Wind Energy: Energy From Moving Air

Topics: Wind power, Wind turbine, World energy resources and consumption Pages: 7 (2407 words) Published: May 1, 2014
Wind Energy: Energy from Moving Air

Abstract
This paper contains the description of the process by which the wind is used to generate mechanical power or electricity, also describe the prospect and history of wind energy. Wind turbines convert the kinetic energy in the wind into mechanical power. This mechanical power can be used for specific tasks (such as grinding grain or pumping water) or a generator can convert this mechanical power into electricity to power homes, businesses, schools, and the like.

Introduction
Wind is air in motion. It is produced by the uneven heating of the earth’s surface by the sun. Since the earth’s surface is made of various land and water formations, it absorbs the sun’s radiation unevenly. When the sun is shining during the day, the air over landmasses heats more quickly than the air over water. The warm air over the land expands and rises, and the heavier, cooler air over water moves in to take its place, creating local winds. At night, the winds are reversed because the air cools more rapidly over land than over water. Similarly, the large atmospheric winds that circle the earth are created because the surface air near the equator is warmed more by the sun than the air over the North and South Poles. Wind is called a renewable energy source because wind will continually be produced as long as the sun shines on the earth. Today, wind energy is mainly used to generate electricity.

The History of Wind
Throughout history, people have harnessed the wind in many ways. Over 5,000 years ago, the ancient Egyptians used wind power to sail their ships on the Nile River. Later, people built windmills to grind their grain. The earliest known windmills were in Persia (Iran). These early windmills looked like large paddle wheels.

Centuries later, the people of Holland improved the basic design of the windmill. They gave it propeller-type blades made of fabric sails and invented ways for it to change direction so that it could continually face the wind. Windmills helped Holland become one of the world’s most industrialized countries by the 17th century. American colonists used windmills to grind wheat and corn, pump water, and cut wood. As late as the 1920s, Americans used small windmills to generate electricity in rural areas without electric service. When power lines began to transport electricity to rural areas in

the 1930s, local windmills were used less and less, though they can still be seen on some Western ranches.
The oil shortages of the 1970s changed the energy picture for the country and the world. It created an environment more open to alternative energy sources, paving the way for the re-entry of the windmill into the American landscape to generate electricity. Windmill Mechanics

Windmills work because they slow down the speed of the wind. The wind flows over the airfoil shaped blades causing lift, like the effect on airplane wings, causing them to turn. The blades are connected to a drive shaft that turns an electric generator to produce electricity.

Wind Machines Today
Today’s wind machines are much more technologically advanced than those early windmills. They still use blades to collect the wind’s kinetic energy, but the blades are made of fiberglass or other high-strength materials.

Modern wind machines are still wrestling with the problem of what to do when the wind isn’t blowing. Large turbines are connected to the utility power network—some other type of generator picks up the load when there is no wind. Small turbines are sometimes connected to diesel/electric generators or sometimes have a battery to store the extra energy they collect when the wind is blowing hard.

Types of Windmills
Two types of wind machines are commonly used today, the horizontal–axis with blades like airplane propellers and the vertical–axis, which looks like an egg-beater. Horizontal-axis wind machines are more common because they use less material per unit of electricity produced. About 95...
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