Environmental Engineering Reference
In-Depth Information
DID YOU KNOW?
Wind speed is generally measured in meters per second (m/s), but Americans
usually think in terms of miles per hour (mph). To convert m/s to mph, a good
rule of thumb is to double the m/s value and add 10%.
manifestations are obvious, the importance of the dynamic state of our atmosphere
is much less obvious. The constant motion of the atmosphere of Earth is both hori-
zontal (
wind
) and vertical (
air currents
). This air movement is the result of thermal
energy produced from heating of the surface of the Earth and the air molecules
above. Because of differential heating of the surface of the planet, energy flows from
the equator poleward.
The energy resources contained in the wind in the United States are well known
and mapped in detail (Hanson, 2004). It is clear that air movement plays a critical
role in transporting the energy of the lower atmosphere, bringing the warming influ-
ences of spring and summer and the cold chill of winter, and wind and air currents
are fundamental to how nature functions. Still, though, the effects of air movements
on our environment are often overlooked. All life on Earth has evolved or has been
sustained with mechanisms dependent on air movement; for example, pollen is car-
ried by the winds for plant reproduction, animals sniff the wind for essential informa-
tion, and wind power was the motive force during the earliest stages of the Industrial
Revolution. We can also see other effects of winds. Wind causes weathering (erosion)
of the Earth's surface, wind influences ocean currents, and the wind carries air pol-
lutants and contaminants such as radioactive particles that impact our environment.
In addition to the natural air movement processes described above, air movement
has been harnessed by the wind industry and is playing a pivotal role in achieving a
balanced energy mix in the United States. In 2012, wind energy was—for the first
time ever—the number one source of new electricity generation capacity. More wind
power capacity was installed in the United States than any other form of power gen-
eration (Siemens, 2014).
In practical terms, a wind turbine is defined as a device that converts kinetic energy
from the wind into electrical power. In esthetic and thoughtful terms, a wind turbine
is described as a clean, presentable structure that benefits the environment by generat-
ing a supply of clean and renewable electricity. When we look closer at wind turbines,
we often find there are impacts associated with them, many of which are described in
this chapter, but first we present the basics of air or wind movement and wind turbine
operation in order to properly prepare the reader for the material that follows.
DID YOU KNOW?
Wind power consists of turning energy from the wind to other energy forms.
There are different ways to harness it; for example, windmills produce mechan-
ical energy to generate electricity.
