Amendment_0002_Question_and_Answer.pdf

Question and Answer

E17PS00128

Amendment 0002

August 16, 2017

Topic 3

1. Can you elaborate or point to the "reports of corrosion and fatigue problems causing premature shutdown or diminished performance"?

a. There have been several recent studies that suggest that corrosion and fatigue are major factors in the design life of offshore wind turbine foundations. A previous TAP study #710, available on BSEE web site, provides a good discussion of fatigue and corrosion issues. Failing to properly design for these factors may lead to premature shutdown or diminished performance.

2. Would addressing the "costs and benefits of a longer design life" of wind turbine foundations be independent of the wind turbine generator and should we estimate how WTGs will evolve over the first-installed generation of WTGs compared with WTGs 25- 30 years or more later?

a. Yes, the study should focus on offshore wind turbine foundations and towers, not the wind turbine generators. The study should anticipate the size and models of WTGs expected to be installed in the US OCS within the next 10 to 20 years.

3. Objective stated is to study how the wind turbine foundation is affected by the corrosion and fatigue issues and see whether longer life is feasible - Is the study meant to be generic or some of specific key aspects of corrosion and fatigue?

a. The main focus of the study should be the design life of the structures and how corrosion and fatigue effect the design life, and what measures can be taken to extend design life considering these main factors. It is not meant to be a comprehensive study of fatigue and corrosion, but more of an assessment of how these factors affect design life and to assess the feasibility and practicality of extending design life with respect to these factors.

4. Is this white paper intends to address specific US marine conditions or be applicable for global locations? Accordingly met ocean conditions will influence the fatigue considerations - wind/wave directionalities and probabilities.

a. This study should focus on projects on the US Outer Continental Shelf, where BOEM has jurisdiction. This should include Atlantic, Pacific, and Gulf of Mexico waters.

5. How many number of studies be allowed to propose to address on number of environment and design parameters that affect life of the foundation?

There are many but to mention a few here are:

a. for corrosion prevention methods for structures in splash zone (coating), cathodic protection systems in submerged zone (anodes), internal corrosion issues for large structures like Monopile, Gravity based structures etc.,

b. for fatigue: design parameters for joint, weld options that improve design life, dynamics response with wind turbine frequencies, cast Vs welded node options, type of analysis opted - spectral / time domain.

This study is not meant to be a comprehensive study of fatigue and corrosion, but more of an assessment of how these factors affect design life and to assess the feasibility and practicality of extending design life with respect to these factors.

6. Does the 5-page limit exclude the cover letter and cover sheet?

It excludes the cover letter and cover sheet.