Sunday, January 31, 2010
"Reach For The Sun" from Edcon Publishing.
Solar energy can be gathered and stored with a flat-plate collector.
Have you ever spent a pleasant day in the sun and suffered that night with a painful sunburn? Have you used a magnifying glass to direct the sun's rays onto a piece of paper and watched the paper burst into flames? At such times, the sun's power is most evident. Even then we find it hard to realize that all the work of the world is made possible by the sun. People's energy comes from food, grown in the warmth of the sun. Meat and dairy products come from animals. The grasses and grains that fed them needed the sun to make them grow.
Over the years, people have used many forms of energy: wind, water, coal, oil, and natural gas. What is the source of these? The heat of the sun causes winds to blow and rain to fall. Coal, oil, and gas are really the remains of green plants. Long ago they were alive, making their own food from sunlight.
All energy comes first from the sun. Why, then, do we hear and read about the prospect of using solar energy to replace other fuels? The difference lies in the fact that other fuels store the sun's energy in changed forms. Solar energy refers only to use of the sun's direct rays. The earth's fuel supply is being used at an alarming rate. How many billion tons are left? No one knows exactly. Experts say oil will be gone in less than one hundred years. Coal is more plentiful, but burning it dirties the air, causing a danger to health. We need new, clean sources of energy.
Atomic energy plants now meet some of our needs. When atoms of hydrogen are split, huge amounts of energy are set free. But the process has some problems. Dangerous metals. must be used, and the waste products are harmful. Another way to free energy from hydrogen is to join the atoms. This process would be safer, but there are still some technical problems. Scientists are working on them. Meanwhile, 93 million miles away, billions of hydrogen atoms are joined every day in the biggest atomic plant of all: the sun.
Solar energy is not, as we might assume, a new idea. We can find examples of its use in the past. A story is told of a clever Greek scientist who, two thousand years ago, set up huge mirrors to reflect the sun's rays. In this way he set fire to the sails of an enemy fleet. A hundred years ago in South America, a solar plant was built in a place where little rain fell. The sun was put to work making water to drink. First, sea water was evaporated by the sun's heat. Then the vapor was collected and cooled. The water thus obtained was fresh and sweet. In France there is a giant solar furnace, described as a huge magnifying glass. For many years it has been melting metals for industry.
The first sun-heated home was displayed at the Chicago World's Fair in 1933. Called "The House of Tomorrow," it was so popular that other homes like it were built. For the last twenty years, solar batteries have been used in spacecraft. All equipment on the Telstar satellites runs on solar power.
All the projects mentioned here have been successful. Yet they remain rare. The advantages of solar energy are evident. It is free and clean, and the supply will last for billions of years. Why hasn't greater use been made of this amazing energy source? For a long time, fuel costs were low. Solar power, on the other hand, was expensive. Sunlight is free, but the equipment needed to collect it is not. A solar heating system for a house built today may cost two to four times as much as one which burns fuel. For industry, the costs are even higher. Before the energy crisis, solar power didn't seem practical. Now rising fuel costs and shrinking supplies have sparked new interest. The prospect of increasing use of direct sunlight seems likely.
Solar energy is available right now in our own backyards. Small systems can take over part, if not all, of the job of heating water for home use. Larger ones can heat homes. As far north as Canada, a house has been heated through the winter by solar energy alone. A popular type of heating system is the flat-plate collector. Metal pipes are attached to flat metal sheets. One or more layers of glass are laid over the pipes. These plates are set on a roof or the ground at an angle to the sun. Water pumped through the pipes on sunny or partly cloudy days can be heated to high temperatures, and can then be used to heat the house. At night or when it rains, tanks can store the heated water for two days or more. Many solar houses have small fuel burning units to use during periods of rainy weather. Other methods of collecting and storing the sun's heat are being explored.Perhaps better ways can be found.
The world's population and its energy needs are growing. Will solar power be the answer, or one of the answers, for the future? Mass production of equipment would help cut costs. This will occur only if the demand is great enough. The states of Indiana and Arizona have lowered taxes on solar homes. Such laws encourage people to try solar heating and help them pay for it. We can assume that as solar power is used more, our methods of collecting and storing will improve. The sun will shine for billions of years, pouring free energy onto the earth. The challenge to us is to find the best ways to use it.
1. The sun is an important source of ____________
2. The use of the sun's direct rays is referred to as ____________
3. The need for new clean sources of energy ____________
4. The sun's rays are ____________
5. The second solar energy project discussed in the story tells of ____________
Solar heating systems for homes would be of most interest to homeowners ____________
7. The costs of solar heating systems for new homes would probably be of most interest to ____________
8. We need to find better ways to ____________
9. Another name for this story could be ____________
10. This story is mainly about ____________
President Kennedy in 1962 applauds the first Telstar communication.