Introduction - Wind Energy: Renewable Energy and the Environment - page 1

1 Introduction
Industrialized societies run on energy, and as third world countries industrialize, especially China and
India with their large populations, the demand for energy is increasing. Economists look at monetary
values (dollars) to explain the manufacture and exchange of goods and services. However, in the final
analysis, the physical commodity is the transfer of energy units. While industrialized nations comprise
only one-fourth of the population of the world, they use four-fifths of the world's energy. Most of these
forms of energy are solar energy, which are subdivided into two classifications;
Stored solar energy: Fossil fuels—coal, oil, and natural gas, which are finite and therefore
depletable.
Renewable energy: Radiation, wind, biomass, hydro, and ocean thermal and waves. Many
people discount renewable solar energy, some even calling it an exotic source of energy.
However, presently it is the source of all food, most fiber, and in many parts of the world,
heating and cooking [1].
Other forms of energy are tidal (due to gravitation), geothermal (heat from the earth), and nuclear
(fission and fusion). In reality, geothermal is a form of renewable energy, because as heat is removed
from the earth's surface, it is replenished from heat from further down.
The main source of energy in industrialized nations is fossil fuels, and when that factor is com-
bined with the increasing demand and increasing population of the world, a switch to other energy
sources is imminent. Whether this change will be rational or catastrophic depends on the enlighten-
ment of the public and their leaders.
1.1 HISTORY
The use of wind as an energy source begins in antiquity. Vertical-axis windmills for grinding grain
were reported in Persia in the tenth century and in China in the thirteenth century [2]. At one time
wind was a major source of energy for transportation (sailboats), grinding grain, and pumping water.
Windmills, along with water mills, were the largest power sources before the invention of the steam
engine. Windmills, numbering in the thousands, for grinding grain and pumping drainage water were
common across Europe, and some windmills were even used for industrial purposes, such as sawing
wood. As the Europeans set off colonizing the world, windmills were built across the world [3].
Except for sailing, the main long-term use of wind has been for pumping water. Besides the
Dutch windmills, another famous example was the sail wing blades for pumping water for irrigation
on the island of Crete. One of the blades had a whistle on it to notify the operator to change the sail
area when the winds were too high.
1.1.1 D UTCH W INDMILL
At one time there were over 9,000 windmills in the Netherlands. Of course there were different designs,
from the earlier post mill to the taller mills where only the top rotated to keep the blades perpendicular
to the wind. Today, the Dutch windmills are a famous attraction in the Netherlands ( Figure 1.1 ) . The
machines for pumping large volumes of water from a low head were as large as 25 m in diameter and
were almost all wood. Even the helical pump, an Archimedean screw, was made of wood ( Figure 1.2 ) .
They were quite sophisticated in terms of the aerodynamics of the blades. The miller would rotate
(yaw) the top of the windmill from the ground with a rope attached to a wooden beam on the cap,
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