Question

why the wind farms can be constructed only at specific location

Answer 1

1] The wind energy farms can be created only where the wind flows at a speed of more than 15 km/h.
2 ] If the wind speed decreases than the required limit then the generator stops working. So, there are very limited places where this condition is satisfied.
3] Wind energy cannot be used commercially only from one windmill.Many windmills have to constructed which requires a lot of area.