- Category: Articles
Issues for Planning of Offshore Wind Farms
Satellites orbiting and observing Earth offer potential for the offshore wind farm industry. Of particular interest are the images from the Synthetic Aperture Radars (SAR) on board satellites belonging to the European Space Agency (ESA): the satellites ERS-1 and ERS-2 from 1992 to present and Envisat from 2002 to present. In the April/May 2005 issue of Windtech International we published an article about this topic. The current article describes more specific issues concerning offshore wind farms.
By Merete Bruun Christiansen, Charlotte Bay Hasager, Risø National Laboratory, Denmark and Frank Monaldo, Johns Hopkins University, USA
- Category: Articles
Prevention of Operational Hazards and Enhancing the Ongoing Maintenance
Monitoring of the condition of rotor blades is performed visually by experts every one to two years, but it is very subjective and superficial. As is common in energy facilities, the increases in stress resulting from greater blade size, coupled with the rising prices for rotor blades, call for a new approach. The continuous monitoring of the status of highly stressed parts offers preventative maintenance as well as troubleshooting of existing problems.
By Dr Peter Volkmer, Managing Director, IGUS, Germany
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- Category: Articles
The Development of an Ultra High-Performance Wind Turbine
Small wind turbines are used in situations that are quite different from those of large turbines, and it is the small turbine market that is now experiencing the entry of new companies seeking to benefit from its expected growth. While a growing market is good news, it has been argued that the levels of performance and safety need to be greatly improved, and prices drastically reduced, before small wind turbines are accepted by society in general. In this article, the author describes the concept of the Airdolphin.
By Ryosuke Ito, President, Zephyr Corporation, Japan
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- Category: Articles
Reducing the costs of operation and maintenance offshore
ICD Projects designed a motion compensated platform following a request from the Norwegian shipowner FOB Shipping for an active heave compensated crane.
- Category: Articles
A Secret to Success for Offshore Wind Turbines
When wind turbines are placed offshore, we introduce a longer and therefore less stiff structure in an environment with more loads than onshore. These loads will cause significantly more motions and stress variations in the structure, making it much more sensitive to fatigue. However, the back and forth motion of the structure’s vibration does have a positive effect. When the tower top moves forward, the turbine feels extra wind, which creates extra loads on the blades pushing against the wind. Moving back, the same principle applies the other way round. This phenomenon is called aerodynamic damping and has a significant effect on a structure during its lifetime. In order to benefit from this phenomenon, it is essential to understand it.
By David Cerda Salzmann and Jan van der Tempel, Delft University of Technology Offshore Engineering, the Netherlands
- Category: Articles
Sluggish Offshore Wind Faces Delays before Tapping Major Potential
Global component shortages, rising project costs and the risks of ‘offshore’ have hampered a much-anticipated Pan-European offshore wind market. These market inhibitors have provided a reality check for the industry and have stalled plans for new offshore entrants. Meanwhile the US offshore market, which does have some high profile projects in the works, has yet to take off and the Asia Pacific market is still years away from large-scale offshore development.
By Keith Hays, Director of Global Wind Research, Emerging Energy Research, USA
- Category: Articles
Design Considerations and Approaches
In the pursuit to increase the megawatts per surface area and to maximise the megawatts/hour output per project dollar the size of wind turbines has been increasing steadily. To capture the higher winds and to accommodate the larger rotor diameter the hub heights have also been steadily increasing. Wind park prospectors and promoters are now required to measure at greater heights than ever before. From 40 to 50 then to 60 metres, the minimum level now seems to be the 80-metre level. The traditional tubular anemometric masts have not been able to go beyond the 60-metre level without becoming inordinately heavy. However, by revisiting the 250-year old Euler column equations and by using the aircraft design approach, a new lightweight structure is now able to achieve the 80-metre measurement at a fraction of the cost of the traditional lattice tower.
In the pursuit to increase the megawatts per surface area and to maximise the megawatts/hour output per project dollar the size of wind turbines has been increasing steadily. To capture the higher winds and to accommodate the larger rotor diameter the hub heights have also been steadily increasing. Wind park prospectors and promoters are now required to measure at greater heights than ever before. From 40 to 50 then to 60 metres, the minimum level now seems to be the 80-metre level. The traditional tubular anemometric masts have not been able to go beyond the 60-metre level without becoming inordinately heavy. However, by revisiting the 250-year old Euler column equations and by using the aircraft design approach, a new lightweight structure is now able to achieve the 80-metre measurement at a fraction of the cost of the traditional lattice tower.
By Pierre-Guy Charette, Ohmega Group, Canada
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