It is possible to install an offshore wind-turbine without the use of a sophisticated but expensive self-lifting sea-jack ship, like the Aeolus (see video at the bottom of this post). During installation the ship is held in place with the DP-2 dynamic positioning system.
[wikipedia.org] – Dynamic positioning
Fourfold functionality TFliner XL for offshore wind turbine installations:
1. installing monopile foundation
2. installing transition pieces
3. installing jacket type foundations
4. reel-lay spread
The ship can handle 75 m monopiles of max. 900 ton, jacket type foundations of 600 ton and transition pieces of 300 ton.
[dutchoi.com] – TFliner XL data sheet