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Alternative Energy: The Sun

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Man has been in a constant search for energy since the dawn of existence. Now, after thousands of years, he has turned his ingenuity, finally, to the least exhaustible, most plentiful, and almost infinite source of sustainment, the sun. The sun creates energy via thermonuclear fusion reactions and it may finally be receiving its due respect, as the root source and primary means of "successful" energy. It has an expected life span that extends far beyond our needs, ending a time when all life on Earth is expected to be destroyed (in about 5 billion years).

Solar energy is energy from the sun. It is responsible for our weather systems as well as almost all biological processes. It provides heat, light, and energy to all the living things on earth. The sun gives off radiant energy (sunlight) which can be collected and stored in batteries. Radiant energy ranges from ultraviolet light, to visible light, to infrared or heat energy. And, despite the minute fraction of the sun's energy that makes it to Earth, it would take just six minutes of the sun's energy to vaporize all the Earth's oceans. Forty minutes of sunlight exposure the land surface of just the United States alone, is equivalent to an entire years's expenditure of fossil fuels. As long as there is a sun, winds will blow and the advantages of wind, a consequent product of solar energy, will be able to be enjoyed. With solar energy there are no harmful emissions, pollution, or radioactive wastes produced as there are with coal, natural gas, and nuclear power respectively. Of course, the disadvantage is that energy/electricity can only be created in the presence of solar energy, when the sun is shining - during daylight hours with no infringing clouds.

Solar cells can convert sunlight directly into electricity. They were first introduced in 1954 and although they were reliable and consumed no fuel, they were only about 15% efficient and very expensive. Advancements have been made, just not to the necessary extent.

If solar energy could be used directly, it would exceed all our present needs. As our other resources decline, research into solar power is intensifying. Solar energy, when it is used to produce electrical power, can provide an alternative to conventional coal and nuclear power. Solar power has been harnessed in the past indirectly through the use of winds, tides, fossil fuels, and the differing ocean temperatures. Direct use of solar energy has involved two main methods: the thermal method whereby the sun's heat is collected to heat water and the nonthermal method which utilizes mirrors to focus the sun's rays. At this time, nonthermal methods are too inefficient and expensive to be used commonly for commercial purposes on earth, although they are vital for undertaking, inclusive of spacecraft.

Currently, photovoltaic cells (PV cells) and solar-trough collectors are two economically feasible methods that use solar energy to produce electrical power. The PV cell is a wafer-like material that puts out electric current when sunlight shines on it. They have the advantage of converting light energy directly into electrical power and because they have no moving parts, they do not wear out. Another advantage is that they are made of silicon which is very abundant on Earth so that their fabrication will not be limited due to a lack of resources. The disadvantage they have is that they break down in everyday weather and



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