2000 years B.C.

Even the ancient Egyptian used the wind energy to propell their sailboats. Frieze of the temple of Edfu, river nile, Egypt.

16. Century

The Dutch are besides the Danish and the German the "Wind Nation Number One" in Europe in the Middle Ages.

Around 1900

Around the turn of the century, it was the time of the so called "western mills", the multibladed metal sheet rotors, the slow running windturbines, especially for the purposes of water pumping. The starting torque of these machines is pretty good high.

1932

Hermann Honnef proposed in den thirties the idea of huge contrarotating rotors with ringgenerators built-in. Rotor and "stator" of the elektric machine belong equally corresponding to one of the contrarotating multibladed rotors. The diameter of the ringgenerator reached 120 meter, the diameter totally was 160 meter. The output of this giant should be 20 MW at a windspeed of 15 m/s. The projekt remained only a paper study.
Nevertheless, Honnef is an important pioneer of windenergy utilization. He proposed early, as first, the"offshore"-technic for windenergy converters.
His plant was installed offshore, floating on a anchored pontoon, harvesting the wind circular, like a grasseating sheep pinned by a rope to a peg. The pontoon takes always the right position, floating downstream away.

1942

This year pass for the starting point of modern wind energy utilization. Ulrich Hütter finished as assistent professor at the "Ingenieurschule Weimar" his masters thesis: "Beitrag zur Schaffung von Gestaltungsgrundlagen für die Windkraftwerke", which means: Creation of rules for the layout of wind energy converters. In this thesis he wrote down the theoretic basics for all modern free- and highspeedrunning turbines (in german: "Freifahrende schnellaufende Turbinen"), with 2 or 3 rotorblades.
His blade-element-momentum-theory, developed with excellent aeronautical knowledge, is even today current. His theory can be learned by the students in lectures at the University of Stuttgart as optional lecture.

1942

In world war II, in the years 1941 to 1945, on the hill called Grandpa's Knob, nearby Rutland,
state Vermont, USA, 330 km northward of New York, there was erected a 1250 kW wind energy converter, build by Smith/Putnam, two famous designing engineers.
Diameter of the plant 53,23 meter, height of tower 32,6 meter, rotorshaft diameter 610 mm. Each of the two rotorblades, material steel, has had a mass of 8 tons. 1942 accured an accident. In a heavy storm the plant loosed one blade. It flew away and was found more than 230 Meter aside the tower. In the year 1945 this pilot plant was shut down.

1957

The master plant of all wind utilizing machines, the StGW-34-unit, according to Ulrich Hütter.

1958 Ulrich Hütter took up the old Honnef idea to go offshore with his small 10 kW, 3-bladed, high sophisticated wind energy converter, the Allgaier WE 10.
As you can see above, Honnef proposed as first (1929/1930), the"offshore"-technic for windenergy converters.

Huetters plant was installed at an small oil platform in the Gulf of Mexico by the former US company 'Automatic Power Inc.", Houston.
In this times the wind has beaten the diesel engine for electricity supply.

1980

shows the absolute and ultimate "Optimierungswut" (mania of optimization) of Professor Dr. Ulrich Hütter. A high tip speed ratio of the rotor delivers a high powercoefficient but extremly slender rotorblades. Such blades look like whip ropes when turning, resulting constructive problems with the tiny airfoil crossections. There exists nearly no material which is strong enough to withstand the complex dynamic forces. Only fiber reinforced plastic material with carbon fibers can build up the bending beam, i.e. the rotorblade, strong enough.
This system additionally has had a special energy transformation chain: rotor shaft,miterwheel gearing on the top with a gear ratio of 1:3, vertical shaft to the bottom of the tower, vertical built-in planetary gearing, vertical positioned generator. Entry through a hatch-door flush with the ground (have a look to the picture). Rated output 300 kW, diameter 52 meter.

1980

1980 the year of birth of a huge machine, once the largest windenergy converter of the world, called GROWIAN. This pilot plant started with experiments in 1983. Erection site was the "Kaiser-Wilhelm-Koog" a very windy and flat North Sea coast region, nearby Marne. The machine was dismantled scheduled in 1987, because of finishing the expertiments.

1990

Some problems with GROWIAN lead to a plant a little bit smaller, the so called GROWIAN II or WKA-60.
M.A.N. was manufacturer. One plant was erected at the german island Helgoland in the North-Sea.

Only 4 plants were build because of some difficulties, also heavy lightning problems (carbon fiber rotroblades). The insurance was not able to pay the third failure.

1995

Today there exist some earnest attempts to realize the break-through of windenergyin all german states. Also in the state of Baden-Württemberg some private users and organisations have erected a small number of windenergy converters. In the same time some projects hold out in a planning status.

1996

In Europe such pictures will not become reality because our areas are a little bit restricted by covering with buildings, woods, cultivated areas, natural parks etc.
Nevertheless,a logical development, i.e. "Ausbau" with windenergy converters should take place within the next decade.

1997

To place plants in cold and icy regions there exist a new rotorblade philosophy. Make the rotorblade colour black, and you have no icing problems. The refection of the solar insolation is not so strong as in the case of white rotorblades and therefore, a dark rotorblade stays longer warmer than a white one.

1998

Since the last april a new big converter is on the market, the Enercon E66. With 1,5 MW output and a diameter of 66 meter this plant is the first member of a new megawatt-family. The also gearless machine, similar to the ENERCON E40, has a multipolar generator with a large diameter (nearly seven meters).

The 12th of september 1998, the biggest windfarm in europe was inaugurated, with windmachines in the megawatt-range.
In the 'Samtgemeinde Holtriem', 8 km northern of Aurich, Ostfriesland, there can be seen now
35 ENERCON-66/1,5 MW-windrotors.
One of the machine has an outlook-cabin, 65 m above ground, near the hub of the rotor. A group of 12 persons (maximum) can enjoy the wonderful landscape, the whirling rotorblades outside, nearby the window pane and the shaking tubular steel tower at rated power. But before, people have to overcome 300 steps of the winding-stairs. It is an amazing experience.
With 52,5 MW installed capacity this windfarm is really the largest in europe today.
Further informationens: The Norderland-Gruppe, Günter und Johann Eisenhauer, Heinz Böttcher, Gartenstraße 2a, 26 556 Westerholt, Tel.: +49 (0)4975/912040.

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doerner@ifb.uni-stuttgart.de Since 24th mars 1997