The world needs a new source of energy, an unspillable source.

how much wind power can be generated in 15km/hr wind speed ?

I am planning to go for a wind turbine of 500 watts to install for domestic use. With average wind speed of 15km/hr in my location, can anybody suggest me how much energy can be generated by this wind turbine and also which are the appliences to which this energy would sffice?