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P50 20-year annual average value = $25.96/kW/yr Michigan; $18.66/kW/yr Montana and consists of turbine specific and minor balance of plant O&M costs. It does not represent total OpEx costs.

Difference in O&M costs estimate is due to turbine and project specific factors. The Baseline turbine used for the Montana location had a higher generating capacity than Michigan, which resulted in a lower cost per kW.

The resulting system LCOE calculated for the Baseline turbine in Michigan and Montana project locations were $42.54/MWh and $32.80/MWh, respectively. We then isolated subsequent analysis on the blade specific contributions to the LCOE calculation to quantify impacts of alternative pathways to achieve supersized blades considered in this study. Blade specific LCOE as a percentage of overall system LCOE was calculated to be 17% for the Michigan project and 14% for the Montana project. These percentages were then used to extrapolate the impact of blade LCOE to system LCOE.

A.1 Segmented blade cost modification for field assembly DNV GL utilized the NREL WISDEM model to calculate turbine and project assembly costs for the Baseline turbine model. For larger turbine models that used segmented blades, we modified the WISDEM model to account for an additional field crew and equipment needed to assemble segmented blades prior to rotor assembly. We added two small capacity support cranes needed to manipulate and stage the blade segments onto assembly fixtured/jigs to ensure alignment and enable the assembly process. Crane costs included equipment, fuel, maintenance, and an operator. We assumed a 5-person work crew, with two support cranes could assemble one mechanical (bolted) segment in four hours. We assumed the process is roughly similar to making the blade/hub bolted connection and consists of staging/preparation, installation, and alignment, installing fasteners and torque checks, and post-assembly quality assurance checks. We assumed the blade segment assembly crew would work in advance of the turbine assembly crew such that there would always be a set of assembled blades ready for turbine erection. The resulting cost estimate is ~$15,000 per segmented joint. This value was doubled for blades with two segmented joints.

A.2 OpEx cost modification for segmented blades Given our assumption of a mechanical joint with fasteners as the method for assembling segmented blades, we developed estimates of increased blade specific O&M costs to include in LCOE analysis. We assumed internal blade joint and fastener inspections would be performed as part of annual turbine service, resulting in increased time and cost of this inspection. We assume contracted specialists perform the inspections who have specialized training and utilize specialized tools. Work is performed up tower and no need for a high capacity crane to lower the rotor or blades to the ground. Table A-1 below summarizes the assumptions and calculations to derive the incremental additional cost per turbine per year for performing blade segment inspections.

DNV GL – Document No.: 10080081-HOU-R-01, Issue: C, Status: FINAL www.dnvgl.com

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Supersized wind turbine blade study  

R&D pathways for supersized wind turbine bladesSupersized wind turbine blade studyLawrence Berkeley National LaboratoryDocument Number: 1008...

Supersized wind turbine blade study  

R&D pathways for supersized wind turbine bladesSupersized wind turbine blade studyLawrence Berkeley National LaboratoryDocument Number: 1008...

Profile for dnvgl