- Category: Articles

Frictional forces due to land properties (such as terrain height and the physical structure of vegetation (height, density, etc.)) influence the strength and direction of the wind at the surface. Therefore, reliable and timely data and information on such properties is critical to accurately assess the availability of wind resources. However, assessment of wind energy resources is a highly complex and time-consuming process, ultimately relying on consistent, accurate and timely models and input data. Yet, in many cases, especially in forested sites, surface data on roughness and forest height is inaccessible or simply not available, and this may impact the ability of wind modellers to accurately assess wind resources.
By Torsten Bondo, Business Development Manager, DHI, Denmark
- Category: Articles

The offshore wind market is accelerating rapidly as global political pressure mounts to transition to clean energy sources. New sites are being selected, many of which are in deep-water locations. This is possible as several floating foundations are now proven in full-scale offshore trials, so building on a commercial scale is theoretically achievable. It is clear that floating offshore wind represents the next frontier, but which floating structure will deliver the best levelised cost of energy? It is as much about the local port infrastructure as it is the floating foundation. With multiple solution providers developing various models across four main structure types, this article outlines some of the factors for consideration and explains how independent naval architecture consultancy can support informed decision-making.
Mark Goalen, Director of Offshore Engineering, Houlder, UK
- Category: Articles

Leading edge erosion of wind turbine blades has been identified as the main factor substantially reducing both blade lifetimes and energy output over time. Field repairs are costly due to lost availability and challenging access, work and weather conditions [1]. During the wind farm planning stage, the lack of validated methods to estimate the overall cost of erosion causes uncertainty in the investment decisions, again raising the levelised cost of energy.
By Raul Prieto, Charlotte Hasager, Sara C. Pryor, Marijn Veraart, David C. Maniaci, Jakob I. Bech, Maral Rahimi, Fernando Sánchez López, Bodil Holst and Sandro di Noi
- Category: Articles

Lightning damage stubbornly remains a major O&M expense for owner-operators in cost and frequency. Damage such as blade skin punctures, shell delamination, split trailing edges, and (less frequently) catastrophic damage to wind turbine blades is costly to repair and causes undesirable downtime. Even with the current mitigation systems in place, it is estimated that lightning damage costs the wind industry more than $ 100 million each year. Strikes are inevitable, and their frequency will only grow as turbines get taller, more onshore and offshore wind farms are developed, and our climate continues to change.
By Neal E. Fine, John A. Cooney and Christopher S. Szlatenyi, Arctura, Inc., USA
- Category: Articles

Wind turbine (WT) designers and wind farm developers are seeking improved tools for maximising power generation while minimising the life-cycle cost of their onshore and offshore projects. The industry recognises that key decisions required to achieve the lowest levelised cost of energy include wind farm: 1) site and WT model selection, 2) spacing or WT density, and 3) active control of each turbine’s operation considering blockage generated by interference of multiple turbulent wakes with the surroundings. Although the current consensus calls for spacing WTs at least seven rotor diameters apart, each WT design can have a different network effect that varies between sites having unique topography, wind patterns and other atmospheric conditions. As a consequence, designers with multiple site, hardware and network configuration options cannot rely on empirical rules of thumb to achieve optimal wind farms. Instead, design decisions should be guided by innovative computational fluid dynamics tools.
By Jacob Krispin and Joel Balbien, Vorcat, USA
- Category: Articles

The increasing length of recent large rotor blades with their growing mass and static moments brings new challenges with regard to the design of their blade connections. Since 2008, WINDnovation has designed approximately 250 blades and blade connections with very different individual solutions.
By Frank Seewald, Torsten Sadowski, Roland Stoer, WINDnovation Engineering Solutions, Germany
- Category: Articles

Enercon is the first wind turbine manufacturer to break entirely new ground in handling rotor hubs on the assembly line – instead of using cranes and slings, Enercon relies on a compact turning table from RUD Ketten Rieger & Dietz, based in Aalen (Baden-Württemberg, Germany).
By Sabrina Deininger
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