Marine energy - Wave, tidal and other water current converters - Part 201: Tidal energy resource assessment and characterization

IEC TS 62600-201:2015(E) establishes a system for analysing and reporting, through estimation or direct measurement, the theoretical tidal current energy resource in oceanic areas including estuaries (to the limit of tidal influence) that may be suitable for the installation of arrays of Tidal Energy Converters (TECs). It is intended to be applied at various stages of project lifecycle to provide suitably accurate estimates of the tidal resource to enable the arrays' projected annual energy production to be calculated at each TEC location in conjunction with IEC 62600-200.

General Information

Status
Published
Publication Date
08-Apr-2015
Current Stage
PPUB - Publication issued
Start Date
09-Apr-2015
Completion Date
09-Apr-2015
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IEC TS 62600-201:2015 - Marine energy - Wave, tidal and other water current converters - Part 201: Tidal energy resource assessment and characterization
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IEC TS 62600-201
Edition 1.0 2015-04
TECHNICAL
SPECIFICATION
colour
inside
Marine energy – Wave, tidal and other water current converters –
Part 201: Tidal energy resource assessment and characterization
IEC TS 62600-201:2015-04(en)
---------------------- Page: 1 ----------------------
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IEC TS 62600-201
Edition 1.0 2015-04
TECHNICAL
SPECIFICATION
colour
inside
Marine energy – Wave, tidal and other water current converters –
Part 201: Tidal energy resource assessment and characterization
INTERNATIONAL
ELECTROTECHNICAL
COMMISSION
ICS 27.140 ISBN 978-2-8322-2591-2

Warning! Make sure that you obtained this publication from an authorized distributor.

® Registered trademark of the International Electrotechnical Commission
---------------------- Page: 3 ----------------------
– 2 – IEC TS 62600-201:2015 © IEC 2015
CONTENTS

FOREWORD ........................................................................................................................... 4

INTRODUCTION ..................................................................................................................... 6

1 Scope .............................................................................................................................. 7

2 Normative references ...................................................................................................... 7

3 Terms and definitions ...................................................................................................... 7

4 Symbols, units and abbreviations .................................................................................... 7

4.1 Symbols and units .................................................................................................. 7

4.2 Abbreviations .......................................................................................................... 8

5 Methodology overview ..................................................................................................... 8

5.1 Project definition ..................................................................................................... 8

5.1.1 General ........................................................................................................... 8

5.1.2 Stage 1: Feasibility study ................................................................................. 9

5.1.3 Stage 2: Layout design study ........................................................................... 9

5.2 Methodology ........................................................................................................... 9

6 Data collection ............................................................................................................... 12

6.1 Introduction ........................................................................................................... 12

6.2 Bathymetry ........................................................................................................... 12

6.3 Tidal characteristics .............................................................................................. 13

6.3.1 General ......................................................................................................... 13

6.3.2 Assessment of data quality ............................................................................ 13

6.3.3 Tidal height ................................................................................................... 14

6.3.4 Tidal current mobile survey ............................................................................ 14

6.3.5 Tidal current stationary survey ....................................................................... 16

6.4 Meteorological data .............................................................................................. 19

6.4.1 General ......................................................................................................... 19

6.4.2 Wind data ...................................................................................................... 19

6.4.3 Atmospheric pressure .................................................................................... 20

6.5 Wave climate ........................................................................................................ 20

6.6 Turbulence ............................................................................................................ 20

6.6.1 General ......................................................................................................... 20

6.6.2 Flow structure / Eddies .................................................................................. 20

6.7 Stratification, seawater density and sediment measurement ................................. 21

7 Model development and outputs .................................................................................... 21

7.1 General ................................................................................................................. 21

7.2 Model coverage, resolution and boundary conditions ............................................ 21

7.2.1 Bathymetric data ........................................................................................... 21

7.2.2 Model coverage ............................................................................................. 22

7.2.3 Model boundary conditions ............................................................................ 22

7.2.4 Model resolution ............................................................................................ 23

7.3 Choice of model (including characteristics) ........................................................... 23

7.3.1 General considerations .................................................................................. 23

7.3.2 Model selection ............................................................................................. 24

7.3.3 Model characteristics ..................................................................................... 25

7.4 Analysing data to provide model inputs, calibration and validation ........................ 25

7.4.1 Bathymetry interpolation ................................................................................ 25

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IEC TS 62600-201:2015 © IEC 2015 – 3 –

7.4.2 Currents ........................................................................................................ 25

7.4.3 Meteorological analysis ................................................................................. 25

7.4.4 Waves ........................................................................................................... 26

7.4.5 Turbulence .................................................................................................... 26

7.4.6 Flow Structures / Eddies ................................................................................ 27

7.4.7 Seawater density, salinity and temperature .................................................... 28

7.4.8 Sediment ....................................................................................................... 28

7.5 Model calibration / Validation ................................................................................ 28

7.5.1 Model calibration ........................................................................................... 28

7.5.2 Model validation ............................................................................................ 29

7.6 Incorporating energy extraction ............................................................................. 30

7.6.1 General ......................................................................................................... 30

7.6.2 Methodology for incorporating energy extraction ............................................ 31

7.6.3 Practical incorporation of energy extraction in modelling................................ 32

8 Data analysis and results presentation .......................................................................... 33

8.1 General model result presentation ........................................................................ 33

8.2 Generation of annual velocity distribution .............................................................. 33

8.2.1 General ......................................................................................................... 33

8.2.2 Potential methodologies for simulating “missing” tidal constituents ................ 34

8.2.3 Long-term model current predictions (harmonic analysis) .............................. 34

8.2.4 Results presentation ...................................................................................... 36

8.3 Velocity distribution curves – Joint probability distribution ..................................... 37

9 Reporting of results ....................................................................................................... 39

9.1 Purpose of reporting ............................................................................................. 39

9.2 Contents of the report ........................................................................................... 39

Annex A (informative) Calculation of TEC Annual Energy Production ................................... 40

A.1 General ................................................................................................................. 40

A.2 Individual TEC Annual Energy Production (AEP) ................................................... 40

A.3 Array Annual Energy Production ........................................................................... 41

Annex B (informative) Guidelines for current profiler measurements .................................... 42

B.1 General ................................................................................................................. 42

B.2 Instrument configuration ....................................................................................... 42

B.3 Correcting for clock drift ........................................................................................ 42

B.4 Depth quality control ............................................................................................. 43

B.5 Velocity quality control .......................................................................................... 43

Bibliography .......................................................................................................................... 44

Figure 1 – The effect of predicting tides with various constituents from Cook Inlet,

Alaska .................................................................................................................................. 36

Figure 2 – Joint velocity and direction probability distribution, a location in Cook Inlet,

Alaska .................................................................................................................................. 38

Figure 3 – Example exceedance curve for velocity magnitude ............................................... 39

Table 1 – Resource assessment stages .................................................................................. 9

Table 2 – Model and field survey recommendations (Overview) ............................................ 11

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– 4 – IEC TS 62600-201:2015 © IEC 2015
INTERNATIONAL ELECTROTECHNICAL COMMISSION
____________
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –
Part 201: Tidal energy resource assessment and characterization
FOREWORD

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9) Attention is drawn to the possibility that some of the elements of this IEC Publication may be the subject of

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• the required support cannot be obtained for the publication of an International Standard,

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• 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 62600-201, which is a technical specification, has been prepared by IEC technical

committee 114: Marine energy – Wave, tidal and other water current converters.
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IEC TS 62600-201:2015 © IEC 2015 – 5 –
The text of this technical specification is based on the following documents:
Enquiry draft Report on voting
114/142/DTS 114/151A/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.

This publication has been drafted in accordance with the ISO/IEC Directives, Part 2.

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.

The committee has decided that the contents of this publication will remain unchanged until

the stability date indicated on the IEC website 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.
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– 6 – IEC TS 62600-201:2015 © IEC 2015
INTRODUCTION

This Technical Specification is for use by appropriately qualified and competent persons. The

development of the tidal power industry is at an early stage and the significance of particular

tidal energy resource characteristics is not well understood. This Technical Specification is

intended to be updated as understanding of the resource and its response to power extraction

becomes better understood. It is noted that it is presently particularly difficult to derive the

uncertainty (within specified confidence limits) of the resource, given lack of field and model

data for a statistically significant number of sites.

The purpose of this Technical Specification is to provide a uniform methodology that will

ensure consistency and accuracy in the estimation, measurement, characterization and

analysis of the theoretical tidal current resource at sites that could be suitable for the

installation of an array of Tidal Energy Converters (TECs), together with defining a

standardised methodology with which this resource can be described and reported.

Application of the estimation, measurement and analysis techniques recommended in this

Technical Specification will ensure that resource assessment 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 overall goal of the methodology is to enable calculation of the Annual Energy Production

(AEP) for the proposed array of TECs at each TEC location in conjunction with IEC 62600-

200.

In this Technical Specification, the theoretical tidal energy resource (undisturbed or disturbed

). For projects over c.
by power extraction) is defined as the velocity probability distribution f(U

10 MW (circa 10 MW), the velocity probability distribution is calculated using hydrodynamic

models that have been appropriately verified using measured data. The methodology for

measuring the required data is also defined. For individual TECs within small projects of less

than c. 10 MW, an alternative method which uses measured data at each TEC location may

also be used to define the resource.

This Technical Specification describes only the aspects of the resource required to calculate

AEP; e.g., it does not describe aspects of the resource required to evaluate design loads or to

satisfy environmental regulations. Furthermore, this Technical Specification is not intended to

cover every eventuality that may be relevant for any particular project. Therefore, this

Technical Specification assumes that the user has access to, and reviews, other relevant IEC

documentation before undertaking work (e.g., surveys and modelling) which could also satisfy

other requirements.
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IEC TS 62600-201:2015 © IEC 2015 – 7 –
MARINE ENERGY –
WAVE, TIDAL AND OTHER WATER CURRENT CONVERTERS –
Part 201: Tidal energy resource assessment and characterization
1 Scope

This part of IEC 62600 establishes a system for analysing and reporting, through estimation

or direct measurement, the theoretical tidal current energy resource in oceanic areas

including estuaries (to the limit of tidal influence) that may be suitable for the installation of

arrays of TECs.

It is intended to be applied at various stages of project lifecycle to provide suitably accurate

estimates of the tidal resource to enable the arrays’ projected annual energy production to be

calculated at each TEC location in conjunction with IEC 62600-200.
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 61400-12-1, Wind turbines – Part 12-1: Power performance measurements of electricity

producing wind turbines

IEC TS 62600-1, Marine energy – Wave, tidal and other water current converters – Part 1:

Terminology

IEC TS 62600-200, Marine energy – Wave, tidal and other water current converters – Part

200: Electricity producing tidal energy converters – Power performance assessment

IHO (International Hydrographic Organisation), 2008, Standards for Hydrographic Surveys.

Special Publication No. 44. 5th Edition
ICES, 2006, Guidelines for Multibeam Echosounder Data
3 Terms and definitions

For the purposes of this document, the terms and definitions given in IEC TS 62600-1 apply.

4 Symbols, units and abbreviations
4.1 Symbols and units
f(U ) Time occurrence likelihood of a velocity in each magnitude bin (%)

f(U , θ ) Time occurrence likelihood of a velocity in each magnitude and direction bin (%)

i k
I Turbulence intensity
i Index for velocity magnitude bin numbers
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– 8 – IEC TS 62600-201:2015 © IEC 2015
j Index for number of time intervals
k Index for direction bin numbers
2 2
K Turbulent kinetic energy (m /s )
N Number of time intervals
N Number of velocity bins
u’ Root-mean-square of the turbulent velocity fluctuations (m/s)
𝑈 Mean velocity magnitude (m/s)
U Central value velocity magnitude in the i bin (m/s)
U Central value velocity magnitude of time step j (m/s)
θ Direction for the k bin (deg)
V Root Mean Cubed Velocity (m/s)
rmc
ρ Density of the water (kg/m )
4.2 Abbreviations
AEP Annual Energy Production
ADV Acoustic Doppler Velocimeter
APD Average Power Density (kW/m
CTD Conductivity, Temperature, Depth
CFD Computational Fluid Dynamics
EEP Energy Extraction Plane
GPS Global Positioning System
IEC International Electrotechnical Commission
NOAA National Oceanic and Atmospheric Administration
PCA Projected Capture Area
RTK Real Time Kinematics
SAR Synthetic Aperture Radar
TEC Tidal Energy Converter
UTC Coordinated Universal Time
5 Methodology overview
5.1 Project definition
5.1.1 General

This Technical Specification should be applied at various stages of the resource assessment

process to provide velocity probability distributions for computing Annual Energy Production

(AEP) with increasing accuracy or lower levels of uncertainty. This specification assumes that

a region of interest has already been identified. Aspects of the methodology to be followed

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IEC TS 62600-201:2015 © IEC 2015 – 9 –

when undertaking a tidal resource assessment depend on the scope of the analysis and its

objectives. Two distinct types of studies, feasibility and layout design, are defined as

indicated in Table 1. The feasibility study generally has a focus on the whole estuary or

channel with a medium level of uncertainty. The layout design study is expected to focus on

the particular sites chosen through the feasibility studies.
Table 1 – Resource assessment stages
Level of uncertainty
Stage Aim Area
Whole estuary, channel,
Stage 1 Feasibility Medium
etc.
Stage 2 Layout design Development site. Low

The expected decrease in uncertainty as the resource assessment stages progress can result

from:
• measurements and/or modelling over longer durations / periods;
• availability of additional, and/or higher quality measurements;
• use of more capable models, as outlined in 7.3;
• finer discretisation in space and time;
• use of improved boundary conditions;
• improvements in modelling techniques during the project’s evolution.
5.1.2 Stage 1: Feasibility study

A Stage 1 study is focused on investigating the scale and attributes of the energy resource

within a particular study area. The results of a Stage 1 resource assessment can be used to

help assess the feasibility of constructing tidal energy arrays at sites within the study area by

estimating the undisturbed site resource.
5.1.3 Stage 2: Layout design study

A Stage 2 study is focused on generating detailed and accurate information on the tidal

energy resource in a specific area to determine AEP, through supporting the layout design of

a tidal array, and may incorporate energy extraction impacts depending upon the project

scale. The Stage 2 study should consider the technology to be installed and locations of TEC

deployments in order to estimate AEP with lower uncertainty.
5.2 Methodology

The resource assessment requirements are defined depending on the scale of the project as

well as the objective of the assessment (feasibility or design layout). The AEP (calculated

using the method outlined in Annex A) may be assessed based on data from either direct

measurements or from hydrodynamic modelling.

For projects where the total power output is expected to be less than c. 10 MW, or those

where the proposed energy extraction is less than 2 % of the theoretical undisturbed tidal

energy resource (see Note) and therefore there is expected to be little if any impact on the

underlying hydrodynamics of the site, AEP may be estimated from direct resource

measurements using static current profiler measurements and harmonic analysis as defined in

8.2.3. In order to use this method, measurements shall be made at each individual turbine

location. Such projects may also use the hydrodynamic modelling required for larger projects.

If the data collection indicates that the TECs should be deployed in different locations to

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– 10 – IEC TS 62600-201:2015 © IEC 2015

where static current profiler data has been collected, then either additional data gathering at

the new location or the modelling approach is required
...

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