Welcome to Task 23 Summary Page

Offshore Wind Energy
Technology Deployment

Riso National Laboratory, Denmark and
National Renewable Energy Laboratory (NREL) United States.


OA Representatives:
Jørgen Lemming
Wind Energy Dept
Risø National Laboratory
P.O. Box 49
4000 Roskilde
Tel: +45 46 77 50 86
Email: joergen.lemming@risoe.dk

Walt Musial
National Wind Technology Center
National Renewable Energy Laboratory
1617 Cole Blvd
Golden, Colorado 80401
United States
Tel +1 303 384-6956
Mobile +1 303 349-9819
Fax +1 303 384-7055 - fax
Email: Walt Musial

Web Site: Task 23 Offshore Wind Energy Technology Deployment

Statistics show a global wind energy capacity in 2008 approaching 1% of the global electricity capacity. Estimates predict a huge increase in wind energy development over the next 20 years. Much of this development will be offshore wind energy.

Installing wind turbines offshore has several advantages over onshore development. Onshore, difficulties in transporting large components and opposition due to various siting issues, such as visual and noise impacts, can limit the number of acceptable locations for wind parks. Offshore locations can take advantage of the high capacity of marine shipping and handling equipment, which far exceeds the lifting requirements for multi-megawatt wind turbines. In addition, the winds blow faster and more smoothly at sea than on land, yielding more electricity generation per square meter of swept rotor area. On land, larger wind farms tend to be in somewhat remote areas, so electricity must be transmitted over long power lines to cities. Offshore wind farms can be closer to coastal cities and require relatively shorter transmission lines, yet they are far enough away to reduce visual and noise impacts.

Recognizing the interest and challenges of offshore development of wind energy, IEA Wind Task 11 Base Technology Information Exchange sponsored a Topical Expert Meeting (TEM 43) in early 2004 in Denmark on Critical Issues Regarding Offshore Technology and Deployment. After the meeting, the IEA Wind ExCo approved Annex 23 (Task 23) to the Implementing Agreement as a framework for holding additional focused workshops and developing research projects. In 2008, 10 countries had chosen to participate in this task, and many research organizations in these countries are sharing their experiences and conducting the work.

This annex will give the participants an overview of the technical and environmental assessment challenges encountered in offshore applications and help them to understand the areas of further R&D needed. The objectives of this annex are:

a To conduct R&D activities of common interest relating to wind turbine facilities operating in offshore environments in order to reduce costs and uncertainties.
b To organize several workshops relating to critical research areas relating to offshore wind deployment issues, including technical research on deeper water structures. The goal of the workshops is to identify R&D gaps in research areas, publish proceedings, and identify specific joint research areas needing further investigation.

This annex has two subtasks with an operating agent for each subtask.

Sub-task 1: Experience with critical deployment issues
A summary of the workshops described below will be published in 2009.

Research Area 1, Ecological Issues and Regulations, held a workshop in February 2008, attended by more than 20 experts. The workshop objectives were to provide a state-of-the-art overview of knowledge about impacts of offshore wind turbine systems on the marine environment; to get a picture of the consequences for regulatory frameworks, such as requirements for environmental impact assessments (EIAs) and protection measures for nature reserve areas; and to generate ideas for frameworks on how results of nature research can be used to (re)formulate regulations and legislation.

Research Area 2, Grid Connection, held workshops in September 2005 and in June 2007. A final workshop, Power Fluctuation, took place in 2009. The meetings focused on five issues:

Offshore wind meteorology and impact on power fluctuations and wind forecasting, behavior and modeling of high-voltage cable systems, grid code and security standards for offshore versus onshore, control and communication systems of large offshore wind farms, and technical architecture of offshore grid systems and enabling technologies.

Research Area 3, External Conditions, Layouts, and Design of Offshore Wind Farms held a workshop in December 2005 and the Task has made contributions to other workshops in 2007, 2008, and 2009. Topics included:

wake modeling and benchmarking of models,
marine boundary layer characteristics,
meteorological and ocean data and loads exchange of data to develop and verify computational models and to understand the physics of wakes and meteorological backgrounds.

Sub-task 2: Technical research for deeper water
A final report on the work described below will be issued in 2009.

This work was begun to address technical issues associated with deeper-water implementation of offshore wind energy. The working group known as the Offshore Code Comparison Collaborative (OC3) included the analysis of shallow, transitional, and deep-water offshore wind turbine concepts. Currently, conservative offshore design practices adopted from marine industries are enabling offshore wind development to proceed. But if offshore wind energy is to be economical, reserve margins must be quantified, and uncertainties in the design process must be reduced so that appropriate margins can be applied. Uncertainties associated with load prediction are usually the largest source and hence the largest risk.

The OC3 project is benchmarking system-dynamics models (i.e., design codes) used to estimate offshore wind turbine dynamic loads. To test the offshore wind turbine system-dynamics models, the main activities of the OC3 project are (1) discussing modeling strategies, (2) developing a suite of benchmark models and simulations, (3) running the simulations and processing the simulation results, and (4) comparing the results. But these activities fall under the following much broader objectives:

Assessing the accuracy and reliability of results obtained by simulations to establish confidence in the predictive capabilities of the models Training new analysts to run and apply the models correctly Identifying and verifying the capabilities and limitations of implemented theories Investigating and refining applied analysis methodologies Identifying further R&D needs. For more information, please visit the Task 23 web site.