Wind Power. Approximately 2% of the solar power that reaches the earth’s surface is converted into...
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Transcript of Wind Power. Approximately 2% of the solar power that reaches the earth’s surface is converted into...
Approximately 2% of the solar power that reaches the earth’s surface is converted into wind.
This is ~30 times our present energy usage.
History Large sailing ships could
generate 10 000 hp. Used extensively in
Europe in the 19th century Used for pumping water
or grinding grain Most rapid new
development for generating electricity
Early wind generators focused on single large generators
Grandpa’s Knob (Vermont) could generate up to 1.2 MW of power in the 1940’s.
200 ft diameter blades
New interest in wind electricity after oil embargo in 1973.
Early NASA wind generator built in Ohio in 1975 could generate 100 kW of power in 18 mph wind using 125 ft long blade diameter.
Boeing Mod 5B wind turbine on Oahu designed to generate 7.2 MW of electricity. Actually, produced 3.2 MW operating from 1987 - 1993
420 ft diameter on a 192 ft tall tower Last government-sponsored project.
Many Different Styles
Savonius Rotor
Darius Rotor
American multivane
2-Blade Wind Turbine
3-Blade Wind Turbine
Choice of style depends on application
Multi-blade has good starting torque. Good for applications like pumps.
3-blade has low starting torque but is more efficient at high rotation rates. Used for generating electricity
Wind Farms
Rather than using single large generator, we usually use several smaller generators to make wind farms
Practicalities
Wind speed tends to increase with increasing height. Optimal height is ~300 m.
Most commercial wind towers are 50 to 100 m high. Get ~80% of wind potential at this height.
Power in the wind(Betz Limit)
P=2.8310-4 D2v3 kW
D is the diameter in metersv is the wind speed in meters per
second
D2 - because area of windmill increases as D2
v3 - because KE in wind is proportional to v2 and an additional v because of rate at which energy is brought to windmill
Maximum theoretical efficiency is 59% of the Betz limit.
Modern wind generators are around 50-70% of maximum theoretical efficiency
Rated Output
A wind generator has a rated power output a a particular wind speed, e.g. 10 kW at 20 mph.
If wind speed drops so does power, e.g. if wind drops to 15 mph, P=(15/20)3 10kW = 4.2 kW.
If wind speed increases, they usually feather the blades so they don’t generate too much power.
Home Wind Power? HORNET - LOW WIND SPEED
turbines with Split-Core PMA Hornet's are designed for
class 3 to 7 or AVERAGE wind zones.
Super low cost turbines! 59" diameter blade 800 Watts @ 33 MPH
1200 Watts MAX. @ 65 MPH (under load)
~$500.00 Note at 11mph P=800/27=30W
Globally averaged growth in wind power has been 34% for the last five years.
Goal: Have wind provide 5-10% of our electricity by 2020. (Currently it is ~2.3 %) Fall 2011: 43.5 GW installed (90 projects for another 8.5 GW under construction)
The EU was attempting to provide 20% by 2010. As of 2010, 84 GW (12 000 turbines), which is 9.1 %.
Illinois Energy Context
Electric Profile (2009)
Energy Source Percent TotalCoal 43.4 %Petroleum 0.05 %Natural Gas 2.3 %Nuclear 52.1 %Hydroelectric 0.05 %Renewables 1.9 %
Data from the Energy Information Administration
Advantages
Renewable No CO2 or other emissions Competitive price per kW-h Less than 1% of the land would be
used for foundations and access roads, the other 99% could still be used for farming or other uses.
Advantages Diversify the predominantly coal and nuclear
energy profile in Illinois and provide a hedge against rising energy costs
Every megawatt of installed wind capacity generates $1.7 million of investment
Renewable energy projects such as wind development contribute significantly to the local tax base
Each wind turbine can provide $2,000-$4,000 per year in lease payments thereby diversifying the income of farmers, ranchers and other landowners
Concerns About Wind Power
Wind is intermittent so you don’t want to rely on it too much. ~15-20% is considered safe.
Aesthetics: Actually more opposed to by people who don’t live near them.
Noise: New designs are very quiet
Concerns About Wind Power
Bats & Birds• 30 % of first year bird deaths are due to
collisions in nature• interactions with humans and human-
made objects cause many bird deaths
Human Objects or Activity Number of Bird Deaths per Year
Power Transmission Lines 130 – 174 million
Collisions with Cars and Trucks
60 – 80 million
Collisions with windows on buildings and homes
100 – 500 million
Exxon Valdez oil spill About 80 000
Collisions with Communications Towers
40 – 50 million
Pesticides About 70 million
Human Objects or Activity Number of Bird Deaths per Year
Cats 200 - 400 million
Jet engines, smoke stacks, and all other structures
300 – 500 million
Altamont Pass, CA wind farm
92
San Gorgono Pass, CA 38 (out of 69 million in 1986 study)
All wind farms 1.8 per wind turbine
Migrating Bats2 – 4 per turbine