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Wind Energy Technology Through History

R Ganesh Rajagopalan Iowa State University

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The Beginning

“Of all the forces of nature, I should think the wind contains the greatest amount of power” - Lincoln

Wind energy has been harnessed for a very long time dating back to the Pharos

who used the wind to sail the Nile.

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Chronology of Wind Energy History

Technology development in wind energy can be traced to the following periods.

Ancient History: 200 BC – 1100 ADMedieval History: 1100 AD – 1800 AD Industrial Revolution: 1800 AD -1900 ADAge of Electric Electricity:1900-1945Large Scale Research Turbines: 1970sWind Farm Development :1980-

Greek Engineer Heron of Alexandria used wind driven wheel to power a musical instrument in the 1st century AD.

The blades spin about a horizontal axis.

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Ancient History

Ancient History – Islamic World

Simple panemones that spin about a verticalaxis for grinding grain. Sails and wood werecommonly used as material. Drag Driven.

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Lift Driven Sail Type Mills

Sail type mills both spinning about the horizonalaxis and vertical axis were common during the ancient period. No direct knowledge of

aerodynamics was used but practiced naturally.

Lift Driven.

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Medieval History (Post Mills)

Crusaders brought the wind energy technology to Europe. Simultaneous development in England and France. The English used metal parts and roller bearings to improve the life of machine.

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The Dutch Mills

Dutch made many design improvements. Supported the sails with wooden bars and placed them away from the leading edge to improve aerodynamic efficiency. Used metal sheets instead of sails and introduced the concept of speed control with shutters and flaps during rough weather.

Use of wind power declined in Europe with the introduction of steam engines during the industrial revolution.

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Dutch Tower Mills

The cap of the tower rotates using a second rotor for yaw control. The blades are twisted from root to tip to become aerodynamically more efficient.

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The New World & Water Pumping

In the beginning of the Nineteenth Century wind mills were common in the east coast of the US around German and Dutch settlements. The pioneers carried the technology with them westward for water pumping. Halladay invented the self regulating all metal wind mill with blade pitch speed control. Introduction of the vane to turn into or away from the wind becomes the standard Eclipse design.

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All Metal US Windmill

Metal parts for blades and tower become standard for wind turbines (Perry Wheel).

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1900: US Windmill’s Success

Shipped as parts and was assembled with minimal tools and erected easily with local labor. Parts were readily available and maintenance was easy (transportation and O&M).

Structure and Material: Durable and Strong galvanized steel

Minimum number of parts: Capital cost is economical.

Efficient Aerodynamics and self governing in speed and orientation (Control).12

Rural Electrification

A windmill used to generate electricity is commonly called a wind turbine. Until the 1960 wind turbines were commonly used to generate electricity on farms. The Jacob turbine (14’ dia.) could deliver one 1KW in a 14 mph wind, an average power consumed by a typical household. Rural Electrification stopped further growth in wind turbine technology and manufacturing as electricity was cheaply available every where.

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MW Size Wind Turbine

Smith Putnam Machine (Grandpa’s Knob) Built During WW II at Rutland Vermont Rated capacity 1.25 MW 53 meters diameter Structural Steel Lost a Blade in 1945 and was decommisioned.

Technology Divisions in DOE

The Oil crisis of the 1970s brought wind energy into focus again. Government labs started scientific study of wind turbines which included wind resource characterization.

Rocky Flats – Small HAWTs < 100 kW NASA Lewis – Large HAWTs > 100 kW Sandia Labs – VAWTs PNL – Wind Prospecting - Resource DOE – Innovative Designs

The “Mod” Series

Mod 0 – Plum Brook, Ohio Mod 1 – Boone, North Carolina Mod2 – Washington, Calif, & Wyoming Mod 5 - Oahu, Hawaii Very Expensive Research turbines meant to be

technology drivers.

Mod 0

NASA Plum Brook 200 kW Downwind rotor Lattice Tower Partial span pitch Speed control

Mod 1

Boone, North Carolina 2 Megawatt 200 foot Downwind Acoustic Problems

Mod 2

2 Megawatt 200 feet diameter – upwind Three units at Goldendale, Washington One at Solano, California One at Medicine Bow, Wyoming All Steel Construction

Mod 5b

Oahu, Hawaii Built in Seattle Shipped with Crane 330 feet 3.2 Megawatt Steel tubular Tower

SANDIA VAWT Turbines

The Darrieus type Verticalaxis wind turbines were developed by SANDIA and A 34 meter diameter Instrumented Turbine was installed in Bushland,TX for collecting data.

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Wind Farm Development

Beginning with 1980 and california tax incentives, wind farms with multiple number of turbines at a site have become common and are being commercially exploited.

Most of the modern wind farm turbines are around 1.5 MW. The new trend is around 2.4 MW as that is the limitation imposed by land based transportation logistics.

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Conclusion

The technology drivers of wind energy conversion systems to-day are the same as it was 50 or 500 years ago.

Aerodynamics and Control, Structure and Materials, Mechanics and Vibration, Transportation and Logistics, O&M and Reliability and above all cost.

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