Wind energy has been found to be a good alternative to fossil fuels. It is unfathomable and hence renewable. It is clean. It does not propagate greenhouse emissions during its conversion to wind power.
The solar energy reaching the earth is not uniform for all places on the earth. The equator receives more solar energy than the two poles. Dry land gets heated more quickly than the sea. This differential heating drives a global atmospheric convection current. This spirals up from the earth to the ceiling created by the stratosphere. Wind movement of the order of over 160kmh can be found at high altitudes.
Wind power has a 5500 years old history of usage. The cue was perhaps taken from flying birds. Sailboats and ships are such ancient examples in which power is used gainfully. Windmills have been used in Asian countries for grinding grains, pumping water for irrigation since the 7th.Century AD. Wind power has now been identified as the most economical renewable energy from which electricity can be derived.
The capacity of wind-powered generator has now crossed 200 GW worldwide. 340 TWh of electrical energy was informed to be generated in 2009. This is 2.5% of worldwide consumption of electrical energy. At present, over 80 countries are using this type power commercially. Denmark, Ireland and Portugal are spearheading this achievement by crossing 10%+ electricity production.
A single windmill is sufficient to accomplish mechanical work and generate electricity for a normal household. Smaller facilities are created for isolated locations. Utility companies mostly buy surplus energy from small turbines. Large-scale wind farms are installed for commercial purpose and are generally connected to the nearby electric power transmission network. The demand is matched by the availability of power. Excess is transported to neighboring areas and internal demand is reduced otherwise.
An estimated 72 TW of wind power can be commercially availed. This is considerably more that our requirement. The present availability in the world from all the resources of electrical energy is around 15-20 TW. It is difficult but not impossible to capture most of the wind energy passing through some point on the earth but what can be accessible is still more than our requirement.
There are places in the world such as Colorado where wind power and solar power complement each other to provide self sufficiency.