GROUND-BASED REMOTE SENSING SYSTEMS - Wind Resource Assessment: A Practical Guide to Developing a Wind Project - page 107

Figure 8-3. NRG/Leosphere's Windcube lidar (left), and Natural Power's ZephIR lidar unit.
Source: AWS Truepower.
Lidars designed for wind energy applications came on the scene after sodars, and are
considerably more expensive. Nevertheless, their popularity is growing, particularly in
Europe, where most of the leading manufacturers are located. Lidars have benefited
from testing campaigns that have helped to establish a reputation for accuracy. In
addition, lidars are increasingly being considered for specialized applications, such as
offshore wind resource assessment, replacements for nacelle anemometers on wind
turbines, and deployment within and around existing wind farms for performance
assessment. The use of lidar is expected to continue growing in the future as prices
decrease and experience with and acceptance of the technology increase.
8.3 REMOTE SENSING CAMPAIGN DESIGN AND SITING
A successful remote sensing campaign, whether it uses sodar or lidar or both, requires
considerable expertise in siting, system operations, and data analysis and interpretation.
Like meteorological masts, remote sensing systems should be placed at sites that
are representative of wind conditions likely to be experienced by the wind turbines.
The units should be installed level, and their orientation relative to true north should
be determined and documented.
To prevent noise echoes that may harm data quality, sodars should be placed no
closer to obstacles, such as meteorological masts, trees, or buildings, than the height
of the obstacles. In many instances, and especially at sites with multiple surrounding
obstacles (such as a clearing within a forest), a larger setback may be necessary.
Rotating the sodar so that its acoustic beams are directed away from objects can
sometimes reduce echoes. Nearby noise sources such as generators, air conditioners,