Structural Integrity of Offshore Wind Turbines: Oversight of Design, Fabrication, and Installation - Special Report 305 (2011)

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Executive Summary The U.S. Department of the Interior’s Bureau of Ocean Energy Man- agement, Regulation, and Enforcement (BOEMRE) is responsible for the orderly, safe, and environmentally responsible development of off- shore renewable energy on the outer continental shelf (OCS). The com- mittee that authored this report was tasked with reviewing BOEMRE’s proposed approach to overseeing the design of offshore wind turbines for structural integrity. The committee was asked to review the applicability and adequacy of standards and practices that could be used for the design, fabrication, and installation of offshore wind turbines. It was also asked to review the role of third-party certified verification agents (CVAs) and the expertise and qualifications needed to carry out the role of a CVA. Because of earlier development of offshore wind energy in Europe, European countries have taken the lead in matters related to the regulation, installation, and operation of offshore wind farms. Their national regula- tions recognize and incorporate International Electrotechnical Commis- sion (IEC) standards for the design of offshore wind turbines. Because the IEC standards, on their own, do not cover all aspects of the design and construction of offshore wind turbines, they have generally been supplemented by national regulatory requirements, other standards and guidelines, and recommended practices developed by industry. The committee found that even such packages of regulations, standards, and guidelines have clear deficiencies, particularly if applied to planned instal- lations along the U.S. East Coast and Gulf of Mexico. Safety and environmental performance are the basis for most U.S. reg- ulations governing the offshore oil and gas, maritime, and civil infrastruc- ture industries. The committee found that the risks to human life and the environment associated with offshore wind farms are substantially lower 1 

2 Structural Integrity of Offshore Wind Turbines than for these other industries, because offshore wind farms are primar- ily unmanned and contain minimal quantities of hazardous substances. This finding implies that, in remedying deficiencies in standards and practices, an approach with significantly less regulatory oversight may be taken for offshore wind farms than for the other industries mentioned above. The U.S. government, however, having expressed a policy com- mitment to the development of alternative energy sources including offshore wind, has a vested interest in the success and performance of off- shore wind turbines. On this basis, the committee recommends that the BOEMRE regulations go beyond safety and environmental risks and also consider policy consequences. Because further improvements in cost, reliability, and efficiency are needed if offshore wind is to be a competi- tive energy source, regulations need to allow for innovative technologies and encourage the introduction of novel concepts. To facilitate the orderly development of offshore wind energy and support the stable economic development of this nascent industry, the United States needs a set of clear requirements that can accommodate future design development. There is a sense of urgency, because plan- ning and design efforts for a number of offshore wind farms to be located in state waters and on the OCS are already under way. The committee recommends that BOEMRE immediately develop a set of requirements that establish goals and objectives with regard to structural integrity, environmental performance, and energy generation. Under this approach, industry would be responsible for proposing sets of standards and recommended practices that meet the performance requirements established by BOEMRE. It is anticipated that classification societies and standards development groups will be interested in offering packages of standards and guidelines that meet the BOEMRE performance requirements. BOEMRE should be prepared to review the packages, iden- tify their deficiencies, and approve them. Such preapproved standards and guidelines will expedite the regulatory review process and provide indus- try with a well-defined approach for proceeding with the development of offshore wind turbines on the OCS. A developer should also be permitted to submit a package of standards and guidelines on a project-specific basis, with the understanding that a CVA will first review and agree to the pro- posed approach. 

Executive Summary 3 Detailed findings and recommendations on CVAs can be found in Chapters 5 through 7. The committee was asked to review the role of CVAs (Chapter 5). The committee notes that such third-party review should be an integral part of the regulatory process. The review should include assess- ment of the blades, turbine control systems, towers and foundations, infield cables and export cables, and ancillary structures such as the elec- tric service platforms. Oversight responsibility should include design, fab- rication and manufacturing, transportation, and installation. Consistent with current international practice, type and project certification may be integral to the wind turbine project and used in a third-party design review. The third-party review team should verify that the design and instal- lation meet the BOEMRE goal-based requirements as well as the stan- dards and guidelines applicable to that particular project. In periodic reports to BOEMRE, the third-party reviewers should describe the extent of their review, indicate the level of compliance, and clearly identify any discrepancies or concerns. Responsibility for final approval should rest with BOEMRE. The committee was also asked to assess the expertise and qualifications needed by potential CVAs (Chapter 6). In evaluating the qualifications of potential CVAs, BOEMRE should seek organizations and individuals that are independent and objective, have the necessary expertise, have a man- agement structure with well-defined roles and responsibilities with over- sight by a registered professional engineer, and have an auditable quality plan and record-keeping processes. The committee recommends that BOEMRE approve CVAs on a project-specific basis as opposed to having a list of preapproved CVAs. BOEMRE should actively manage the CVA process for offshore wind facilities by disseminating lessons learned from the CVA process to promote best practices to the industry. The success of offshore wind energy in U.S. waters may depend in part on how quickly and effectively BOEMRE develops the regulations and oversees compliance. It is critical that BOEMRE establish within the agency a substantial core competency with the capacity and expertise to lead the development of the performance-based standards, review the rules and guidelines submitted by third-party rulemaking bodies and developers, and review the competency of proposed CVAs. BOEMRE should be fully engaged in the national and international processes for 

4 Structural Integrity of Offshore Wind Turbines developing standards for offshore wind turbines, particularly in stan- dards and guidelines issued by the IEC technical committees and other relevant national and international committees. BOEMRE should also consider creating an expert panel to provide feedback and guidance for the initial offshore wind development projects as a means to fill the expe- rience gap for both industry and regulators.