Wind Power

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

You want to place wind generators in a location that get consistently high wind power.

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 %.

as of June 2011

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