermal resource – the location in one place not only of a geological hot spot, but also of highly permeable, water-laden layers of rock. Fortunately for other parts of our state and country, the company that operates The Geysers, Calpine, and the U.S. Department of Energy are working on ways to exploit the Earth’s limitless geothermal potential in new areas by developing methods of fracturing less-permeable subterranean rock in additional hot spot locations. Until that happens, we in Wine Country can feel lucky to enjoy our source of clean, renewable, reliable geothermal power.