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Parabolic Troughs - Collectors of Solar Energy

written by: Ricky•edited by: Lamar Stonecypher•updated: 2/27/2009

The sun may be providing a free source of energy but how do we convert the heat contained in the sunlight into electrical energy useful for domestic and commercial use. We need collectors of solar energy and parabolic troughs are one of them

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    The vast amount of energy that the sun is radiating needs to be focused in order to utilize it in a proper manner. There are various ways of collecting the energy of the sun and parabolic troughs are one of these as you will learn in this article. Basically it is something like putting a trough shaped object when it is raining so that the water gets collected at the bottom of the trough. The solar parabolic trough is quite similar with the only exception that it is used for the collection of something which is visible yet intangible namely sunlight.

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    The Parabolic Trough

    The concept of a parabolic trough can be best understood if you take a look at the picture below which gives an overview of a section of the parabolic trough. Upon seeing the picture you will intuitively realize the reason for the name given to this arrangement. The term parabolic signifies the shape and it is a trough since it is used for collection of sunlight.

    parabolic trough 

    When sunlight falls on the parabolic shape which is coated which is having a reflective material so that it absorbs the minimum possible light but reflects the maximum possible light that falls on its surface; the sunlight gets reflected and due to the shape of the trough it concentrates at a point which is the focus of the concave shaped trough. There are absorbing tubes running across the length of these troughs passing through the foci of the series of troughs.

    These pipes have water running in them and you can very well imagine who the system works. Since the sunlight is reflected at the focus and the tube is located at the same point, it absorbs most of this light since it is made out of special materials which absorb the heat. This heat naturally gets transferred to the water flowing inside these tubes and gets transported to along with the flowing water

    This water is then utilized as boiler feed water which generates steam and that steam is used to turn the turbines which in turn provide rotary power to the electric generators. Of course the water itself is not sufficient to generate steam and the boiler also consumes fuel to convert the water into steam, yet the pre-heating of water using the freely available sunlight saves a considerable amount of fuel.

    Hence we see that parabolic trough solar power collectors help to increase the efficiency of conventional power plants by helping to heat the feed water by a significant amount. Another advantage of this arrangement is that when the sunlight is not fully available due to weather conditions, the plant does not get effected since it can still generate steam by using more quantity of fuel during that time period.