Below are the first 10 and last 10 pages of uncorrected machine-read text (when available) of this chapter, followed by the top 30 algorithmically extracted key phrases from the chapter as a whole.
Intended to provide our own search engines and external engines with highly rich, chapter-representative searchable text on the opening pages of each chapter.
Because it is UNCORRECTED material, please consider the following text as a useful but insufficient proxy for the authoritative book pages.
Do not use for reproduction, copying, pasting, or reading; exclusively for search engines.
OCR for page 62
4
A Risk-Informed Approach to
Performance Assurance
Task I of the committee’s charge, “Standards and Practices” (see Box 1-2),
calls for the committee to review the applicability and adequacy of exist-
ing standards and practices for the design, fabrication, and installation of
offshore wind turbines. Chapter 3 reviewed some of the most important
standards that are in use and described some of those that are under devel-
opment. It also identified some of the deficiencies that would have to be
remedied and the analyses that would have to be done before these stan-
dards and practices could be used in the United States.
As discussed in Chapter 1, the committee believed that, to respond
fully to this task, it had to do more than simply review existing stan-
dards and guidance and point to where the deficiencies lie. Other
studies have identified at least some of these deficiencies, and the com-
mittee has drawn on these studies in developing Chapter 3 of this
report. But the committee’s view was that, to provide the Bureau of
Ocean Energy Management, Regulation, and Enforcement (BOEMRE)
with useful feedback, the committee should offer its perspectives on
how BOEMRE might remedy the deficiencies. The best way to do this,
it believed, was to step back and review the underlying philosophies
that could guide the development of additional standards, regulations,
or other guidance documents for offshore wind turbines in the United
States.
In applying this broader perspective, the committee reviewed the
approaches to oversight of offshore wind turbines taken by European
countries. The committee also reviewed how the safety of engineered
structures is overseen in other U.S. industries—oil and gas production,
waterborne shipping, and buildings—and especially how regulation and
other forms of oversight in these industries have evolved.
62
OCR for page 63
A Risk-Informed Approach to Performance Assurance 63
This chapter begins with a brief review of the risks to human safety and
the environment posed by structural failures in offshore wind turbines. It
compares these risks with those associated with other offshore industries
and with land-based energy industry infrastructure. It then considers how
regulation in these areas has evolved away from a detailed, prescriptive
model and toward a more performance-based model, and what this sug-
gests about approaches to overseeing wind energy development on the
U.S. outer continental shelf (OCS).
RISKS TO HUMAN LIFE AND THE ENVIRONMENT POSED
BY STRUCTURAL FAILURE OF OFFSHORE FACILITIES
Government regulation of offshore facilities, such as oil and gas structures
and marine vessels, and of land-based infrastructure, such as buildings and
bridges, focuses on mitigating risk to human life and the environment.
Other risks, such as those of direct economic losses from structural dam-
age and of indirect losses due to interruption of function, forgone oppor-
tunities, and loss of amenity, are generally not addressed in government
regulations, although they may be of concern to individuals, project oper-
ators, insurers, and other stakeholder groups.
Risk to Human Life and Safety
Risk to human life from the structural failure of offshore wind installa-
tions is limited compared with risks from other offshore facilities, such as
oil and gas platforms and marine vessels. Offshore wind towers are nor-
mally unmanned, so they pose limited risk to human life. The most dan-
gerous element in the operation of an offshore wind farm is the transfer
of personnel to the turbines for installation, inspection, and maintenance.
Because the turbines can only be accessed by boat or helicopter, the abil-
ity to reach the turbines is highly dependent on the sea state. Personnel
may find themselves stranded on a turbine structure if waves increase in
magnitude while maintenance is being conducted. With the exception
of wind turbine installations in regions of high seismic activity, how-
ever, it is not anticipated that humans would be on any turbine struc-
ture throughout the duration of an extreme external condition such as
a powerful storm.
OCR for page 64
64 Structural Integrity of Offshore Wind Turbines
The transmission platform, however, might house personnel for
indefinite periods of time, and this fact must be taken into account in
designing for human safety in extreme conditions. The need for person-
nel to be stationed on a centralized transmission platform will increase as
farms move farther offshore and the logistics of personnel transfer to
shore become more difficult. Designs must also address the potential
need for stationing personnel on transmission platforms during inclement
weather.
Risk to the Environment
As stated in Chapter 1, the scope of this report is limited to oversight of
structural integrity as it is affected by turbine design, fabrication, and
installation. As shown in Figure 1-1, the environmental hazards associated
with the establishment and operation of offshore wind energy facilities
are covered through the National Environmental Policy Act (NEPA)
process. These hazards include effects on birds, other wildlife, and the
seabed. An environmental assessment or environmental impact state-
ment, as required by NEPA, will be performed for each proposed offshore
project (as was done for the Cape Wind project).
The most significant risk to the environment emanating from
structural failure of an offshore wind turbine or transmission platform
involves the release of transmission fluid or other hydrocarbon-based
liquids from the wind farm structures or from the installation and ser-
vice vessels that would be navigating through an offshore wind park.
Proper design and construction of the turbine and transmission plat-
form should preclude all but minor damage due to collision with a
service vessel that is moving slowly. However, if the vessel suffered
sufficient damage, it could leak its fuel into the ocean. In the event of a
catastrophic failure of a structure or vessel, the worst-case scenario
would involve discharge into the ocean of the following amounts of
hydrocarbon-based fluids:
• Wind turbine (5 MW), approximately 150 gallons (Cape Wind n.d.);
• Transmission platform, approximately 40,000 gallons (Cape Wind
n.d.); and
• Installation and service vessels, up to 500,000 gallons (see Box 4-1).
OCR for page 65
A Risk-Informed Approach to Performance Assurance 65
BOX 4-1
Offshore Wind Installation and Service Vessels
Installation of the foundations (driving monopiles or setting
jackets) will likely be carried out with barges and tugs. A recently
delivered derrick barge has a fuel capacity of 300,000 gallons pro-
tected by inner bottom and wing tanks. Each tug typically has an
aggregate fuel and lubricating oil capacity of 5,000 gallons.
Transportation and installation of turbine components may
be accomplished by using (a) a specially designed self-propelled
vessel or (b) a combination of barges and barge cranes. As an
example of the first case, a turbine component installer design
offered by Keppel Amfels carries 500,000 gallons of diesel fuel. In
the second case, the barge and crane barge described for founda-
tion installation could be used, with the fuel capacities given
above. If a lift vessel is used, fuel capacity would likely not exceed
50,000 gallons.
For reference, the amount of oil estimated to have been released into
the ocean during the Exxon Valdez oil spill was 10.8 million gallons (Exxon
Valdez Oil Spill Trustee Council n.d.).
Comparison with Offshore and Land-Based Fossil
Fuel Facilities
Table 4-1 presents the committee’s judgment, based on its experience
across industries, of the relative risks of offshore wind facilities, offshore
oil and gas facilities, land-based fossil fuel extraction facilities, and lique-
fied natural gas terminals. The table indicates the level of risk to human life
and the environment under normal operating conditions. It also shows
the risk levels under “design conditions,” which are the conditions that
the facility is designed to resist or withstand. As shown, the risks to human
safety and the environment associated with structural failure of offshore
OCR for page 66
66 Structural Integrity of Offshore Wind Turbines
TABLE 4-1 Comparison of Risks with Traditional Offshore and Land-Based
Energy Industries: Safety and the Environment
Level of Risk
Liquid Life Safety: Life Safety:
Hydrocarbon Normal Design
Energy Industry Release Operations Conditions
Oil and gas—shelf M L M
Oil and gas—“frontier” H M H
Land fossil (coal and natural gas), Texas VL L M
Land fossil (coal and natural gas), VL L M
Cook County, Illinois
Land wind facility VL VL L
Offshore winda—“tower” L VL L
Offshore windb—central platform L, Mc
L M
Offshore liquefied natural gas terminal VL H H
Land liquefied natural gas terminal VL H H
NOTE: VL = very low, L = low, M = moderate, H = high. Coding criteria include life safety,
protection of the environment, and economic thresholds.
a
Turbines and turbine support.
b
Central facilities.
c
L if evacuated prior to design condition; M if manned.
wind turbines are generally lower than for structural failure in the fossil
energy industries.
REGULATORY OPTIONS AND POLICY CONSIDERATIONS
Because the environmental and life safety risks of offshore wind facilities
are relatively low, the form and extent of government regulation comes
into question. If there are smaller safety and environmental risks associ-
ated with structural failure of an offshore wind farm, then a natural ques-
tion to ask is whether the financial and insurance risk assumed by the
developer is sufficient for regulating the industry. Or, to put it another
way, are there reasons for overseeing the performance of offshore wind
structures beyond mitigating these low risks?
Policy Considerations
In 2010 the United States made significant strides in the offshore wind
rulemaking process, and several projects proposed off the East Coast are
OCR for page 67
A Risk-Informed Approach to Performance Assurance 67
progressing through their development phases. Currently, renewable
energy development is largely driven by individual state policies and
renewable portfolio standards. However, several examples, highlighted
below, indicate that federal policy will promote renewable energy on a
national level and that offshore wind is an essential component of this
policy. National security, energy independence, and economic benefit are
cited by government officials as justification for promoting offshore wind
development.
Creating an Offshore Wind Industry in the United States: A Strategic Work
Plan for the United States Department of Energy was prepared by the U.S.
Department of Energy (USDOE) Office of Energy Efficiency and Renew-
able Energy’s Wind and Water Power Program to outline the actions that
it will pursue in supporting the development of a world-class offshore
wind industry in the United States. The Strategic Work Plan is an action
document that amplifies and draws conclusions from a companion
report, Large-Scale Offshore Wind Power in the United States (Musial and
Ram 2010).
A joint initiative between USDOE and the U.S. Department of the Inte-
rior (USDOI) titled “Smart from the Start” was announced in November
2010, with a goal of speeding appropriate commercial-scale wind energy
development (USDOI 2010). A fact sheet issued on this effort by USDOI
states:
A top priority of this Administration is developing renewable domestic energy
resources to strengthen the nation’s security, generate new jobs for American
workers and reduce carbon emissions. A major component of that strategy is
to fully harness the economic and energy benefits of our nation’s vast wind
potential, including Outer Continental Shelf Atlantic winds, by implementing
a smarter permitting process that is efficient, thorough, and unburdened by
unnecessary red tape. (USDOI n.d.)
In February 2011, USDOE and USDOI unveiled the “joint National Off-
shore Wind Strategy: Creating an Offshore Wind Industry in the United
States, the first-ever interagency plan on offshore wind energy” (USDOE
2011). As a part of this initiative, several high-priority offshore wind
regions were identified to “spur rapid, responsible development of wind
energy.” In addition, USDOE announced a research and development
program at this time to “develop breakthrough offshore wind energy
OCR for page 68
68 Structural Integrity of Offshore Wind Turbines
technology and to reduce specific market barriers to its deployment”
(USDOE 2011).
SEEKING THE RIGHT REGULATORY BALANCE
The federal government has embraced offshore wind energy as an integral
component of its overarching policy of developing clean, renewable energy
sources. Thus, the government has a fundamental interest not only in the
safety and environmental performance of offshore wind farms but also in
their reliability and cost-effectiveness. At the same time, the risks of struc-
tural failure to human safety and the environment are low.
The committee’s view thus is that minimal regulation will allow market
forces to guide offshore wind energy to an efficient solution. Such an
approach has policy risk, since lack of a regulatory framework could lead
to early project failures that negatively affect public perception and
jeopardize future offshore wind development. Other countries have had
this experience, with serial component failures leading to repercussions
across the global offshore wind industry. For example, in Europe the
Horns Rev 1 (see Box 4-2) failures and similar problems encountered by
other offshore wind farm projects led to the introduction of site-specific
project certification and an expanded scope for verification that extended
beyond the generic type certification scheme. As discussed later in this
report, it is important that a feedback mechanism be established to ensure
that lessons learned are incorporated into the regulatory requirements,
standards, and recommended practices.
The committee recommends that U.S. regulation be sufficient to ensure
a consistent minimum standard for the design and construction of off-
shore wind turbines to mitigate the risk of catastrophic failure, such as the
failure of a single turbine or of multiple turbines that renders repair and
recovery extremely difficult or impossible.
REGULATORY EVOLUTION IN THE OIL AND GAS,
MARINE, AND CIVIL INFRASTRUCTURE INDUSTRIES
As noted in Chapter 3, standards, guidelines, and regulation of offshore
wind turbines in Europe are primarily prescriptive in nature.
OCR for page 69
A Risk-Informed Approach to Performance Assurance 69
BOX 4-2
Horns Rev 1
One of the first large offshore wind farms, the 80–wind turbine,
160-MW Horns Rev 1 facility located off the coast of Denmark,
was built in 2002. Early in the facility’s operating life the turbines
experienced numerous failures, including each of the 80 wind tur-
bine transformers, generators, torque arms on gearboxes, light-
ning receptors on blades, and foundation coatings. All 80 nacelles
were taken ashore for modification. The failures likely set back
development of the offshore wind industry throughout Europe as
industry and regulators evaluated technical risk and reliability
issues. Subsequently, widespread failures in the grouting connec-
tion between the foundation and the intermediate support struc-
tures have occurred at Gunfleet Sands wind farms and at the
Danish Horns Rev 2 facility (Wan 2010). If such systemwide fail-
ures are not avoided, they will negatively affect the development
of offshore wind resources as they erode the confidence of both
potential investors and the public.
Regulatory oversight in other U.S. industries began with such a pre-
scriptive approach but, in some areas, has been evolving toward a more
“performance-based” approach (see Box 4-3). The following discussion
illustrates this evolution by reviewing regulatory developments in the oil
and gas industry, the marine shipping industry, and the civil infrastruc-
ture industry. It then turns to options for addressing the deficiencies of
existing standards and regulations when applied to oversight of the U.S.
offshore wind industry.
Oil and Gas Industry
As discussed in History of the Oil and Gas Industry in Southern Louisiana
(MMS 2004), the first oil and gas structure, built in 1937, was a massive
wooden platform constructed in about 15 feet of water in the Creole field
OCR for page 70
70 Structural Integrity of Offshore Wind Turbines
BOX 4-3
Performance-Based Standards and Innovation
As generally understood, a performance-based standard specifies
the outcome required but allows each regulated entity to decide
how to meet it. Performance standards give firms flexibility and
make it possible for them to seek the lowest-cost means to achieve
the stated level of performance (Coglianese et al. 2003).
By focusing on outcomes, performance-based standards accom-
modate technological change and innovation, which can be key
to lowering costs. To the extent that they reduce the costs of
power generated by using offshore wind, they increase the abil-
ity of this source to compete with other sources of electricity.
See Box 4-4 on the International Maritime Organization’s goal-
based standards for an example.
in the Gulf of Mexico (GOM). This was at a time when there were no
data on the response of frame structures to hurricane forces. Land-based
steel design codes, principally the American Institute of Steel Construc-
tion (AISC) Manual of Steel Construction, were the standards most
closely aligned with offshore design and construction materials. Offshore
developments progressed over roughly 20 years in the GOM under a
variety of operator-specific design approaches and criteria. Design con-
ditions (conditions that the structure must be designed to withstand)
were specified probabilistically, where the probability of an event occur-
ring is expressed in terms of the percentage chance that it will occur in
any given year.
The most common design condition was a 25-year return period,
though other operators used return periods of up to 100 years according
to their appetite for risk (MMS 2004). Data to develop the design criteria
were collected on an ad hoc basis with limited cooperation between oper-
ators (MMS 2004).
OCR for page 71
A Risk-Informed Approach to Performance Assurance 71
By the early 1960s, there were several hundred platforms in the GOM.
No major storms affected areas with large numbers of offshore structures
until the mid-1960s. The first significant platform failures under storm
conditions came in 1964, when Hurricane Hilda destroyed 13 platforms
and damaged five others beyond repair (MMS 2004). The following year,
Hurricane Betsy destroyed eight platforms (MMS 2004). The storms
emphasized the need for developing more consistent design approaches
and for gathering better data on wind speeds, wave heights, and soil char-
acteristics for use in the design process. Hurricane Camille in 1969 was
another damaging storm, with measured waves far higher than those pre-
dicted by the use of existing data (MMS 2004; Berek 2010).
In 1966, the American Petroleum Institute (API) created the Commit-
tee on Standardization of Offshore Structures (Berman et al. 1990), and
the Ocean Data Gathering Program was set up in 1968 (Ward 1974). These
steps were among the first by the industry as a whole to standardize the
design of offshore platform structures in the GOM, and they led to the first
API design standard for fixed jacket structures, Recommended Practice 2A
(RP 2A), in 1969 (Berek 2010). This standard did not specify a design
return period for storm conditions. A design wave with a 100-year
return period was first specified in the 7th edition of API RP 2A in 1976
(Berek 2010). The 9th edition of RP 2A (which included, among other
improvements, more robust joint design guidance) was issued in 1978,
and platforms designed to this or later editions are considered by the
industry to be “modern.” The superiority of such platforms was demon-
strated in the aftermath of Hurricane Andrew in 1992, when 75 structures
were destroyed, the majority of which were older platforms designed
with 25-year return periods and lower decks (Berek 2010; Energo
Engineering 2010).
Though storms and their damage were not the only drivers for changes
to design guides and industry practice, they have had a significant effect.
Figure 4-1 shows a timeline of GOM oil and gas development from its
beginnings to the present along with significant storms and subsequent
standards developments and changes, as well as changes in industry prac-
tice and regulations (Puskar et al. 2006). The storms of the late 1960s led
directly to the establishment of the RP 2A standard and its subsequent
improvement through the 1970s. Hurricane Andrew led directly to the
OCR for page 72
72 Structural Integrity of Offshore Wind Turbines
FIGURE 4-1 Timeline of GOM development, industry standards, and
practices. (SOURCE: Puskar et al. 2006.)
development of revised load calculations represented in the 20th edition
of RP 2A as well as the development of guidance on reassessment of exist-
ing structures (Berek 2010; Puskar et al. 2006). The magnitude of destruc-
tion brought about by Hurricanes Ivan, Katrina, Rita, and Ike in the
mid- and late 2000s has led to a reassessment of the definition of the design
waves for GOM structures. The GOM has been divided into four regions,
each with its own design criteria, and the use of older storm data (i.e., pre-
1950 data) has been revised in formulating the statistics for calculating
design waves (Berek 2010; Puskar et al. 2006).
Just as industry cooperation and standardization were limited in the
early years of GOM development, the regulatory environment was limited
and uncoordinated. As discussed in Chapter 1, leasing was handled by
both state and federal authorities (via USDOI through the Outer Conti-
nental Shelf Lands Act of 1953); the U.S. Army Corps of Engineers had
some authority, especially as related to installations in navigable waters;
and the U.S. Coast Guard (USCG) was responsible for safety (MMS 2004).
Setting forth and enforcing design standards were not a focus of any of
these groups. The Bureau of Land Management and the Conservation
OCR for page 85
A Risk-Informed Approach to Performance Assurance 85
goal-based standards). There are parallels between the situations faced by
BOEMRE in rule development for offshore wind turbines and by IMO for
oceangoing ships:
1. IMO did not have the expertise or resources to develop rules with suf-
ficient specificity. Although the committee strongly recommends that
the size and capability of BOEMRE staff be enhanced, it is not envi-
sioned that BOEMRE will have the means to develop detailed rules.
2. The classification societies had well-developed and validated rules
before IMO’s involvement in regulating hull structures. Similarly, inter-
national standards for offshore wind turbines (e.g., IEC 61400-3) and
class rules and guides (GL, DNV, and ABS) are already in place.
3. Deficiencies and inconsistencies among the various classification soci-
ety rules for shipbuilding were identified as an area of concern. Simi-
larly, there are deficiencies and inconsistencies in the rules for offshore
wind turbines, as discussed in Chapter 3.
4. In the case of both offshore wind turbines and shipbuilding, the clas-
sification societies and international standards groups are prepared to
maintain the currency of their rules and regulations through continu-
ous validation and revision.
The committee envisions the federally mandated goal-based standards
for offshore wind energy installations to be a relatively short document—
perhaps four or five pages. The goal-based standards should be high-level
objectives expressed in terms of performance expectations. The standards
will apply to the design, fabrication, and installation of offshore wind farms
within U.S. waters and are intended to ensure a level of consistency meet-
ing safety, environmental performance, and policy expectations, while
being sufficiently flexible to enable introduction of new technologies and
concepts.
While the committee does not have the time, the resources, or the
expertise to establish a complete set of specific criteria, an example of the
scope and type of evaluation criteria that should be incorporated is given
below. Tier 1–type high-level general requirements are given first, followed
by Tier 2–type functional requirements. In the latter, the numerical values
shown as examples for various items are provided for illustrative purposes
only. Actual criteria would be subject to development by BOEMRE and its
consultants.
OCR for page 86
86 Structural Integrity of Offshore Wind Turbines
Examples of General Requirements
Structures, foundations, and nonstructural components shall be designed
by analysis or by a combination of analysis and testing to provide a per-
formance not less than as stated below when they are subjected to the
influence of operating, environmental, and accidental loads. Consider-
ation shall be given to uncertainties in loading and in resistance.
Analysis shall employ rational methods based on accepted principles
of engineering mechanics and shall consider all significant sources of
deformation and resistance. Assumptions of stiffness, strength, damp-
ing, and other properties of components and connections shall be based
on approved test data or referenced standards.
Testing used to substantiate the performance capability of structural
and nonstructural components shall accurately represent the materials,
configuration, construction, load intensity, and boundary conditions
expected. Where an approved industry standard or practice that governs
the testing of similar components or materials exists, the test program
and determination of design values shall be in accordance with that
industry standard or practice.
Examples of Functional Requirements
The examples below are provided for illustrative purposes only.
1. Offshore wind turbines and electric service platforms shall have a
service life of at least _____ years (e.g., at least 20 years).
2. Site-specific environmental conditions shall be used for design.
3. The primary structures (foundations, superstructure, platforms,
blades, nacelle supports, etc.) shall be designed and constructed so
that the probabilities of falling short (during their service life) of
limit states associated with deflections, ultimate strength, loss of sta-
bility (buckling), and fatigue are sufficiently small for each individ-
ual structure as well as for the fleet of structures (typically installed
near one another) that make up an offshore wind farm.
4. The probability, given the design-basis event, of collapse of primary
structures (towers, platforms, blades, nacelle supports, etc.) within a
wind energy–generating facility shall not exceed ___ (e.g., shall not
exceed 10 percent).
OCR for page 87
A Risk-Informed Approach to Performance Assurance 87
5. Wind turbine towers and electric service platforms shall be designed
with sufficient robustness that localized damage does not lead to
progressive, catastrophic failure.
6. The design fatigue life shall be not less than _____ times the speci-
fied service life. For uninspectable areas, the design service life shall
be not less than _____ times the specified service life (e.g., 1×, 5×).
7. The primary structures shall have protection against corrosion ade-
quate to ensure that sufficient strength is maintained over the spec-
ified service life.
8. Wind energy generation facilities shall be designed to minimize
emission of pollutants as far as practical.
9. Wherever practical, structures and equipment shall be constructed
of materials that can be recycled in an environmentally acceptable
manner without compromising safety.
10. The towers and other structures shall be designed to provide ade-
quate means of access to all internal structures to facilitate close-up
inspections of structures and equipment.
11. Designs shall take due consideration of the health and safety of
personnel accessing offshore wind turbines and power platforms,
including ready access and protection against falls, lightning, and
other hazards.
Industry Compliance with BOEMRE Goal-Based Standards
Industry will be responsible for proposing a collection of national and
international standards, rules, industry-developed guidelines, and rec-
ommended practices (referred to here as a “package of Guidelines”) that
conform to the goal-based standards established by BOEMRE. As noted
later in this section, the standards, rules, industry guidelines, and recom-
mended practices making up the packages of Guidelines could be drawn
from classification societies, the International Electrotechnical Commis-
sion (IEC), or elsewhere. The packages of Guidelines will likely have
prescriptive elements, which are often easier to implement than perfor-
mance-based requirements. This is acceptable provided that they comply
with the goals and objectives established by BOEMRE. It is anticipated
that these packages of Guidelines will have as their basis the IEC stan-
dards, with additional rules, industry guidelines, and recommended
OCR for page 88
88 Structural Integrity of Offshore Wind Turbines
practices to cover all necessary aspects of wind turbine design covered by
the BOEMRE goal-based standards and to rectify any areas of noncon-
formance with the BOEMRE requirements.
To streamline the regulatory compliance process and provide a level
of regulatory certainty to the developer, the committee recommends that
BOEMRE be prepared to review the packages of Guidelines proposed by
a rulemaking or standards development body in the light of BOEMRE’s
goal-based standards before their application to any particular project.
The review process would proceed as follows:
1. The rulemaking body develops a package of Guidelines conforming to
the BOEMRE goal-based standards along with the underlying docu-
mentation and analysis. Examples of standards, rules, industry guide-
lines, and recommended practices that could be considered are those
developed by GL, DNV, and ABS, or the standards and recommended
practices currently being developed by the American Wind Energy
Association.
2. When it submits its package of Guidelines for approval, the rulemaking
body shall provide documentation and analysis demonstrating that the
standards, rules, industry guidelines, and recommended practices con-
tained in the package fulfill all the requirements of the BOEMRE goal-
based standards, or it shall clearly identify which requirements are not
covered by its package of Guidelines.
3. BOEMRE reviews the package of Guidelines and the underlined docu-
mentation and analysis for conformance with the goal-based standards.
Once compliance is ascertained, BOEMRE publishes notification of its
approval of the package of Guidelines. If the package Guidelines does
not fully cover BOEMRE requirements, any deficiencies that must be
covered by other standards, rules, industry guidelines, and recom-
mended practices should be identified in the notification.
Alternatively, a developer should be permitted to identify a package of
Guidelines that will be apply to a specific project, along with the underly-
ing documentation and analysis, and BOEMRE should be prepared to
review and approve such packages on a case-by-case basis. This process is
anticipated to take longer than would use of preapproved packages of
Guidelines, but it will allow for the introduction of novel concepts that
OCR for page 89
A Risk-Informed Approach to Performance Assurance 89
may not be covered in existing, preapproved packages of Guidelines. This
approach would proceed as follows:
1. The developer assembles the package of Guidelines (see above) that it
proposes to use for a particular project, and it prepares documentation
and analysis demonstrating that all requirements of the goal-based stan-
dards are satisfied.
2. A third-party CVA reviews the developer’s package of Guidelines and
the underlying documentation and analysis and provides a statement
indicating that the package is in full compliance with the goal-based
standards. If the CVA identifies deficiencies or has concerns that are not
fully reconciled by the developer, they should be explained in the CVA’s
report.
3. The developer submits its package of Guidelines, including the CVA’s
report, to BOEMRE, seeking approval for the package of Guidelines to
be applied to the project. BOEMRE either approves the package or
sends it back to the developer requesting revisions or further documen-
tation and analysis, or both.
The approval of the package of Guidelines (standards, rules, industry
guidelines, and recommended practices) that will be followed to ensure
compliance with the goal-based standards does not imply that site-specific
assessment and analysis are not required. Project certification (see Chap-
ter 3) with on-site assessment is expected to be a standard part of the design
and review process.
OVERVIEW OF PROJECTED BOEMRE ROLE
It is important that a single government agency, presumably BOEMRE,
have overall responsibility for regulatory development, monitoring and
maintenance of the regulations, and implementation of the verification
and oversight regime.
Below is a summary of the role that BOEMRE would play under the
approach recommended by the committee. The role is a large one, and
BOEMRE may wish to consider creating an expert panel to assist with the
initial development of the goal-based standards and then with continuous
monitoring and evaluation of the standards and regulations.
OCR for page 90
90 Structural Integrity of Offshore Wind Turbines
a. If so decided, establish an expert panel to assist in initial development
of the goal-based standards and then continuous monitoring and
evaluation of the regulations (see Chapter 6).
b. Determine the scope of the regulatory standards. To ensure a level of
reliability consistent with public policy expectations, the committee
believes that the standards must consider design, fabrication, instal-
lation, and commissioning from the export cable through to the tow-
ers and incorporated systems.
c. By the end of calendar year 2011, develop the goal-based standards
and functional requirements, including a rigorous public review
process.
d. Review proposed “packages of Guidelines” (compilations of interna-
tional and national standards, rules, industry-developed guidelines,
and recommended practices) for compliance with the U.S. goal-
based standards. (As submitted)
e. Review proposed packages of Guidelines during project assessment,
where preapproved packages are not applied or where gaps in the
preapproved packages are identified. (As requested)
f. By the end of calendar year 2011, establish the intent and scope of the
third-party review process (see Chapter 5).
g. By the end of calendar year 2011, establish qualifications for CVAs—
third-party reviewers (see Chapter 6).
h. Exercise final approval authority for design and construction in com-
pliance with the regulations (see Chapter 5).
i. Review qualifications and approve CVAs on a project-specific basis
(see Chapter 6).
j. Monitor performance of projects versus regulatory expectations and
provide periodic feedback to the industry (see Chapter 6).
k. Monitor the effectiveness of the goal-based standards and periodi-
cally revise them as appropriate.
l. Monitor the effectiveness of the preapproved packages of Guidelines
(national and international standards, rules, industry guidelines, and
recommended practices) to ensure compliance with the latest goal-
based standards.
m. Monitor the effectiveness of the third-party review process.
n. Periodically review and update the goal-based standards.
OCR for page 91
A Risk-Informed Approach to Performance Assurance 91
o. Serve as the U.S. representative on offshore wind standards develop-
ment committees, both nationally and internationally.
IMPLEMENTATION: CAPACITY AND EXPERTISE
USDOI’s Offshore Energy and Minerals Management program includes
both offshore oil and gas and offshore renewable energy regulatory pro-
grams. It is staffed by roughly 900 professionals in three regional offices
(GOM, Alaska, and Pacific); associated district offices; and headquarters
offices in Washington, D.C., and Herndon, Virginia. The headquarters
staff has one engineer with a background in civil and marine engineer-
ing and naval architecture, and the GOM regional office is supplying
an engineer to support the Office of Alternative Energy Projects on an
as-needed basis.
The Office of Structural and Technical Support (OSTS) is responsible
for ensuring that the platforms operating on the OCS are designed, fab-
ricated, installed, and maintained in accordance with regulations. This
group is based in the GOM regional office in New Orleans, Louisiana, and
serves as structural support for the Pacific region as well. On the oil and
gas side, roughly 3,500 facilities are installed in the U.S. OCS (primarily
GOM), and OSTS has fewer than 10 engineers to address permit applica-
tions, inspection data, repair information, and all other structural data
and requests. Since Hurricane Katrina in 2005, many of the more experi-
enced staff in OSTS, including its director, have left the organization.
Remaining staff have less experience in addressing offshore structural
issues and no experience in addressing issues related specifically to off-
shore wind structures.
To enhance its ability to oversee the offshore wind industry effectively,
BOEMRE may wish to focus on obtaining staff or contractors with experi-
ence in the following areas: offshore structures design, with a preference for
experience in offshore wind design; offshore installations, with a preference
for experience in pile-founded structures; wind turbine hookup and com-
missioning, with a preference for offshore experience; and offshore struc-
tures operation and maintenance, with a preference for offshore wind
facilities experience. Experience with the standards development process
would also be beneficial.
OCR for page 92
92 Structural Integrity of Offshore Wind Turbines
FINDINGS FOR TASK I: CHAPTER 4
As noted above, the federal government has embraced offshore wind
energy as an integral component of its overarching policy of developing
clean, renewable energy sources. Thus, the government has a fundamen-
tal interest not only in the safety and environmental performance of off-
shore wind farms but also in their reliability and cost-effectiveness.
1. 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 grad-
ually replacing prescriptive standards in other industries including the
civil infrastructure, offshore oil and gas, and shipping industries, pro-
vide the flexibility needed to accommodate new technologies. They can
be administered and modified by the regulatory bodies in a straightfor-
ward way, they clarify the responsibility of industry in meeting project
goals, and they result in the transparency that comes with the delin-
eation of goals and objectives.
2. As a result of the significant uncertainties affecting facility performance
under operating and extreme conditions, recent PBE standards have a
risk-informed basis.
3. Unless its staffing levels and experience are substantially enhanced,
BOEMRE will be unable to provide the leadership and decision-
making capability necessary for development of U.S. offshore wind
standards.
RECOMMENDATIONS FOR TASK I: CHAPTERS 3 AND 4
These recommendations flow from the findings in Chapters 3 and 4.
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. The regulations should be risk-informed
(see Appendix A) and should cover design, fabrication, and installation.
Offshore wind energy is an emerging technology; therefore, the stan-
OCR for page 93
A Risk-Informed Approach to Performance Assurance 93
dards should be crafted to allow and encourage introduction of inno-
vative solutions that improve the safety, environmental performance,
reliability, and efficiency of offshore wind facilities. BOEMRE should
either develop these regulations within the agency in a timely manner
or facilitate development through, or with the advice of, an outside
group of experts. In any case, it is imperative that BOEMRE take
responsibility for the process and the final product.
2. Because offshore wind projects are already under way, it is essential
that BOEMRE provide industry with a well-defined regulatory frame-
work as soon as practical. The U.S. offshore wind turbine regulations
should be promulgated 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 compliance2 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 turbines. Examples of rules and guidelines that could be
considered are those developed by GL, DNV, and ABS. Preapproved
rules should have the benefit of expediting the regulatory review process.
However, BOEMRE should be prepared to review standards and guide-
lines proposed by a developer and accepted by a CVA for compliance
with its goal-based regulations on a case-by-case basis.
4. It is critical that BOEMRE establish a substantial core competency within
the agency with the capacity and expertise to lead the development of
the goal-based standards and review the packages of standards, rules,
industry guidelines, and recommended practices submitted by project
developers and rules-development bodies. The section “Goal-Based
Standards for Offshore Wind Turbines” in this chapter contains more
details with regard to the experience and capabilities that are needed.
5. BOEMRE should take a leading role in promoting awareness of lessons
learned in the offshore wind and offshore oil and gas industries among
2
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.
OCR for page 94
94 Structural Integrity of Offshore Wind Turbines
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.
6. BOEMRE should be fully engaged in the national and international
process for developing standards for offshore wind turbines and should
be represented on IEC technical committees and other relevant national
and international committees.
REFERENCES
Abbreviations
AASHTO American Association of State Highway and Transportation Officials
BOEMRE Bureau of Ocean Energy Management, Regulation, and Enforcement
IMO International Maritime Organization
MMS Minerals Management Service
TRB Transportation Research Board
USDOE U.S. Department of Energy
USDOI U.S. Department of the Interior
AASHTO. 2007. AASHTO LRFD Bridge Design Specifications. Washington, D.C.
Berek, G. 2010. Changing Practice in Gulf of Mexico Design and Operating Criteria.
http://www.iooc.us/wp-content/uploads/2010/09/Changing-Practice-in-Gulf-of-
Mexico-Design-and-Operating-Criteria.ppt.
Berman, M. Y., N. D. Birrell, J. T. Irick, G. C. Lee, M. Rubin, and M. E. Utt. 1990. The
Role of the API Committee on Standardization of Offshore Structures. Paper 6206.
Proc., Offshore Technology Conference.
BOEMRE. n.d. Overview of OCS Regulations. http://www.gomr.boemre.gov/homepg/
regulate/regs/reg_sum.html.
Cape Wind. n.d. Frequently Asked Questions. http://www.capewind.org/FAQ-Category8-
Cape+Wind+and+the+Environment-Parent0-myfaq-yes.htm#44. Accessed Dec. 13,
2010.
Coglianese, C., J. Nash, and T. Olmstead. 2003. Performance-Based Regulation: Prospects
and Limitations in Health, Safety, and Environmental Protection. Administrative Law
Review, vol. 55, issue 4, pp. 705–730.
Ellingwood, B., and J. R. Harris. 1977. Reliability-Based Performance Criteria for
Structures. Proc., 2nd Engineering Mechanics Division Specialty Conference, ASCE,
pp. 124–127.
OCR for page 95
A Risk-Informed Approach to Performance Assurance 95
Energo Engineering. 2010. Assessment of Damage and Failure Mechanisms for Offshore
Structures and Pipelines in Hurricanes Gustav and Ike. MMS TA&R No. 642, Feb.
http://www.boemre.gov/tarprojects/642/642AA_FinalReport.pdf.
Exxon Valdez Oil Spill Trustee Council. n.d. Details About the Accident. http://www.
evostc.state.ak.us/facts/details.cfm. Accessed Oct. 30, 2010.
IMO. 2002. Guideline for Formal Safety Assessment (FSA). MSC/Circ. 1023, MEPC/
Circ. 392.
IMO. 2010. Resolution MSC.287(87), Annex 1. Adoption of the International Goal-Based
Ship Construction Standards for Bulk Carriers and Oil Tankers. Adopted May 20.
MMS. 2004. History of the Oil and Gas Industry in Southern Louisiana. Interim Report,
Vol. 1. MMS 2004-049. http://www.gomr.mms.gov/homepg/regulate/environ/studies/
2004/2004-049.pdf.
Musial, W., and B. Ram. 2010. Large-Scale Offshore Wind Power in the United States:
Assessment of Opportunities and Barriers. Report TP-500-40745. National Renewable
Energy Laboratory, Golden, Colo.
Puskar, F. J., H. S. Westlake, P. E. O’Connor, and J. Bucknell. 2006. The Development of
a Recommended Practice for Structural Integrity Management (SIM) of Fixed Offshore
Platforms. Paper 18332. Proc., Offshore Technology Conference, May.
TRB. 2008. Special Report 293: Risk of Vessel Accidents and Spills in the Aleutian Islands:
Designing a Comprehensive Risk Assessment. National Academies, Washington, D.C.
USDOE. 2011. Salazar, Chu Announce Major Offshore Wind Initiatives. Press release.
Feb. 7. http://www.energy.gov/news/10053.htm. Accessed Feb. 7, 2011.
USDOI. 2010. Salazar Launches “Smart from the Start” Initiative to Speed Offshore Wind
Energy Development off the Atlantic Coast. Press release. Nov. 23. http://www.doi.
gov/news/pressreleases/Salazar-Launches-Smart-from-the-Start-Initiative-to-Speed-
Offshore-Wind-Energy-Development-off-the-Atlantic-Coast.cfm. Accessed Feb. 13,
2011.
USDOI. n.d. Smart from the Start Fact Sheet. http://www.doi.gov/news/pressreleases/
loader.cfm?csModule=security/getfile&PageID=73317. Accessed Feb. 13, 2011.
Wan, K. W. 2010. Flaw Hits Hundreds of EU Offshore Wind Turbines. Reuters, April 23,
2010. http://uk.reuters.com/article/2010/04/23/uk-offshore-wind-flaw-idUKTRE63M
3H720100423. [Accessed February 13, 2011]
Ward, E. G. 1974. Ocean Data Gathering Program—An Overview. Paper 2108. Proc.,
Offshore Technology Conference.
