Energy Resources

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Wind Energy

Introduction

Wind is not treated in any detail in Greek mythology. However, in a very

general sense, mythological winds are referred to in two principal ways: as

male gods who engage in humanlike activities and are also the winds them-

selves, and as nonhuman entities that can be conned in a bag. There are

also the three principal winds: Zephyros (the west wind), Boreas (the north

wind), and Notos (the south wind).

In a technical sense, wind can be dened as air in motion. It can be pro-

duced by the uneven heating of the Earth’s surface by energy from the sun.

Since the Earth’s surface is made of very different types of land and water,

it absorbs the sun’s radiant energy at different rates. Much of this energy is

converted into heat as it is absorbed by land areas, bodies of water, and the

air over these formations.

As noted, the Earth is not uniformly heated by the sun, in that the poles

receive less energy from the sun than the equator. Along with this, dry land

heats up (and cools down) more quickly than do the seas. Solar insolation

causes temperature difference driving forces between the equator and the

poles. These create a global atmospheric convection system reaching from

the Earth’s surface to the stratosphere, which acts as a virtual ceiling. On a

local scale, the warm air over the land expands and rises, and the heavier,

cooler air over the water rushes in to take its place, creating winds.

Wind power is the conversion of wind energy into a useful form of energy.

This is accomplished by using wind turbines to make electricity, windmills

for mechanical power, wind pumps for water pumping or drainage, or sails

to propel ships. The total amount of usable power available from the wind

is estimated to be considerably more than present human power use from

all other sources [1]. For example, planes traveling from west to east use jet

stream winds to increase groundspeed. Thus, transcontinental airline times

are usually shorter west to east and longer east to west. However, airstreams

within a few hundred feet of the ground are of primary importance to

ground-based wind energy systems.