Topography

The analysis of topography is very important when choosing a site. This is an important point when mountainous locations are under consideration. For those

TABLE 4.2 Estimation of Wind Speed (Beaufort Table)

Degree

Classification

Effects of the Wind on Nature

Speed (m/s)

0

Calm

Everything is still. Smoke goes up vertically.

0.00-0.30

1

Almost calm

Smoke is dispersed. Weather vanes are still. Wind is felt on the face.

0.30-1.40

2

Breeze

Wind is felt on the face. The noise of leaves agitated by the wind is heard. Weather vanes move.

1.40-3.00

3

Fresh wind

Leaves and small branches of trees are agitated constantly. Flags are stretched out.

3.00-5.50

4

Moderate wind

The wind lifts dust and paper from the ground. Small tree branches are agitated.

5.50-8.00

5

Regular wind

Small trees with leaves begin to balance.

8.00-11.00

6

Wind mildly strong

Large branches move, electrical lines whistle. It begins to be difficult to walk against the wind.

11.00-14.00

7

Strong wind

Entire trees are agitated. It is definitely difficult to walk against the wind.

14.00-17.00

8

Very strong wind

Branches of trees break. It requires a great effort to walk.

17.00-21.00

9

Windstorm

Tiles are lifted.

21.00-25.00

10

Gale

Trees are torn down. There is construction damage.

25.00-28.00

11

Storm

The wind assumes characteristics of a hurricane (rarely happens far away from coasts).

28.00-33.00

12

Hurricane

The air is full of solid particles and drops of water. The sea is entirely whitish.

33.00-36.00

areas, the wind speed increases on the front side of the mountain and decreases on the opposite side. In plane areas, the position of tree barriers should be observed with respect to the wind, as their proximity to the place chosen for turbine installa­tion is critical. There should be a maximum of free space between tree barriers and the power plant, to avoid any slowing down of the wind (see Section 4.3).

With increased altitude, the movement of a wind draft takes a more complex form, due to different land shapes. Thus, it is necessary to have a reasonable knowl­edge of the characteristics of the soil to be occupied. The roughness of the ground surface causes wind shear, which changes significantly with altitude. Some data collected at Merida Airport in Mexico show that the wind speed can be four to five times higher at an altitude of about 450 m with respect to the ground surface, and then it starts to decrease again [4]. At about 100 m from the surface, many

Topography

places on Earth have a wind speed sufficient for wind energy, but the costs of such high installation severely limit a decision in favor of using such heights.

Updated: September 26, 2015 — 6:04 pm