History of Danish Wind Power - Wind Power for the World: The Rise of Modern Wind Energy - page 71

leader of the new wind facilities, Helge Petersen, came from Risø's
reactor department, he had as a private person been involved
in the development of the blades for the Tvind turbine. Young
engineers employed at the new centre had backgrounds in
renewable energy projects and grassroots movements, and during
the following years, the test centre became a valuable partner for
the Danish wind turbine industry.

Figure 3.31 Erik Grove-Nielsen with the final version of the Økær blade

with revolving tip brakes (Photo: Erik Grove-Nielsen, www.
windsofchange.dk) (above).

Three stages in the development
of blades for modern Danish wind turbines: To the left is a
Riisager blade with wooden main beam, to the right of the first
are 4.5 m Økær blades based on the original Tvind design and
used for 11 kW Adolphsen turbine. In the middle is a late 5 m
Økær blade, produced by Alternegy for 30 kW Bonus (Photo:
Benny Christensen, DVS) (below).