Renewable Energy Technology Assessments - Kauai Island Utility ...

Kaua’i Island Utility Cooperative
Renewable Energy Technology Assessments
3.0 Renewable Energy Technology
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Table 3-30. Wind speeds and power densities (W/m 2 ) at a Class 1 site and at a 50 m
height can go as high as 5.5 m/s and 200 W/m 2 . In comparison, wind speeds and power
densities at a Class 7 site and at the same hub height may be above 8.80 m/s and 800
W/m 2 . Class 4 sites and higher are usually considered the lowest economically viable for
wind project development, although Class 3 sites also may be viable in Hawaii. At Class
3 sites, annual average wind speeds may reach 7.0 m/s with a power density of 400 W/m 2
at a 50 m height. Regardless of the existence of high resolution resource maps for some
regions, a minimum of one-year of site data collection is typically required to determine
if utility-scale wind energy is viable at a specific location.
Table 3-30. US DOE Classes of Wind Power.
Height Above Ground: 50 m (164 ft) *
Wind Power Class
Wind Power Density, W/m 2 Speed ** m/s
1 0 – 200 0 – 5.60
2 200 – 300 5.60 – 6.40
3 300 – 400 6.40 – 7.00
4 400 – 500 7.00 – 7.50
5 500 – 600 7.50 – 8.00
6 600 – 800 8.00 – 8.80
7 800 – 2000 8.80 +
Notes:
* Vertical extrapolation of wind speed based on the 1/7 power law.
** Mean wind speed is based on Rayleigh speed distribution of equivalent mean wind
power density. Wind speed is for standard sea-level conditions. To maintain the
same power density, wind speed must increase 3%/1000 m (5%/5000 ft) elevation.
Cost and Performance Characteristics
Table 3-31 provides typical characteristics for a 10 MW wind farm and a single
600 kW turbine for distributed applications. Substantially higher costs are necessary for
wind projects that require upgrades to transmission and distribution lines.
21 March 2005 3-69 Black & Veatch