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The LiDAR meteorological buoy belonging to the Fraunhofer IWES has been anchored near the alpha ventus research wind farm in the immediate vicinity of the FINO 1 measuring mast.
© Fraunhofer IWES
Mobile LiDAR system

Staff members from Fraunhofer IWES erect the buoy on the edge of the quay before lowering the measuring device into the harbour. From Bremerhaven, the buoy started its journey towards the alpha ventus offshore test field, which is situated 45 km off the coast of Borkum.
© Fraunhofer IWES

Buoy replaces meteorological mast at sea

Scientists from Fraunhofer IWES have anchored a LiDAR meteorological buoy near the alpha ventus offshore test field. It measures the wind quality and is intended to reduce the risks for offshore wind farms during the planning, construction and operational phases. In contrast to measuring masts, the buoy can be deployed at any location – with considerable cost benefits.

A proven technology is conquering new territory: LiDAR (Light Detection And Ranging) is an established process for measuring wind speed at heights of between 40 to 200 metres on land or fixed platforms at sea. However, the reliable use of mobile LiDAR devices at sea has previously been prevented by their own movement, caused by the moving surface underneath them, which distorts the measurement values.
As part of the “Offshore Measuring Buoy” project, scientists from the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) have equipped a buoy with floating LiDAR (FLiDAR) technology. It is intended to ensure quicker implementation and reduce the costs for wind farm developers and the generation costs for offshore wind energy. The quality of the data from masts and buoys is to be comparable. The measuring buoy will cost around one million euros in total. By way of comparison, the construction of a measuring mast such as FINO 1 requires a tenfold investment.

Data quality and reducing costs

The IWES buoy will remain in the North Sea until October in order to verify its offshore suitability and, by comparing its measurements with the measurement data from the stationary mast, to validate their preciseness. “A system for measuring the buoy movement in combination with a correction algorithm developed at Fraunhofer IWES forms a substantial part of this technology. This therefore ensures a high data quality with wind measurements from a moving platform,” explains IWES project head, Dr Julia Gottschall.
According to Gottschall, the floating LiDAR system enables offshore wind resources to be determined precisely and reliably – including over longer periods of time and with greater water depths. The main arguments for using mobile systems are the considerable time and cost advantages compared with measuring masts and the flexibility in terms of their use. The precise determination of weather windows during the installation phase enables the individual construction stages to be reliably planned. Ongoing measurements made during operation provide information on the efficiency of the wind turbines and potential wind energy yields.

The RAVE research wind farm

The use of offshore wind energy in Germany officially started in April 2010 with the commissioning of twelve wind turbines at the alpha ventus test field. The wind farm is being scientifically supported by the “RAVE – research at alpha ventus” research initiative. This project encompasses more than 40 research institutes, companies and agencies that are conducting basic scientific research and are working on optimising the system technology. The BINE-Themeninfo brochure “RAVE – Research on the offshore test field” (I/2012) provides an overview of the initiative and presents the initial findings relating to the system technology, basic and ecological support research and grid integration.



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