Company with the intent of building larger solar power plants. He, along with his technical advisor A.S.E. Ackermann and British physicist Sir Charles Vernon Boys, developed an improved system using mirrors to reflect solar energy upon collector boxes, increasing heating capacity to the extent that water could now be used instead of ether. Shuman then constructed a full-scale steam engine powered by low-pressure water, enabling him to patent the entire solar engine system by 1912. Shuman built the world's first solar thermal power station in Maadi, Egypt between 1912 and 1913. Shuman's plant used parabolic troughs to power a 45-52 kilowatt (60-70 hp) engine that pumped more than 22,000 litres of water per minute from the Nile River to adjacent cotton fields. Although the outbreak of World War I and the discovery of cheap oil in the 1930s discouraged the advancement of solar energy, Shuman's vision and basic design were resurrected in the 1970s with a new wave of interest in solar thermal energy. In 1916 Shuman was quoted in the media advocating solar energy's utilization, saying: Commercial plants Commercial plants using parabolic troughs may use thermal storage at night while some are hybrids and support natural gas as a secondary fuel source. In the United States the amount of fossil fuel used in order for the plant to qualify as a renewable energy source is limited to a maximum 27% of electricity production. Because they include cooling stations, condensers, accumulators and other things besides the actual solar collectors, the power generated per square meter of area varies enormously. As of 2014, the largest solar thermal power systems using parabolic trough technology include the 354 MW SEGS plants in California, the 280 MW Solana Generating Station with molten salt heat storage, the 250 MW Genesis Solar Energy Project, the Spanish 200 MW Solaben Solar Power Station, and the Andasol 1 solar power station. See also Parabola Parabolic reflector Solar cooker List of solar thermal power stations References Bibliography External links Kramer Junction Solar Power Plants, satellite image, Google Map. ParabolaTool – Tool for calculating the shape of a parabolic trough Solar thermal energy