EnergySource adds another California geothermal site

The first geothermal power plant to be built at the Salton Sea in California in 20 years is now operating.

EnergySource LLC, an independent renewable energy generation company, recently announced the successful integration of the 49.9 MW Hudson Ranch I plant into the grid. The Salton Sea field, in the Imperial Valley, is one of the largest and highest temperature geothermal resources in North America.

The plant is completing its start-up testing and initial delivery of power to the grid, with commercial operation expected later this month.

Hudson Ranch I is the first new geothermal plant constructed in the well-proven Salton Sea field in more than 20 years. The Salton Sea field is characterized as a very hot and extremely permeable liquid dominated resource, ideal for power generation, but with the challenge of high minerals concentration, making energy project development in this resource a very specialized endeavor. Construction of the $400 million plant began in May 2010.

“Tests to date on the wells and resource have confirmed the company’s belief that the Salton Sea resource is very hot, high in total dissolved solids and highly prolific,” said John Featherstone, senior vice president of engineering and operations at EnergySource. “The well tests have exceeded our expectations.”

According to the Geothermal Energy Association, there are about 30 geothermal power plants in various stages of development in California. Of those with announced generation capacities, a dozen are in the approximate 50 MW range.

The Hudson Ranch power plant has four injection wells for water to flow through the rocks and three production wells that capture the steam. The wells produce between 15 and 40 MW of power each, making the wells some of the largest geothermal producers in the world.

“The Salton Sea geothermal resource is robust, with 326 MW in 10 existing projects currently operating at a capacity factor substantially greater than 90%, with a development potential of 1,400 MW or more,” said Subir Sanyal, president and manager of reservoir engineering services at GeothermEx.

Hudson Ranch I will sell all of its energy, capacity and environmental attributes to Salt River Project,  a municipal power and irrigation district in Tempe, Arizona, for 30 years. In late 2011, SRP announced that a second Power Purchase Agreement was executed to purchase all of the output of EnergySource’s next project, Hudson Ranch II, also a 49.9 MW plant.