The LIght
Detection
And
Ranging
(LIDAR) system is designed to measure atmospheric
characteristics including wind speed and direction at a
number of heights from ground level. This instrument emits
a stream of photons that interact with a variety of
particulates in the air, some of which is scattered back
toward the LIDAR where the signal is analyzed and wind data
is reported based on the Doppler shift phenomenon. This
technology uses the same basic principle that radar
uses. An important benefit of the LIDAR is its capability
to provide a description of the vertical wind shear profile
at a given site location.
Typical meteorological towers
measure wind speed and direction at heights of 30 to 50
meters. The industry standard for calculating the wind
speed at the hub height of a modern wind turbine (60 to 80
meters) utilizes mathematic equations to extend the height
resolution of data that is collected from meteorological
towers. This data extrapolation technique is subject to
errors of up to 15% depending on site terrain and length of
measurement data. The consequences associated with this
source of measurement error can carry significant
implications to areas from turbine component life to actual
power production. Since the characteristics of the local
wind shear are often only partially understood, the higher
elevation wind speed and direction data that the LIDAR
provides can play a key role in making wind energy projects
more effective and, in consequence, more profitable.
The concept of measuring wind speed and direction from a
ground-based instrument has already been established with
SODAR technology, but the LIDAR is unique in that it is not
subject to echo interactions with surrounding topography
and structures. Also, the LIDAR operates silently which can
help avoid possible disturbance conflicts and it does not
require a special building permit, which has previously
caused problems with the erection of meteorological
towers.