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What is a Parabolic Trough?

Keith Koons
Keith Koons

A parabolic trough is a specialized device that is designed to collect sunlight and convert it into energy by the use of a collector tube and a storage device. A parabolic trough collector normally is constructed from treated glass or other highly reflective materials in order to allow as much sunlight as possible to be absorbed. They also are often fitted with mechanical arms that will allow the parabolic trough to follow the sun’s path throughout the day in order to maximize the possible absorption efficiency. After the sunlight strikes the mirror-like surface, it is reflected toward a Dewar tube and absorbed, then passed on to either a battery source or a turbine to create electricity.

The technology behind making an effective parabolic trough is the reflective quality of the actual panels and their relative positioning to the Dewar tube. The parabolic trough collector normally is located in the center of the curved, reflective paneling so that it can absorb the sun’s rays from many different angles at once, eliminating the need for a more complex design. The panels themselves normally are quite large and are constructed in one solid piece.

Man with a drill
Man with a drill

The alignment of a parabolic trough normally is on a north/south axis to maximize daily exposure to the sun, and the mechanized features that are installed on them to track the sun’s natural path usually are fully automated. This means that during early morning hours, the parabolic trough collector will be facing almost due east, and it will finish the day facing west. A timer allows the unit to make the adjustments throughout the day, and the timer usually is very accurate, needing to be adjusted only once a year.

An east/west configuration also is utilized in some of the stationary parabolic troughs. This reduces efficiency but allows them to be placed in areas where other options might not be available. These units are adjusted manually during the spring equinox and fall equinox to maximize daily sunlight exposure. They can capture 30 percent to 60 percent of a parabolic trough that uses a motorized north/south configuration, so the popularity of a stationary trough is limited.

Other types of parabolic troughs are used for farming and agriculture, and some have curved panels that encircle a particular focal point. The reflective panels in all parabolic troughs once were comprised mainly of glass, but this type of configuration was difficult to employ because of the excess weight and manufacturing complications. Silver and other alloys have been implemented in the making of parabolic troughs, and these models are much lighter and can rival the efficiency of even the costliest standard parabolic troughs.

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      Man with a drill