Offshore Wind Farm Construction: Easier, Safer and More Cost Effective

Converting wind energy into a useful form of energy is one of the fastest growing alternative sources of energy in the present and foreseeable future. At the end of 2009, worldwide nameplate capacity of wind-powered generators was 159 gigawatts (GW). Energy production at onshore, near shore and offshore locations was 340 TWh, which is about 2% of worldwide electricity usage, and has doubled in the past three years and will continue to grow substantially. This growth comprises not only more wind farms, but wind mills with more capacity as well [1–3]. To achieve this growth, (heavy) lift companies and offshore contractors meet various challenges. Since primary cost for producing wind energy is construction, with up to 10 lifts per wind mill, a very competitive environment has been created in which efficient logistic and lifting operations, flexibility, avoiding damage to loads and safety are paramount [4,5]. Appropriate lifting gear provides an essential tool to meet these challenges; especially at offshore locations. Currently, steel wire ropes and grommets are extensively being used as lifting gear during the construction of wind farms, with its low cost being the key driver. But its weight together with the risk for damage to loads and injuries to operators are serious concerns. Synthetic slings, especially those made from polyester fiber, have gained popularity as a way to overcome these concerns. But, such slings are very sensitive to damage, hence its value and risk-avoidance is more and more being questioned; especially considering currently applicable legislation such as the European Machinery Directive 2006/42/EC [6]. With the introduction of high performance fibers, such as Dyneema® (Ultra-High Molecular Polyethylene (UHMwPE) fiber), not “just another synthetic fiber” has been introduced. The use of this UHMwPE fiber in protective sleeves and load bearing constructions holds the characteristics to overcome the concerns of the traditional materials as it has been proven by well-respected lifting companies. Since durability of a synthetic sling is largely determined by the performance of the protective sleeves, this paper comprehensively presents the abrasion, cut and tear resistance improvement created by sleeves made with fibers such as Dyneema®. In combination with its functionality in load bearing constructions and the key elements of the European Machinery Directive 2006/42/EC, this paper proves that Ultralift® roundslings made with Dyneema® provide not only safer and easier but also more cost effective construction (logistics and lifting) operations. So, slings made with Dyneema® have been entrusted to meet the lifting challenges of today and tomorrow.