A launching of a very special kind awaited IWES scientists near the research wind farm alpha ventus, 45 km off Borkum: a LiDAR wind measuring buoy for measuring wind speeds was put to anchor in the direct vicinity of FINO1 meteorological mast. Wind speed information greatly improves risk minimization in the planning, construction and operation phases of offshore wind farms. When compared with measuring masts, the buoy has one decisive advantage: It can be employed at any location with no extra installation costs and requires a less time-consuming authorization procedure. This is all made possible by a correction algorithm, developed at the Fraunhofer IWES, which removes the proper motion of the floating platform from the values measured.
A validated technology conquers new terrain: Using LiDAR (“Light Detection And Ranging”) appliances on land and on fixed platforms for measuring wind speeds at heights of 40-200 m are a proven process. Proper motion, which falsifies measurement values taken from moving surfaces, has hitherto hindered the reliable employment of LiDAR applications offshore. Within the framework of the project “Offshore Measuring Buoy” – funded by the German Federal Ministry for the Environment– Fraunhofer scientists are now extremely excited about the first North Sea deployment of the gloating LiDAR system. A Windcube LiDAR device made by the company Leosphere has been integrated into the buoy.
Rapid implementation and marked cost reductions through floating LiDAR technology should make it possible for wind farm developers to reduce the actual costs of offshore wind energy. The construction of an authorized measuring mast such as FINO1 requires a double-digit million investment. The data quality of mast and buoy should be comparable.
High Data Quality Despite Floating Platform
The buoy will remain in the North Sea until October to prove its offshore suitability and to allow a validation of measurement accuracy using comparisons with the measurement data from the stationary mast. “A system for measuring buoy movement in combination with a correction algorithm, developed at the Fraunhofer IWES, is the key ingredient of this technology. In this way, high quality wind measurement data can be assured from a moving platform,” explained IWESProject Leader Dr. Julia Gottschall.
Cost Reduction in every Expansion and Operations Phase
Using a floating LiDAR system, the provisions of offshore wind resources are followed exactly and reliably – also in the long term and at greater water depths. Considerable time and cost advantages compared with measuring masts and flexible application potentials are the main arguments for the deployment of mobile systems. Exact determination of weather windows during the installation phase allows reliable planning of individual construction steps. Accompanying measurements during operations allow statements concerning turbine efficiency and potential wind energy yield.