Two part question. Please help explain a & b. It has been...

Two part question. Please help explain a & b.

It has been proposed that large underwater single-stage multi-blade turbines be 
installed in ocean currents such as the Gulf Stream off Florida and the Kuroshio near Japan. 
These units are entirely analogous in their fluid mechanics to the wind turbines discussed in the 
wind energy lesson. 
Using the wind power equation: Power in the Wind = ½  A V3 and 'Power produced by a Turbine' = Cp ½ pAV3

a) Evaluate the power output you would achieve from a current turbine 
having a rotor diameter of 15 m and an overall power coefficient (Cp) of 0.3, driven by seawater 
of density 1,025 kg/m3 flowing in a steady 2 m/s current. 
b) Compare the pros and cons of this approach for renewable energy