page_title: ESolar
section_title: Sierra SunTower
hierarchical_section_title: ESolar / Sierra SunTower
caption_attribution_description: English: The Sierra SunTower, a 5 MW commercial concentrating solar power plant, in Lancaster, California.
context_page_description: eSolar is a privately held company that develops concentrating solar power plant technology. The company was founded by the Pasadena-based business incubator Idealab in 2007 as a developer of CSP plant technology. The company aims to develop a low cost alternative to fossil fuels through a combination of small heliostats, modular architecture, and a high-precision sun-tracking system. In October 2017, an article in GreenTech Media suggested that eSolar ceased business in late 2016.
context_section_description: In the summer of 2009, eSolar unveiled the 5 MW Sierra SunTower plant, a commercial facility in Lancaster, California that demonstrated the company's technology.  Sierra SunTower is interconnected to the Southern California Edison (SCE) grid and, in spring 2010, is was the only commercial CSP tower facility in North America.  As of mid-August, 2018, the two towers that were the center of the facility are no longer standing.  The plant, however, is still present.
  Sierra SunTower included two eSolar modules. 24,000 heliostats, divided between four sub-fields, tracked the sun and focussed its energy onto two tower-mounted receivers.  The focused heat converted feedwater piped to the receivers into superheated steam that drove a reconditioned 1947 GE turbine generator to produce electricity. The steam passed through a steam condenser, reverted to water through cooling, and the process repeated.
  During the 12 months of construction, Sierra SunTower created over 300 temporary jobs. In operation, the site employed 21 permanent employees.
  Sierra Suntower was certified by the California Energy Commission as a renewable energy facility. Power from the facility is sold under a Power Purchase Agreement (PPA) with SCE, providing  renewable energy for up to 4,000 homes.
  The 5 MW output from Sierra SunTower reduced CO
  2 emissions by 7,000 tons per year, an amount equivalent to planting 5,265 acres (21.31 km²) of trees, removing 1,368 automobiles from the road, or saving 650,000 gallons of gasoline.
  However, in 2015, the Sierra SunTower was shut down for commercial operation, as it was deemed to be too costly to operate except on the sunniest of days. Thus, it served to show the real-world problems, and unpredictable nature, of concentrated solar power.
caption: The Sierra SunTower power plant in Lancaster, California.
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