Yes, taller is always better, because the farther away from the ground the larger can the wind speeds be while staying within the laminar (as opposed to turbulent) boundary layer. The surface of the sea is smoother than the surface of land, which also helps.
The density per square kilometer is at least 1 MW/Km^2 (effective). Depending on the average capacity factor (25%, 30%, 40% - I think it is larger on the sea than on land) this is between 2.5 and 4 MW/Km^2 (nominal). But this is a function of wind speeds (goes as the cubic power), which are better at higher altitudes and on water (back to boundary layers). Can the last politician to go out the revolving door please turn the lights off?
