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Edited on Tue Jan-15-08 04:09 PM by proud patriot
(edited for copyright purposes-proud patriot moderator democratic underground)
Combining Wind Power with Solar Chimneys Harry Valentine Commentator/Energy Researcher The demand for electric power is increasing worldwide as economies develop and economies begin to prosper. In unregulated markets the price of electricity increases along with rising demand. That higher cost encourages entrepreneurs to develop methods of generating electric power from technologies that would otherwise be considered uncompetitive. Over time improvements are made to these technologies that reduce the cost at which they produce power. In its broadest sense, solar energy conversion has undergone and still is undergoing such development that began with waterwheels, windmills and water turbines. Wind energy and hydroelectric power are indirect forms of solar thermal energy. Solar chimneys, solar towers and the vortex engine are among the more recent proposals by which to generate electric power from solar thermal energy. A scale model solar chimney of 50-kW output has operated for several years in Spain, while a scale model of the vortex engine is being tested in Utah.
Solar energy is used to heat the tower or chimney as well as a skirt that is built around the base of the tower. Heated air rises inside the chimney and draws air through turbines that are located at its base. While the efficiency of solar towers is low, they can be built at competitive costs for their power output and rival the output of solar thermal steam power plants as well as photovoltaic technologies. It is a large-scale technology that uses air as its working fluid and that can greatly surpass the estimated power output at lower cost than other competing solar technologies that could occupy the same land area. Solar chimneys could be combined with certain types of photovoltaic power conversion.
There are several regions around the world where prevailing winds undergo very little change in direction with the change of season. In these regions solar towers can be combined with wind energy to increase power output. The skirt at the base of the solar towers collects solar heat and preheats air prior to it passing through turbines and going up the chimney. That skirt could be built in a semi-circular shape to capture wind and duct the wind toward the base of the tower.
A spiral-shaped skirt could capture a large cross section of wind energy and duct it toward the angled inlet vents at the base of the tower to produce a fast swirling air mass or vortex immediately inside the tower. An intake of a very large cross section can capture a large amount of wind energy that would accelerate to higher velocity in the decreasing cross section area of the spiral section. It would pass through the small cross sectional area of the turbines at high velocity, high efficiency and deliver higher power output that would be based on the cube of the wind velocity through the turbines.
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