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Science project idea on how direct use may be made of the sun’s energy.
Use of Sun Energy Science Project Idea  How direct use may be made of the sun's energy.
Cold frame and sun parlor  A large part of the sun's energy is turned into heat when it strikes the earth. Much of this energy radiates back into space, and while it is considered that no energy can be destroyed, yet so far as it's utility to us on the earth is concerned, it is lost. The effect of clouds in preventing the direct escape of this energy into space has been touched upon elsewhere.
The cold frame and sun parlor are other examples of the capture of this energy. In both of these cases rays of the sun, in the form of light, pass through the glass; but the heat into which it is changed does not pass through the glass easily, and as a result the space enclosed in the glass becomes considerably warmer than the outside air.
Solar engines  We sometimes wonder what the world will do for its supply of usable energy after the coal and oil deposits have been exhausted. Here we have suggested one possible solution. If the energy which is radiating into space could be caught and used, all demands of energy for light, heat, and power would be met. The amount of this energy is enormous; it has been calculated that the amount of energy of the sun's rays falling upon the deck of a ship when the sun is directly overhead, if turned into work without loss, would be sufficient to drive the vessel at a fair rate of speed.
Efforts have been made to develop a solar engine by which this energy which now is lost to us might be applied to practical uses. In California, by means of great reflectors, the sun's rays were thrown upon the surface of a boiler composed of a coil of blackened copper tubing. Sufficient heat was developed to run an engine which pumped water for irrigation purposes. The cost of the power, however, because of expense of construction and repairs, was much greater than if an ordinary engine had been used. Other plants have been constructed in which the sun's rays were permitted to fall upon a series of shallow trays whose sides and bottoms were made of a substance which is a poor conductor of heat. The trays were covered with a double layer of glass which acted in the same way as the glass cover of a cold frame or sun parlor. Explain. A thin layer of water which flowed through the trays absorbed the heat. The most successful plants for the direct use of solar energy have been constructed in northern Africa. Suggest a reason for this. Unfortunately, however, regions of this kind are not apt to become centers of industry. Why? This objection is now overcome to a great extent by the development of methods of transmission of electric power.
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