Techno-Economic Implications of Electrical Machine Scaling for Wave Energy Converters

Aryana Nakhai, Ben McGilton

Research output: Contribution to conferencePaperpeer-review


The sizing of an electrical machine for a Wave Energy Converter (WEC) can have a substantial impact on the overall sizing, cost, and rating of the device. An electrical generator is typically part of the power take-off system, which is the mechanism by which the energy absorbed by the prime mover is transformed into usable electrical energy. For practically all WECs, the rate of change of actuation is predominantly determined by the wave resource (i.e., the wave height and frequency), and devices will see a sinusoidal varying velocity according to the wave conditions. The same can then be said for both directly and indirectly coupled power take-offs with electrical generators. This techno-economic study investigates electrical machine scaling and associated cost implications through core machine design theory, manufacturer data, supporting literature, and the Reference Model Project sponsored by the U.S. Department of Energy. The Reference Model Project was a partnered effort to develop open-source marine energy point designs as reference models to benchmark marine energy technology performance and costs, methods for design and analysis of marine energy technologies, estimations for capital costs, operational costs, and levelized cost of energy. The results from this study show torque is directly related to (1) the physical size of the machine required to increase the air-gap sheer stresses, (2)the amount of active material, (3) the support structure, (4) bearing size and rating, and (5) offshore cable rating, all of which have a significant effect on overall system costs in terms of both capital and operational expenditures. This paper aims to be a critical benchmark in helping determine an 'optimal' nameplate rating for wave energy devices and their associated power take-offs. With an optimized rating and sizing process, WEC costs can be reduced and overall performance can be improved.

Original languageAmerican English
Number of pages6
StatePublished - 2022
Event2022 OCEANS Hampton Roads, OCEANS 2022 - Hampton Roads, United States
Duration: 17 Oct 202220 Oct 2022


Conference2022 OCEANS Hampton Roads, OCEANS 2022
Country/TerritoryUnited States
CityHampton Roads

Bibliographical note

See NREL/CP-5700-83695 for preprint

NREL Publication Number

  • NREL/CP-5700-85181


  • cables
  • capacity factor
  • cost
  • electrical machine
  • force
  • induction
  • mass
  • permanent magnet
  • power
  • PTO
  • rating
  • scaling
  • torque
  • wave energy
  • WEC


Dive into the research topics of 'Techno-Economic Implications of Electrical Machine Scaling for Wave Energy Converters'. Together they form a unique fingerprint.

Cite this