Optimization and Comparison of Modern Offshore Wind Turbine Generators Using GeneratorSE 2.0: Preprint

As the offshore wind industry keeps growing at a rapid pace, developers are bracing themselves for a huge demand in critical rare-earth metals that are already threatening a vulnerable supply chain. The wind energy industry is addressing this problem by investing in modern generator technologies employing magnets with reduced rare-earth content and high-field magnets enabled by rare-earth-free superconductors. In this paper we introduce the National Renewable Energy Laboratory's newly advanced GeneratorSE 2.0, which is a design and optimization tool that was developed to investigate the feasibility of such modern generators. Two direct-drive generator topologies with different magnet materials and mounting arrangements are investigated: an outer-rotor, V-shaped interior permanent magnet generator, and an inner-rotor normally conducting armature, paired with a low-temperature superconducting field with racetrack coils. These technologies were evaluated for a range of power ratings between 15-25 MW, which represent the next generation of offshore wind energy turbines for both fixed-bottom and floating applications. The analyses indicate a new trend favoring the low-temperature superconducting technology for the direct-drive system.