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7
Summary of Key Findings
and Recommendations
The charge of this committee was to review the proposed approach of
the Bureau of Ocean Energy Management, Regulation, and Enforcement
(BOEMRE) in overseeing the structural safety of offshore wind turbines. It
was to consider the design, fabrication, and installation of these turbines.
Specifically, the committee was charged with providing findings in three
areas: standards and practices, the role of certified verification agents
(CVAs), and the qualifications needed by CVAs. Specific findings and rec-
ommendations in these areas are given at the ends of Chapters 3, 4, 5, and
6 of this report. Those chapters should be consulted for details. The sections
below summarize the committee’s key findings and recommendations.
During its review, the committee noted that the U.S. government, hav-
ing committed to exploiting the offshore wind energy resource, has an
interest in industry performance for reasons beyond its statutory mandate
to ensure the safe, orderly, and environmentally responsible use of the
outer continental shelf (OCS). For policy reasons, it also wants to foster
the growth of the nascent U.S. offshore wind industry (see the Chapter 4
section “Regulatory Options and Policy Considerations”), which will
require setting clear regulatory expectations soon and encouraging the
innovation that will help make offshore wind power generation more eco-
nomically competitive with other sources of electricity.
FINDING: SAFETY AND THE ENVIRONMENT
The risks to life safety and the environment and the consequences associ-
ated with those risks are much lower for offshore wind plants than for off-
shore oil and gas platforms, ships, and land-based civil structures such as
buildings. Oversight of offshore wind development should take this into
127
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128 Structural Integrity of Offshore Wind Turbines
account but will also need to reflect the importance of successful and reli-
able operation of offshore wind turbines to policy goals.
FINDINGS AND RECOMMENDATIONS:
STANDARDS AND PRACTICES (TASK I)
The committee was tasked with reviewing the applicability and adequacy
of existing standards and practices for the design, fabrication, and instal-
lation of offshore wind turbines. In response to this charge, the commit-
tee reviewed the standards and guidance documents (the latter including
guidelines, recommended practices, and similar documents) that have
been developed or are under development by nongovernmental organiza-
tions, classification societies, standards-development bodies, and govern-
ment entities. It also considered ways in which BOEMRE might address
deficiencies in existing standards and guidance documents.
Applicability and Adequacy
• In reviewing existing sets of standards and guidance documents, the
committee found that many could be applied in the United States
but that no one set was complete.
Many sets of standards and guidance documents for offshore wind
turbines are available from standards organizations, classification soci-
eties, and at least one government. Many, if not most, have elements
that are relevant to the United States and can be applied to installations
in U.S. waters.
Most of these standards and guidance documents—notably, those
used in continental Europe—are detailed and prescriptive. However,
they are incomplete in that no one set covers all aspects of structural
design, fabrication, and installation. All existing standards and guidance
documents have shortcomings that will have to be overcome if they are
to be applied in the United States.
The following are some of the most important areas where existing
standards need more work for use in the United States:
– Environmental site conditions for the United States, especially storm
and hurricane conditions for the Gulf of Mexico and the East Coast.
These and other conditions—such as ice loading (for the Great
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Summary of Key Findings and Recommendations 129
Lakes) and seismic activity (especially on the Pacific coast)—would
need to be covered appropriately.
– Transparency. Methodologies for strength analysis1 differ among the
standards and guidance documents and are not always fully delin-
eated, making it difficult to compare the standards and guidance
documents against one another to determine whether they provide
equivalent safety levels, especially when applied to novel concepts.
The methodologies, assumptions, and data used for strength analy-
sis must be laid out clearly to provide the necessary transparency.
• BOEMRE’s own regulations (published in 30 CFR 285) and accom-
panying guidance are inadequate in that they do not identify spe-
cific criteria that a proposed project must meet to be approved and
gain the necessary permits.
Although regulations2 promulgated by BOEMRE require that
detailed reports for design, construction, and operation of offshore
wind turbines be submitted for BOEMRE approval, they do not spec-
ify standards that an offshore wind turbine must meet. Rather, a third
party (CVA) is asked to comment on the adequacy of design, fabrica-
tion, and installation and provide reports to BOEMRE indicating the
CVA’s assessment of adequacy. Moreover, when a general level of per-
formance such as “safe” is stipulated, no guidance is provided on how
to assess whether this level of performance has been met.
• The United States urgently needs a set of clear and specific standards
to reduce uncertainty in the requirements that projects must meet,
facilitate the orderly development of offshore wind energy, and sup-
port the stable economic development of a nascent industry.
States and private companies are developing plans for offshore wind
energy projects in state waters and on the OCS. Well-defined U.S. reg-
ulations for development on the OCS are needed (a) to provide a
resource for states as they develop requirements for projects in state
waters and (b) to supply industry with sufficient clarity and certainty on
1
Some standards and guidance documents are based on strength or limit states design; others are
based on allowable stress design. The philosophies underlying these methods are fundamentally
different. See Chapter 4.
2
30 CFR Part 285, 74 FR 81, pp. 19638-29871.
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130 Structural Integrity of Offshore Wind Turbines
how projects will be evaluated as companies seek the necessary financ-
ing. Further delays in developing an adequate national regulatory frame-
work are likely to impede development of offshore wind facilities in U.S.
waters. Moreover, developments in state waters could proceed in the
absence of federal regulations, possibly leading to inconsistent safety and
performance across projects.
Filling the Gaps
• Performance-based standards are a regulatory framework that best
meets two government objectives: (a) fulfilling BOEMRE’s mission of
overseeing the safe, orderly, and environmentally responsible devel-
opment of the OCS and (b) fostering innovation and competitiveness.
Improvements in the efficiency of offshore wind turbine installations
and reductions in capital and operating costs are needed if offshore wind
energy is to become a highly competitive renewable energy source.
Performance-based (goal-based) standards, which are gradually replac-
ing prescriptive standards in other industries (such as civil infrastructure,
offshore oil and gas, and shipping), provide the flexibility needed to
accommodate new technologies. They can be administered and modi-
fied by the regulatory bodies in a straightforward way, they clarify the
responsibilities of industry in meeting project goals, and they result in
the transparency that comes with the delineation of goals and objectives.
Recommendations
To enable timely development of U.S. offshore wind energy within a
robust regulatory framework, the following approach is recommended:
1. BOEMRE should proceed immediately with development of a set of
goal-based standards governing the structural safety of offshore
wind turbines and power platforms. These regulations should be risk-
informed (see Appendix A) and should cover design, fabrication, and
installation. Offshore wind energy is an emerging technology; there-
fore, the standards should be crafted to allow and encourage introduc-
tion of innovative solutions that improve the safety, environmental
performance, reliability, and efficiency of offshore wind facilities.
BOEMRE should either develop these regulations within the agency
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Summary of Key Findings and Recommendations 131
in a timely manner or facilitate development through, or with the
advice of, an outside group of experts. In any case, it is essential that
BOEMRE take responsibility for the process and the final product.
2. Because offshore wind projects are already under way, BOEMRE should
provide industry with a well-defined regulatory framework as soon as
practical. The U.S. offshore wind turbine regulations should be promul-
gated no later than the end of calendar year 2011, and a specific plan for
meeting that target should be established as soon as possible.
3. On request of a rule development body, BOEMRE should review
the rules and guidelines proposed by that body for compliance3 with
BOEMRE’s goal-based standards and identify any deficiencies. Once
BOEMRE deems a set of rules to be in full compliance with the goal-
based standards, it should approve such rules for application to U.S. off-
shore wind facilities. Examples of rules and guidelines that could be
considered are those that have been developed by Germanischer
Lloyd, Det Norske Veritas, and the American Bureau of Shipping. Pre-
approved rules should have the benefit of expediting the regulatory
review process. However, BOEMRE should be prepared to review stan-
dards and guidelines proposed by a developer and accepted by a CVA
for compliance with its goal-based regulations on a case-by-case basis.
4. BOEMRE should take a leading role in promoting awareness of lessons
learned in the offshore wind and offshore oil and gas industries among
project developers, industry professionals, and standards development
bodies. The goal is to help industry avoid mistakes that have been
encountered elsewhere and to promote practices that have proved to be
successful.
FINDINGS AND RECOMMENDATIONS:
ROLE OF THE CVA (TASK II)
1. The responsibility for proposing a comprehensive set of standards,
guidelines, and recommended practices should rest with the develop-
ers. The CVA’s role should be to review and comment on the adequacy
3 A set of rules is deemed compliant if meeting those rules will be taken as sufficient evidence that
the performance-based goals have been met.
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132 Structural Integrity of Offshore Wind Turbines
of the proposed standards and rules in meeting the objectives defined
in the BOEMRE goal-based standards. Although BOEMRE should con-
sider the documentation provided by the developer and the report of
the CVA, the responsibility for approval of the proposed standards and
guidelines and for determination of their conformance with the goal-
based standards should rest solely with the agency.
2. The scope of the BOEMRE third-party review process should include
the following:
– Blades,
– Blade controls (if reliance on active controls is required for load
reduction),
– Tower and structural support,
– Foundation and station keeping,
– Infield cables and connectors,
– Other structures—structural and electrical systems, and
– Export cables.
The third-party review should ensure the following:
Design: The design adheres to good industry practice, the basis of
the design is applicable for the location and stated objectives of the
project, site-specific conditions have been appropriately addressed,
and the identified codes and standards are adhered to.
Fabrication and manufacturing: Quality assurance/quality control
processes are in place to ensure that fabrication and manufacturing
comply with the design and the identified codes and standards.
Installation: All transportation and field installation activities are
performed in a manner ensuring that the facility meets the design
intent.
The third-party reviewer should provide periodic reports to
BOEMRE with regard to the review findings and should note any devi-
ations or concerns.
3. Type certification of a wind turbine may be substituted for portions of
third-party design review if the type certificate is appropriate for site
conditions [e.g., the International Electrotechnical Commission (IEC)
wind class].
4. BOEMRE should retain responsibility for final approval. It is essential
that BOEMRE have staff who are competent to select qualified third
parties (see Task III) and to approve projects.
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Summary of Key Findings and Recommendations 133
FINDINGS AND RECOMMENDATIONS:
CVA QUALIFICATIONS (TASK III)
Findings
The committee’s key findings with regard to CVA qualifications, which are
based on a review of the implementation of the CVA process for offshore
oil and gas facilities, the proposed Code of Federal Regulations language
for an offshore wind CVA, and how other engineered systems implement
third-party reviews, are as follows:
1. A qualified CVA must be
a. Independent and objective, with no involvement in the scope of
work being reviewed (i.e., design, fabrication, or installation);
b. Experienced in performing scopes of work similar to that being
reviewed, with detailed knowledge of the codes and standards being
applied; familiarity with the approaches proposed by the developer;
and the technical expertise and engineering judgment to verify
assumptions, conclusions, and results independently; and
c. Directed by a registered professional engineer (or international
equivalent).
2. A CVA for the design stage must have expertise in
a. Identification, specification, and implementation of design limit
states;
b. Fatigue and strength design approaches, including the effects of
coupled wind–wave dynamics;
c. Determination of the adequacy of proposed design environmental
condition for the site;
d. Evaluation of foundation design;
e. Evaluation of interaction between the foundation and the turbine
system;
f. Determination of the adequacy of the geotechnical assessment; and
g. Performance of design calculations similar to those provided in the
design reports. This is not a requirement that independent calcu-
lations be performed but that the CVA be able to perform them as
necessary.
3. A CVA for the fabrication stage will need expertise in
a. Fabricator quality control,
b. Material quality evaluation,
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134 Structural Integrity of Offshore Wind Turbines
c. Welder qualifications,
d. Nondestructive testing,
e. Destructive testing (e.g., full-scale blade tests), and
f. Blade materials and fabrication.
4. A CVA for the installation stage will need expertise in
a. Evaluation of installation plans and procedures;
b. Witnessing of installation operations including loadout, towing,
launching, uprighting, submergence, and so forth;
c. Marine operations;
d. Subsea cabling activities including trenching, burial, and connections;
e. Offshore construction activities; and
f. Installation equipment.
5. The CVA for design, for fabrication, and for installation need not be
the same organization or person, and it is unlikely that a single person
would have sufficient expertise to lead an effective CVA for all phases.
6. It would be beneficial, though not essential, for a CVA to have experi-
ence in third-party reviews and in interacting with regulatory agencies.
7. Given the variety of controlling environmental loads (e.g., hurricanes,
seismic activity, ice loads) and installation requirements (e.g., mudslide
areas, tidal erosion effects) in U.S. waters, the CVA’s experience should
be related to the installation location.
8. Experience with the use of project-specific CVA approval in the offshore
oil and gas CVA industry indicates that project-specific approval of
CVAs is better than maintenance of a list of BOEMRE-accepted CVAs.
Recommendations
The committee recommends the following with regard to CVA qual-
ifications:
1. In evaluating potential CVAs, BOEMRE should seek organizations
and individuals that
a. Are independent and objective;
b. Have experience, technical expertise, and engineering judgment suf-
ficient to verify assumptions, conclusions, and results independently;
c. Have experience with the dominant environmental effects for the
project location (e.g., earthquake-resistant design experience for
offshore West Coast locations);
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Summary of Key Findings and Recommendations 135
d. Have experience in the areas described in the findings section above
for the CVA tasks (i.e., design, fabrication, and installation) for
which they are nominated;
e. Have clearly defined roles and responsibilities with adequate
oversight by a registered professional engineer (or international
equivalent); and
f. Have an auditable quality plan for the processes and record keep-
ing involved in the CVA activities.
2. BOEMRE should hire sufficient staff with adequate technical expertise
(as described in Chapter 4 in the section “Implementation: Capacity
and Expertise”) to oversee the development of offshore wind farms in
U.S. waters.
3. BOEMRE should approve CVAs on a project-specific basis as opposed
to maintaining an approved list of qualified CVAs.
4. BOEMRE should actively manage the CVA process for offshore wind
facilities by disseminating lessons learned from the CVA process to pro-
mote best practices to the industry.
5. BOEMRE should actively participate in the IEC Wind Turbines Certi-
fication Bodies Advisory Committee as a means of staying informed on
issues relating to wind turbine certification and the accreditation of
CVAs.
FINDINGS AND RECOMMENDATIONS:
IMPLEMENTATION
• In the committee’s view, unless BOEMRE’s staffing levels and expe-
rience are substantially enhanced, the agency will be unable to pro-
vide the leadership and decision-making capability necessary for
development of U.S. offshore wind facility standards.
• It is essential that BOEMRE establish a substantial core competency
within the agency with the capacity and expertise to lead the develop-
ment of the goal-based standards, review the rules and guidelines
submitted by the third-party rule developers, and review the qualifi-
cations of proposed CVAs.
The committee’s findings and recommendations on standards and
practices, the role of the CVA, and the qualifications needed by a CVA
call for BOEMRE to take a leadership role in developing new, goal-based
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136 Structural Integrity of Offshore Wind Turbines
standards; to review sets of standards and guidance documents put for-
ward by industry for preapproval, identify gaps and deficiencies, and
determine whether they have been sufficiently addressed; to review the
full set of standards and guidance documents submitted for specific
projects; and to select CVAs who can take part in all these functions as
necessary.
The expertise required to carry out these tasks is substantial. More-
over, the critical advisory roles that the CVA could play in these tasks
could require that BOEMRE make a more detailed appraisal of CVA
nominations than in the past, which also implies in-depth expertise.
BOEMRE will likely be asked to apply this expertise extensively and in
the near future, both because regulatory expectations need to be estab-
lished soon and because several offshore wind projects are already being
developed and many more will likely be entering the pipeline for review
and approval.
• As a means of filling the experience gap for both industry and regula-
tors, BOEMRE should consider creating an expert panel to provide it
with guidance and feedback for the development of goal-based
standards, for the review of proposed standards and guidelines for
compliance with the goal-based standards, and for the initial wind
development projects.
Such an expert panel could help BOEMRE in developing goal-based
standards expeditiously. It could also advise BOEMRE on how CVAs
can assess compliance with goal-based standards and on how the agency
and industry can learn from the deficiencies and other concerns that
CVAs identify in projects. Finally, for the initial offshore wind develop-
ment projects, such an expert panel could help BOEMRE review the
packages of Guidelines—standards, rules, industry guidelines, and rec-
ommended practices—submitted for application to a particular project
or submitted for preapproval for use in future projects.
• BOEMRE should be fully engaged in the national and international
process for developing standards for offshore wind turbines, and it
should be represented on the International Electrotechnical Com-
mission’s technical committees and on other relevant national and
international committees.
