Siting

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Siting

Prevailing winds: the most frequent direction which the wind travels from. Typically, a wind turbine would be sited between the northwest and southwest of the buildings and structures that are on the property. This is assuming that conventional airflow is from this direction. In Wisconsin, the people that live along the shoreline of Lake Michigan may receive more wind from the east than the west--because of the large water body (which is referred to offshore winds).

The wind turbine and it's blades should also be 30 feet above the highest object in the immediate vicinity. Siting a wind turbine that only has a 100 foot tower down wind of a 80 foot silo will definitely disrupt the air flow to the wind turbine. The rotor of the 20 kw wind turbine has the blades reaching 15.5 feet above the hub and 15.5 feet below the hub (or center of the rotor). Since the bottom most tip of the blade in the furthest down-ward swing is now at the 85 foot section of the tower, the air flow to the rotor will surely be impeded--since the blades in the downward position further lessons the distance above the tall object.

The distance between the next tall object (like a silo) and the tower which the wind turbine is on should be a couple hundred feet away. The short distance in height from another object in front of a wind turbine will result in turbulence. Turbulence will cause the wind turbine to search the wind and veer off, and may be caught in a direction where the wind isn't. All sorts of stresses can be induced from shearing type forces when the wind turbine is not facing the wind. The Jacobs wind turbine has duo fold tail vane. If the wind turbine is caught in the wrong place, the tail vane will swing off to the side and move the rotor to the new direction where the wind is coming from. And, it will move again if the wind abruptly changes from a new direction. The Jacobs wind turbine was designed to move about on an horizontal axis.

Thus, the distance between the next tall object and the tower which the wind turbine is mounted to should always be a couple hundred feet away. And, whenever possible, the tower for the wind turbine should always be as tall as possible.

A taller tower not only places the wind turbine up higher to avoid turbulence from other tall objects, but it also puts the wind turbine in a higher wind regime, enabling more output to be achieved and producing more power, more of the time.

Here are some illustrations to view regarding this topic of sighting issues. They say, a picture is worth a 1000 words.

	Wind speed has been known to increase with increments in height above ground. Surface friction appears to hamper wind speed. In this diagram, wind speed appears to increase as surface friction of the ground becomes less of a factor. There is a table that has a hyperlink directly from my main page that provides an idea what the increase in wind speed would be at 80', 100' and 120'--if one measured the wind speed at 30' high.
	Wind speed varies from place to place, and second by second. In this figure, the air mass does not appear to be a solid stream of air current presented to the rotor. Wind plants may turn continually sometime after when there appears to be no wind and may not turn immediately when there appears to be wind.
	The air profile decreases in speed when obstructions are in the path. As shown, vectors are used to illustrate the decrease in speed due to the tree line.
	There is a considerable amount of height difference between the tree plantation and the bottom tip of the blades. If the trees were to continue to grow, the distance between the two would decrease. It would be the same as moving the ground line up over the years, or lowering the length of the tower.
	Air tends to pile up in front of obstacles, then it swirls behind and off to the sides. Don't site a wind turbine immediately adjacent to a building.
	An illustration of disturbed air flow, upstream and downstream a building.

	Expected problems in percent due to an obstructed upwind.
	Obstructions don't have to be buildings.
	Vegetation is a good indicator of wind swept areas.

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