By Reshet Gebremariam
Introduction
Global Warming is a very critical topic in today’s world. The world’s economy depends
largely on fossil fuels for our energy needs. However, this is no longer a viable way of
life because we will eventually run out of some natural resources and we are
degrading the environment. One of the best ways to prevent Global warming and
environmental degradation is to use renewable resources as a source for energy. Some
of these renewable resources are solar energy, biomass energy, hydroelectric energy,
and wind energy.
This site focuses on wind energy and tells you everything you need to know about
wind energy, from its history and how it works to the current industry of wind energy
and its potential in the future.
To learn more about wind energy, go to My Research Paper.
See also
Wind energy and how it works
The wind energy industry in the US
The future of wind energy
Related Links
Research paper
Hesston College
References
About me
Hesston College - Physics department
Introduction
One of today’s concerns about the world is climate change and global warming.
The preservation of the environment has become a priority in our world. Technological
advances and the growth of industrialization have led to the gradual degradation of the
environment. According to the EIA, the increase in green house gases, mainly coming
from the combustion of fossil fuels for energy, has caused global warming to increase
rapidly. The energy coming from the sun into the surface of the world and the energy the
earth radiates back into the earth should be equal, leaving the temperature of the surface
of the earth constant.
However, green house gases trap heat from sunlight in the atmosphere, thus
making the surface of the earth hotter. Climate change and environmental degradation
can have a lot of harmful effects on our world. As reported by the UCAR, it can cause
droughts in some countries, the rise of sea level due to melting ice, the endangerment of
some species due to changes in ecosystem, heath problems and so forth. There are a lot
of things that can be done to slow the process of climate change.
One of the things we can do is to use renewable resources to produce energy.
Some of these renewable resources are solar energy, biomass energy, hydroelectric
energy, and wind energy. This paper focuses on wind energy, which is one of the
cheapest renewable energies in the world and a fast growing industry.
1) Historical Background
2) How Wind Energy Works
3)Types of Wind Turbines and their Performance
4) Advantages and Disadvantages of Wind Energy
5) Future of Wind Energy in Kansas and in the US
6) Conclusion
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Historical Background
Wind energy is the ability to use wind turbines and to convert wind energy into other forms of energy like electricity.
Wind energy driven boats existed as early as 5000 BC. The first wind-powered electric generator in the US was built in Cleveland,
Ohio. In the years 1887-1888, Charles F. Brush built the first wind powered machine to produce electricity for his house and his
laboratory. Charles F. Brush was a mining engineer and owner of Brush Electric Company.
His generator was a 60 foot high tower with windmill’s wheel had 144 blades and a 56 feet long diameter ("Charles F.
Brush.")
Image of the first wind propelled machine
(from "Charles F. Brush.")
Wind energy was further developed in the 20th century and since. In 1979, Danish manufacturers began the modern
wind power industry. The capacities of these wind turbines were from 20 to 30kW. Today’s wind turbines have capacities that go
from 750kW to 2MW.
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How Wind Energy Works
The wind energy that is converted into electricity by wind turbines varies depending on the speed of the wind and the
flow area. The maximum energy available from the wind is given by the formula for kinetic energy:
KE = (1/2) mv2 ( in Joules)
Where m is the mass flow, meaning the mass of the substance which is passed through a given surface per unit time. v
is the speed of the wind. By definition, the rate of mass flow is given by:
m/t = ρ A v ( in Kg/s)
where ρ is the density of air, A the flow area( or rotor swept area) and v the speed of the wind.
So when we rewrite the energy from the wind, we get:
KE = (1/2) mv2
P = (1/2) ρAv*v2
(in Joules)
(in Watts)
P = (1/2) ρAv3
(in Watts)
But this is simply theoretical. In reality, wind turbines are not this effective. So the power of the wind turbines is not
equal to the maximum power available from the wind. So to find the power of the wind turbines, we multiply P with a
coefficient of performance C (which is around 30% to35% for good design; Betz limit -> 59% being the maximum efficiency.)
So the power of the wind turbines is given by:
P = (1/2) ρAv3C
2
We can then replace A= πr , where r is the radius of the wind turbine. Then we obtain:
P = (1/2) ρ πr2v3C
Wind turbines convert kinetic energy in the wind to mechanical energy. A generator converts this mechanical energy to
electricity or it can be converted to other forms of energy.
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Types of wind turbines and their performance
There are two major kinds of wind turbines. The first one is the Horizontal Axis Wind Turbine (HAWT) and the second
one is the Vertical Axis Wind Turbine (VAWT). The HAWTs are very common today and are made of a couple of blades
that are preferably light and corrosion resistant. The VAWTs have a rotor shaft that runs vertically. Both of the turbines
rotate with the power of the wind.
Horizontal Axis Wind Turbine
(By the Ministry of Agriculture, Food & Rural Affairs)
(Philip's Encyclopedia)
Horizontal axis wind turbines’ main parts are: the blades, the electronic equipments, the gearbox, the generator, the
cable and the tower. The blades spin and convert the kinetic energy in the wind to rotational energy. This rotational
energy is then converted to high speed rotational energy in the gearbox. This high speed rotational energy is then converted into
electricity by the generator. This electricity is carried to transmission lines by the cable.
Vertical Axis Wind Turbine
The other type of wind turbine is the vertical axis wind turbine. It is made of two blades that are attached to the
opposite ends of the tower. Like the HAWT, the VAWT works in the same way except the rotor spins vertically and it uses the lift
and drag method. The drag force is the force acting on the object in a direction parallel to the flow. The lift force corresponds
to the force acting on the object in a direction normal to the flow.
Vertical Axis Wind Turbine
(by the EIA)
These two kinds of wind turbines are found in different areas in the US. There are more wind powered generators in areas where
the wind’s power and speed is relatively high like in East and Central America.
Current Installed Wind Power Capacity (MW) (by USDE)
Kansas has one of the biggest current installed wind powered capacity that ranges between 1,000 to 8,300 MW (MegaWatts.)
Back to Research Paper Introduction
Advantages and Disadvantages of Wind Energy
Studies have shown that wind energy has grown in the US. According to the Energy Information Administration, Wind
energy represented 2.3% of the US’ energy sources. In addition, wind energy is quite cheap compared to other renewable
resources. It is efficient because it is environmentally friendly and is the fastest growing energy source. This may be due to the
reduction of the cost by more than 80% since the first modern wind propelled machine. On top of that, it comes from a free
source: the wind. Some regions have high potential for wind power than others, thus the installation of wind turbines will depend
on the wind resources of the different regions.
Annual Average Wind Resource Estimates (by USDE)
In addition, wind energy is very environment friendly and causes no pollution. It is also an inexhaustible resource; we
can never run out of wind while we can run out of other natural resources like Coal, oil, gas (fossil fuels) and so forth.
However, there are some disadvantages to using wind energy. First of all, wind propelled machines are installed on
wide territories. The wind farms are very big and take up so much space. Other things could have been done with these wide
lands like agriculture. The height of the turbines is enormous. But the height of the turbines has a great influence on the velocity
of the wind, hence on the maximum power available from the wind.
Fig 3.2. Variation of wind velocity with height
(from Wind energy: fundamentals, resource analysis and economics by Sathyajith Mathew )
In addition, wind energy would destroy the beauty of natural landscapes with the installation of big turbines.
If we look at the ethical aspect of using wind energy, it kills birds. But the number of birds killed by wind turbines is
more than five thousand times lower than the number of birds killed by buildings ("Wind Power Myths vs. Facts.")
Data source: Erickson et al., 2002, Summary of
Anthropogenic Causes of Bird Mortality
Future of Wind Energy in Kansas and in the US
The comparison between the advantages and the disadvantages of wind energy leads to the conclusion that wind
energy is a growing industry and has great potential in the US, especially in East and Central America. For instance, in Kansas,
wind energy is expected to be a very effective resource in the future. Although wind energy will not replace other forms of
energy, it will reduce their use. Recently, only 2% of Kansas’ electricity source comes from renewable energy, the remaining 80%
depends on fossil fuels which are very pollutant to the environment. It is expected that this situation will change significantly by
the year 2020.By this year, 20% of Kansas’ electricity source will come from wind, solar, hydro, geothermal and distributed
energies.
(By Climate and Energy Project)
Back to Research Paper Introduction
Conclusion
Overall, wind energy is a growing industry and has great potential. It won’t replace other forms of energy in the future
but it can be a great source of energy. It is one of the renewable resources that doesn’t cost a lot of money and is inexhaustible.
Since wind energy has as many advantages and disadvantages, the focus needs to be on how to make wind energy more effective
in the future. One of the ways to make wind energy effective is to change the way it is produced. The main problem is the design
of the wind turbines that are too big and yet generate a relatively small amount of energy. Another option would be creating a
system that can control or manipulate the power from the wind so that it remains within the desired range of speed and power.
Thus, wind power is one of the things that be a factor in the process of environmentally and economically sustainable future.
Back to Research Paper Introduction
References
"Charles F. Brush." Charles F. Brush. 13 Sept. 2004. Web. 27 Sept. 2009. <http://www.brushwind.org/>.
Clarke, S. "Electricity Generation Using Small Wind Turbines at Your Home or Farm." Ministry of Agriculture, Food & Rural
Affairs. Queen's Printer for Ontario, Oct. 2009. Web. 09 Oct. 2009.
<http://www.omafra.gov.on.ca/english/engineer/facts/03-047.htm>.
Gardiner, Lisa. "Effects of Climate Change Today." University Corporation for Atmospheric Research. UCAR, 23 June 2004. Web.
27 Sept. 2009. <http://www.windows.ucar.edu/tour/link=/earth/climate/cli_effects.html&fr=t%20t>.
"Greenhouse Gases, Climate Change, and Energy." Energy Information administration. EIA, May 2008. Web. 27 Sept. 2009.
<http://www.eia.doe.gov/bookshelf/brochures/greenhouse/Chapter1.htm>.
"How Can I Calculate the Amount of Power Available at a Given Wind Speed?" American Wind Energy Association. American Wind
Energy Association, 2009. Web. 25 Sept. 2009. <http://www.awea.org/faq/windpower.html>.
"How Wind Turbines Work." U.S. Department of Energy. USDE, 30 Nov. 2006. Web. 27 Sept. 2009.
<http://www1.eere.energy.gov/windandhydro/wind_how.html>.
Mathew, Sathyajith. Wind energy: fundamentals, resource analysis and economic. Vol. 1. New York: Springer Berlin Heidelberg,
2006. Print.
"Record year for wind energy: Global wind power market increased by 40.5% in 2005." Global Wind Energy Council. GWEC, 17
Feb. 2006. Web. 11 Oct. 2009.
<http://www.gwec.net/index.php?id=30&no_cache=1&tx_ttnews[tt_news]=21&tx_ttne>.
"Renewable Energy Sources in the United States." National Atlas of the United States. FOIA, 17 Sept. 2009. Web. 27 Sept. 2009.
<http://www.nationalatlas.gov/articles/people/a_energy.html>.
"Renewables." Energy Information Association. U.S. Department of Energy, 29 Apr. 2003. Web. 28 Sept. 2009.
<http://www.eia.doe.gov/cneaf/solar.renewables/ilands/fig13.html>.
"Sound options for state energy policies." Climate and Energy Project. CPE, 05 Dec. 2008. Web. 12 Oct. 2009.
<http://blog.climateandenergy.org/2008/12/05/>.
"Using wind to power our future." Community Environmental Council. 2009. Web. 25 Sept. 2009.
<http://www.cecsb.org/index.php?option=com_content&task=view&id=61&Itemid=100&gclid=CKXVhceUm50CFado5Qo
dsCA53A>.
"Wind Energy Basics." American Wind Energy Association. American Wind Energy Association, 2009. Web. 25 Sept. 2009.
<http://www.awea.org/faq/wwt_basics.html>.
"Wind Power Myths vs. Facts." American Wind Energy Association. Web. 09 Oct. 2009.
<www.awea.org/pubs/.../050629_Myths_vs_Facts_Fact_Sheet.pdf>.
"Wind Power." Philip's Encyclopedia 2008. London: Philip's, 2008. Credo Reference. Web. 15 October 2009.
"Wind Powering America." U.S. Department of Energy. USDE, 2009. Web. 25 Sept. 2009.
<http://www.windpoweringamerica.gov/wind_installed_capacity.asp>.
Tuttle, Chris. "Renewable Energy: Wind Power." United States Department of Agriculture. USDA, 6 Mar. 2002. Web. 25 Sept.
2009. <http://www.usda.gov/rus/electric/engineering/sem2002/tuttle.htm>
Back to Research Paper Introduction
My name is Reshet Gebremariam and I am a sophomore at Hesston College.
I am an international student from Ethiopia where I was born and raised.
I am majoring in Engineering, either in civil or architectural engineering.
This research project is an assignment for College Physics I (Phys 203.)
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Research Paper
Hesston College
(By the Ministry of Agriculture, Food & Rural Affairs)
(Philip's Encyclopedia)
My name is Reshet Gebremariam and I am a sophomore at Hesston College.
I am an international student from Ethiopia where I was born and raised.
I am majoring in Engineering, either in civil or architectural engineering.
This research project is an assignment for College Physics I (Phys 203.)