history of wind mill developments

8/10/2019 History of wind mill developments

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Historyofwindmillsdevelopment

Introduction

The wind mill is a very old invention but nowadays is one of our more powerful sources of renewable

energy.

Windmills flourished with water mills and during 17thand 18thcenturies, then began to decay on behalf

of thermal sources of energy based on the combustion of different fuels but subsisted the industrial

revolution as a source of energy for isolated communities for example in the USSR, Australia and

Argentina.

Wind turbines flourished again in 20th

century due to the development of aerodynamics and the spread

of electricity as a convenient form of energy. Experiments to use wind generators to produce electricity

were carried from 1888 to 1900 in the US and in Denmark.

Precisely in Denmark, owing to the lack of petrol, wind energy experienced an important development

during the first years of 20th

century but was lately abandoned in 1910.

The

first

windmills

Information from first stages of wind energy comes from books either with explicit references to

different windmill alike machines or with implicit references found in the verses of some poems or

illustrations.

First references to wind power are in the 1st

century, come from India, Tibet, Afghanistan and Persia

and talks about Heron of Alexandria who wrote a monograph entitled Pneumatica in which he

describes some ingenious which operate on air or water and a musical instrument that reminds us of an

organ. Pitifully most transcriptions of the book have been lost and the remaining text is subject to

different interpretations.


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Figure 1: Some images related to the invention described by Heron is his book Pneumatica

We have to wait till 7thcentury to find another reference to a windmill, a captured Persian technician

slave that claims to be able to build mills driven by the wind, but this information was transmitted orally

for many years and no written record from the 7thcentury confirms this fact.

[Comment: We know about this man because he was angry due to the higher taxes and kil led Caliph

Omar in Medina in 644 AD]

[Note: AD = Anno Domini = BC]

But we have reliable written information and some old drawings stating that in the 10thcentury

inhabitants from the region of Sistan in eastern Persia used some wind powered devices to keep the

sand away from some fences and to grind grain. This is considered the first vertical-axis wind mill of

history.

This windmill design, with some natural improvements, is still in use by some communities.


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Figure 2: Existing windmill of the Persian type in Neh

This invention spread quickly during 12thcentury through Islam and beyond far East but never came to

the Northwest Europe in which the horizontal-axis wind mill was invented at the end of 12th

century and

quickly spread through France, Germany, Great Britain, Iberia and the low countries.

This horizontal-axis wind mill supposed a revolution because of its horizontal shaft and four sails turned

a small angle from the rotation plane. To transfer the power to a vertical axis a cog-and-ring gear was

invented, to face the rotor to the wind they invented rotation systems and the first brakes were

invented.

One important fact to take into account is that they discovered the aerodynamic lift by the orientation

of the sails. Is generally agreed that the horizontal-axis wind mill is a natural evolution of the water mills.

Horizontalaxiswindmills

In 13th

century a natural evolution of the horizontal-axis windmill is recorded on books, it is the post-

mill, a design in which the whole mill is mounted on a central post to the ground. This wind-mill model

appears in different drawings all through 14thand 15thcenturies but we are not sure about the actual

development as no details of these machines are available, indeed we should wait till 1588 to see a

detailed drawing, including internal elements, of a pole-mill.


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Figure 3: Post mill sketch

Despite their aspect the truth is that the first pole-mills were fixed and could not change its orientation.

[Comment: we suppose that many of these pole-mills were destroyed during prototype phase due to

the fact that is difficult to calculate a post that can successfully bear the weight of the complete mill]

Lately two improvements were made:

The first one was a model with rotating capabilities to face the wind was invented, but the procedure to

rotate the mill was problematic as there were no bearings or antifriction mechanisms.

Second one was the tilt axis design in which a weather beam supports the weight of rotor and sails while

a tail beam takes the axial trust.


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Figure 4: Tilt axis wind mill sketch

The neck of the shaft was coated with iron and the neck of the bearing was of stone and replaced by

brass or bronze in later designs.

[Comment: brass or bronze is now widely used in antifriction bearings]

Some initial brake design were carried during this century consisting of big iron coated wheels with

some friction elements made of wood with a high risk of fire if the brake was operated on high winds. It

is know that some of these brakes operated in a fail-safe mode being the braked position the default

one, having to explicitly release the brake to operate the wind-mill.

The post-mill, in many different forms and designs, was a success from medieval times to the Industrial

Revolution and was widely used all over Europe.

Figure 5: Advanced post-mill used in England

The pole-mill design was adequate for small and light mills, but to build more powerful and bigger mills

it was necessary to think about another design in which only the rotor needed to be faced to the wind;

this design is the tower-mill and appeared during the 14th

century.

The tower-mill lead to more improvements in sails, brakes and antifriction elements mainly to the need

of facing the rotor to the wind in a handy way.


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Figure 6: Dutch tower-mill

[Comment: pole-mills and tower mills were used to grind grain or species, to pump water (including

water drainage), to saw wood and in some military applications]

First windmills in China are dated 17thcentury and are based on vertical-axis concept and sails.


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Figure 7: Chinese mill from 17th

century.

American

windmills

American wind-mill is from 19thcentury, the first commercial ones are from 1854 and were created for

water pumping matters. They were small units with a rotor of about 5 meters able to develop 1 hp witha wind of 7 m/s. Lately bigger rotor units were successfully used in industrial water pumping

applications.

The American wind-mill has a characteristic design consisting of flat wooden blades joined to an iron

shaft with a crank in its opposite end and a wooden tail vane attached to the shaft perpendicularly to

the rotor plane. Some models also included a centrifugal governor to modify the rotor blades angle to

the wind speed.


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Figure 8: American wind-mill from 20th

century

In 1888 the Aermotor mill was born, it was an evolution of the American wind-mill using thin curved

sheet-metal blades properly angled and supported by steel parts with minimum drag resistance. This

mill had higher rotational speeds than normal mills made from wood so it implemented a reduction

gearbox.

Electricity

generation

with

wind

turbines

In July 1887 the first wind electricity generator mill was born in Glasgow (UK). It was designed by

Professor James Blyth, an electrical engineer teaching at what we know now as Strathclyde University.

The wind turbine was a vertical axis one based on cloth sails that he used to charge some accumulators

and provide his own cottage with electricity for lighting purposes.


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Figure X: Professor James Blyth and his invention.

The same year, on Winter of 1887, Professor Charles Francis Brush built a 12 kW turbine able to charge

408 batteries. The turbine had a rotor diameter of 50 m and 144 blades.

Figure X: Professor Charles Francis Brush and his 12 kW wind turbine.

In 1891 Scientist Poul la Cour living in Askov starts his experiments to try to introduce wind electricity

generation in Denmark. He was a very active scientist that did extensive research on aerodynamics and

energy storage using hydrogen and oxygen through electrolysis. He also invented a differential

regulation called Kratostate which was widely used in wind generator in Nordic countries and Germany.


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Figure X: Scientist Poul la Cour.

In 1927 in Minneapolis the brothers Joe and Marcellus Jacobs open the Jacobs Wind Factory which still

exists and is known as the first renewable energy company in the USA. They first started designing windpower systems and now offer a great variety of renewable energy products and services.

Figure X: Marcellus Jacobs with one of their wind turbines and Joe Jacobs with his wife Mabel and son

Richard.

During 1920s the French engineer George Darrieus invented the vertical axis wind turbine known as

Darrieus turbine still in used nowadays.


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Figure X: George Darrieus and his turbine.

In 1931 in Yalta, former USSR, it is recognized they built what we can consider a precursor of modern

wind turbine generators. It was a 100 kW unit with a performance of 32 % on top of a 30 m tower.

Unfortunately it seems not to be pictures available of this machine.

In 1941 the first megawatt turbine is connected to the grid in Castleton (US). The turbine was mounted

on top of a tower of about 33 m and had blades of almost 23 m length. Then turbine worked for 1100

hours until it broke down, repair was impossible due to the lack of supplies during World War II.

Figure X: Vermont wind turbine.

In 1957 in Gedser, Denmark, Johannes Juul, a former student of Poul la Cour, builds a 200 kW windturbine called Gedser turbine using a three blade design which is the usual in nowadays designs. This

wind turbine was placed on a tower of 25 m and worked without maintenance for 10 years. Johannes

also invented the emergency aerodynamic tip breaks which are still in use nowadays.


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Figure X: Vermont wind turbine.

International Molinology Society (TIMS) was founded in Portugal in 1965 to research, and promote all

aspects of molinology including the restoration of mills. TIMS is still active today and among its activities

are the writing of different publications and the organization of symposia and mill tours.

During 1970s the United States government, led by NASA, begins research into large commercial wind

turbines. Thirteen experimental turbines are put into operation and the research paves the way for

many of the multi-megawatt technologies used today.

In 1980 a Danish carpenter called Christian Riisager built a small 22 kW wind turbine 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) whereverpossible. 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.


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Figure X: Riisager's turbine.

First

wind

farms

In 1980 at Crotched Mountain in New Hampshire, United States, the first wind farm is built. It consisted

of 20 wind turbines of 30 kW each, but was unsuccessful because most of the turbines broke down.

In 1991 in Vindeby, Denmark, it was erected the first offshore wind farm of the world. It consisted of 11

wind turbine generators of 450 kW with a tower height of 35 m and a rotor diameter of 35 m.

Figure X: Vindeby offshore wind farm.


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Megawatt

wind

turbines

In September 1995 the prototype of NEG Micon 1500 kW was commissioned. It was a wind turbine with

a 64 m rotor diameter on a 60 m tower with two 750 kW generators working in parallel.

Figure X: NEG Micon 1500 kW wind turbine installed near Esbjerg (Denmark).

In 1996 the prototype of Vestas 1500 kW was commissioned. It was a wind turbine with a 63 m rotor.

Figure X: Vestas 1.5 MW wind turbine nacelle mounting close to a NEG Micon 1500 kW.

In spring of 2000 the prototype of Nordex 2.5 MW was commissioned. It had a rotor of 80 m.


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Figure X: Nordex 2.5 MW wind turbine.

In 2002 the prototype of Enercon E112 of 4.5 MW was commissioned near Magdeburg in Germany. The

rotor size of this machine is 112 m and was mounted in a 120 m steel tower.

Figure X: Enercon E112 4.5 MW wind turbine in Magdenburg-Rothensee (Germany).

On October 2004 REPower 5M of 5 MW wind turbine generator was commissioned in Brunsbuttel. Rotor

diameter of 123 m on top of a 120 m tower.


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Figure X: REPower 5M wind turbine mounting Elbenhafen port in Brunsbuttel (Germany).

References

Historical development of the windmill, Dennis G. Shepherd, Cornell University, 1990

The story of wind power, Niki Nixon, The Guardian, 2008

Wikipedia

history of wind mill developments

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