Photos of Vestas’ Cantilevered Bi-blade Darrieus

Portions of the following have been adapted from a interview with one of Denmark’s pioneering wind turbine designers at, the web site of the Danish wind turbine manufacturer’s association, Vindmølleindustrien.

Vestas, the world’s largest wind turbine manufacturer, is famous for it’s three-blade, upwind turbines. Today, this configuration is so universal that I identify them as “conventional” in contrast to what are now “unconventional” designs such as various forms of Vertical Axis Wind Turbines (VAWTs). But it wasn’t always so and the history of the Danish manufacturer Vestas’ entry into wind energy illustrates that.

In the 1970s and 1980s research programs in the US, Britain, Canada, Sweden, as well as Denmark were investigating VAWTs. Several manufacturers entered the market in the late 1970s and early 1980s with their versions of Darrieus wind turbines.

One company experimenting with a Darrieus design was Vestas, a manufacturer of portable cranes and other machinery on the west coast of Jutland near the city of Ringkøbing.

In 1980 I was travelling with Farrell Seiler and Ken Bosley from Copenhagen where we had just attended one of the first European Wind Energy Association’s conference to Jutland. It was a Sunday when we stumbled upon the Vestas plant at Lem. That was fortunate because it allowed us to mill around their test site at will.

We found an upwind, three-blade horizontal axis turbine, and a Darrieus turbine. If I remember correctly, the three-blade turbine was operating but the Darrieus was not.

Since then I’ve learned that the turbine we saw in operation was probably the original HVK turbine that Vestas had bought from a local machine shop, the forerunner of all later Vestas turbines.

The Darrieus turbines was a beautifully designed machine. It had two bi-blades attached to a cantilevered tapered and faceted torque tube. Despite the misuse of the term today, this wind turbine was truly innovative and a work of art. I’ve never seen another bi-blade Darrieus turbine anywhere, and there are very few who have tackled a cantilevered rotor.

This design was the work of Danish wind turbine pioneer and political activist, Leon Bjervig.

Bjervig was a member of Enhedslisten or the Red-Green alliance as were other pioneers of the wind energy movement in Denmark such Preben Maegaard and Jane Kruse among others.

In 1975 Bjervig began developing his own wind turbine. In 1978 he built the bi-blade Darrieus that I saw at Vestas in 1980. The 9 kW turbine was unusual in other ways as well. The rotor drove three 3-kW generators.

Bjervig had sold his turbine to Peder Hansen at Vestas in Lem. I believe Peder was the father of Finn Hansen who eventually brought Vestas’ famed V15 units to California in 1983.

In late 1979, Bjervig installed a three-bladed, cantilevered Darrieus. This was probably the rotor that we saw laying on the ground.

At this time Peder Hansen built a three-blade HAWT from a local machine shop in Herborg, the HVK or Herborg Vind Kraft. This led to Vestas adoption of what has become the conventional design.

This ended Bjervig’s work with Vestas. But he didn’t give up the dream of building bigger VAWTs. In 1986 he interested a local distribution utility in a 600 kW version and by 1988 he had developed a detailed design. Nevertheless, the turbine was never built and Danish development of phi-configuration Darrieus came to an end.