1. Floating lidar fields of application and challengesFloating lidar fields of application and challenges
Floating Lidar Systems for Offshore Wind Energy Applications:
A Look at Opportunities and Challenges
J. Gottschall*, G. Wolken-Möhlmann, S. Lazuhina, T. Viergutz, I. Bastigkeit, B. Lange
Fraunhofer IWES, Bremerhaven, Germany
*julia.gottschall@iwes.fraunhofer.de
PO.IDPO.ID
246246
Offshore wind measurements with lidars on floating platforms is being introduced as flexible and particularly cost-effective alternative to the conventional met. mast solutions
(as onshore state-of-the-art transferred to offshore sites). So-called floating lidar systems may comprise buoy- as well as vessel-based applications of lidar remote sensing
technology, and the operating times offshore may vary from a few days to months according to the purpose of the measurement project.
For establishing floating lidars as acceptable or even preferred wind measurement technology offshore, we have to prove their reliability, verify the accuracy and precision of
their measurements, and not least determine the respective business value in the different phases of a wind farm project. While wind lidar technology already has proven to
be a useful and by all means advantageous technology for various onshore applications (with corresponding performance verification and calibration schemes developed
within the scope of the revision of the IEC 61400-12-1 standard), floating lidar applications are essentially affected by the motions of the sea leading to systematic errors in
the wind measurements. Therefore motion compensation and correction strategies, together with reliable offshore motion measurements, are indispensable for an optimal
outcome of an offshore measurement campaign with a floating lidar system.
The findings from our studies may build the basis for a recommended practices scheme that is to be shared and discussed with the offshore wind energy and lidar
community. Floating lidars are an exceedingly appealing concept with promising opportunities for the wind industry, but there are also challenges that are to be carefully
considered (bringing together experiences and developed standard procedures for onshore lidar applications with the understanding and handling of the marine conditions) to
make its application successful and have an optimal business value in the different steps of an offshore wind farm project.
Floating lidar business studyFloating lidar business study
EWEA 2013, Vienna, Austria: Europe’s Premier Wind Energy EventEWEA 2013, Vienna, Austria: Europe’s Premier Wind Energy Event
Approaches for testing and calibrating floating lidar systemsApproaches for testing and calibrating floating lidar systems
Figure 1: Concept of floating lidar system –
in front of FINO1 met. mast.
(←) Figure 2: Setup from
Tauche measurement campaign
(for details see [1]).
(→) Figure 3: Example results of
Floating Lidar Simulation Tool
developed at Fraunhofer IWES –
for cw lidar (top) and pulsed lidar
(bottom), resp. (for details see [2]).
22.10 23.10 24.10 25.10 26.10 27.10 28.10 29.10
0
50
100
150
200
250
300
350
400
time
winddirectionin°
Winddirection, 10minmeans
Cuxhaven
Heligoland
Measureddata
Correcteddata
Figure 4: Results of first validation
campaign for Ship-Lidar-System
developed at Fraunhofer IWES
(for details see [3]).
Table 1: Description of the three different 1 year-long
measurement campaign setups at the selected site
1st
wind measurement
campiagn setup
Construction of 60 m high MET mast with cup
anemometers at the selected wind farm site.
2nd
wind measurement
campaign setup
Construction of 60 m high MET mast with cup
anemometers and application of a floating
LIDAR for 12 month period to correct vertical
data extrapolation uncertainties.
3rd
wind measurement
campaign setup
Application of a floating LIDAR wind
measurement device only.
SummarySummary
ReferencesReferences
Figure 5:
Figure 6: Total expenditures for the cost of capital (interests)
and costs of measurement campaign technology setup in €.