Nevada Solar One is a concentrated solar power plant, with a nominal capacity of 64 MW and maximum steam turbine power output up to 72 MW net (75 MW gross), spread over an area of . The projected CO2 emissions avoided is equivalent to taking approximately 20,000 cars off the road. The project required an investment of $266 million USD, and the project officially went into operation in June 2007. Electricity production is estimated to be 134 GWh (gigawatt hours) per year. In 2007, when the plant came on line, it was the second solar thermal energy (STE) power plant built in the United States in more than 16 years, and in 2007, the largest STE plant built in the world since 1991. It is located in Eldorado Valley in the southwest fringe of Boulder City, Nevada, and was built in that city's Energy Resource Zone, which requires renewable generation as part of plant development permits; Nevada Solar One was approved as part of Duke Energy's larger El Dorado Energy project that built 1 GW of electrical generation capacity. The solar trough generation was built by Acciona Solar Power, a partially owned subsidiary of Spanish conglomerate Acciona Energy. Lauren Engineers & Constructors (Abilene, TX) was the EPC contractor for the project. Acciona purchased a 55 percent stake in Solargenix (formerly Duke Solar) and Acciona owns 95 percent of the project. Nevada Solar One is unrelated to the Solar One power plant in California. History In 2006, located north of Tucson, Arizona Public Service's Saguaro Solar Facility opened, with 1 MW of electrical generation capacity. Nevada Solar One went online for commercial use on June 27, 2007. It uses similar technology and was constructed over a period of 16 months. The total project site is approximately , while the solar collectors cover . Technology Nevada Solar One uses proprietary technology to track the sun’s location and concentrate its rays during peak demand hours. The plant uses 760 parabolic trough concentrators with more than 182,000 mirrors that concentrate the sun’s rays onto more than 18,240 receiver tubes placed at the focal axis of the troughs and containing a heat transfer fluid (solar receivers). Fluid that heats up to flows through these tubes and is used to produce steam that drives a Siemens SST-700 steam turbine, adapted to the specific requirements of the CSP technology, which is connected to a generator to produce