Wind turbine in Luxembourg Horizontal axis wind turbine, the Enercon model E-66 wind energy converter, in Germany. ... Wind machines were used for grinding grain in Persia as early as 200 B.C. This type of machine was introduced into the Roman Empire by 250 A.D. By the 14th century Dutch windmills were in use to drain areas of the Rhine River delta. ... Multibrid 5000 Prototype, north of Bremerhaven (Germany) Acciona [1] (Spain) AN Windenergie [2] (Germany) - Siemens Clipper Windpower [3] (USA) DeWind [4] (Germany) Ecotècnia [5] (Spain) Enercon [6] (Germany) Eozen [7] (Spain) Fuhrländer [8] (Germany) Gamesa Eólica [9] (Spain) General Electric [10] (USA) Goldwind [11] (China) Leitwind [12...

Modified HAWT

Ducted rotor

Still something of a research project, the ducted rotor consists of a turbine inside a duct which flares outwards at the back. They are also referred as Diffuser-Augmented Wind Turbines (i.e. DAWT). The main advantage of the ducted rotor is that it can operate in a wide range of winds and generate a higher power per unit of rotor area. Another advantage is that the generator operates at a high rotation rate, so it doesn't require a bulky gearbox, so the mechanical portion can be smaller and lighter. A disadvantage is that (apart from the gearbox) it is more complicated than the unducted rotor and the duct is usually quite heavy, which puts an added load on the tower. A gearbox is an assembly of gears allowing the rotational speed of an input shaft to be changed to a different speed. ...

Co-axial, multi-rotor horizontal axis turbines

Two or more rotors may be mounted to the same driveshaft, with their combined co-rotation together turning the same generator — fresh wind is brought to each rotor by sufficient spacing between rotors combined with an offset angle alpha from the wind direction. Wake vorticity is recovered as the top of a wake hits the bottom of the next rotor. Power has been multiplied several times using co-axial, multiple rotors in testing conducted by inventor and researcher Douglas Selsam, for the California Energy Commission in 2004. The first commercially available co-axial multi-rotor turbine is the patented dual-rotor American Twin Superturbine from Selsam Innovations in California, with 2 propellers separated by 12 feet. It is the most powerful 7-foot diameter turbine available, due to this extra rotor.

Counter-rotating horizontal axis turbines

Counter rotating turbines can be used to increase the rotation speed of the electrical generator. As of 2005, no large practical counter-rotating HAWTs are commercially sold. When the counter rotating turbines are on the same side of the tower, the blades in front are angled forwards slightly so as to avoid hitting the rear ones. If the turbine blades are on opposite sides of the tower, it is best that the blades at the back be smaller than the blades at the front and set to stall at a higher wind speed. This allows the generator to function at a wider wind speed range than a single-turbine generator for a given tower. To reduce sympathetic vibrations, the two turbines should turn at speeds with few common multiples, for example 7:3 speed ratio. Overall, this is a more complicated design than the single-turbine wind generator, but it taps more of the wind's energy at a wider range of wind speeds.

Appa designed and demonstrated a contra rotor wind turbine in FY 2000–2002 funded by California Energy Commission. This study showed 30 to 40% more power extraction than a comparable single rotor system. Further it was observed that the slower the rotor speed better the performance. Consequently Megawatt machines benefit most.

Vaneless ion wind generator

For an unusual way to induce a voltage using an aerosol of ionised water, see vaneless ion wind generator. Wind energy is usually etracted to make electricity by means of a Wind turbine, but that is not the only way to do it. ...

Solar updraft tower

Wind turbines may also be used in conjunction with a solar collector to extract the energy due to air heated by the Sun and rising through a large vertical Solar updraft tower. A Solar thermal collector absorbs sunlight to provide heat. ... now. ...

Aerial

Main article: Airborne wind turbine Bryan Roberts, a professor of engineering at the University of Technology, in Sydney, Australia, has proposed a helicopter-like craft which flies to 15,000 feet altitude and stays there, held aloft by wings that generate lift from the wind, and held in place by a cable to a ground...

It has been suggested that wind turbines could be flown in high speed winds at high altitude taking advantage of the steadier winds at high altitudes. No such systems currently exist in the marketplace. The idea of airborne wind turbines reappears in the industry every few years, and seldom (if ever) gets off the drawing board.

Observation Deck

One wind turbine of the type Enercon E-66 at Windpark Holtriem, Germany carries an observation deck, open for visitors. Enercon E-112 Friesian Enercon GmbH is a company based in Germany that operates in the wind turbine industry. ... Windpark Holtriem is one of the greatest windparks Europes. ...

Another Enercon E-66 wind turbine with an observation deck is in the English town of Swaffham. Map sources for Swaffham at grid reference TF8109 Swaffham is a town (population 6935) in Norfolk, England and is named after an Anglo-Saxon tribe named the Swaefas. In the 14th and 15th centuries, the town had a flourishing sheep and wool industry. ...