Large-scale exploitation of the potential of geothermal energy to generate electric power seems to be becoming a reality at Southern California’s Salton Sea, a highly saline lake in the Imperial Valley formed by floodwaters from the Colorado River in 1905.
Described by a May 3rd Barron’s article as “one of few areas in the U.S. rich with geothermal resources” and a possible “launch site for geothermal energy in the U.S.”, the area attracts geothermal development because of its unique topographical access to subsurface geothermal formations. As Barron’s explains,
The shallow, salty lake sits atop the San Andreas fault, 226 feet below sea level. About a mile beneath Salton’s southern tip, the earth burns at 680 degrees Fahrenheit, a perfect place to convert naturally occurring heat into electricity.
According to the Center for Land Use Interpretation (CLUI), the Salton Sea already hosts several clusters of geothermal plants, creating :a network of deep wells drilled in the geothermal field” that “allow water, heated by the earth’s mantle, to come to the surface and to power electrical generators.” The largest of these geothermal production clusters, notes a CLUI article, is a group of seven plants owned by the CalEnergy Company.
CalEnergy’s electricity, sold to the local power utility, is channeled into the power grid. “The seven plants in this field produce enough electricity to power over 100,000 homes” reports CLUI.
Barron’s describes other efforts by a local utility, Imperial Irrigation District (IID), to develop geothermal resources. Since it owns of the land, IID hopes to farm geothermal energy profits back into restoration projects to preserve the Salton Sea, which is receding, particularly from the effects of drought.
But geothermal development isn’t necessarily easy or cheap, explains Barron’s.
The tricky part will be to find viable locations for injection wells, which can be several miles deep depending on the area. After that, the plants are essentially self-sufficient. Hot water is pumped to the surface, where it turns to steam, driving turbines connected to generators. The steam is then converted to water and pumped back into the ground.
IID estimates that a single 50-megawatt plant might cost $300 million. Furthermore, viability of geothermal development depends on cooperation from the state of California, which “must approve building a $2.5 billion transmission line that would plug the facility into the grid.” ■