IEC TS 62600-101:2015

IEC TS 62600-101 ®
Edition 1.0 2015-06
TECHNICAL
SPECIFICATION
colour
inside
Marine energy – Wave, tidal and other water current converters –
Part 101: Wave energy resource assessment and characterization

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IEC TS 62600-101 ®
Edition 1.0 2015-06
TECHNICAL
SPECIFICATION
colour
inside
Marine energy – Wave, tidal and other water current converters –

Part 101: Wave energy resource assessment and characterization

INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.140 ISBN 978-2-8322-2724-4

– 2 – IEC TS 62600-101:2015 © IEC 2015
CONTENTS
FOREWORD . 5
INTRODUCTION . 7
1 Scope . 8
2 Normative references. 8
3 Terms and definitions . 8
4 Symbols and units . 10
5 Classes of resource assessment . 11
5.1 Introductory remarks . 11
5.2 Resource assessment and characterization flow chart . 11
6 Study planning and data collection . 14
6.1 Introductory remarks . 14
6.2 Study area . 14
6.3 Bathymetry . 14
6.4 Existing wave data . 14
6.5 Wave measurement . 15
6.5.1 Purpose . 15
6.5.2 Selection of measuring instrument and analysis methodology . 15
6.5.3 Instrument calibration . 16
6.5.4 Instrument deployment . 16
6.5.5 Redundancy . 17
6.5.6 Analysis of measurements . 17
6.6 Wind data . 17
6.7 Tide data . 18
6.8 Current data . 18
6.9 Ice coverage and/or exceptional environmental conditions . 18
6.10 Water density . 18
6.11 Gravitational acceleration . 18
7 Numerical modelling . 19
7.1 Introductory remarks . 19
7.2 Suitable numerical models . 19
7.3 Definition of boundary conditions . 21
7.4 Modelling the nearshore resource . 22
7.5 Effect of WEC array on wave energy resource . 23
7.6 Validation of numerical models . 23
7.6.1 Introductory remarks . 23
7.6.2 Validation data specification . 23
7.6.3 Procedure . 24
7.6.4 Extent of validation . 27
7.7 Model tuning and calibration . 28
8 Measure-Correlate-Predict (MCP) . 29
8.1 Introductory remarks . 29
8.2 Procedures . 29
9 Data analysis . 30
9.1 Introductory remarks . 30
9.2 Characterization using two-dimensional wave spectra . 31
9.2.1 Overview . 31

9.2.2 Omni-directional wave power . 31
9.2.3 Characteristic wave height . 31
9.2.4 Characteristic wave period . 32
9.2.5 Spectral width . 32
9.2.6 Directionally resolved wave power . 32
9.2.7 Wave system partitioning . 33
9.3 Estimation of wave power using parameterized sea states . 33
9.4 Aggregation and statistics of results . 34
9.4.1 General . 34
9.4.2 Mean . 34
9.4.3 Standard deviation . 34
9.4.4 Percentiles . 34
9.4.5 Monthly variability . 34
9.5 Uncertainty of the resource assessment . 35
10 Reporting of results . 35
10.1 Introductory remarks . 35
10.2 Selection of study points . 36
10.3 Technical report . 36
10.4 Digital database . 36
10.5 Presentation of regional information . 37
10.6 Presentation of information at study points . 38
Annex A (informative) A method for sensitivity analysis . 42
A.1 General . 42
A.2 Specification of significance . 42
A.3 Sample sea states . 42
A.4 Condition of insensitivity . 43
Annex B (normative) Evaluation of measurement uncertainty . 44
B.1 General . 44
B.2 Uncertainty analysis . 44
Annex C (informative) Example calculation of long-term uncertainty . 45
C.1 General . 45
C.2 Climatic variability . 46
C.3 Anthropogenic climatic variability . 49
C.4 Conclusion . 49
Annex D (informative) Nearshore resource . 50
D.1 General . 50
D.2 Limiting water depth . 50
D.3 Bathymetry . 51
D.4 Fluctuating water level . 51
D.5 Currents . 51
D.6 Validation . 51
D.7 Uncertainty . 52
Bibliography . 53

Figure 1 – Wave resource assessment and characterization flow chart . 13
Figure 2 – Validation flow chart . 27
Figure 3 – Example map of mean annual wave power . 38

– 4 – IEC TS 62600-101:2015 © IEC 2015
Figure 4 – Example of a scatter table summarizing a long-term wave climate in terms
of H and T . 40
m0 e
Figure 5 – Example of a wave power rose . 40
Figure 6 – Example plot showing the distribution of wave power for different months . 41
Figure C.1 – Annual wave power variability in the UK. Eleven sites in North East,
North West and South West Regions [4] . 45
Figure C.2 – Comparison between mean annual power from the E04 model dataset
and the North Atlantic Oscillation index from 1988 to 2006 [5] . 46
Figure C.3 – Recorded North Atlantic Oscillation index from 1825 to 2010 (red bars),
with a five year moving average (black line) [5] . 47
Figure C.4 – Annual, 5-year, 10-year and 20-year moving averages of available wave
power at the a site [7] . 48
Figure C.5 – Annual mean power and running 5, 10 and 20 year mean values, 150 km
North of Scotland [6] . 48

Table 1 – Classes of resource assessment . 11
Table 2 – Resolution of bathymetric data . 14
Table 3 – Minimum requirements for wave measuring instruments and associated
analysis . 16
Table 4 – Resolution of wind data . 17
Table 5 – Elements of suitable numerical models. 19
Table 6 – Minimum validation requirements . 25
Table 7 – Uncertainty categories . 35
Table 8 – Summary of wave energy resource parameters to be archived and mapped . 37
Table A.1 – Recommended sensitivity thresholds . 42
Table A.2 – Recommended condition of insensitivity . 43
Table B.1 – List of uncertainty components . 44
Table C.1 – Comparison of Mean Average Error (MAE) and Maximum error (Max
error) between the 3, 5 and 10 year averages of the data at the combined UK sites
and the E04 Dataset (WaveHub) . 46

INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –

Part 101: Wave energy resource
assessment and characterization

FOREWORD
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The main task of IEC technical committees is to prepare International Standards. In
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• the required support cannot be obtained for the publication of an International Standard,
despite repeated efforts, or
• the subject is still under technical development or where, for any other reason, there is the
future but no immediate possibility of an agreement on an International Standard.
Technical specifications are subject to review within three years of publication to decide
whether they can be transformed into International Standards.
IEC TS 62600-101, which is a technical specification, has been prepared by IEC technical
committee 114: Marine energy – Wave, tidal and other water current converters.

– 6 – IEC TS 62600-101:2015 © IEC 2015
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
114/145/DTS 114/154A/RVC
Full information on the voting for the approval of this technical specification can be found in
the report on voting indicated in the above table.
A list of all parts in the IEC 62600 series, published under the general title Marine energy –
Wave, tidal and other water current converters, can be found on the IEC website.
This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.
The committee has decided that the contents of this publication will remain unchanged until
the stability date indicated on the IEC web site under "http://webstore.iec.ch" in the data
related to the specific publication. At this date, the publication will be
• transformed into an International standard,
• reconfirmed,
• withdrawn,
• replaced by a revised edition, or
• amended.
A bilingual version of this publication may be issued at a later date.

IMPORTANT – The 'colour inside' logo on the cover page of this publication indicates
that it contains colours which are considered to be useful for the correct
understanding of its contents. Users should therefore print this document using a
colour printer.
INTRODUCTION
This Technical Specification provides a uniform methodology that will ensure consistency and
accuracy in the estimation, measurement, and analysis of the wave energy resource at sites
that could be suitable for the installation of Wave Energy Converters (WECs), together with
defining a standardised methodology with which this resource can be described. The wave
energy resource is primarily defined using hydrodynamic models that are successfully
validated against measured data. This Technical Specification deals directly with the
theoretical resource and the main focus of the defined methodology is to generate the
resource information required to estimate energy production. Practical energy production can
then be estimated in conjunction with other Technical Specifications in this series (IEC
TS 62600), and by considering available technology and external constraints.
This Technical Specification provides guidance relating to the measurement, modelling,
analysis and reporting of the wave energy resource, and the linkages between these
activities. A framework for estimating the uncertainty of the wave energy resource estimates
is also provided. Application by all parties of the methodologies recommended in this
document will ensure that continuing resource assessment of potential development sites is
undertaken in a consistent and accurate manner. This Technical Specification presents
techniques that are expected to provide fair and suitably accurate results that can be
replicated by others.
The development of the wave power industry is at an early stage and the significance of
particular wave energy resource characteristics is poorly understood. Because of this, the
present document is designated as a Technical Specification and will be subject to change as
more data is collected and experience with Wave Energy Converters develops.
This Technical Specification, when used in conjunction with other Technical Specifications in
this series (IEC TS 62600), is intended for several types of users, including but not limited to
the following:
• Project developers – income, return on investment
• Device developers – performance of device
• Utilities/investors – reliability/predictability of supply, return on investment,
• Policy-makers/Planners – usage of seascape, optimisation of resource, power supply
issues
• Consultants to produce resource data/due diligence – compatible/readable data format
The report required by this Technical Specification is highly technical and may be difficult to
understand for some intended users. It is recommended that a short (2 to 4 pages) summary
of the key findings of the resource assessment is also produced, converting some of the more
technical language into information that could be readily understood by a non-technical user.

– 8 – IEC TS 62600-101:2015 © IEC 2015
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –

Part 101: Wave energy resource
assessment and characterization

1 Scope
This part of IEC 62600, which is a Technical Specification, establishes a system for
estimating, analysing and reporting the wave energy resource at sites potentially suitable for
the installation of Wave Energy Converters (WECs). This Technical Specification is to be
applied at all stages of site assessment (from initial investigations to detailed project design)
and in conjunction with the IEC Technical Specification on WEC performance (IEC TS 62600-
100) enables an estimate of the annual energy production of a WEC or WEC array to be
calculated. This Technical Specification is not intended for estimation of extreme wave
conditions.
The wave energy resource is primarily defined using hydrodynamic models that are
successfully validated against measurements. The framework and methodologies prescribed
in this Technical Specification are intended to ensure that only adequate models are used,
and that they are applied in an appropriate manner to ensure confidence and consistency in
the reported results. Moreover, the document prescribes methods for analysing metocean
data (including the data generated by modelling) in order to properly quantify and characterize
the temporal and spatial attributes of the wave energy resource, and for reporting the results
of a resource assessment in a comprehensive and consistent manner.
2 Normative references
The following documents, in whole or in part, are normatively referenced in this document and
are indispensable for its application. For dated references, only the edition cited applies. For
undated references, the latest edition of the referenced document (including any
amendments) applies.
IEC TS 61600-100, Marine energy – Wave, tidal and other water current converters –
Part 100: Electricity producing wave energy converters – Power performance assessment
ISO/IEC Guide 98-3:2008, Guide to the expression of uncertainty of measurement
ASME 20-2009, Standard for Verification and Validation in Computational Fluid Dynamics and
Heat Transfer
IHO (International Hydrographic Organisation), 2008, Standards for Hydrographic Surveys,
Special Publication No. 44, 5th Edition
3 Terms and definitions
For the purposes of this document, the following terms and definitions apply.

3.1
class of resource assessment
3.1.1
class 1: Reconnaissance
resource assessment class requiring relatively low effort, and resulting in a resource
characterization with relatively high uncertainty
Note 1 to entry: Reconnaissance (Class 1) resource assessment is one of three distinct classes of resource
assessment. The remaining two classes are Feasibility (Class 2) and Design (Class 3). A Reconnaissance resource
assessment is most suitable for application over large areas of seascape and would typically be the first resource
assessment conducted in an area.
3.1.2
class 2: Feasibility
resource assessment class requiring relatively moderate effort, and resulting in a resource
characterization with relatively moderate uncertainty
Note 1 to entry: Feasibility (Class 2) resource assessment is one of three distinct classes of resource
assessment. The remaining two classes are Reconnaissance (Class 1) and Design (Class 3). A Feasibility resource
assessment is most suitable for refinement of a Reconnaissance resource assessment prior to undertaking a
Design resource assessment.
3.1.3
class 3: Design
resource assessment class requiring relatively high effort, and resulting in a resource
characterization with relatively low uncertainty
Note 1 to entry: Design (Class 3) resource assessment is one of three distinct classes of resource assessment.
The remaining two classes are Reconnaissance (Class 1) and Feasibility (Class 2). A Design resource assessment
is most suitable for application over small areas of seascape and is typically the final and most detailed
assessment conducted for a particular project.
3.2
wave energy resource
amount of energy that is available for extraction from surface gravity waves
Note 1 to entry: This may be characterised using the directional spectrum or by spectral parameters.
3.3
wave propagation model
3.3.1
parametric wave model
wave model using aggregate sea state parameters such as significant wave height and peak
period to calculate the propagation and transformation of waves
3.3.2
nd
2 generation spectral wave model
wave model using a phase-averaged spectral representation of the sea-state and simplified
parametric representations of non-linear interactions to calculate the propagation and
transformation of waves
3.3.3
rd
3 generation spectral wave model
wave model using a phase-averaged spectral representation of the sea-state and explicit
representation of the physical processes to calculate the propagation and transformation of
waves
3.3.4
mild-slope wave model / parabolic wave model / elliptical wave model
wave model using the associated phase-resolving equation (e.g. mild-slope equation) to
calculate the propagation and transformation of waves

– 10 – IEC TS 62600-101:2015 © IEC 2015
4 Symbols and units
The results of the resource assessment shall be presented in accordance with the SI system
of units. Results may also be presented in terms of an alternative system of units if desired.
th
𝑐 group velocity of the i discrete frequency [m/s]
g,𝑖
directionality coefficient
𝑑
th
𝑓 i discrete frequency [Hz]
𝑖
𝑓 peak frequency [Hz]
p
acceleration due to gravity [m/s ]
𝑔
water depth [m]
ℎ
𝐻 spectrally estimated significant wave height [m]
m0
omni-directional wave power [W/m]
𝐽
𝐽 wave power resolved along the direction 𝜃 [W/m]
𝜃
𝐽
maximum directionally resolved wave power [W/m]
𝜃
𝐽𝐽𝐽𝐽
th –1
𝑘 wave number associated with the i discrete frequency [m ]
𝑖
th 2 –n
spectral moment of n order [m s ]
𝑚
𝑛
MV(p) monthly variability statistic of parameter, p
p any parameter used to characterise the resource

maximum value of the monthly mean values of p
p
max
minimum value of the monthly mean values of p
p
min
order of the spectral moment
𝑛
s directional spreading parameter
th 2
variance density over the i discrete frequency [m /Hz]
𝑆
𝑖
[m /Hz/
th th
𝑆 variance density over the i discrete frequency and j discrete direction
𝑖𝑖
rad]
𝑇 spectrally estimated average zero-crossing wave period. [s]
spectrally defined energy period (also written as T ) [s]
𝑇
e -10
𝑇
peak wave period [s]
p
𝑇 average zero-crossing wave period [s]
z
factor insuring that only positive components are summed
𝛿
th
frequency width of the variance density of the i discrete frequency [Hz]
Δ𝑓
𝑖
th
Δ𝜃 angular width of the variance density of the j discrete direction [rad]
𝑖
𝜖 spectral width
reference sea water density [kg/m ]
𝜌
𝜃 direction of wave propagation [deg]
𝜃 direction of maximum directionally resolved wave power [deg]
Jmax
φ geographical latitude [rad]
5 Classes of resource assessment
5.1 Introductory remarks
This document is intended to be applied across a range of resource assessment study types,
from reconnaissance studies spanning a large region to detailed design studies focused on a
specific site. The procedure to be followed when undertaking an assessment of a wave
energy resource depends on the stage of the study and the study objectives.
Three distinct types of studies, reconnaissance, feasibility and design, are defined as
indicated in Table 1. Class 1 studies are typically conducted at low to medium resolution,
span a relatively large area, and produce estimates with considerable uncertainty. Resource
assessments conducted to investigate the feasibility of one or more potential sites or to
support the design of a specific project normally will focus on smaller areas, will employ
greater resolution and should generate more certain estimates of the wave energy resource.
The user shall declare the class of study being undertaken and shall follow the appropriate
procedures prescribed herein.
Table 1 – Classes of resource assessment
Uncertainty of wave energy
Typical long-shore
Class Description
extent
resource parameter estimation
Class 1 Reconnaissance High Greater than 300 km
Class 2 Feasibility Medium 20 km to 500 km
Class 3 Design Low Less than 25 km

NOTE Information on typical extent is provided for guidance only. The class of resource assessment depends on
the degree of certainty required, not on the extent or size of the study area.
The results and outputs from previous resource assessment studies can be considered for
use as boundary conditions in more detailed studies. As the project progresses through a
number of development stages, the wave energy propagation model and its application should
be refined such that the uncertainty of the resource estimation decreases. The following
factors may reduce uncertainty:
• use of more capable models that include more accurate representation of the physical
processes, as outlined in Table 5 in 7.2;
• finer discretization in frequency, direction, space and time;
• use of more realistic boundary conditions and system forcing (winds, currents, etc.);
• availability of additional measurements for model validation; and
• modelling longer durations.
5.2 Resource assessment and characterization flow chart
The flowchart in Figure 1 depicts the general methodology outlined in this Technical
Specification. Different procedures are to be followed depending on the class of the resource
assessment. For class 1 studies, the resource assessment may be based either on:
a) analysis of existing archived sea state parameters, provided they were generated using a
methodology consistent with the requirements for Class 1 studies set forth herein, or
b) analysis of directional spectra generated through the application of a numerical wave
propagation model in a manner consistent with the requirements for Class 1 studies set
forth herein, or
c) application of measure-correlate-predict methods as specified in Clause 8.
For Class 2 and Class 3 studies, the assessment shall be based on either

– 12 – IEC TS 62600-101:2015 © IEC 2015
d) analysis of directional wave spectra generated through the application of a numerical
wave propagation model in a manner consistent with the requirements for Class 2 or Class
3 studies set forth herein, or
e) application of measure-correlate-predict methods as specified in Clause 8.
Regardless of assessment class, the numerical model used to generate the directional wave
spectra spanning space and time shall be appropriate for the task, configured in an
appropriate manner, and successfully validated against measured oceanographic data. The
boundary conditions and source terms (i.e. wind fields, current fields) used to force the
numerical model shall also be suitable and verified.

Start resource
assessment
Class of
Class 1, 2, or 3 Class 1 only
study
(Clause 5)
Class 1, 2 or 3
Metocean Metocean Validated
data data archived
(Clause 6) (Clause 6)
sea-states
Wave propagation
MCP model
model
(Clause 8)
(Clause 7)
Frequency-
Sea-state
directional
parameters
spectra
Resource Resource
Resource
characterization characterization
characterization
(9.2) (9.3)
(9.2)
Validation of
Validation of
results
results
(7.6)
(7.6)
Valid
Valid
model?
model?
No
No
Yes
Yes
Aggregation of
statistics of results
(9.4)
Reporting of results
(Clause 10)
IEC
Figure 1 – Wave resource assessment and characterization flow chart

– 14 – IEC TS 62600-101:2015 © IEC 2015
6 Study planning and data collection
6.1 Introductory remarks
To obtain an overview of the factors affecting the wave energy resource across the study
area, and to identify the data that will be required to conduct the resource assessment, a site
description shall be prepared. The site description shall include, but need not be limited to, a
description of the elements in the following sub-clauses.
6.2 Study area
The study area is the area in which the wave resource is of interest and is to be assessed and
characterized. The extent of the study area shall be declared. The main physiographic and
oceanographic features of the study area shall be reviewed, especially those features that
influence wave propagation and wave climate. When wave modelling is used to assess the
resource, the model domain is the area across which the wave conditions are modelled. The
model domain may extend beyond the study area. In this case, the extent of the model
domain shall also be declared. When MCP methods are used to assess the resource, the
study area is restricted to a single location or a finite number of discrete locations.
NOTE It is possible that the model domain is larger than the study area because it extends to the known boundary
conditions. In the offshore direction that will typically be to the 100 m – 200 m depth contour. In the long-shore
direction this will generally be greater than the distance from the off-shore boundary to the area of interest.
6.3 Bathymetry
The bathymetry of the model domain shall be described, and a bathymetric contour map shall
be prepared. Where existing data sets are used, their source shall be provided. Existing
bathymetric data sets will normally be employed in a Class 1 assessment. Depending on the
quality of the bathymetric data that is available, new high-resolution bathymetric surveys may
be required for higher class assessments. All bathymetric surveys used, whether existing or
new, should comply with IHO S44:2008). A Survey Order 2 or better, as specified in IHO S44,
should be used for water depths of less than 200 m, and a Survey Order 3 or better should be
used for water depths greater than 200 m.
The bathymetric data shall be used to construct a digital elevation model for use in the wave
propagation modelling. In general, the bathymetry shall be defined with sufficient horizontal
and vertical resolution to adequately describe the bathymetric features influencing wave
propagation. Better resolution is generally required in shallower water (where the waves are
more strongly affected by the seabed) and in areas with steep bottom slopes. The spatial
resolution of the bathymetric data should meet the minimum requirements shown in Table 2.
Table 2 – Resolution of bathymetric data
Class of assessment: 1 2 3
Recommended maximum horizontal spacing of bathymetric data
5 km 2 km 1 km
in water depths greater than 200 m
Recommended maximum percentage difference in water depth
between adjacent bathymetric points in water depths less than 10 % 5 % 2 %
200 m
Recommended maximum horizontal spacing of bathymetric data
500 m 100 m 25 m
in water depths less than 200 m
Recommended maximum horizontal spacing of bathymetric data
100 m 50 m 10 m
in water depths less than 20 m

6.4 Existing wave data
Existing data and study reports characterising wave conditions across the study area shall be
collected, reviewed and described. Existing data may come from previous numerical
simulations, physical measurements, earlier resource assessment studies or previous wave

climate studies. The existing data and information may help guide the user in setting up the
resource assessment, as it may describe key aspects of the wave resource including but not
limited to seasonal variability, inter-annual variability, frequency of storms, prevalence of
multimodal wave systems, expected spectral shape and the variability of dominant wave
direction. Furthermore, this data may be used to define boundary conditions for numerical
modelling provided it conforms to the requirements of 7.3. In the case of Class 1
assessments, the archived data may serve as the primary data source, provided it conforms
to the requirements detailed in 6.5. Measured wave data coincident with model grid points
may be used to validate the numerical modelling, provided it satisfies the requirements of 6.5.
If the existing wave data is characterised using parameters that differ from those used in this
Technical Specification, then the data shall be converted to match these specifications. The
methods used to convert the data shall be detailed and justified. The uncertainty associated
with the existing data shall also be calculated and presented as detailed in 9.5.
6.5 Wave measurement
6.5.1 Purpose
Measured wave data is required to validate the numerical wave model used to estimate the
wave resource over the study area, and to support application of the measure-correlate-
predict method. If suitable physical measurements of wave conditions are not available, then
new measurements shall be acquired for these purposes. Measured wave data may also be
used to develop suitable boundary conditions for wave modelling (see 7.3), but data used for
such purposes shall be independent of data used for model validation.
The measurements used for model validation shall satisfy the requirements of 7.6. In
particular the measurements shall provide an accurate, complete and unbiased description of
the wave climate at the validation locations(s). This implies that, for Class 1 assessments,
analysis of the measurements shall provide reliable estimates of significant wave height,
energy period and omni-directional wav
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