An Investigation of the Blade
Designs of Wind Turbines
Research question: How Does the Angle of Attack, Chord Length and Serrated Trailing Edge of
Wind Turbine Blades Affect the Efficiency?
Physics: Extended Essay
Word Count: 3998
, Table of Contents
Introduction 1
Theoretical Background 3
Experimental Investigations 11
Experiment 1: Angle of Attack 11
Analysis 13
Experiment 2: Chord Length 16
Analysis 18
Experiment 3: Trailing Edge 20
Analysis 21
Evaluation 23
Conclusion 25
References 26
Appendices 28
Appendix 1 28
1.1 A raw data table of experiment 1 28
1.2 Processed data table of experiment 1 28
Appendix 2 29
2.1 Raw data tables of experiment 2 29
2.2 Processed data table of experiment 2 29
Appendix 3 30
3.1 A raw data table of experiment 3 30
3.2 A processed data table of experiment 3 30
3.3 An quadratic graph of experiment 3 31
,Introduction
The wind turbine for pumping water was first used in China, around 200 BC. By the 11th
century, people in the Middle East used the turbines extensively for food production. The
technology of wind turbines was spread out very shortly to Europe and then eventually to the
United States. In the late 1800s and early 1900s, wind turbines for electricity generation were
first invented. Around 1930, the number of wind turbines and wind pumps declined as the
availability of electricity to most farms improved. However, with the growing concerns on global
warming, wind turbines for electricity generation have gained the societies’ attention again.
Nowadays, wind turbines are one of the leading contributors to green energy in the battle to
reduce reliance on fossil fuels to generate electricity. Wind turbines generate approximately 5%
of the world’s total electricity generation which is approximately 1.5 PWh (Alves, 2021). Wind
turbines use wind energy which is an unlimited source from nature to turn electric generators
for electrical power. Today’s wind turbines have an efficiency of 50% out of the total wind energy
passing through the blades (University of Michigan, 2021). However, research suggests a Betz
Limit that suggests the theoretical maximum efficiency of wind turbines is around 59% (Andres,
2010). Maximizing efficiency is beneficial not only environmentally but also economically.
The fact that wind turbines do not emit CO2 is extremely beneficial for the environment because
limited sources such as fossil fuel often increase carbon dioxide emission and air pollution that
are harmful to both the environment and public health.
Economically, companies or individuals who own wind turbines gain profits from selling the
electricity generated by their turbines. The owner of one wind turbine can earn approximately
3000$ to 10,000$ per year depending on its capacity of electricity within the average lifespan of
1
, 20 years. This means that a possible increase in efficiency may result in an increase in the profit
of owners as they will be able to sell a bigger amount of electricity. This makes it a more
attractive proposition to those considering investing in this technology. The efficiency can be
increased by changing the geometrical characteristics of blades or adding some parts since
aerodynamics on blades contain complex variables and there are still new technologies in
development.
Efficiency also takes an important role considering the challenges wind turbines face when
getting recycled. As mentioned, most wind turbines have the lifespan of 20 years. After their life
span, wind turbines stop their operations and are disassembled. The issue is that the composite
materials that wind turbine blades are made out of such as fiberglass are considered as materials
that are hard to recycle. Most of the used wind turbine blades nowadays often wind up in the
landfill. Efficiency is an important factor because it governs the total amount of green energy
produced before waste occurs.
In this Extended Essay, I will investigate multiple ways of maximizing the efficiency of wind
turbines in terms of the blade design.
2
Designs of Wind Turbines
Research question: How Does the Angle of Attack, Chord Length and Serrated Trailing Edge of
Wind Turbine Blades Affect the Efficiency?
Physics: Extended Essay
Word Count: 3998
, Table of Contents
Introduction 1
Theoretical Background 3
Experimental Investigations 11
Experiment 1: Angle of Attack 11
Analysis 13
Experiment 2: Chord Length 16
Analysis 18
Experiment 3: Trailing Edge 20
Analysis 21
Evaluation 23
Conclusion 25
References 26
Appendices 28
Appendix 1 28
1.1 A raw data table of experiment 1 28
1.2 Processed data table of experiment 1 28
Appendix 2 29
2.1 Raw data tables of experiment 2 29
2.2 Processed data table of experiment 2 29
Appendix 3 30
3.1 A raw data table of experiment 3 30
3.2 A processed data table of experiment 3 30
3.3 An quadratic graph of experiment 3 31
,Introduction
The wind turbine for pumping water was first used in China, around 200 BC. By the 11th
century, people in the Middle East used the turbines extensively for food production. The
technology of wind turbines was spread out very shortly to Europe and then eventually to the
United States. In the late 1800s and early 1900s, wind turbines for electricity generation were
first invented. Around 1930, the number of wind turbines and wind pumps declined as the
availability of electricity to most farms improved. However, with the growing concerns on global
warming, wind turbines for electricity generation have gained the societies’ attention again.
Nowadays, wind turbines are one of the leading contributors to green energy in the battle to
reduce reliance on fossil fuels to generate electricity. Wind turbines generate approximately 5%
of the world’s total electricity generation which is approximately 1.5 PWh (Alves, 2021). Wind
turbines use wind energy which is an unlimited source from nature to turn electric generators
for electrical power. Today’s wind turbines have an efficiency of 50% out of the total wind energy
passing through the blades (University of Michigan, 2021). However, research suggests a Betz
Limit that suggests the theoretical maximum efficiency of wind turbines is around 59% (Andres,
2010). Maximizing efficiency is beneficial not only environmentally but also economically.
The fact that wind turbines do not emit CO2 is extremely beneficial for the environment because
limited sources such as fossil fuel often increase carbon dioxide emission and air pollution that
are harmful to both the environment and public health.
Economically, companies or individuals who own wind turbines gain profits from selling the
electricity generated by their turbines. The owner of one wind turbine can earn approximately
3000$ to 10,000$ per year depending on its capacity of electricity within the average lifespan of
1
, 20 years. This means that a possible increase in efficiency may result in an increase in the profit
of owners as they will be able to sell a bigger amount of electricity. This makes it a more
attractive proposition to those considering investing in this technology. The efficiency can be
increased by changing the geometrical characteristics of blades or adding some parts since
aerodynamics on blades contain complex variables and there are still new technologies in
development.
Efficiency also takes an important role considering the challenges wind turbines face when
getting recycled. As mentioned, most wind turbines have the lifespan of 20 years. After their life
span, wind turbines stop their operations and are disassembled. The issue is that the composite
materials that wind turbine blades are made out of such as fiberglass are considered as materials
that are hard to recycle. Most of the used wind turbine blades nowadays often wind up in the
landfill. Efficiency is an important factor because it governs the total amount of green energy
produced before waste occurs.
In this Extended Essay, I will investigate multiple ways of maximizing the efficiency of wind
turbines in terms of the blade design.
2
