WMOD00387

• Title: Wind Site Prospecting Studies
• Prepared By: W. F. Harrison, S. J. Hightower
• Date: 10/1/1982
• Weather Modification - Doc Type: Report

INTRODUCTION

This is the 22nd of a continuing group of monthly
reports to be prepared by the ~ivision of Atmo-
spheric Resources Research for the Pacific North-
west Region, in support of the Wind Site Survey
Program. This particular report represents the
data for Ellensburg, Washington.

The PROBE (Portable, Remote OBservations of
the Environment) set has been supplemented
with a 22.5-foot tower on which the anemometers
are mounted. The PROBE samples data every 15
minutes for a 5-minute average, and broadcasts
the data to the satellite once each hour.

DEFINITION OF TERMS

1. Thefour-wind averages per hour are averaged
together to present a single hourly average. The
PROBE units use a U (east/west) and a V (north/-
south) component system to minimize ambiguity.
The U and V components are averaged, and then
an average direction and speed are computed.
Unusable data are edited out prior to averaging.

2. The windspeeds are extrapolated to 10, 50,
61, and 80 meters, using the 1/7 power law:

(H )'11
V2= V1 H~

where V1 = measured windspeed, H1 = height of
measured wind anemometer, H2 = height to
which wind is being extrapolated, and V2 =
extrapolated windspeed.

3. The power versus windspeed curves for the
MOO-2 and WTS-4 generators were shifted from
the Medicine Bow, Wyoming site to sea-level
values using the equation(: ) 1/3

VSL = V M PM
PSL

where V SL = windspeed curve values at sea level,
PM = density value at Medicine Bow, PSL = density
value at sea level, and V M = windspeed curve
values at Medicine Bow.

4. The power versus windspeed curves for the
MOO-2 cut-in and the WTS-4 cut-in and cut-out
are shifted to the station density values using the
equation:

VS1TE= VSL

( PSL )
PSITE

'/3

where V SL = windspeed curve values at sea level,
PSL = density value at sea level, PSITE = density
value of the specific site, arid V SITE = windspeed
curve values for the specific site. .

The power versus windspeed curve for the MOO-
2 cut out is shifted to the station-density value,
using the equation: .

VS1TE= VSL (PSL) 112
PSITE

where VS1TE' VSL' PSL' and PSITE are as defined
above.

5. The density values are calculated as follows:

1. Calculate IACO pressure P (mb) at site
elevation from Smithsonian Tables.
2. Use USAF Skew- T Log' P diagram to obtain
mean Kelvin temperature at site elevation
for a U.S. standard atmosphere.
3. Use dry gas constant.
4. Calculate the density, using the equation:

Density = :r

6. The power density is calculated, using:
PD = Y2 PSL (DM) V3

where DM = density multiplier, V = windspeed at
height of concern. An annual available power at
50 meters exceeding 400 W/m2 is a "rule-of-
thumb" for a potential site.

7. The plant capacity factor is calculated as
follows:
PCF = . . Cumulative energy (kWh)
Valid wrnd hours X system maximum power

8. All times indicated are local standard time.

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