Solar thermal enhanced oil recovery (abbreviated solar EOR) is a form of thermal enhanced oil recovery (EOR), a technique applied by oil producers to extract more oil from maturing oil fields. Solar EOR uses solar thermal arrays to concentrate the sun's energy to heat water and generate steam. The steam is injected into an oil reservoir to reduce the viscosity, or thin, heavy crude thus facilitating its flow to the surface. Thermal recovery processes, also known as steam injection, have traditionally burned natural gas to produce steam. Solar EOR is proving to be a viable alternative to gas-fired steam production for the oil industry. Solar EOR can generate the same quality steam as natural gas, reaching temperatures up to 750 °F (400 °C) and 2,500 PSI. While typical fuel-fired steamflood operations inject steam into the ground at a constant rate, research conducted by leading oil producers shows that variable rate steam injection has no negative impact on production levels. In effect, solar EOR could supply up to 80 percent of a field's annual steam requirements, by injecting solar-generated steam during the sunny hours, and a reduced amount of gas-fired steam at night or in less sunny weather or climates. This method of integrating solar EOR will displace larger amounts of gas consumption without affecting oil output. Technology While there are many types of solar-to-steam technologies, often referred to as solar thermal or concentrated solar power, only two are currently deployed for solar EOR. Central tower Originally designed for generating electricity, central tower, or power tower technology, uses a field of large tracking mirrors, called heliostats, to concentrate the sunlight on a boiler filled with water that rests on a central tower. The sun's energy is reflected on the boiler to produce steam, which is used to turn a traditional turbine to create electricity. For EOR, the process ends at steam production. High-temperature steam made from demineralized water in the tower receiver passes through a heat exchanger, generating steam of lower temperature from high-contamination oilfield feedwater at lower temperatures. The steam is fed into distribution headers which lead to injection wells, which convey steam into the oil-bearing formation. Enclosed trough The enclosed trough architecture encapsulates the solar thermal system within a greenhouse-like glasshouse. The glasshouse creates a protected environment to withstand the elements that can negatively impact reliability and efficiency of the solar thermal system. Lightweight curved solar-reflecting mirrors are suspended