Ballast Mass of 5MW OC3, Phase IV

[Garrett.Hanrahan]

Dear Dr. Jonkman

I wanted to ask about some of the specs of the spar buoy based turbine described in the phase IV of the OC3.

What is the mass of the ballasted material needed to stabilize the turbine? By my simple calculations I have gotten nearly 6,000,000 kg, but that seems a bit unreasonable. What is the material used as the ballast material?

More generally, do you have information on the mass and costs of both the gearbox and the generator for the 5MW reference turbine.

Sorry for the collection of questions. Any information that you may have on this is helpful, thank you for your time.

[Jason.Jonkman]

Dear Garrett,

Regarding the ballast of the OC3-Hywind spar, a similar question was asked in the following forum topic: viewtopic.php?f=3&t=706&p=2661.

The mass and cost of the gearbox and generator of the NREL 5-MW baseline turbine were not part of the original specification. I've seen a paper related to your question that may be helpful: viewtopic.php?f=3&t=706&p=2661, but I'm not sure if there is a paper more directly applicable. I would reach out directly to the lead author of this paper.

Best regards,

[Garrett.Hanrahan]

Thank you for the quick response. I think you posted the same link to the other topic twice. Would you mind re-sending the link to the paper that you were suggesting.
Thank you.

[Jason.Jonkman]

Oops; sorry about that! See: https://www.nrel.gov/docs/fy17osti/67444.pdf.

Best regards,