To date, there were until recently just a few players in the manufacture of multi-megawatt scale offshore-wind turbines, though with the entrance of new Chinese manufacturers, that's been expanding quickly.
How quickly can the supply of offshore wind turbines expand? If a company wanted to a whole new manufacturing chain for blades, nacelles, tower, etc, let's say for 500 MW per year manufacturing capacity, how long would that take, including planning and construction of the manufacturing plant?
(source: ZZ2; CC-BY-SA; wikipedia)