Can Windmills cause Global Cooling???

During another one of my now frequent brain storming sessions, where I think about everything from the upcoming harry Potter flick, to the electro magnetic pulses generated as a result of a Nuclear explosion, I made a rather startling observation. Wind power which is touted as one of the most promising alternative source of energy, might actually have long term consequences on the regional weather and may be even climate.

Winds, as we all know, are caused mainly by differential heating of Earth, so they can be imagined as agents taking energy (heat) from the hot regions (near the equator which receive maximum solar radiation)towards the poles. Similarly there are seasonal winds and local ones near large water bodies, where they are produced due to high specific heat of water, which makes sure that there is always a temperature gradient during the day and night(Wind blows from the water body towards the Land during day, and vice versa during the night). There are also localized forms, where vertical winds are produced due to high temperature at the sea level compared to higher altitudes.

Now, a wind turbine taps the Kinetic energy of the wind (which is in turn a function of the temperature gradient across which wind flow is taking place). So, at the outlet, the wind will have significantly less speed as compared to the upstream of the turbine. So, for this subdued wind to reach its destination (where it would have reached had there not been a wind turbine), the wind will have to absorb the heat from the downstream of the wind mill. And there we have it, the wind mill has resulted in localized regional cooling.

So, let us assume that we install a sufficient number of wind turbines near, say a coastline. So by above logic, wind flowing from the sea towards the surface will loose a major part of its energy at the turbine(where we are harnessing this energy to produce electricity), and will absorb heat from the surface in the turbines's downstream to renew its onward journey. So, we are seeing a localized cooling effect (neglecting heat generated due to blade friction, which might as well cancel out the marginal cooling thus produced).

So, while also helping the cause of Green energy, the wind mills may also offset global warming.

But it should be noted that in a sufficiently large number they can also influence local weather in the immediate vicinity and the implications of any such trends can not be simplified based on just a few scientific variables.