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Fig.1 The alpha ventus wind farm. The two rows of three wind turbines at the front of the photo are Areva wind turbines while the ones behind are REpower wind turbines. The FINO 1 research platform can just be seen in the distance to the rear. The lower right image shows the neighbouring transformer station with a helicopter pad.
© AREVA Wind / Jan Oelker
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Stress tests in the middle of the ocean

Many people will be familiar with the use of the term RAVE in music, where it describes techno dance events. In the context of offshore wind energy, RAVE stands for “research at alpha ventus”, a major research initiative that is investigating the use of wind energy in the “raving” oceans. With more than 40 project partners, it is supporting the construction and operation of the alpha ventus offshore test field. It is aimed at providing fundamental knowledge to optimise offshore wind energy.

The alpha ventus test field, which is located 45 kilometres north of Borkum at a depth of 30 metres, began operation in April 2010. It contains twelve 5-MW wind turbines that are arranged in an approximately 800 x 800-metre grid. Half of the turbines come from the REpowercompany and use a jacket structure, while the other half come from Areva Wind and use a tripod structure (Fig. 1). The developer and operator of the test field is Deutsche Offshore-Testfeld und Infrastruktur GmbH & Co. KG (DOTI), a consortium comprising the three energy supply companies EWE, E.ON and Vattenfall. Four of the wind turbines are equipped with numerous sensors in order to determine the external forces acting on the structures and to record as much operating data as possible. In particular, it is intended to incorporate the operating data and experience gained into the “Monitoring of offshore wind energy utilization” project (Offshore WMEP). Other international operators of offshore wind farms have also offered to participate in the OWMEP project as long as the confidentiality of the operating data is maintained. All participants have been assured that the data will be protected.

The 12 wind turbines are linked via inter-array cabling with a transformer station, which is installed on a platform within the test field. Here the electricity is converted into 110-kV current and fed to the mainland via a 60 km-long three-phase connection. Alpha ventus is located in the immediate vicinity of the FINO 1 research platform.

Around 40 research institutes, companies and authorities are working in 34 individual projects as part of the RAVE research initiative. Page 15 shows the structure of the initiative. Central components in the concept include the project coordination, which is being conducted by the Fraunhofer Institute for Wind Energy and Energy System Technology (IWES) in conjunction with the RAVE steering committee, and the central measurement service, which is being supervised by the Federal Maritime and Hydrographic Agency (BSH).

The areas being focussed on as part of RAVE are:

  • Operation, measurement technology and coordination
  • Foundation and support structures
  • Wind turbine technology and monitoring
  • Grid integration
  • Currents and turbulences in the wind farm
  • Accompanying ecological research
  • Safety and social acceptance

 

This BINE-Themeninfo brochure presents three main research areas in detail. The first section is concerned with improvements to the wind turbines, rotor blades and foundation structures. Themes covered here include the ongoing investigations into the wind turbine technology and possibilities for lowering costs, reducing weight and optimising the maintenance intervals. The following section then focuses on the comprehensive accompanying research. Oceanographic and geological investigations are presented here that include research into scouring. This section is rounded off with a look at accompanying ecological research based on the StUK standard assessment concept. The third section examines how the large volumes of wind power generated offshore can be integrated into the electricity grid and how the supply and demand can be better aligned. In particular, it takes a look at the requirements for wind power made by the grid service providers in conjunction with wind farm cluster management and wind output forecasts.

Social acceptance

The development of offshore wind energy requires social acceptance. Therefore the expectations and experiences of the population before and after the construction of offshore wind farms have been surveyed as part of an interdisciplinary project funded by the German Federal Ministry for the Environment, Nature Conservation and Nuclear Safety. The project is being coordinated by the Health and Environmental Psychology working group at Martin-Luther-Universität Halle-Wittenberg. Local residents, tourists and regional experts in various coastal regions along the North and Baltic Sea with and without offshore wind farms were questioned in two surveys in 2009 and 2011. Workshops for residents are being held in spring 2012 and a third survey will take place this summer. Interim results indicate that wind farms remote from the coast are more accepted than wind farms near the coast. The project aims to develop recommendations for action for the purpose of increasing acceptance and achieving development strategies that avoid conflicts as much as possible.

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Addresses

Wind turbine technology
Universität Stuttgart, IFB

Wind turbine technology
BSH

Basic and ecological research
Fraunhofer IEE

Grid integration and overall coordination
Leibniz Universität Hannover, FI

Conference

RAVE International Conference
May 8 – 10, 2012
Bremerhaven, Germany
www.rave2012.de

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Movie

A 16 minute long movie showing "Alpha ventus".

RAVE Online

The online portal of the RAVE research initiative. It provides an overview of the complete spectrum of topics and, in addition to information sheets (RAVE Info), it also provides scientific documentation with unique photos of alpha ventus, selected research projects and 3D animations.

The alpha ventus test field is also presented online, providing a comprehensive overview of the construction and operation of the test field as well as the latest news.