Comparative Assessment of Direct Drive High Temperature Superconducting Generators in Multi-Megawatt Class Wind Turbines B. Maples, M. Hand, and W. Musial NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. Technical Report NREL/TP-5000-49086 October 2010 Contract No. DE-AC36-08GO28308 Comparative Assessment of Direct Drive High Temperature Superconducting Generators in Multi-Megawatt Class Wind Turbines B. Maples, M. Hand, and W. Musial Prepared under Task No. WER8.1030 NREL is a national laboratory of the U.S. Department of Energy, Office of Energy Efficiency & Renewable Energy, operated by the Alliance for Sustainable Energy, LLC. National Renewable Energy Laboratory Technical Report 1617 Cole Boulevard NREL/TP-5000-49086 Golden, Colorado 80401 October 2010 303-275-3000 • www.nrel.gov Contract No. DE-AC36-08GO28308 NOTICE This report was prepared as an account of work sponsored by an agency of the United States government. Neither the United States government nor any agency thereof, nor any of their employees, makes any warranty, express or implied, or assumes any legal liability or responsibility for the accuracy, completeness, or usefulness of any information, apparatus, product, or process disclosed, or represents that its use would not infringe privately owned rights. Reference herein to any specific commercial product, process, or service by trade name, trademark, manufacturer, or otherwise does not necessarily constitute or imply its endorsement, recommendation, or favoring by the United States government or any agency thereof. 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Table of Contents Introduction ..................................................................................................................................... 1 Background ................................................................................................................................. 1 Objective ..................................................................................................................................... 2 Approach ..................................................................................................................................... 2 The NREL Cost and Scaling Model ............................................................................................... 3 History ......................................................................................................................................... 3 Early Version Cost and Scaling Model Description ................................................................... 4 Description of Cost and Scaling Model Improvements .............................................................. 5 General..................................................................................................................................... 5 Low Speed Shaft ...................................................................................................................... 5 Direct Drive Generator ............................................................................................................ 6 Main Frame.............................................................................................................................. 7 Drive Train Efficiency Curves ................................................................................................ 8 Industry Power Curve Data ..................................................................................................... 8 Model Inputs ................................................................................................................................... 9 Turbine Design Parameters ......................................................................................................... 9 AMSC Supplied Preliminary Designs ....................................................................................... 10 Wind Characteristic Input Parameters ....................................................................................... 11 AMSC Preliminary Design Comparison ...................................................................................... 11 Assumptions for Comparison .................................................................................................... 11 Component Comparisons .......................................................................................................... 12 Drive Train/Nacelle Assembly .............................................................................................. 12 Generator ............................................................................................................................... 13 Main Frame............................................................................................................................ 15 Low Speed Shaft .................................................................................................................... 17 Gear Box ................................................................................................................................ 18 System Comparisons ................................................................................................................. 19 Drivetrain Cost Of Energy ..................................................................................................... 20 Total Levelized Cost Of Energy (LCOE) .............................................................................. 22 Conclusions and Recommendations ............................................................................................. 23 References ..................................................................................................................................... 26 Appendix A. Fixed Charge Rate Calculation .............................................................................. 29 Appendix B. Sample cost and scaling model output with LCOE calculation ............................. 30 Appendix C. PMDD generator calculations ................................................................................ 33 iii Table of Figures Figure 1: Drivetrain efficiencies for various drivetrain designs from 6% to 100% of rated power............................................................................................................................. 8 Figure 2. Rotor, nacelle, and tower mass for AMSC preliminary designs ranging from 3.1 to 10 MW. .................................................................................................... 10 Figure 3. Rotor, nacelle, and tower cost for AMSC preliminary designs ranging from 3.1 to 10 MW. ............................................................................................................. 10 Figure 4. Comparison of overall drive train mass for geared, PMDD, and AMSC turbines. .... 12 Figure 5. Comparison of overall drive train cost for geared, PMDD, and AMSC turbines. ...... 13 Figure 6. Comparison of generator mass for geared, PMDD, and AMSC turbines. .................. 14 Figure 7. Comparison of generator cost for geared, PMDD, and AMSC turbines. ................... 15 Figure 8. Comparison of main frame mass for geared, PMDD, and AMSC turbines. .............. 16 Figure 9. Comparison of main frame cost for geared, PMDD, and AMSC turbines. ................ 17 Figure 10. Comparison of low speed shaft mass for geared, PMDD, and AMSC turbines. ........ 17 Figure 11. Comparison of low speed shaft cost for geared, PMDD, and AMSC turbines. ......... 18 Figure 12. Gearbox masses for turbines 3-10 MW. ..................................................................... 18 Figure 13. Gearbox costs for turbines 3-10 MW. ......................................................................... 19 Figure 14. Efficiency differences between analyzed drivetrains ................................................. 21 Figure 15. Comparison of levelized drive train costs for geared, PMDD, and AMSC turbines. 22 Tables Table 1. Overarching turbine parameters used in all three design types. ................................... 9 Table 2. Rotor, nacelle, and tower mass breakdown for AMSC supplied turbines. ................. 11 Table 3. Wind characteristic input parameters used for all three drivetrain configurations. .... 11 Table 4. Annual energy production in gigawatt hours .............................................................. 21 Table A-1. Offshore wind power project financing scenarios .....................................................