colorado school of mines adventure engineering physical science workshop for teachers wind resource...

Colorado School of Mines Adventure Engineering Physical Science Workshop for Teachers

Wind Resource

References:

NREL (Tony Jimenez, Neil Kelley)

June 19 – 20, 2007 Wind Energy 2


Where Does Wind Come From?

• The differential heating of earth’s atmosphere causes wind.



The Jet Stream

• The jet stream is responsible for the transport of heat and momentum in the mid latitudes



Measuring the wind

• Wind speed is typically measured using anemometers.

• How might you measure the speed of the wind from a fan without an anemometer?



Characterizing the Wind Resource

• How might you characterize the wind?

– average wind speed– variation in wind speed

– most frequent wind direction (“prevailing wind direction”)

– frequency of other wind directions



Probability Distributions

• Create a table like the one below:

Range (“bin”) Number Percent

0 – 2

2 – 4

4 – 6

6 – 8

8 – 10



Probability Distributions - 2

• Consider this list of numbers.– 1, 3.5, 7, 6.5, 1.5, 9, 1, 0.5, 8.5, 9.5– What is the average?

• Fill in the second column of your table with the number of numbers in the list that fall within each of your bins.

• Fill in the third column of your table with the percent of the numbers in each range.

• Create a plot showing the percent in each range. Mark the average on your plot.



Wind Speed DistributionWeibull Distributions

0.000

0.050

0.100

0.150

0.200

0.250

0 2 4 6 8 10 12 14 16 18 20

Wind Speed Bin (m/s)

Pro

po

rtio

n o

f T

ime

AWS = 5.0 m/sk = 2.0PD = 146 watts/m^2

AWS = 5.0 m/sk = 3.0PD 108 watts/m^2

AWS = 6.0 m/sk = 2.0PD = 253 watts/m^2



Turbine Power Curve

• Power is usually limited to a certain maximum for real turbines (to ensure safe operation)

0 5 10 15 20 250

100

200

300

400

500

600

700

800

900

1000

Cp = 0.593

(Betz Limit)

Cp = 0.4

Cp = 1

Wind Speed (m/s)

Po

we

r (k

W)

Wind PowerIdeal Turbine PowerNon-Ideal Turbine Power



Power

• Power available in the wind

– = air density– v = wind speed– A = cross sectional area

swept by rotor

3

2

1AvPwind



Power Density

Power Density =

Wind Class W/m2 at 50 m Wind speed at 50 m1 0 - 199 0 - 5.9 m/s2 200 - 299 5.9 - 6.7 m/s3 300 - 399 6.7 - 7.4 m/s4 400 - 499 7.4 - 7.9 m/s5 500 - 599 7.9 - 8.4 m/s6 600 - 800 8.4 - 9.3 m/s7 > 800 > 9.3 m/s

3

2

1v

A

P



United States Wind Resource



Colorado Wind Resourcehttp://w

ww

.eere.energy.gov/windandhydro/w

indpoweringam

erica/images/w

indmaps/

co_50m_800.jpg



Activity

• Use the Wind Living Lab to evaluate the wind resource at a location of your choosing. Create a wind speed probability distribution (like the one on slide 6) showing the proportion of time the wind spends at each wind speed value.

• Which turbine produces more energy for your wind speed distribution?

colorado school of mines adventure engineering physical science workshop for teachers wind resource...

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