Green Stack: Deep offshore wind

To find the theoretical energy per day per person of deep offshore wind in the Netherlands the following calculations were done:
Assume the deep offshore area is twice the size of the shallow offshore area, so the area is 3600 km^2
Assume the average wind speeds are similar to that of the coastline
Also, we'll assume that 50% of the deep offshore area can be used

3.5 kWh/d (shallow offshore energy) * 2 (double in size) * 2 (50% rather than 25%)
              
= 14 kWh/d per person