Wind Resource - Wind Energy: Renewable Energy and the Environment

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FIGURE 4.7 European offshore wind resources at five heights for open sea. (From I. Troen and E. L. Petersen,

European Wind Atlas , Riso National Laboratory, Denmark, 1989. With permission.)

Digital instruments or analog inputs, which are digitized, typically have sample rates of 0.1

to 1 Hz (Hertz number/second). Values can be stored in a histogram of wind speeds, or wind

speed and other selected variables can be stored for selected averaging time periods, along with

standard deviations. Events such as maximums and time of occurrence can also be recorded and

stored. Micro data loggers were designed specifically for wind potential measurements and record

time sequence data (averaging time is selectable) on chips. The chips can store data from a number

of channels, and the data loggers can even be queried by telephone (cell or direct), radio link, or

satellite, so data are transmitted directly to the base computer. Now Internet connection is avail-

able. More detailed information on instrumentation and measurement can be found in Rohatgi and

Nelson [17]. Also see the Wind Resource Assessment Handbook [ 24 ] for detailed information on

wind measurement, instrumentation, and quality assurance.

The advantages of sonic detection and ranging (SODAR) and light detection and ranging

(LIDAR) are that the instrumentation is at ground level and no tower is needed, and wind speeds

can be measured to 500 m (SODAR) and even out to several kilometers (LIDAR). The disadvantage

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