Electricity generation in kwH

21) Assume a wind turbine w/ a hub 50m above ground, a rotor diameter of 25m, and a wind conversion efficientcy of 25 percent. The turbine operates in an area w/ an average windpower density of 600 watts/sq meter at 50m altitude. How much electricity (in kwH) can the turbine generate per year?Wind densities greater than or equal to 500 watts/sq meter at an altitude of 50m are present on 1.3 percent of the land area of the USA. If, on average, wind farms contain 8 turbines/sq km, how much electricity (in kwH/yr) could be generated from these wind turbines? (The area of the USA is 7,827, 989 sq km).