Back, Pictures, Forward

Wind Turbines From the 1980s


The Riisager Turbine
Riisager TurbineA carpenter, Christian Riisager, however, built a small 22 kW wind turbine (39K, JPEG) in his own back yard using the Gedser Wind Turbine design as a point of departure. He used inexpensive standard components (e.g. an electric motor as generator, and car parts for gear and mechanical brake) wherever possible.
Riisager's turbine became a success with many private households around Denmark, and his success gave the present day Danish wind turbine manufacturers their inspiration to start designing their own wind turbines from around 1980.
(Photograph © 1996 Copyright The Electricity Museum, Bjerringbro, Denmark).



Competing Turbine Designs

Léon Bjervig
Picture from the secret testing grounds of Vestas Wind Systems in 1979: The engineer Léon Bjervig next to his 12 kW 7.3 m rotor diameter Darrieus "biplane" machine.
Picture © BTM Consult 1979.

at Vestas in Lem, DenmarkSome designs, including the Riisager design were partly based on solid experience from the classical Gedser wind turbine, or classical slow moving multi-bladed American "wind roses", others were more revolutionary including vertical axis Darrieus machines, machines using flaps for power control, or hydraulics for the transmission system, etc. etc. Most machines were very small by today's standards, usually 5 to 11 kW.


The Tvind 2 MW Machine
One important exception to the rule of small machines was the Tvind 2 MW machine, a fairly revolutionary machine, (in a political sense, too, having been built by idealist volunteers, practising gender quotas and other politically correct activities, including waving Chairman Mao's little red book.) The machine is a downwind machine with 54 m rotor diameter running at variable speed with a synchronous generator, and indirect grid connection using power electronics. The machine is still running nicely. (Photograph © 1998 Soren Krohn)
Early Danish wind turbine development was thus a far cry from simultaneous government sponsored research programmes on very large machines in Germany, USA, Sweden, the UK, or Canada.
In the end, improved versions of the classical, three-bladed upwind design from the Gedser wind turbine appeared as the commercial winner of this wild competition, but admittedly not without a number of wreckages, mechanical, and financial.

Risoe National Laboratory
Risoe National Laboratory was really born to become the Danish answer to Los Alamos, i.e. the national centre for nuclear research. Today it is far better known for its work on wind energy.
Risoe National Laboratory's Department of Wind Energy and Atmospheric Physics has a staff of some 100 people working on basic research into aeroelastics, i.e. the interaction between aerodynamics and structural dynamics, on wind turbine technology, and wind resource assessment. It also has a separate, small, commercial activity dealing with type approval of wind turbines.
Risoe was originally founded with this last purpose in mind, when the Danish Government instituted a support programme for the erection of wind turbines in Denmark. In order to protect the buyers of wind turbines (and their surroundings) the Government required that all supported wind turbines be type approved for safety. The strict safety regulations (including requirements for dual braking systems) indirectly helped developing safer and more reliable wind turbines. (The support programme was abandoned in 1989).

Bonus 30 kW
Bonus 30 kW
The Bonus 30 kW machine (21K, JPEG) manufactured from 1980 is an example of one of the early models from present day manufacturers.
Like most other Danish manufacturers, the company was originally a manufacturer of agricultural machinery.
The basic design in these machines was developed much further in subsequent generations of wind turbines.
(Photograph copyright Bonus Energy A/S).



Back, Pictures, Forward

| Back | Home | Forward |

© Copyright 1998 Søren Krohn.
Updated 15 December 2000