Function
Steel is the most commonly used material for the manufacture of towers.
What it costs*
The steel cost for a wind turbine tower varies significantly by tower design.
Who supplies them
CASC, Dillinger Hütte, Ilsenburger, Rukki, Salzgitter, Siegthaler, Severfield, Tata Steel and thyssenkrupp. Agents are also used to source and manage supply.
Key facts
Towers are manufactured by cutting and rolling steel plate, welding to make “cans” then welding these to make tower sections, with bolted flanges each end.
Steel plate of grade S355J2G3 NL and thickness up to 150 mm is typically used.
Steel thickness is varied for each “can” in steps down to its thinnest at the upper part of the tower. Thickness is optimised by considering overall natural frequency of the support structure (including foundation) and fatigue life and other design drivers for each “can”.
Flanges are generally forged and rolled from grade S355 EN10.113-2 NL steel with weld necks in order to improve the weld fatigue class. Tower top flanges are machined post welding to ensure top flange flatness is within tolerances required for the yaw bearing.
Other specialised steel is used for the door frame at the tower base, typically of grade S235 J2G3 NL. The frame needs to compensate for the cutaway of important amounts of material for personnel access [T.3.2.1] at this fatigue-critical location.
What’s in it
- Steel plate
- Steel flanges
- Surface finish