Ten years of solar power plant operation in the Mojave desert

Nine Solar Electric Generating Systems (SEGS), ranging from 13.8 to 80 MWe of rated name plate capacity, have been operating on a commercial basis in the Mojave desert of southern California since the mid-1980s. Each facility was developed as an Independent Power Producer (IPP) which sells power to the Southern California Edison Company (SCE). The nine SEGS plants provide a combined capacity of 354 MWe, and produce over 90% of the solar electric generation in the world. The SEGS plants utilize large fields of parabolic trough Solar Collector Assemblies (SCAs) supplying thermal energy to produce steam for a Rankine steam turbine/generator cycle. The parabolic trough SCAs have silvered low-iron glass reflectors which focus direct solar radiation on an efficient evacuated receiver, or Heat Collection Element (HCE). After reviewing the technology and plant characteristics, this paper will describe the trends in performance and operating experience over the last ten years. As part of the plant improvements, the paper will also describe the cost-shared program for SEGS III-VII between Sandia National Laboratories and KJC Operating Company (KJC OC). Functioning since 1992, this program is intended to reduce operating and maintenance cost by developing new management methods and technical improvements.