THE EFFECTS OF DIFFERENT VARIABLES AND FORCES ON THE

PRODUCTION OF ELECTRICITY THROUGH WIND TURBINES

Cedric Tucker

Cary Academy

ABSTRACT:

The purpose of this study was to determine what shape of wind turbine blade can

produce the largest amount of v (volts). Electricity is a form of energy that is the result of

the existence of charged particles, such as electrons and protons, and wind turbines

use wind energy to generate electricity. For this experiment, three different shapes of

wind turbine blades were cut out of Styrofoam and placed on a model wind turbine:

rectangular, triangular, and curved blades (see Figure 6). The curved blades generated

the largest amount of v, the rectangular blades generated a smaller amount of v, and

the triangular blades generated the smallest amount of v. The wind turbine blades that

were larger in width and length were able to capture more wind on the blades’ surfaces,

and this caused more lift power to be created to allow the blades to revolve faster and

generate more electricity.

INTRODUCTION:

Just what are those giant fan-like objects on huge metal poles that are said to be

generators of electricity and are mostly found in enormous fields and other large

grounds? The answer is windmills, of course. But how exactly do windmills produce that

special form of energy that is relied on by homo-sapiens to do almost everything, which

is electricity? How do they actually work in general? First of all, what is electricity?

Electricity is the set of physical phenomena associated with the presence and flow of

electric charge, and is measured in volts. It is also a form of energy that is the result of

the existence of charged particles, such as electrons or protons. Electricity has many

forms and effects, such as lightning, static electricity, electromagnetic induction, and the

flow of electrical currents. Electricity is considered a second source of energy because it

is created from first sources such as wind, water, and solar panels.

An electric charge is a physical property of matter that causes it to experience a force

when near other electrically-charged matter. The two types of electric charges are

positive and negative charges. Positively charged substances will repel from other

positively charged substances, but will attract to a negatively charged substance.

Negatively charged substances will attract positively charged substances but repel other

negatively charged substances. The movement of an electric charge is called an electric

current. An electric current can consist of any moving charged particles, mostly

electrons, but any charge in motion causes an electric current. A positive current is

defined as having the same direction of flow as any positive charge it contains, or to

flow from the most positive part of a circuit to the most negative part. The motion of

negatively charged electrons around an electric circuit is determined positive in the

opposite direction to that of the electrons. An electric current can consist of a flow of

charged particles in either direction or even in both directions at once.

The process by which electric current passes through a material is called electrical

conduction. Some examples of this are metallic conduction, where electrons flow

through a conductor made of a type of metal, or electrolysis, where ions (charged

atoms) flow through liquids. An electric field is created by a charged body in the space

that surrounds it, and results in a force exerted on any other charges placed within the

field. The electric field acts between two charges and extends toward infinity and shows

an inverse square relationship with distance. An electric field can result in attraction or

repulsion. An electric circuit is an interconnection of electric components so that electric

charge may flow along a closed path (circuit), usually to perform a task. The

components of an electric circuit include items such as resistors, capacitors, switches,

and electronics.

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Figure 1: This diagram shows a model of an electric circuit and how the electrical current flows through each component.

Wind is used all over the world for processes and activities such as electricity

generation, transportation, erosion, recreation, and water pumping. Wind is caused by

the sun’s uneven heating of Earth’s surface and the atmosphere, in combination with

the irregular surface of the earth and the earth’s rotation. The definition of wind energy

and wind is the kinetic energy of air in motion across the surface of the earth. Wind is

also affected by areas of high and low pressure. The kinetic energy of wind can turn the

blades of a wind turbine by the force of the wind hitting the back of wind turbine blades,

which is called lift, and the wind’s force hitting the front of the blades, which is called

drag. This action turns the rotor, and thus turning the blades of a wind turbine. A wind

turbine changes and can harness the kinetic energy of the air into electrical energy by

turning a generator. Wind power is the conversion of wind energy into a useful from of

energy, such as using wind turbines to create electrical power, windmills for mechanical

power, wind pumps for water pumping or drainage, or sails to propel ships. Large wind

farms consist of hundreds of individual wind turbines which are connected to the

electrical power transmissions network. Almost all large wind turbines have the same

design: a horizontal axis wind turbine having an upwind rotor with three blades,

attached to a nacelle on top of a tall tubular tower. On a wind farm, individual turbines

are interconnected with a medium-voltage power collection system and communications

network. As a substation, this medium-voltage electric current is increased in voltage

with a transformer for connection to the high-voltage electric power transmission system.

Windmills store the energy that they collect in a storage system called a grid. A grid

looks similar to a high-voltage power line, and it stores the energy that a windmill

collects until that energy needs to be released.

Figure 2: This diagram shows the components of a wind turbine.

Figure 3: This diagram shows how a wind turbine converts wind energy into electricity and how that electricity is stored into the grid.

Figure 4: This diagram is a simpler version of the wind turbine diagram shown in Figure 2.

Windmills have been used for many years and can be found all over the world, and

today they are used to produce electricity through wind power. The difference between

a wind turbine and a windmill is that wind turbines are used to convert wind energy into

mechanical energy (a process known as wind power), and mechanical energy into

electricity (Wind power plants also use this process to turn mechanical energy into

electricity). Windmills convert wind energy into mechanical energy to drive machinery,

such as for grinding grain or for pumping water (The type of machinery that uses

mechanical energy to pump water is called a wind pump). The three most common

types of wind turbines are the Savonius VAWT, the Modern HAWT, and the

Giromill/Darrieus VAWT.

Figure 5: This diagram shows the three most common types of wind turbines that are used today.

Wind energy has been used for over a thousand years to do things like sail boats, grind

grain, and of course to produce electricity. Windmills were among the first devices to

replace animal power on the farm. Though many windmill designs exist, two are the

most common. A windmill may consist of a lower tower with, on one side, a vertical

contrivance that has four arms arranged in the shape of an “X”. Each arm has a wide

sail that resists the wind, and a breeze causes the arms to revolve, and their turning

energy is transferred through gears to a vertical shaft. The other common windmill is a

tall tower having a metal framework, with the turning mechanism on top and the sails

arranged in a circle like the petals of a flower. A vertical vane behind this mechanism

keeps it pointed toward the wind. There are also two main types of windmills and wind

turbines: horizontal-axis and vertical-axis windmills and wind turbines, but the

horizontal-axis design is most common.

The blades of a wind turbine are shaped to obtain the maximum amount of wind energy

and convert that energy into electricity at a minimum cost. The aerodynamic design of

the windmill blades greatly affects how much wind power is collected and how much

electricity is generated. For instance, one windmill might have thin, more pointed blades,

and another might have thick rounded blades. The propellers on a windmill or wind

turbine are created so that they can adapt to different wind speeds and directions. The

propellers that can produce the most electricity are also the propellers that can harness

a large amount of wind. Wind turbine blades revolve because wind passes the blades,

and the rotor will be forced to turn by the movement of wind on the blades. It is this

motion that will turn the generator inside of the wind turbine, thus producing electricity.

The shape of the windmill blades can vary by the age of the windmill or wind turbine, the

location, or the number of blades on a windmill or wind turbine. The number of blades

on a windmill can also be a large factor in how it collects wind energy and generates

electricity. The limitation on the available power in the wind means that the more blades

there are, the less power each can extract. A consequence of this is that each blade

must also be narrower to maintain aerodynamic efficiency. The higher number of blades,

the narrower each one must be to be able to slip through the air easily and quickly, but

a large number of thick and heavy blades will move slowly and drag through the air,

which will not cause very much electricity to be generated.

It has been discovered that wind turbines use almost 2 times the amount of electricity

that they collect just for the turbines to operate correctly. Wind turbines are collecting

less and less electricity because they are using most of it to drive all of the turbines’

components, and this action has been called a conspiracy. This means that wind

turbines are not really collecting very much energy, and they are wasting it on just

running the turbine alone. A wind turbine is said to consume more than 50% of its rated

capacity in its own operation, and the wind plant itself may only be generating 25% of its

rated capacity. This means that 1 turbine alone consumes more energy than the whole

wind plant produces and sells by almost 2 times, and that wind turbines don’t at all

produce as much energy that they are said to.

A scientist who tested an experiment based on the shape and size of windmill blades is

Matsuo Griffin. This scientist wanted to learn about the different shapes and sizes of

windmill propellers and how much MV (millivolts) the windmill generates based on the

blades. The experiment that was executed by Griffin was that three different sizes and

shapes of propellers were placed on a model windmill with two pieces of tape and the

amount of MV that was generated by each shape and size of windmill propeller was

recorded. The purpose of this scientist’s experiment was to determine what shape and

size windmill propellers generate the most MV. The results of Griffin’s experiment were

that the propellers shaped like a pyramid performed the best by generating the most MV,

the propellers shaped like an octagon were in close second, and the rectangular

propellers created the least MV. Griffin learned that wider and larger propellers are able

to catch more wind, spin faster, and create more MV from this experiment.

MATERIALS AND METHODS:

The items that were used in these experiments were a model windmill; a digital volt

meter; a heat lamp; a freezer; a fan; small and large paperclips; windmill blades made

out of cardboard, paper plates, and Styrofoam; and curved, triangular, and rectangular

windmill blades.

In the first experiment, 3 Styrofoam windmill blades were placed under a heat lamp for 2

min, 3 more were placed in a freezer for 2 min, and another 3 were left on a table inside

a building for 2 min. Each group of blades was placed on the windmill and the average

number of volts that each group generated in front of the fan was recorded.

In the second experiment, 2 large paperclips each weighing about 0.07 g were taped to

each of the three blades on the windmill. The amount of volts that were generated in

front of the fan was recorded. Then, 2 small paperclips each weighing about 0.03 g

were added to each of the 3 windmill blades, and the amount of volts that were

generated in front of the fan was recorded. Lastly, the windmill blades without anything

on them were placed on the windmill and the amount of volts generated in front of the

fan was recorded.

In the third experiment, the windmill was placed in front of a fan at different distances

from the fan. First, the windmill was placed at about 87 cm from the fan, then at 59 cm,

then at 26 cm, and lastly at 5 cm. The amount of volts generated at each distance from

the fan was recorded.

In the fourth experiment, three different shapes of Styrofoam windmill blades were cut

out and placed on the windmill: curved blades, triangular blades, and rectangular blades.

The amount of volts that each different shape of blade generated on the windmill in front

of the fan was recorded.

This is what the triangular windmill blades that were used in the fourth experiment looked like.

This is what the rectangular windmill blades that were used in the fourth experiment looked like.

This is what the curved windmill blades that were used in the fourth experiment looked like.

Shape of Blades in Experiment #4

Figure 6: This diagram shows the different shapes of the windmill blades that were used in the fourth experiment.

In the fifth and final experiment, three windmill blades were cut out of three different

materials: cardboard, Styrofoam, and paper plates. Each group of different material

blades was placed on the windmill in front of the fan and the amount of volts generated

was recorded.

RESULTS AND DISCUSSION:

Figure 7: The amount of volts of electricity generated by windmill when blades are at different levels of temperature.

In this experiment, the room temperature wind turbine blades generated the largest

amount of v, the cold turbine blades generated the second largest amount of v, and the

heated blades generated the smallest amount of v. The reason for this data is because

large wind turbines require a large amount of energy just to be able to operate correctly.

If the blades of a turbine are heated, then the turbine can lose up to 10% - 20% of the

electricity it collects through wind energy. Power is consumed from the wind turbine if

the propellers of the wind turbine, the wind turbine itself, or the nacelle component

needs to be heated or dehumidified, especially during periods of high humidity levels,

low temperatures, and low wind speeds. If the generator needs heat or dehumidification,

then 1% - 2% of the electricity that it collects is lost. For example, on a sunny, windless

day, idle wind turbine blades would experience uneven heating from the sun, something

that would easily cause bowing and warping. Major amounts of incoming electrical

power is needed to turn the power train (generator) and the blades, and when power is

taken from the wind turbine’s stored electricity, the turbine wastes much energy on just

trying to work that there is a much less amount of stored electricity left.

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Figure 8: The amount of volts of electricity generated by windmill when blades have paperclips of different sizes and weights on them.

In this experiment, the wind turbine blades with no weight added to them generated the

largest amount of v, the blades with 0.03 g added to them generated the second-largest

amount of v, and the blades with 0.07 g added to them generated the smallest amount

of v. The reason for this data is that when wind turbine blades have weight added to

them, it becomes harder for the blades to slice through the air easily and quickly, and

they begin to drag slowly and at an inconsistent pace through the air. This is so

because the heavier the blades are, the more difficult it is for the wind to lift and push

the blades so that they can spin on the wind turbine. When weight is subtracted from

the blades, the wind can easily propel the blades precisely and quickly through the air,

and the blades will not slow down so quickly. If too much weight is added to the blades,

eventually they will get so heavy that the wind will not be able to push and lift the blades

at all, and this is why wind turbine blades cannot be designed so large, thick, and fat.

The blades must be able to glide swiftly and quickly through the air to allow a large

amount of electricity to be generated. If a wind turbine’s blades are too heavy and large,

they will not be able to stay at a consistent pace, but rather an uneven and shifting one,

which causes a graduate sluggish behavior.

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Figure 9: The amount of volts of electricity generated by windmill when it is at different distances from a fan.

In this experiment, the wind turbine generated the largest amount of v when it was 5 cm

from the fan, it generated the second largest amount of v when it was 26 cm from the

fan, it generated the third largest amount of v when it was 59 cm from the fan, and it

generated the least amount of v when it was 87cm from the fan. The reason for this

data is that when a wind turbine is closest to the source of the wind, it can capture more

lift power and wind on its blades to propel them faster. If the wind turbine is too far away

from the source of the wind, then the majority of the wind could have already been

captured by another machine that uses wind power, but most likely the wind could have

died down before it reached the wind turbine. Also, if the wind turbine is far from the

source of the wind, it might get some of the wind energy, but not enough to push the

blades very forcefully or quickly. A wind turbine needs to be close enough to a strong

wind source to obtain the energy it needs to generate electricity before the wind

disperses in a different direction or completely dies down.

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Figure 10: The amount of volts of electricity generated by windmill when blades are different shapes.

In this experiment, the curved wind turbine blades generated the largest amount of v,

the rectangular blades generated the second largest amount of v, and the triangular

blades generated the smallest amount of v. The reason for this data is that because the

curved blades were the largest in width and in length, they were able to capture more

wind on their surfaces, thus creating more lift power to propel the blades faster and to

generate more electricity. Since the triangular blades were the smallest in size, they

were not able to capture a large amount of wind to generate lift power to push them very

quickly. Also, since the top area of the triangular blades is not very wide or large in size,

almost no wind will be caught there at all because of its small size, but the top area of

the curved blades is the largest part of the blade, so a large amount of wind will be

caught in that area. Almost all of the lift power will be applied to the large, rounded part

of the curved blades because of its size and ability to catch large amounts of wind

energy and power.

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Figure 11: The amount of volts of electricity generated by windmill when blades are created out of different materials.

In this experiment, the wind turbine blades that were constructed out of Styrofoam

generated the largest amount of v, the blades constructed out of paper plates generated

the second largest amount of v, and the blades constructed out of cardboard generated

the least amount of v. The reason for this data is that because a material like cardboard

is relatively thick and heavier than the other materials, it became difficult for the wind to

push and lift the blades to allow them to spin. The heavier that the blades are, the

harder it is for them to revolve quickly and for the wind to propel them. Because the

Styrofoam blades were the lightest and thinnest, the wind was easily able to push and

lift the blades on the wind turbine. Also, when wind turbine blades spin faster, they

generate more electricity. Since the cardboard blades were heavy and thick, the wind

could not push the blades very quickly, causing very little electricity to be generated.

Unlike the cardboard blades, the Styrofoam blades could be pushed quickly, easily,

precisely, and swiftly through the air because of their thin and light qualities.

CONCLUSION:

It was determined that the blades that were larger and thicker in width at the top of the

blade, which were the curved blades, were able to catch more wind, spin faster, and

generate more v. The hypothesis was correct because it was thought that because the

curved blades were the largest in length and width, they would be able to capture more

wind on the surface of the blade and create more lift power, which would propel the

blades faster and generate more electricity for the windmill. This data is important to

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share with the world because when wind turbine blades are being created, the

manufacturers can use this data to determine how large or thick the blades need to be

to be able to capture more wind and generate a large amount of electricity. Some new

follow-up experiments that could be executed in the future are to test if the number of

blades on the wind turbine affects how much electricity is generated and if the size of

the tower of the wind turbine affects how much electricity is generated.

CITATIONS:

Books:

Beedell, Suzanne M.. Windmills . Illustrated Edition. Flint, Michigan: Scribner, 1975.

Print.

Watts, Martin. Windmills. Illustrated Edition. Volume 456 of Shire Album and Shire

Series. Long Island, New York: Osprey Publishing , 2006. Print.

Dumas, Leila. Forces, Motion, and Energy (Holt Science and Technology). Orlando,

Florida: Holt, Rinehart and Winston, 2007. Print.

Websites:

Gipe, Paul. Wind Power. April 2009. http://en.wikipedia.org/wiki/Wind_power. [Accessed

February 11, 2013].

Jones, Donald A. Electricity. August 1991. http://en.wikipedia.org/wiki/Electricity.

[Accessed February 11, 2013].

Blyth, James. Wind Turbine. May 2009. http://en.wikipedia.org/wiki/Wind_turbine.

[Accessed February 22, 2013.]

Lucas, Adam. Windmills. January 2006. http://en.wikipedia.org/wiki/Windmills.

[Accessed February 22, 2013]

Wind Turbine Blade Aerodynamics.

http://www.gurit.com/files/documents/2_aerodynamics.pdf. [Accessed February 20,

2013]

Research Papers:

D., Katie. What is electricity? Part 1. Cary Academy. September 27, 2012.

http://researchthetopic.wikispaces.com/What+is+electricity%3F+Part+1. [Accessed

February 17, 2013].

Matsuo, Griffin. THE STUDY OF DIFFERENT SHAPED WINDMILL PROPELLERS ON

HOW MUCH MV THEY CREATE. Cary Academy. 2008.

E. Miller, Lawrence. Energy Consumption in Wind Facilities. Gerrardstown, WV. 2009.

[Accessed February 18, 2013]

Databases:

“Farm Machinery." Compton's by Britannica. Encyclopædia Britannica Online School

Edition.

Encyclopædia Britannica, Inc., 2013. Web. 20 Feb. 2013.

<http://school.eb.com/comptons/article-200569>.

Diagram Pictures:

http://windeis.anl.gov/guide/basics/turbine.html

http://greenpoweroregon.com/Images/WindDiagram_Lg.gif

http://www.rowan.edu/colleges/engineering/clinics/cleanenergy/rowan%20university%2

0clean%20energy%20program/Energy%20Efficiency%20Audits/Energy%20Technology

%20Case%20Studies/Wind%20Power/wind_power.html

http://upload.wikimedia.org/wikipedia/commons/c/ce/HAWT_and_VAWTs_in_operation

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