Six Sigma Quality Methodology Utilised

Clipper Windpower installed its first production ‘Liberty’ turbines in mid-2007 and since that time hundreds of turbines have been assembled at project sites around the USA. However, a couple of ‘teething troubles’ cropped up with the blades, which are manufactured at Clipper’s Brazilian supplier. In 2007 Clipper identified a blade spar deficiency that required dozens of field reinforcements to assure a 20-year blade life. After small cracks appeared in the surface skin of several blades in 2008 the company engaged upon a scientific process to identify the root cause and fix hundreds of blades in the field. The procedure included an intricate curing process necessary to enable the fixes to take place in temperatures well below zero.

By Drew Robb, Robb Editorial, USA

Foundation Work on the next Danish Offshore Wind Farm

In April 2009, offshore work started on the Rødsand 2 wind farm, in the south of Denmark. A concrete gravity-based foundation is to be used, giving a 30% price reduction when compared to current offshore monopile foundation systems used in the UK. This article describes the project and the current stage of the construction works.

By Jens H.M. Larsen, Grontmij │Carl Bro A/S, Denmark

Modelling of the Utsira Wind/Hydrogen Demonstration System in Norway



A wind / hydrogen demonstration project located at the island of Utsira, about 20km off the west coast of Haugesund in Norway, was officially launched by StatoilHydro and Enercon in July 2004. The main objective of this study, part of a joint venture between SgurrEnergy, the University of Strathclyde and the Institute for Energy Technology in Norway, was to evaluate the technical concept being demonstrated, both with respect to system design and operation. The method chosen was to use actual operational data to validate a set of wind/hydrogen-energy system modelling tools using HYDROGEMS and TRNSYS. This article describes how calibrated system models were used in system simulations to identify improved system designs and control regimes. The article also presents the results of the simulations performed to optimise the design of the plant in order to guarantee a 100% stand-alone operation.

By Arnaud Eté, SgurrEnergy, UK

Texas Company Introduces ISO-e Technology

ISO-e refers to a new design and manufacturing process that is currently being developed at Greenward Technologies, Inc. It was originally conceived as part of an effort to drive down the steel content of the tower and array frame for the company's Wind Turbine Quad Array concept. It has the potential to reduce the steel content of a conventional tower with a specific rating while greatly increasing the tower's survivability in very high winds, and to uprate existing tower designs to a higher power rating. It does this by combining a relatively thin inner steel shell with a much thicker outer jacket of a proprietary concrete–polymer composite. Residual strain energy is shared equally and oppositely between the inner shell and the outer jacket, and the name ‘ISO-e’ refers to this optimal distribution of strain energy.

By Ed Salter, CTO, Chairman, and Co-founder, Greenward Technologies, USA