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Comparing Parabolic Trough Collector and the Sterling Engine Methods for Harnessing Solar Energy

written by: Shane Burley•edited by: Lamar Stonecypher•updated: 10/30/2009

There are a variety of developing technologies designed to use solar energy, and many have not been heard of by most people.

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    An Important Technology

    Solar energy is a concept that excites consumers and researchers alike because of non-invasive requirements and its ability to tap a resource that is so obvious. The energy that beats down on us on a daily basis is consistent for the most part and the collection of it is relatively cheap and easy.

    Often issues arise due to its difficulty to properly store solar energy and the lack of efficiency within the collection panels. Often the panels used simply cannot collect enough solar power to make their use worthwhile. What then occurs is an absence of solar use because the space that it would require the solar panels all running at low efficiency would be over twice as high as the number of Mega Watts that were being produced. There are two new solar technologies to collect and store the power of the sun that are looking to remedy that problem.

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    Unlimited Sunlight, but Limited Technology

    Over a normal eight hour day of sunlight a 1000 sq ft. areas receives about 450 KWH, which compared to other fuels is about 12 gallons of gasoline. The problem with it is that the typical solar panel runs at about 10% efficiency level. This means that only a minute percentage of the radiated energy is being collected and generated. For a household with solar panels located on the roof, which is a typical setup for the use of such panels, the efficiency issues as well as those surrounding weather concerns leave solar panels as a less than reliable main source of power.

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    Parabolic Trough Converters

    One of the most viable solutions within the field of solar panels is Parabolic Trough Converters. The shape of the Trough panel is what makes it so effective. A parabolic reflector points at the sun and reflects light energy to the focal point. At this location, and the target of the light's concentration, is liquid in a flowing pipe which begins to evaporate. Obviously the steam from the retaining liquid creates a massive amount of electrical generation. The steam is sent through a turbine based generator to achieve the electrical extraction.

    Since the liquid, often a blend of different synthetic oils, is so heated by the Trough panels (Up to regions of 400 degrees) there is no reason to apply exterior heating apparatus to this liquid. The combination of this technology with the constant tracking of the sun by the fleet of panels allows for a consistent energy collection. It should be noted though that this is not the same principle behind most solar panels as the solar energy is just used to produce the steam, which is then tapped to produce the electricity.

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    Solar Sterling Engine

    Another technology that is being thrown around quite a bit is the Solar Sterling Engine. The Sterling Engine is based of the original patent given to Robert Sterling in 1816. Sterling was a clergyman who used to work on heat engines in his spare time. Simply put, a Sterling Engine is a heat engine of the "eternal combustion engine." It is marked for its incredible efficiency for turning heat into mechanical movement within its engine system. The principle for which the engine works is by heating and cooling sealed gases through a method of transferring them back and forth between warm and cool heat exchangers. The basic physical properties of gases are the key to this, when the sealed gas is heated the pressure rises and works against the power piston causing it to move. Once it cools the pressure falls and there is less work that must be done by the piston to put the gas in recompression on the second stroke back. This all creates a constant cycle between the hot and cold gases for which there is no exhaust. The engine is truly just a constant quantity of gases just expanding and contracting. The gases in question can be a variety, including Hydrogen, Helium, and common air.

    This is a technology that does not have to exclusively involve a solar panel, but the solar panel is used in conjunction with the engine to maximize the energy collected by the solar panel. Since the engine requires a heat source anyway the solar reflectors are the best bet, though a cold source must also be contracted.

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    Both Are Important

    Both these applications of solar technologies for an expanded use are interesting in their own right, yet the actual solar collectors are not receiving and advancement. In the first one steam is still the primary generator, and in the following it is simply used as a temperature source for a heat engine. A more effective use of research would be going toward raising the efficiency percentages on the panels.