Agriculture Reference
In-Depth Information
Water output of commercially available windmills at wind speeds below 10 km/h
is very low. The areas with annual monthly mean wind speeds greater than 10 km/h
should be considered for windmill-pump-based irrigation.
13.5.7 Types of Wind Machines
There are two types of wind machines (turbines) used today based on the direction
of the rotating shaft (axis):
•
horizontal-axis wind machines, and
•
vertical-axis wind machines
The size of wind machines varies widely. Small turbines used to power a single
home or business may have a capacity of less than 100 kW. Some large commercial-
sized turbines may have a capacity of 5 million watts, or 5 MW. Larger turbines are
often grouped together into wind farms that provide power to the electrical grid.
13.5.7.1 Horizontal-Axis
Most wind machines being used today are the horizontal-axis type. Horizontal-
axis wind machines have blades like airplane propellers. A typical horizontal wind
machine stands as tall as a 20-story building and has three blades that span 200 ft
across. Wind machines stand tall and wide to capture more wind.
13.5.7.2 Vertical-Axis
Vertical-axis wind machines have blades that go from top to bottom and the most
common type looks like a giant two-bladed egg beaters. The type of vertical wind
machine typically stands 100 ft tall and 50 ft wide. Vertical-axis wind machines
make up only a very small percent of the wind machines used today.
The Wind Amplified Rotor Platform (WARP) is a different kind of wind system
that is designed to be more efficient and use less land than wind machines in use
today. The WARP does not use large blades; instead, it looks like a stack of wheel
rims. Each module has a pair of small, high capacity turbines mounted to both of
its concave wind amplifier module channel surfaces. The concave surfaces channel
wind toward the turbines, amplifying wind speeds by 50% or more.
13.5.8 Suitable Site for Windmill
Wind plant owners must carefully plan where to locate their machines. One impor-
tant thing to consider is how fast and how much (time period) the wind blows. Wind
speed varies throughout the country. It also varies from season to season. As a rule,
wind speed increases with altitude and over open areas with no windbreaks. Good
Search WWH ::
Custom Search