Quantifying O&M savings and availability improvements from wind turbine design for maintenance techniques

Design for maintenance has the potential to significantly reduce the cost of offshore wind energy. This paper shows the results of an O&M cost and availability analysis when different design for maintenance techniques are applied to wind turbines. The design for maintenance techniques considered, reduce repair times and the need for jack up vessels as well as introducing redundancy to the power train of the wind turbines. A detailed lifetime O&M cost and availability model is used in this analysis and populated with empirical operational and cost data from a population of ~350 offshore wind turbines from between 5 and 10 offshore wind farms throughout Europe. A base line availability and O&M cost per MWh are obtained from the model and input data, these inputs are then adjusted based on different design for maintenance techniques. The subsequent outputs from the model using the adjusted inputs allow for the quantification of O&M savings and availability improvements for the different design for maintenance techniques. These design for maintenance techniques may have different effects on different wind turbine types. As a means of investigating this, a comparison of the O&M saving and availability improvements will be carried out for both a DFIG turbine type and a PMG FRC turbine type. For a hypothetical site located 50km offshore using a verified O&M model and empirical operational and cost data this paper shows that the overall combination of these improvements reduces the total O&M cost by ~16% for the DFIG and ~17% for the PMG FRC. It also shows that in both turbine types the largest reduction in O&M costs are seen to come from the elimination of the need for heavy lifting vessels.