What’s Hot About Geothermal Power

jen%20in%20hard%20hat.jpgGeothermal energy is all the rage these days, with the talk of its capability to solve all our energy woes. I had a chance to visit The Geysers, North America’s largest Geothermal operation (generating about 40% of the geothermal power in the US) and I’ve gotta tell you, I’m more fired up than I was before. (I can’t promise not to throw a couple more bad puns in there before this post is through but I hope you’ll bear with me)
Green, Clean Operation
Geothermal power produces emission free, steam-based energy by utilizing heat from the earth’s core. It is so cool. Each plant will have a slightly different set-up based on the rock formations below the surface, but here’s how it works at the Geysers. Two miles below the surface of the earth is hot magma (say it with me: liquid hot mag-ma). One level above that is a porous seabed rock, filled with thousands of tiny cracks. The water from the ancient seabed is filtered through those cracks, and heat from the magma turns that water to steam. The plant works by drilling a narrow hole down 2 miles to the porous rock level, and the steam shoots up the hole. Pressure from the steam turns a turbine, and then, boys and girls, electricity is made.
Here’s a picture of the plant:
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Big Money, Big Power
The Geysers is operated by Calpine, an energy generation company in northern California. Calpine operates 19 power plants at the Geysers, employs 350 full time staff, and is capable of generating 725 megawatts of power– enough to power 40,000 homes! The firm also has a fleet of natural gas powered plants. All in all, it’s one of the cleanest power generation companies in the US, and it supplies about 20% of California’s renewable energy. Renewable energy is big business in California, where the state’s utilities are required to source 20% of their power from renewables by 2010 as well as 33% by 2020. This means that locally produced clean power like geothermal will continue to be in high demand. The high demand is evidenced by a higher premium for renewable energy– around 11c/kwh for renewable power compared to an average price of around 7.5c paid for energy that doesn’t meet the renewable standard. (source)

Closed Loop System
Over time, that steam, the bread and butter of a geothermal operation, can be depleted, since it’s blowing out at a constant rate. The Geysers plant has been operating since 1960-that’s a lot of hot air. The folks at Calpine have figured out an innovative way to replenish their cash cow. They have contracted with the city of Santa Rosa as a handy disposal for wastewater produced there. 4,015 million gallons of treated wastewater make the 40-mile trek each year to the Geysers, where it’s sent down old shafts to refill the porous rock layer. This water quickly becomes heated and goes up the operational vents as steam. The whole process can take an hour or a day-it’s tough to tell for sure because it depends on where the water goes 2 miles underground, but it’s pretty fast all around.

Old Faithful Plugging Away

Whenever I go on tours like this I’m always struck by how not ecologically minded the folks working at the plant are. At the Geysers, each plant is maintained by a single tech who works a 12 hour shift. The tech we spoke to had been working at the plant for 25 years-and he gave Homer Simpson a run for his money with mutton chops, 70s child molester glasses, suspenders over Carhartts and an expression on his face somewhere between surprise, irritation, and boredom at the presence of these environmentalists drooling over his plant. This man was no treehugger. But he doesn’t have to be. The Geysers has been operational since the 60s not because it’s green or trendy but because the economic model for producing electricity makes good business sense. These are the types of solutions we really need for the green revolution.

Jen is editor in chief of TriplePundit. She has an MBA in Sustainable Management from the Presidio Graduate School and lives in Oakland with her husband and baby. 
Hit her up at on twitter @jenboynton to discuss diapering strategies or sustainability reporting methodology.