Ever has been a resource we cannot


Ever since the dawn of time, the sun has been a resource we cannot live or dowithout, so its not such a shock that man has come up with the idea of solarenergy. Solar energy had many uses.

Some can be dangerous and some, a veryvaluable asset to the modern world. Solar energy is energy derived from the sunin a form of ultra-violet rays. Its was first applied to use in 212 B.C., by theGreek genius Archimedes. Solar energy was used to defend the habor of Syracuseagainst the Roman fleet. Archimedes used a mirror or “burning mirror” asthey had called it, to set fire to the ships of the Roman fleets while standingon shore (McDaniels 83).

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It wasnt until 1615 when Salomon de Caux constructedthe first solar device; a solar engine. His device was made of glass lenses,supporting frame, and an airtight metal vessel containing water and air. Thisproduced a small water fountain when the air heated up during operation. Thiswas considered to be more of a toy than a device, but it was the first publishedaccount of the use of solar energy since the fall of the Roman Empire (Cheremisinoff1). Some other use of solar energy after that was the solar roof and the solaroven. The solar roof was thought up by Harold Hay. In a solar roof system, wateris contained in a clear plastic bag and it is placed on a black metal roof.

Haygot the idea while traveling in India on a technical aid mission for the U.Sgovernment. While there, he noticed that many people were living in rusty, sheetmetal shacks, which were hot in the day and cold at night. Hays plan was toremove the insulation from the roof on winter days so that the roof would gethot, and Replacing the insulation at night to allow the shack to be warm throughthe night. Then in the summer, he would so the reverse of what he did in winterto let the house cool at night and replacing the insulation in the daytime toblock out the heat. Then over the years, Hay and a man named John Yellottconstructed a 3- by 3.7-m building using water basins as the actual roofingmaterial.

During the summer, a slab of foam insulation was rolled back at night,and the water would become cold through the night sky evaporation. Since thewater supply sat directly on a metal ceiling, it absorbed the heat from the roomand kept the building air-conditioned all day. During the winter, the movableinsulation was rolled back in the daytime which allowed for it to collect heat.This generated enough heat into the house through the ceiling at night to keepthe room comfortable (McDaniels 179-181). Then there was the solar cooker.Developed by Augustin Mouchot in France and by John Ericsson in the UnitedStates in the nineteenth century. They wanted to develop a solar cooker that notonly reached high temperatures, but also was to be used as a means of heatstorage enabling food to be cooked after sundown.

Mouchot built a solar steamengine that operated a printing press in Paris in 1882. In the United States,John Ericsson invented what he called the “Ericsson-cycle” which was ahot-air engine for the making of solar heat. The suns rays would beconcentrated with the use of a parabolic reflector, which was designed to trackthe sun across the sky in order to keep a constant power output. (McPhillips86-89) There was also the solar oven.

In 1837, and astronomer from England namedJohn Fredrick Herschel introduced to the world a solar oven. He built a smallsolar oven while on a trip to Africas Cape of Good Hope. He constructed it asa mahogany, painted it black and buried it in the sand for purposes ofinsulation.

a doubled-glazed cover, which was the only portion of the oven leftexposed, serve to limit heat losses through the top, while at the same time,letting in sunlight. The maximum temperature of the oven was of about 240 degreeF and it was used throughout his expedition by him and his staff to cook bothmeat and vegetables (Regino 5). Not all solar energy inventions and discoverieswere good. Some solar energy is dangerous. One for example would be lasers.Laser, an electromagnetic wave that is made up of excited atoms. It producescoherent light. This means that the light produced is orderly, with all theexcited atoms making up the laser beam that is emitting their flashes in unison.

The laser often consist of polished ruby rod that has a solid mirror at one end,and a high voltage flash tube wound around the rod. The flash tube acts as thepower source for the laser beam and the energy that is emitted as pulse isvisible light (Holsroemn 12-14). Another dangerous solar energy is Ultra-violetrays. Ultra-violet rays is also referred to as UV rays for short. They areenergy rays that is given off from the sun. UV rays were first discovered byastronomers in the 1960s. It can be dangerous because too much rays can causeyou to sun burn, tan, damages your hair, and at the worst; skin cancer.

You canget skin cancer if your are not careful about how to spend and protect yourselffrom the sun. One way to protect yourself is by applying sun tan lotion to yourskin every time that you plan on spending a lot of time in the sun, especiallyif you are going to the beach. To be on the safe side for sure, you should applyit everytime you are in the sun. (Rose 123-125). There is basically a lot ofsolar powered inventions in our society today. Like in our household, there aremany solar equipment. There is the solar heating, solar satellite, solar waterheating, solar cooling, solar radio, solar battery, etc. As you can see, thereare so many solar items in the world so solar is an important source.

(Holstroemn182). We believe that solar energy is worth it. It is a good thing that ourplanet has so many ways of generating energy. We have electricity, solar power,nuclear power, propane, so many! We think that out of all the choice of energy,we prefer solar. Why you ask, because think of what will happen when we lose allof our other source of energy.

The sun is always here for us. Solar energy isthe only energy source that can not be controlled. We could lose all of ourelectricity and still live because we can live off of solar power. You dontneed electricity or gas to power your stove because when there is a storm, thepower can be knocked out and you wouldnt have to worry if you have furniturethat were powered by solar. Every other power source can be destroyed but thegreatest power of all is the sun. This is one power source that can always bedepended on. The best part about solar energy is that it is free. It can lastforever.

In a poll that we had conducted around our neighborhood, we found thatonly five percent of the people on our street have solar powered products. Thisis very surprising to me. We had expected the average to be somewhat higher.Mrs.

Richard is one of the person who we asked that had solar products such as:solar battery and solar heating. She believes that everyone should at least givesolar products a try because you can always depend on it when you need it. Otherpeople like Mr. Pham said that there is no use to solar power because when thesky is cloudy, there is no sun to power any of the solar product. He prefers tostick to electricity. People have different ways of looking at solar energy soits up to them if they want sun energy or electricity.

Who knows, maybe one day,everyone will agree on using solar energy. As for us, we still prefer solar overelectricity any day.BibliographyCheremisinoff, Pual N.

Principles & Applications Of Solar Energy. AnnArbor Science Publishers: Michigan, 1979. Holstroemn, Isaac R. Energy From TheSun. Tab Books, Inc: Pennsylvania, 1981.

McDaniels, David K. The Sun. John Wiley& Sons, Inc: Canada, 1984.

McPhillips, Martin. The Solar Energy. EverestHouse: New Yrok, 1983. Regino, Thomas C. Solar Energy.

St. Martins Press,Inc: New Yrok, 1986. Rose, Harvey. Solar Energy Now. Ann Arbor SciencePublishers:1982.

About absorb heat more efficiently. However, this


About 47 percent of the energy that the sun releases to the earth actually reachesthe ground.

About a third is reflected directly back into space by the atmosphere. Thetime in which solar energy is available, is also the time we least need it least – daytime. Because the sun’s energy cannot be stored for use another time, we need to convert thesuns energy into an energy that can be stored. One possible method of storing solar energy is by heating water that can beinsulated. The water is heated by passing it through hollow panels. Black-coated stealplates are used because dark colors absorb heat more efficiently. However, this method only supplies enough energy for activities such as washingand bathing.

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The solar panels generate “low grade” heat, that is, they generate lowtemperatures for the amount of heat needed in a day. In order to generate “high grade”heat, intense enough to convert water into high-pressure steam which can then be used toturn electric generators there must be another method. The concentrated beams of sunlight are collected in a device called a solar furnace,which acts on the same principles as a large magnifying glass. The solar furnace takes thesunlight from a large area and by the use of lenses and mirrors can focus the light into avery small area. Very elaborate solar furnaces have machines that angle the mirrors andlenses to the sun all day.

This system can provide sizable amounts of electricity and createextremely high temperatures of over 6000 degrees Fahrenheit.Solar energy generators are very clean, little waste is emitted from the generatorsinto the environment. The use of coal, oil and gasoline is a constant drain, economicallyand environmentally.

Will solar energy be the wave of the future? Could the worlds requirement of energy be fulfilled by the “powerhouse” of our galaxy – the sun? Automobiles in the future will probably run on solar energy, and houses will have solarSolar cells today are mostly made of silicon, one of the most common elements onEarth. The crystalline silicon solar cell was one of the first types to be developed and it isstill the most common type in use today. They do not pollute the atmosphere and theyleave behind no harmful waste products.Photovoltaic cells work effectively even in cloudy weather and unlike solar heaters,are more efficient at low temperatures.

They do their job silently and there are no movingparts to wear out. It is no wonder that one marvels on how such a device would function. To understand how a solar cell works, it is necessary to go back to some basicatomic concepts. In the simplest model of the atom, electrons orbit a central nucleus,composed of protons and neutrons.

Each electron carries one negative charge and eachproton one positive charge. Neutrons carry no charge. Every atom has the same numberof electrons as there are protons, so, on the whole, it is electrically neutral. The electrons have discrete kinetic energy levels, which increase with the orbitalradius. When atoms bond together to form a solid, the electron energy levels merge intobands. In electrical conductors, these bands are continuous but in insulators andsemiconductors there is an “energy gap”, in which no electron orbits can exist, betweenthe inner valence band and outer conduction band Book 1.

Valence electrons help to bind together the atoms in a solid by orbiting 2 adjacentnuclei, while conduction electrons, being less closely bound to the nuclei, are free to movein response to an applied voltage or electric field. The fewer conduction electrons thereare, the higher the electrical resistively of the material.In semiconductors, the materials from which solar sells are made, the energy gapE.g.

is fairly small. Because of this, electrons in the valence band can easily be made tojump to the conduction band by the injection of energy, either in the form of heat or lightBook 4. This explains why the high resistively of semiconductors decreases as thetemperature is raised or the material illuminated. The excitation of valence electrons to the conduction band is best accomplishedwhen the semiconductor is in the crystalline state, i.

e. when the atoms are arranged in aprecise geometrical formation or lattice. At room temperature and low illumination,pure or so-called “intrinsic” semiconductors have a high resistively. But the resistively canbe greatly reduced by

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