wave and tidal power assessment for the victorian …/media/resources...wave and tidal power...

Sustainable Energy Authority

Wave and Tidal Power Assessment for the Victorian Coastline

Report No. J121/R01

October 2004

WATER TECHNOLOGY Specialist Water and Coastal Engineers

Median Annual Wave Height

Sustainable Energy Authority

Wave and Tidal Power Assessment for the Victorian Coastline

Report No. J121/R01 October 2004

WATER TECHNOLOGY PTY LTD 8 Business Park Drive Notting Hill VIC 3168 Telephone (03) 9558 9366 Fax (03) 9558 9365 ACN No. 093 377 283 ABN No. 60 093 377 283

Wave and Tidal Power Assessment for the Victorian Coastline WATER TECHNOLOGY

J121/R01, October 2004, Rev 1 Page i

DOCUMENT STATUS

Issue Revision Date Issued

To Prepared By

Reviewed By

ApprovedBy

R01

Rev 1

Oct 04

ABC

AMC

AMC

QFORM-AD-18 REV 5 It is the responsibility of the reader to verify the currency of revision of this report.

Copyright

Water Technology Pty Ltd has produced this document in accordance with instructions from Sustainable Energy Authority for their use only. The concepts and information contained in this document are the copyright of Sustainable Energy Authority. Use or copying of this document in whole or in part without written permission of Sustainable Energy Authority constitutes an infringement of copyright. Water Technology Pty Ltd does not warrant this document is definitive nor free from error and does not accept liability for any loss caused, or arising from, reliance upon the information provided herein. H:\J121WAVEPOWER\DOCS\REPORT\R.J121.02.FINALREPORTDRAFT.DOC


J121/R01, October 2004, Rev 1 Page ii

EXECUTIVE SUMMARY

Water Technology Pty Ltd has been commissioned by the Sustainable Energy Authority to investigate the potential for wave and tidal power generation along the Victorian coastline. The study seeks to identify those areas along coastal Victoria where environmental conditions are sufficient to support wave and/or tidal power generation.

Wave Power

Ocean waves represent a considerable renewable energy resource. They travel great distances without significant losses and act as an efficient energy transport mechanism across thousands of kilometres. Waves generated in the Southern Ocean arrive at the southern coast of Australia without significant loss of energy. Furthermore, most of the wave energy is located near the water surface. This means that wave power is a concentrated energy source with potentially much smaller hourly and day-to-day variations than other renewable resources such as wind or solar power.

The highest concentrations of wave power can be found in the areas of the strongest winds, i.e. between latitudes 40 deg. and 60 deg. in both the northern and southern hemispheres. This means that locations such as the southern coast of Australia are highly favoured for the extraction of wave power.

Waves occur at all locations along the coast, with varying height and wave period. These parameters directly influence the amount of wave power available, with greater energy potential in areas exposed to larger waves. There are economic costs associated with the extraction of wave energy and, typically, it is considered viable in areas where potential annual wave power exceeds 30kW/m.

Potential energy generation from waves along the Victorian coastline appears to be restricted to those areas west of Cape Otway where median annual wave power exceeds 30kW/m. This section of coastline is influenced by larger ocean swells propagating from the Southern Ocean. Median annual wave power in central Bass Strait is much lower, with up to 15-20kW/m potentially availably along the coastline between Phillip Island and Wilson’s Promontory. The east Gippsland coastline is influenced by large infrequent wave events, while the median wave climate is relatively slight. Accordingly, the resultant wave power potential is this area is also low, with annual median wave power of approximately 10-15kW/m.

Based on a comparison of Cape Sorell long term data with 2003 data used in this study, the estimates determined are considered an accurate representation of longer term wave characteristics of the Bass Strait region.

Tidal Power

The potential for tidal power generation depends upon the tidal range, and the tidal current velocity. High flow velocities are generally associated with restricted entrances to large tidal embayments (e.g., the Rip at the entrance to Port Phillip Bay, and the Eastern Entrance to Westernport Bay, at San Remo).

It has been estimated that, world-wide, approximately 3000 GW of energy is continuously available from the action of tides. However, it is also estimated that only approximately 2% (60 GW) can potentially be recovered from tides for electricity generation.


J121/R01, October 2004, Rev 1 Page iii

There are currently primarily two technologies for tidal power extraction. The first involves the use of structures where the incoming tide floods into a basin and is trapped behind a barrage or dam. As the tide recedes, the tidal waters behind the dam/barrage are discharged via energy turbines. Variations on this technology include turbines that are active on both the flooding and ebbing tide. This technology is only economic in areas with large tidal range (greater than 5 meters). The second technology utilises tidal turbines placed in areas of high tidal currents created as a result of the existing tidal regime and bathymetry. This technology is still developing and is considered only potentially viable where tidal currents are in the range 2-3m/s.

Tidal turbines are typically less expensive than tidal barrage systems and offer a number of advantages. They are less disruptive to wildlife, allow small boats to continue to use the area, and have much lower material requirements than the dam. Tidal turbines function well where coastal currents run at 2-3 m/s (slower currents tend to be uneconomic while larger ones put a lot of stress on the equipment).

Typical peak tidal variation in Bass Strait is approximately 2.5m, and it is unlikely that barrage style tidal power extraction will be viable in the region. However, throughout Bass Strait there are numerous areas of higher tidal currents where tidal turbine technology could be viable.

Summary

Key findings of this assessment are as follows:

Wave Power

• Wave Power generation is typically considered viable where annual median wave power exceeds 30kW/m

• Potential energy generation from waves along the Victorian coastline appears to be restricted to those areas west of Cape Otway. This section of coastline is influenced by larger ocean swells propagating from the Southern Ocean.

• Median annual wave power in central Bass Strait is up to 20kW/m, and is highest along the section of coastline between Phillip Island and Wilson’s Promontory.

• The East Gippsland coastline does receive relatively large waves associated with storm events, but the median wave climate is relatively low. The resultant wave power potential is this area is also low, with annual median wave power of approximately 10-15kW/m available, depending on location.

Tidal Power

• Tidal power generation opportunities along coastal Victoria are limited due to the small tidal range present in Bass Strait. The use of dams or tidal barrages to capture tidal energy would appear unviable. However, opportunities may exist to utilise emerging tidal turbine technology in areas of moderate to high tidal current speeds.

• Appropriate sites for tidal turbines would be relatively close to shore in water depths of about 30m. Port Phillip entrance presents opportunities for application of this technology, but some areas within The Rip may be unsuitable as current speeds may be too high (and potentially destructive), there is insufficient depth, the area is of high environmental significance and is subject to significant navigational requirements. However, there are areas within Westernport that may offer some potentially viable opportunities, particularly those areas away from the main navigational channels.


J121/R01, October 2004, Rev 1 Page iv

TABLE OF CONTENTS

1 Introduction ...................................................................................................................... 1 1.1 Background ................................................................................................................ 1 1.2 Scope of Works .......................................................................................................... 1

1.2.1 Wave Power Assessment ................................................................................... 1 1.2.2 Tidal Power Assessment .................................................................................... 2

2 Wave Power Assessment.................................................................................................. 3 2.1 Introduction ................................................................................................................ 3 2.2 Available Data............................................................................................................ 3

2.2.1 Bureau of Meteorology WAM Model................................................................ 3 2.2.2 Cape Sorell ......................................................................................................... 4 2.2.3 Portland and Cape Otway Region ...................................................................... 4 2.2.4 Point Lonsdale.................................................................................................... 5 2.2.5 Kingfish B .......................................................................................................... 6 2.2.6 Comparison of 2003 Data Series with Long Term Data.................................... 7 2.2.7 Comparison of BOM Hindcast with Measured Data ......................................... 8

2.3 MIKE 21 Spectral Wave Modelling......................................................................... 11 2.3.1 Modelling Overview ........................................................................................ 11 2.3.2 Model Description............................................................................................ 11 2.3.3 Model Setup ..................................................................................................... 11 2.3.4 Model Boundary Conditions ............................................................................ 12 2.3.5 Model Verification ........................................................................................... 12

2.4 Wave Power ............................................................................................................. 14 2.4.1 Wave Power Calculation.................................................................................. 14 2.4.2 Potential Wave Power ...................................................................................... 15

2.5 Discussion ................................................................................................................ 16

3 Tidal Power Assessment ................................................................................................ 18 3.1 Introduction .............................................................................................................. 18 3.2 Available Data.......................................................................................................... 19

3.2.1 Tidal Constituents ............................................................................................ 19 3.3 Tidal Modelling........................................................................................................ 21

3.3.1 Modelling Overview ........................................................................................ 21 3.3.2 Model Description............................................................................................ 21 3.3.3 Model Setup ..................................................................................................... 21 3.3.4 Model Verification ........................................................................................... 23

3.4 Tidal Power .............................................................................................................. 24 3.4.1 Tidal Power Calculation................................................................................... 24 3.4.2 Potential Tidal Power ....................................................................................... 24

3.5 Discussion ................................................................................................................ 27

4 Conclusion....................................................................................................................... 28

5 References ....................................................................................................................... 29


J121/R01, October 2004, Rev 1 Page v

APPENDICIES Appendix A – MIKE 21 SW Model Description Appendix B – Wave Power Maps Appendix C – MIKE 21 FLOW Model Description Appendix D – Tidal Power Maps

LIST OF FIGURES

Figure 2-1 Cape Sorell Wave Data 2003 .................................................................................. 4

Figure 2-2 Cape de Couedic Wave Data 2003.......................................................................... 5

Figure 2-3 Lonsdale Wave Data 2003 ...................................................................................... 6

Figure 2-4 Kingfish B Measured Wave Heights....................................................................... 7

Figure 2-5 Comparison of 2003 Wave Data with Long Term Data Cape Sorell...................... 8

Figure 2-6 Cape Sorell Measured and Hindcast Wave Heights................................................ 8

Figure 2-7 Cape de Couedic Measured and Hindcast Wave Heights ....................................... 9

Figure 2-8 Point Lonsdale Measured and Hindcast Wave Heights ........................................ 10

Figure 2-9 Kingfish B Measured and Hindcast Wave Heights............................................... 10

Figure 2-10 MIKE21 SW Model Setup .................................................................................... 12

Figure 2-11 MIKE21 SW Model Verification – Portland (as Cape Sorell).............................. 13

Figure 2-12 MIKE21 SW Model Verification – Point Lonsdale.............................................. 13

Figure 2-13 MIKE21 SW Model Verification – Kingfish B (Hindcast) .................................. 14

Figure 2-14 Median Annual Wave Height, Period and Power – MIKE21 SW Model............. 16

Figure 3-1 Tidal Constituent Locations .................................................................................. 20

Figure 3-2 MIKE 21 Flow Model Extent – Bass Strait .......................................................... 21

Figure 3-3 MIKE 21 Flow Model Extent – Port Phillip ......................................................... 22

Figure 3-4 MIKE 21 Flow Model Extent – Westernport........................................................ 23

Figure 3-5 MIKE 21 Flow Model Extent – Corner Inlet ........................................................ 23

Figure 3-6 Tidal Power – Bass Strait ...................................................................................... 25

Figure 3-7 Tidal Power – Port Phillip ..................................................................................... 25

Figure 3-8 Tidal Power – Westernport.................................................................................... 26

Figure 3-9 Tidal Power – Corner Inlet .................................................................................... 26


J121/R01, October 2004, Rev 1 Page 1

1 INTRODUCTION

1.1 Background Water Technology Pty Ltd has been commissioned by the Sustainable Energy Authority to investigate the potential for wave and tidal power generation along the Victorian coastline. The study seeks to identify those areas along coastal Victoria where environmental conditions are sufficient to support wave and/or tidal power generation. This report presents findings of our investigations including an overview of the assessment methodology and maps of wave and tidal power representing the energy generating potential along the Victorian coastline.

1.2 Scope of Works 1.2.1 Wave Power Assessment A preliminary wave power assessment was undertaken by Water Power Consultants and Lawson & Treloar in 1992 (WPC, 1992). The study looked at the potential for energy production from waves along the Victorian coastline. The study was based on available wave data and hindcast wave characteristics based on the Bureau of Meteorology’s 250km grid regional wave model. The Bureau’s model appeared to underestimate wave characteristics and was considered by WPC to be unsuitable for general wave climate determination. The study provided an estimate of potential wave power at a number of discrete locations along the coast (Portland, Lorne, Cape Patterson, Cape Liptrap, Wilson’s Promontory, Delray Beach, Kingfish B and Cape Sorell).

Since that time additional and/or updated information has been collected that may provide improved accuracy in the estimation of wave power potential. These include:

• Implementation by the Bureau of Meteorology of a “Meso Scale WAM” model to hindcast wave conditions in coastal areas of south eastern Australia, a more detailed and sophisticated model than that used previously. The model operates on a grid size of 0.125º (about 12km), and is suitable for helping define the offshore wave climate and concurrent wind conditions throughout the area of interest. This model runs operationally and provides hindcast wind and wave fields on a 12-hourly basis.

• Longer term and/or additional wave measurements carried out at a number of different locations around the coast. These measurements cover the three main regions of the Victorian coastline: west of Cape Otway, Central Bass Strait, and east of Wilsons Promontory. As such, these measurements are useful for derivation of a regional wave climate and verification of the hindcast wave data available from the Bureau of Meteorology WAM model. These data include:

o Approximately 12 months of wave data from offshore of Port Campbell

o On-going measurements from Cape Sorell on the west coast of Tasmania (this site was used as a long-term reference site for the previous study)

o On-going measurements from offshore of Port Phillip Heads

o On-going measurements from the Kingfish B oil and gas platform in Eastern Bass Strait.

In consideration of the above, the scope of works for the wave power assessment was:



• Acquisition and review of available new wave data (requiring collaboration with the Bureau of Meteorology, Woodside Offshore Petroleum, Melbourne Ports Corporation and Esso Australia Ltd.

• Acquisition of Bureau of Meteorology wave model hindcast data for representative offshore areas along the Victorian coastline.

• Development of a fine grid wave model of Bass Strait and the Victorian coastline (down to a scale of about 3km) for transferring offshore wave conditions into the coast.

• Verification of the wave model transformation process against the measured wave data.

• Use of the wave model to establish the main wave climate parameters, in terms of wave height, period and direction around the coastline.

• Use of the wave climate data to establish the wave power generation potential around the coastline, and to assess the seasonal and inter-annual variation in wave power.

• Provision of maps of wave climate and wave power generation potential in a form that can be readily incorporated into a GIS system.

• Provision of a report describing the work carried out and presenting the main findings of the investigation.

1.2.2 Tidal Power Assessment The potential for tidal power generation depends upon the tidal range (an indicator of the pressure available), and the tidal current velocity (an indicator of the discharge available). High flow velocities are generally associated with restricted entrances to large tidal embayments (e.g., the Rip at the entrance to Port Phillip Bay, and the Eastern Entrance to Westernport Bay, at San Remo).

The tidal power investigation has assessed the potential for tidal power generation throughout Bass Strait with detailed modelling assessments around selected embayment entrances. The scope of work for the tidal power assessment included:

• Re-establishment of a tidal model of Victorian coastal waters (extending from west of the South Australian border to east of Cape Otway, and including all of Bass Strait).

• Validation of the model against tidal measurements from representative points along the coastline.

• Preparation and validation of high resolution models of Port Phillip Bay, Westernport, and Corner Inlet

• Use of the models to develop tidal height and current data along the coastline

• Use of the tidal height and current data to determine the tidal power generation potential around the coastline for a given loss in tidal range.

• Provision of maps of tidal heights, current velocities and tidal power generation potential in a form that can be readily incorporated into a GIS system.

• Provision of a stand-alone report describing the work carried out and presenting the main findings of the investigation.



2 WAVE POWER ASSESSMENT

The following sections present the methodology and results of an assessment of potential wave power generation for the Victorian coastline.

2.1 Introduction The main influx of energy to the Earth is solar energy. Through a variety of natural processes a proportion of this energy is converted to wind generation, and ultimately transferred to ocean waves. Waves are generated by the wind as it blows across the ocean surface. The energy contained in waves may be significant, with estimates of up to 70 MW/km of wave frontage in favourable latitudes.

Ocean waves represent a considerable renewable energy resource. They travel great distances without significant losses and act as an efficient energy transport mechanism across thousands of kilometres. Waves generated in the Southern Ocean arrive at the southern coast of Australia without significant loss of energy. Furthermore, most of the wave energy is concentrated near the water surface. This means that wave power is a concentrated energy source with potentially smaller hourly and day-to-day variations than other renewable resources such as wind or solar power.

The highest concentrations of wave power can be found in the areas of the strongest winds, i.e. between latitudes 40 deg. and 60 deg. in both the northern and southern hemispheres. In the southern hemisphere the fetch at these latitudes is long, and the predominantly west to east winds initiate and build significant wave fields. This means that the southern coast of Australia, which frequently experiences large ocean swells propagating from the southern ocean, is a highly favoured location for the extraction of wave power.

Waves occur at all locations along the Victorian coast, with varying height and wave period. These parameters directly influence the amount of wave power available, with greater energy potential in areas exposed to larger waves. There are economic costs associated with the extraction of wave energy and, typically, it is considered viable in areas where median annual wave power exceeds 30kW/m (WPC, 1992).

2.2 Available Data The assessment of wave power along the Victorian coastline has been undertaken with reference to available con-current data from 2003, including measured wave data from various sites in Bass Strait and hindcast wave data from the Bureau of Meteorology.

2.2.1 Bureau of Meteorology WAM Model WAM is an ocean wave model incorporating the effects of steady and inhomogeneous currents and depth on ocean waves. The model simulates the evolution of the energy spectrum for ocean waves by solving the wave transport equation. The numerical formulation is represented as superposition of source terms such as wind input, non-linear wave-wave interaction, dissipation due to wave breaking, and bottom friction.

The Bureau of Meteorology has supplied available hindcast data from their meso-scale WAM model for Bass Strait. The data was supplied on a 0.125º grid extending from 140ºE (just west of the Victoria/South Australia border) to 151ºE (east of Cape Howe).



The data was supplied at 12 hour intervals for all of 2003 and includes such parameters as:

• Wind speed and direction

• Wave height, period and direction

These data were used as a baseline from which numerical model boundary conditions were derived and to assist with model calibration.

2.2.2 Cape Sorell Wave Rider Buoy data was retrieved from Cape Sorell, off the west coast of Tasmania (approx 42.1S 145.0E). Figure 2-1 below presents the wave data.

0

2

4

6

8

10

12

01/03 03/03 05/03 07/03 09/03 11/03 01/04

Wav

e He

ight

(m)

4

6

8

10

12

14

16

18

01/03 03/03 05/03 07/03 09/03 11/03 01/04

Wav

e P

erio

d (s

)

Figure 2-1 Cape Sorell Wave Data 2003

For the 2003 data period the maximum significant wave height measured was 10.41m, and the maximum wave height recorded was 16.77m (recorded at 17/09/03 10pm). The mean significant wave height for the period was 2.97m and the median significant wave height 2.74m. The mean significant wave period was 10.53s and the median significant wave period was 10.56s. The wave heights measured in 2003 are consistent with previous wave data collected from July 85 to June 89 where a mean significant wave height of 2.80m was observed over that four year period (WPC, 1992).

2.2.3 Portland and Cape Otway Region Limited measured data from the Portland region is presented in the WPC 1992 report. The data is for the period Jan-Apr 1991 recorded at a location approximately 30km southeast of



Cape Nelson. The data shows a strong correlation between Cape Sorell and Portland with wave heights in deepwater offshore from Portland approximately 97% of concurrent measurements at Cape Sorell.

Data has been sourced from the Bureau of Meteorology for Cape de Couedic, on the south west tip of Kangaroo Island in South Australia. This data has been reviewed to gain a better understanding of the north-south variation in wave characteristics, and the representation of these in the WAM model. The Cape de Couedic data is presented below in Figure 2-2.

0

1

2

3

4

5

6

7

01/03 03/03 05/03 07/03 09/03 11/03 01/04

Wav

e He

ight

(m)

Figure 2-2 Cape de Couedic Wave Data 2003

For the 2003 data period the maximum significant wave height measured was 6.52m (recorded on 06/06/03). The mean significant wave height for the period was 2.6m and the median significant wave height 2.4m.

Other data for the region is held by Woodside, but was not available for use in this study. Limited anecdotal evidence indicates that wave heights in the Woodside data are consistent with those concurrently measured at Cape Sorell, and occasionally higher.

Together, these data indicate that wave heights measured at Cape Sorell are also representative of deepwater wave conditions along the western Victorian coastline.

2.2.4 Point Lonsdale The Port of Melbourne Corporation have been recording wave data at a location approximately 2nm southwest of Point Lonsdale (approx 38º 18.2S 144º 34.2E). Available data for 2003 was retrieved and is presented below in Figure 2-3.



00.5

11.5

22.5

33.5

44.5

01/03 03/03 05/03 07/03 09/03 11/03 01/04

Wav

e He

ight

(m)

0

2

4

6

8

10

12

14

16

01/03 03/03 05/03 07/03 09/03 11/03 01/04

Wav

e P

erio

d (s

)

Figure 2-3 Lonsdale Wave Data 2003

For the 2003 data period (approx 160 days) the maximum significant wave height measured was 3.85m, and the maximum wave height recorded was 6.78m (recorded at 15/04/03 7am). The mean significant wave height for the period was 1.35m and the median significant wave height 1.29m. The mean significant wave period was 9.34s and the median significant wave period was 9.60s.

2.2.5 Kingfish B Figure 2-4 below shows a time history of measured wave heights for Esso’s Kingfish B for 2003.



0

0.5

1

1.5

2

2.5

3

3.5

4

01/01/03 20/02/03 11/04/03 31/05/03 20/07/03 08/09/03 28/10/03 17/12/03

Wav

e H

eigh

t (m

)

Figure 2-4 Kingfish B Measured Wave Heights

The maximum wave height recorded over the period was 3.41m on 25th August. The median measured wave height over the period was 1.2m.

2.2.6 Comparison of 2003 Data Series with Long Term Data Measured data from Cape Sorell has been compared with long term statistical data from the same location to determine whether 2003 is representative of low, average, or high wave energy year. This comparison provides a mechanism to place the results of subsequent modelling in a longer term context.

Figure 2-5 below compares long term wave data at Cape Sorell with that of 2003 used in subsequent analysis in this study. Median (50th percentile) significant wave heights for the two data sets compare well with the 2003 data showing 2.74m and the long term data showing 2.80m. Above the median, the 2003 data shows that approximately 7% of observed waves exceed 5m, whereas the long term data suggests that only 2% of waves exceed 5m. Below the median there is reasonable agreement between the two data sets. As the 2003 data set spans only 1 year, it is inappropriate to draw comparisons below the 1 and above the 99 percentiles.

The comparison indicates that the 2003 data appears to contain a greater number of large wave events than the long term average. However, wave power calculations for this study and presented in this report have been determined based on median wave conditions, which for the 2003 wave data appear consistent with the long term average.



99.9999.99995908070605040302010510.10.01

10.07.05.0

3.0

2.01.5

1.00.70.5

Exceedance Probability (%)

Sign

ifica

nt W

ave

Heig

ht (m

)

Long TermYear 2003

Figure 2-5 Comparison of 2003 Wave Data with Long Term Data Cape Sorell

2.2.7 Comparison of BOM Hindcast with Measured Data 2.2.7.1 Cape Sorell Figure 2-6 below shows a time history of measured and hindcast wave heights for Cape Sorell for the autumn and winter period.

0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

1/01/03 3/03/03 3/05/03 3/07/03 2/09/03 2/11/03 2/01/04

Wav

e H

eigh

t (m

)

Measured

Hindcast

Figure 2-6 Cape Sorell Measured and Hindcast Wave Heights

Analysis of all available data for 2003 indicates that measured wave heights at Cape Sorell are about 15.5% higher than those in the hindcast.



2.2.7.2 Portland and Cape Otway Region Data was sourced from the Bureau of Meteorology for Cape de Couedic, on the south west tip of Kangaroo Island in South Australia. This data has been reviewed to gain a better understanding of the north-south variation in wave characteristics, and the representation of these in the WAM model. Analysis of this data indicates that corresponding wave heights are approximately 8.5% higher at Cape Sorell. Comparison of measured and hindcast wave heights at Cape de Couedic (see Figure 2-7) indicates that measured wave heights are approximately 12.9% higher than hindcast wave heights. Noting that the Cape Sorell measured wave heights were approximately 15.5% higher than hindcast, the comparison at Cape de Couedic suggests that the meso-scale WAM model’s performance at Cape Sorell and Cape de Couedic is similar, and provides a reasonable representation of the north-south spatial variability of wave height.

Furthermore, analysis by the Bureau of the meso-scale WAM model results show similar rms error and bias for Cape Sorell and Cape de Couedic, indicating similar performance for the hindcast model compared with measured data at these two locations. In consideration of the above, it was concluded that the meso-scale WAM model appears to underestimate wave heights in western Bass Strait, but provides a reasonable representation of the spatial variability of wave heights. Accordingly, the relationship adopted for the hindcast to “actual” wave heights in the Cape Otway region is that of Cape Sorell, ie 15.5% increase of hindcast wave heights.

0

1

2

3

4

5

6

7

8

01/03 03/03 05/03 07/03 09/03 11/03 01/04

Wav

e H

eigh

t (m

)

Hindcast

Measured

Figure 2-7 Cape de Couedic Measured and Hindcast Wave Heights

2.2.7.3 Point Lonsdale Figure 2-8 below shows a time history of measured and hindcast wave heights for Point Lonsdale for the autumn and winter period.



0.00

1.00

2.00

3.00

4.00

5.00

6.00

7.00

8.00

1/01/03 3/03/03 3/05/03 3/07/03 2/09/03 2/11/03 2/01/04

Wav

e H

eigh

t (m

)

Measured

Hindcast

Figure 2-8 Point Lonsdale Measured and Hindcast Wave Heights

Analysis of all available data for 2003 indicates that measured wave heights off Point Lonsdale are reasonably well represented in the hindcast, being only about 5.1% higher.

2.2.7.4 Kingfish B Figure 2-9 below shows a time history of measured and hindcast wave heights for Kingfish B for the autumn and winter period.

0

1

2

3

4

5

6

01/01/03 03/03/03 03/05/03 03/07/03 02/09/03 02/11/03 02/01/04

Wav

e H

eigh

t (m

)

MeasuredHindcast

Figure 2-9 Kingfish B Measured and Hindcast Wave Heights

Analysis of the available data for 2003 indicates that measured wave heights at Kingfish B are about 67% of those in the hindcast. The median wave height for the hindcast data was 1.56m. Previous experience with wave data from this region indicates that a median wave height of 1.5-1.6m is typical. Consultation with Lawson & Treloar has confirmed that the measurements at Kingfish B are potentially erroneous, particularly during higher wave conditions (pers comm., Ray Rice, Lawson & Treloar, Sept 2004). Furthermore, the hindcast wave data compares well with long term wave exceedance information report in WPC 1992.



As such, the hindcast wave heights are considered more reliable than the measured data and have been adopted directly for use in determining wave power.

2.3 MIKE 21 Spectral Wave Modelling 2.3.1 Modelling Overview As discussed earlier, wave modelling undertaken by the Bureau of Meteorology utilises a “meso-scale WAM” model to hindcast wave conditions in coastal areas of south eastern Australia. While this is a significantly more detailed and sophisticated model than that used previously by the Bureau, the model operates on a fixed grid size of 0.125º (about 12km), which limits its ability to adequately represent the detailed features of the coastline. Accordingly, a more detailed model was established with sufficient resolution to represent the coast and allow the propagation of offshore wave conditions to the nearshore areas.

The general approach in undertaking the wave modelling was:

• Prepare a model grid with appropriate spatial resolution;

• Apply appropriate wave conditions along the boundaries of the detailed model extracted from the BoM WAM model;

• Apply wind conditions over the entire computational domain of the detailed model extracted from the BoM WAM model;

• At selected locations, verify the detailed model’s results with the WAM model and available measured data. The results of this comparison have been used to calibrate the detailed model; and,

• Utilise the calibrated detailed model’s wave climate to determine potential wave power along the coastline (See Section 2.4).

2.3.2 Model Description MIKE21 SW is a spectral wind wave model developed by DHI Software. The model simulates the growth, decay and transformation of wind generated waves and swell in offshore and coastal areas. The model uses an unstructured (spatially varying) finite element grid composed of triangular elements to represent the computational domain so that regional and local scale topographic and bathymetric features may be readily incorporated. A more detailed description of the MIKE21 SW model is attached as Appendix A.

2.3.3 Model Setup A MIKE21 SW model was developed for Bass Strait extending from 140ºE (just west of the Victoria/South Australia border) to 151ºE (east of Cape Howe). Model resolution varies between approximately 30km at the ocean boundaries to less than 1.5km along the Victorian coastline. As the focus of this investigation was the assessment of wave climate in nearshore areas (rather than coastal embayments), the representation of the coastline was modified to remove Port Phillip, Westernport, Corner Inlet and other smaller embayments. Bathymetric data has been extracted from the DHI Cmap database based on the AUS Chart series. Figure 2-10 below illustrates the modelling domain, bathymetry and computational grid.



BathymetryAbove -1

-2 - -1-5 - -2

-10 - -5-20 - -10-50 - -20

-100 - -50-200 - -100-500 - -200

-1000 - -500-2000 - -1000-5000 - -2000Below -5000Undefined Value

140 141 142 143 144 145 146 147 148 149 150 151

-42.0

-41.5

-41.0

-40.5

-40.0

-39.5

-39.0

-38.5

-38.0

-37.5

-37.0

Figure 2-10 MIKE21 SW Model Setup

2.3.4 Model Boundary Conditions Wave conditions along the boundaries of the detailed model are extracted from the BoM WAM model. Each of the 4 model boundaries are represented (West, South-west, South-east and East). The wave conditions on each boundary vary spatially and temporally, and are interpolated onto the MIKE21 SW model boundary.

Wind conditions are included in the WAM model data. These are extracted from the WAM model over the entire computational domain and applied over the MIKE21 SW model. Again, these conditions vary in space and time (provided at 12 hourly intervals in the WAM model). Waves develop in the MIKE21 SW model based on the Shore Protection Manual 1984 formulation.

The comparison of the hindcast data with measured data (Section 2.2.7) indicates that the BOM hindcast slightly underestimates wave heights, particularly at Cape Sorell. At Kingfish B, the measured data does not appear to be reliable. The hindcast wave heights are considered more typical and have been adopted directly for use in the modelling.

The boundary conditions for the MIKE21 SW model are derived from the hindcast data and to account for variations from measured observations and regional experience, have been scaled according to the following rules:

• West Boundary scaled by 1.155

• West South Boundary scaled by 1.155

• East South Boundary scaled by 1.000

• East Boundary scaled by 1.000

2.3.5 Model Verification Figure 2-11 to Figure 2-13 compare the MIKE21 SW wave model results with measured data from sites where data was available. The model performance at Portland (taken as equivalent to Cape Sorell) and Kingfish B (taken as the Hindcast data) is good, with an adequate representation of the measured wave height data in these areas. However, the model slightly



overestimates wave heights in central Bass Strait (as measured at the Point Lonsdale Wave Buoy). It is known that strong spatially varying gradients of wave height are observed near the entrance to Port Phillip, due to localised effects such as rapid changes in bathymetry, and the influence of strong current fields. This means that the measured observations are highly location dependent. This spatial variation occurs at a resolution at or below that used in the model and the model does not include effects resulting from wave-current interactions.

It is recognised that the modelled wave conditions in Bass Strait may be a slight overestimate, but could be attributed to local spatial variations (the model’s spatial resolution may be insufficient to represent these local variations). Nevertheless, the modelled wave heights do not result in adequate wave power (>30kW/m) for this area to be considered a viable wave power generation location.

0

2

4

6

8

10

12

Jan 03 Mar 03 May 03 Jul 03 Sep 03 Nov 03 Jan 04

ModelMeasured

Figure 2-11 MIKE21 SW Model Verification – Portland (as Cape Sorell)

0

1

2

3

4

5

6


ModelMeasured

Figure 2-12 MIKE21 SW Model Verification – Point Lonsdale



0

1

2

3

4

5

6


ModelMeasured/Hindcast

Figure 2-13 MIKE21 SW Model Verification – Kingfish B (Hindcast)

2.4 Wave Power 2.4.1 Wave Power Calculation Wave power represents the potentially available wave energy flux per unit width of wave crest. It is related to the wave height and group velocity, the rate at which energy is transmitted in the direction of travel. Wave power is given by:

gCEP *=

Where E* = wave energy density Cg = wave group velocity

The total wave energy is the sum of the kinetic and potential energy components of the wave system. It is usually expressed as a wave energy density, E*, given by

16

*2SHg

Eρ

=

Where ρ = density of sea water (1026 kg/m3) g = acceleration due to gravity (9.81 m/s), and HS = significant wave height

The second component of the wave power calculation, group velocity, Cg, depends on the wave period and water depth, and is given by:

CLd

LdCg

+=

)/4sinh(/41

21

ππ

Where d = water depth (m) L = wave length (m) C = wave speed (m/s) = )/2tanh(2/ LdgT ππ T = wave period (s)

However, in deep and shallow water the equations for Cg simplify to:



π4

gTCg = Deep water, d>L/2, and

dgCg = Shallow water

And the corresponding equations for wave power become:

π

ρ416

2 gTHgP S= Deep water, d>L/2, and

dgHg

P S

16

2ρ= Shallow water

2.4.2 Potential Wave Power As wave power is a function of wave height squared and wave period, an average annual wave power calculation may be incorrectly biased and over estimated due to the influence of a few major storm events. Accordingly, the median wave power is presented, such that half the incident wave energy is higher than this value and half lower.

Potential wave power has been calculated from the MIKE21 SW model results. Appendix B presents monthly plots of potential wave power for coastal Victoria derived from the MIKE21 SW model results. Figure 2-14 below shows the median annual wave characteristics for Bass Strait based on these model results.

The model results indicate that potential annual wave power greater than 30kW/m is limited to the western part of the Victorian coastline, west of Cape Otway. On a month to month basis (see Appendix B), wave power along the Victorian coastline west of Cape Otway exceeding 30kW/m was observed during March through to October. During the period November to February, wave heights are typically insufficient to generate potential wave power greater than 30kW/m. In central Bass Strait, east of Cape Otway, wave power greater than 30kW/m was limited to the months of June-September, and may be limited to relatively deep water southwest of Westernport Bay and Phillip Island.



Wave Height Htot MedianAbove 3.53.25 - 3.5

3 - 3.252.75 - 32.5 - 2.75

2.25 - 2.52 - 2.25

1.75 - 21.5 - 1.75

1.25 - 1.51 - 1.25

0.75 - 10.5 - 0.75

0.25 - 0.50 - 0.25

Below 0Undefined Value

Wave Period Ts MedianAbove 16

15 - 1614 - 1513 - 1412 - 1311 - 1210 - 11

9 - 108 - 97 - 8


Wave Power MedianAbove 60

55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure 2-14 Median Annual Wave Height, Period and Power – MIKE21 SW Model

2.5 Discussion Potential energy generation from waves along the Victorian coastline appears to be restricted to those areas west of Cape Otway where median annual wave power exceeds 30kW/m. This section of coastline is influenced by larger ocean swells propagating from the Southern



Ocean. At Portland we estimate potential annual median wave power at 40-50kW/m2 and WPC 1992 indicate levels of 46kW/m2.

Median annual wave power in central Bass Strait is much lower, with up to 15-20kW/m potentially availably along the coastline between Phillip Island and Wilson’s Promontory, consistent with WPC 1992.

The East Gippsland coastline does receive relatively large waves associated with storm events, but the median wave climate is relatively low. The resultant wave power potential is this area is also low, with annual median wave power of approximately 10-15kW/m available, depending on location. Again, these results are consistent with those of WPC 1992 who estimate 13kW/m2 at Kingfish B.

Based on a comparison of Cape Sorell long term data with 2003 data used in this study, the estimates determined are considered an accurate representation of longer term wave characteristics of the Bass Strait region.



3 TIDAL POWER ASSESSMENT

The following sections present the methodology and results of an assessment of potential tidal power for the Victorian coastline.

3.1 Introduction The potential for tidal power generation depends upon the tidal range (an indicator of the pressure available), and the tidal current velocity (an indicator of the discharge available). High flow velocities are generally associated with restricted entrances to large tidal embayments (e.g., the Rip at the entrance to Port Phillip Bay, and the Eastern Entrance to Westernport Bay, at San Remo).

It has been estimated that, world-wide, approximately 3000 GW of energy is continuously available from the action of tides. However, it is also estimated that only approximately 2% (60 GW) can potentially be recovered from tides for electricity generation. Currently, only in places with large tidal range (greater than 5 meters) can tidal power be extracted economically.

In some places of the world tidal energy is quite attractive. For coastal areas, usually at the entrances to large estuaries, resonance can occur, leading to far greater than average tidal ranges which could relatively conveniently be blocked off. Such circumstances are found in the Bay of Fundy in Canada, with a mean tidal range of 10.8 metres or in the Severn Estuary in Britain with a mean range of 8.8 metres, making large scale projects at both these locations attractive.

There are currently two primary technologies for tidal power extraction. The first involves the use of structures where the incoming tide floods into a basin and is trapped behind a barrage or dam. As the tide recedes, the tidal waters behind the dam/barrage are discharged via energy turbines. Variations on this technology include turbines that are active on both the flooding and ebbing tide. This technology is only economic in areas of high tidal range. There are three commercial-scale tidal power plants (barrages) in operation: a 240 MW plant which was completed on the estuary of the La Rance River near St. Malo, France in 1967, a 1MW plant on the White Sea in Russia completed in 1969 and a 16 MW plant in Nova Scotia, Canada.

The second technology utilises tidal turbines placed in areas of high tidal currents created as a result of the existing tidal regime and bathymetry. This technology is still developing and is considered only potentially viable where tidal currents are in the range 2-3m/s.

Tidal turbines are typically less expensive than tidal barrage systems and offer a number of advantages. They are less disruptive to wildlife, allow small boats to continue to use the area, and have much lower material requirements than the dam. Tidal turbines function well where coastal currents run at 2-3 m/s (slower currents tend to be uneconomic while larger ones put a lot of stress on the equipment).

Typical peak tidal variation in Bass Strait is approximately 2.5m, and it is unlikely that barrage style tidal power extraction will be viable in the region. However, throughout Bass Strait there are areas of higher tidal currents where tidal turbine technology could be viable.



3.2 Available Data 3.2.1 Tidal Constituents Oceanic tides are determined by the gravitational relationship between the Earth, Moon, Sun, and other satellites in our solar system. The relationships between these bodies are well known and can be predicted. Tidal constituents are the harmonic (sine and cosine) representations of these relationships. At any given location the tide can be predicted by applying appropriate amplitude and phase constants to the tidal constituents. The resultant tidal predictions are said to be astronomical tides and are not affected by external influences such as wind, changes in barometric pressure, and storm surges.

Moreover, tidal constituents can be derived from a period of measured data and used to predict tides during another separate period. Therefore, temporally disjoint data sets can be analysed to produce an effectively coincident data set. As such, tidal constituents provide a useful mechanism for assessing the performance of numerical models over long periods and large areas with limited measured data.

Tidal constituent information is available at numerous locations throughout the study area. Key constituents are documented in the following sections, sourced from the 2004 Australian National Tide Tables (AHS, 2003).

Figure 3-1 below shows the location of tidal constituent information in Bass Strait. Tidal constituent information at these locations has been used to develop boundary conditions for the models as well as for verification of model performance.



17

18

19

20

21

27

28

22

2625

23

24

11

12

13

14

8

910

16

15

14

2

3

56

7

ID Name

1 Port Phillip Heads2 Geelong3 Melbourne4 Rip Bank5 Queensclif f6 Hovell Pile7 West Channel8 Stony Point9 Flinders

10 Cow es11 San Remo12 Elizabeth Island13 Sandy(Spit) Point14 Eagle Rock15 Port Welshpool16 Rabbit Island17 Cape Wickham18 Stokes Point19 Doughboys20 St. Helens21 North of Flinders Island22 Eden23 Waratah Bay24 Lorne25 Burnie26 Devonport27 Portland28 Port Macdonnell

Bass StraitKing IslandFlinders Island

CornerInlet

Westernport

Port Phillip

145

144

-40

-39

-38

-37

-41

143

142

141

146

147

148

149

150

Figure 3-1 Tidal Constituent Locations



3.3 Tidal Modelling 3.3.1 Modelling Overview A numerical hydrodynamic model has been used to investigate tidal power potential throughout Bass Strait. In high current areas near entrances to large embayments, detailed local models have been prepared separately to assess tidal power in those areas.

3.3.2 Model Description The two-dimensional model used for the assessment of tidal power was developed using DHI Software's MIKE 21 Flow modelling system. MIKE 21 Flow is a comprehensive modelling package for simulating two-dimensional free-surface flows. It is applicable for modelling hydrodynamic and related phenomena in lakes, bays, estuaries and coastal areas where the effects of stratification can be neglected. MIKE 21 Flow is a proven and accepted numerical modelling tool for coastal applications. A more detailed description of the MIKE 21 Flow model is attached as Appendix C.

3.3.3 Model Setup 3.3.3.1 Bass Strait A MIKE 21 Flow model was established covering Bass Strait. This model was used to assess the overall tidal power characteristics of Bass Strait and also provide boundary conditions for detailed localised models. The model derives its bathymetry from the DHI CMap database, which is based on the AUS Chart series produced by the RAN. The model domain extends from Port MacDonnell in the west to Eden in the east and south to 42ºS. The MIKE 21 Flow model domain and bathymetry is illustrated in Figure 3-2 below. The three rectangles shown in Figure 3-2 represent areas of detailed models prepared to investigate tidal power in Port Phillip, Westernport and Corner Inlet.

BathymetryDepth [m]

1,000 to 5,500500 to 1,000100 to 25080 to 9060 to 7040 to 5020 to 3010 to 155 to 10

Figure 3-2 MIKE 21 Flow Model Extent – Bass Strait

The spatial resolution of the model was set at 5000m to balance computational efficiency with the adequate representation of the bathymetry, coastline and other features of the region.



Boundary conditions for the model were prepared as interpolated tidal constituents. On the west boundary of the model boundary conditions were prepared based on tidal constituent information from Port MacDonnell, SA and Pieman River, Tas. On the east boundary of the model boundary conditions were prepared based on tidal constituent information from Bermagui, NSW and Spring Bay, Tas.

3.3.3.2 Port Phillip The numerical modelling domain for the Port Phillip model is shown below in Figure 3-3. The model resolution was set at 250m.

BathymetryDepth [m]

-5 to 1-10 to -5-15 to -10-20 to -15-30 to -20-40 to -30-50 to -40-60 to -50-70 to -60-80 to -70

Figure 3-3 MIKE 21 Flow Model Extent – Port Phillip

Boundary conditions for the model were prepared as interpolated tidal constituents. The ocean boundary conditions were prepared based on tidal constituent information from Lorne, Vic and Flinders, Vic.

3.3.3.3 Westernport The numerical modelling domain for the Westernport model is shown below in Figure 3-4. The model resolution was set at 100m.



BathymetryDepth [m]

-5 to 1 (40546)-10 to -5 (14554)-15 to -10 (8993)-20 to -15 (6839)-30 to -20 (10443)-40 to -30 (11661)-50 to -40 (10947)-60 to -50 (6692)-70 to -60 (9337)-80 to -70 (17832)

Figure 3-4 MIKE 21 Flow Model Extent – Westernport

Boundary conditions for the Westernport model were derived from corresponding locations in the Bass Strait model.

3.3.3.4 Corner Inlet The numerical modelling domain for the Corner Inlet model is shown below in Figure 3-5. The model resolution was set at 100m.

BathymetryDepth [m]

-5 to 1-10 to -5-15 to -10-20 to -15-30 to -20-40 to -30-50 to -40-60 to -50-70 to -60

Figure 3-5 MIKE 21 Flow Model Extent – Corner Inlet

Boundary conditions for the model were prepared based on tidal constituent information from Rabbit Island, Vic.

3.3.4 Model Verification The numerical models developed for this investigation have been verified by comparing the 5 major tidal constituents derived from the models with those previously established from,



typically, long records of measured tidal data. Comparisons of tidal constituent information indicate that the model is generally ±5cm of published amplitudes and ±15 degrees of the published phase. The comparison demonstrates adequate model performance suitable for the broad assessment of tides in the region and the determination of resultant tidal power.

The Port Phillip model exhibits a mean spring tidal range of approximately 0.8m relative to a mean spring tidal range of 1.6m in Bass Strait and is consistent with measured data. Similar conditions in Bass Strait result in an amplification of the tides in Westernport to a range of approximately 2.2m, again consistent with measured data. The Corner Inlet model exhibits a mean spring tidal range of 1.9m at Port Welshpool relative to oceanic mean spring range of 1.7m, and is a appropriate representation of tidal conditions in this area.

3.4 Tidal Power 3.4.1 Tidal Power Calculation Tidal power represents the potentially available tidal energy flux per unit area of flow. It is related to the tidal pressure head (water level above mean sea level) and flow. Tidal power, P, per square metre of flow area is given by:

QgP ςρ=

Where ρ = density of water g = acceleration due to gravity ζ = tidal elevation, and Q = tidal flow per unit area.

This formulation is applicable where tidal power is to be derived from large ranges in tidal elevation. Typical peak tidal variation in Bass Strait is approximately 2.5m, and it is unlikely that power derived from tidal barrages would be viable.

A second formulation for tidal power relates to current speed where the extraction of power is via the use of tidal turbines. In this case tidal power is given by:

QvP 2

21 ρ=

Where ρ = density of water v = tidal current velocity Q = tidal flow per unit area.

Tidal current velocity can be extracted directly from the MIKE21 Flow model and has been used for the determination of potential tidal power presented in the following sections.

3.4.2 Potential Tidal Power 3.4.2.1 Bass Strait Figure 3-6 presents potential tidal power for Bass Strait.



Average Tidal Power[Watt/m2]

900 to 2,050490 to 900290 to 490180 to 290110 to 18070 to 11040 to 7020 to 4010 to 200 to 10

Figure 3-6 Tidal Power – Bass Strait

Tidal flow into Bass Strait from the east and west is constricted by islands and headlands (eg. King Island and Cape Otway). The tidal currents tend to accelerate around these constrictions resulting in localised higher current speeds. These localised higher current speeds result in areas of higher potential tidal power, as presented in Figure 3-6. To the north and south of King Island there are areas offering 70-110W/m2, north of Flinders Island there are area of up to 290W/m2, and areas between Cape Barren Island and the northeast cape of Tasmania offer potential tidal power in excess of 1000W/m2.

3.4.2.2 Port Phillip Figure 3-7 presents potential tidal power for Port Phillip.



Figure 3-7 Tidal Power – Port Phillip

Strong tidal currents exist in The Rip, the entrance to Port Phillip, and along South and West Channel. Peak tidal current speeds in excess of 3.5m/s are typically observed, and these are reproduced in the modelling. Figure 3-7 indicates that significant potential tidal power



opportunities exist in these very high current speed areas, with tidal power in excess of 1000W/m2.

3.4.2.3 Westernport Figure 3-8 presents potential tidal power for Westernport.



Figure 3-8 Tidal Power – Westernport

Figure 3-8 indicates that potential tidal power generation opportunities exist along the deeper sections of the Western Channel to the northwest of Phillip Island, adjacent to Sandy Point, in the constrictions between Settlement Point and Stockyard Point, and at San Remo, with tidal power in excess of 1000W/m2..

3.4.2.4 Corner Inlet Figure 3-9 presents potential tidal power for Corner Inlet.



Figure 3-9 Tidal Power – Corner Inlet



Figure 3-9 indicates that limited tidal power opportunities exist in Corner Inlet, and are probably restricted to those deeper areas of the entrance channel adjacent to Entrance Point and Snake Channel south of Sunday Island, with tidal power up to 200W/m2.

3.5 Discussion Tidal power generation opportunities along coastal Victoria are limited due to the small tidal range present in Bass Strait. The use of dams or tidal barrages to capture tidal energy would appear unviable. However, several opportunities exist to utilise emerging tidal turbine technology in areas of moderate to high tidal current speeds.

Appropriate sites for tidal turbines would be relatively close to shore in water depths of about 30m. Port Phillip entrance presents opportunities for application of this technology, but some areas within The Rip may be unsuitable as current speeds may be too high (and potentially destructive), there is insufficient depth, the area is of high environmental significance and is subject to significant navigational requirements. However, there are areas within Westernport that may offer some potentially viable opportunities, particularly those areas away from the main navigational channels.



4 CONCLUSION

Water Technology Pty Ltd has undertaken an assessment of wave and tidal characteristics along the Victorian coastline to identify areas of potentially viable wave and/or tidal power generation. The following presents the key findings of the assessment:

Wave Power

• Wave Power generation is typically considered viable where annual median wave power exceeds 30kW/m

• Potential energy generation from waves along the Victorian coastline appears to be restricted to those areas west of Cape Otway. This section of coastline is influenced by larger ocean swells propagating from the Southern Ocean.

• Median annual wave power in central Bass Strait is up to 15-20kW/m, and is highest along the section of coastline between Phillip Island and Wilson’s Promontory.

• The East Gippsland coastline does receive relatively large waves associated with storm events, but the median wave climate is relatively low. The resultant wave power potential is this area is also low, with annual median wave power of approximately 10-15kW/m available, depending on location.

• Based on a comparison of Cape Sorell long term data with 2003 data used in this study, the estimates determined are considered an accurate representation of the longer term wave characteristics of the Bass Strait region.

Tidal Power

• Tidal power generation opportunities along coastal Victoria are limited due to the small tidal range present in Bass Strait. The use of dams or tidal barrages to capture tidal energy would appear unviable. However, opportunities may exist to utilise emerging tidal turbine technology in areas of moderate to high tidal current speeds.

• Appropriate sites for tidal turbines would be relatively close to shore in water depths of about 30m. Port Phillip entrance presents opportunities for application of this technology, but some areas within The Rip may be unsuitable as current speeds may be too high (and potentially destructive), there is insufficient depth, the area is of high environmental significance and is subject to significant navigational requirements. However, there are areas within Westernport that may offer some potentially viable opportunities, particularly those areas away from the main navigational channels.



5 REFERENCES

AHS 2003. Australian National Tide Tables 2004. Prepared by the Australian Hydrographic Service, Commonwealth of Australia 2003.

WPC 1992. Wave Energy Study. Report prepared for the State Electricity Commission of Victoria and the Renewable Energy Authority Victoria. Report prepared by Water Power Consultants Pty Ltd and Lawson & Treloar Pty Ltd, February 1992.

USACE 1984. Shore Protection Manual. Coastal Engineering Research Center, Waterways Experiment Station, US Army Corps of Engineers. US Govt Printing.


J121/R01, October 2004, Rev 1 Page A-1

APPENDIX A – MIKE 21 SW MODEL DESCRIPTION

J121/R01, October 2004, Rev 1 Page B-1

APPENDIX B – WAVE POWER MAPS


LIST OF FIGURES

Figure B - 1 Median Wave Height and Power, January ................................................... 3

Figure B - 2 Median Wave Height and Power, February ................................................. 4

Figure B -3 Median Wave Height and Power, March ..................................................... 5

Figure B - 4 Median Wave Height and Power, April ....................................................... 6

Figure B - 5 Median Wave Height and Power, May ........................................................ 7

Figure B - 6 Median Wave Height and Power, June ........................................................ 8

Figure B - 7 Median Wave Height and Power, July......................................................... 9

Figure B - 8 Median Wave Height and Power, August .................................................. 10

Figure B - 9 Median Wave Height and Power, September ............................................ 11

Figure B - 10 Median Wave Height and Power, October................................................. 12

Figure B - 11 Median Wave Height and Power, November............................................. 13

Figure B - 12 Median Wave Height and Power, December ............................................. 14

Figure B - 13 Median Wave Height and Power, Annual.................................................. 15

Figure B - 14 Median Wave Height and Power, Summer ................................................ 16

Figure B - 15 Median Wave Height and Power, Autumn ................................................ 17

Figure B - 16 Median Wave Height and Power, Winter .................................................. 18

Figure B - 17 Median Wave Height and Power, Spring................................................... 19


Wave Height Htot MedianAbove 4.5

4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1

0 - 0.5Below 0Undefined Value


55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 1 Median Wave Height and Power, January



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 2 Median Wave Height and Power, February



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B -3 Median Wave Height and Power, March



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 4 Median Wave Height and Power, April



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 5 Median Wave Height and Power, May



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 6 Median Wave Height and Power, June



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 7 Median Wave Height and Power, July



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 8 Median Wave Height and Power, August



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 9 Median Wave Height and Power, September



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 10 Median Wave Height and Power, October



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 11 Median Wave Height and Power, November



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 12 Median Wave Height and Power, December



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 13 Median Wave Height and Power, Annual



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 14 Median Wave Height and Power, Summer



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 15 Median Wave Height and Power, Autumn



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 16 Median Wave Height and Power, Winter



4 - 4.53.5 - 4

3 - 3.52.5 - 3

2 - 2.51.5 - 2

1 - 1.50.5 - 1



55 - 6050 - 5545 - 5040 - 4535 - 4030 - 3525 - 3020 - 2515 - 2010 - 15

5 - 100 - 5


Figure B - 17 Median Wave Height and Power, Spring

J121/R01, October 2004, Rev 1 Page C-1

APPENDIX C – MIKE21 FLOW MODEL DESCRIPTION


MIKE 21 HD - BASIC HYDRODYNAMIC MODULE

General Overview

MIKE 21 HD is the basic computational hydrodynamic module of the entire MIKE 21 system, providing the hydrodynamic basis for other MIKE 21 modules such as for Advection-Dispersion (AD), ECO Lab, Particle tracking (PA) and Sediment Transport (ST, MT).

MIKE 21 HD simulates the water level variations and flows in response to a variety of forcing functions in lakes, estuaries, bays and coastal areas. The water levels and flows are resolved on a rectangular grid covering the area of interest.

MIKE 21 HD includes formulations for the effects of

• convective and cross momentum • bottom shear stress • wind shear stress at the surface • barometric pressure gradients • Coriolis forces • momentum dispersion (through eg the

Smagorinsky formulation) • wave-induced currents • sources and sinks (mass and

momentum) • evaporation • flooding and drying

Hydrographic boundary conditions can be specified as a constant or variable (in time and space) level or flux at each open model boundary, as a constant or variable source or sink anywhere within the model, and as an initial free surface level map applied over the entire model.

Application Areas

MIKE 21 HD can be applied to a wide range of hydraulic and related phenomena. This includes modelling of tidal hydraulics, wind and wave generated currents, storm surges and flood waves. MIKE 21 is an invaluable tool to the engineer, adding in the determination of design parameters used in coastal protection works as well as for offshore structures and subsea pipelines. As mentioned previously, the MIKE 21 HD output results are also used as input for many of the other MIKE 21 modules such as the Advection-Dispersion module (AD), the Sediment Trans-port (ST, MT), the Particle tracking (PA) and the ECO Lab module.

As MIKE 21 HD is a very general hydraulic model, it can easily be set up to describe specific hydraulic phenomena. Examples of such applications are:

• tidal exchange and currents • storm surge • secondary circulations, eddies and

vortices • harbour seiching • dam-break • tsunamis


Basic Equations

The hydrodynamic model in MIKE 21 is a general numerical modelling system for the simulation of water levels and flows in estuaries, bays and coastal areas. It simulates unsteady 2D flows in one layer (vertically homogeneous) fluids.

The following equations for the conservation of mass and momentum are integrated over the vertical to describe the flow and water level variations:

Continuity

x-Momentum

y-Momentum

Solution Technique

The equations are solved by implicit finite difference techniques with the variables defined on a space staggered rectangular grid as shown below. A 'fractioned-step' technique combined with an Alternating Direction Implicit (ADI) algorithm is used in the solution to avoid the necessity for iteration. Second order accuracy is ensured through the centering in time and space of all derivatives and coefficients. The ADI algorithm implies that at each time step a solution is first made in the x-momentum equations followed by a similar solution in the y-direction.

The application of the implicit finite difference scheme results in a tridiagonal system of equations for each grid line in the model. The solution is obtained by inverting the tridiagonal

Boundary Conditions

• Water levels or flow magnitude


matrix using the Double Sweep algorithms, a very fast and accurate form of Gauss elimination.

The implicit scheme is used in MIKE 21 in such a way that stability problems do not occur, provided, of course, that the input data is physically reasonable, so that the time step used in the computations is limited only by accuracy requirements.

Input Data Requirements

The necessary data can be divided into several groups as briefly described below.

Basic Model Parameters

• Model grid size and extent • Time step and length of simulation • Type of output required and its frequency

Calibration Factors

• Bed resistance • Momentum dispersion coefficients • Wind friction factors

Initial Conditions

• Water surface level • Flux densities in x- and y-directions

• Flow direction

Other Driving Forces

• Wind speed and direction • Source/sink discharge • Wave radiation stresses

Output Data

• Computed output results at each grid point for each time step.

Basic Output

• Water surface elevation • Flux densities in x- and y-directions

Derived Output

• Water depth • Water particle velocity • Speed • Flow direction

All output data can be post-processed, analyzed and presented in various graphical formats using the pre- and post-processing module, MIKE 21 PP.

Hydraulics In General

Chow, T V (1959) Open-Channel Hydraulics, McGraw-Hill, New York.

Lamb, H (1945) Hydrodynamics, Dover, New York.

Milne-Thomson, L M (1950) Theoretical Hydrodynamics, Macmillan, New York.

Phillips, O M (1966) The Dynamics of the Upper Ocean, Cambridge University Press.

Rouse, H (1946) Elementary Mechanics of Fluids, John Wiley and Sons, New York.

Rouse, H (editor) (1959) Advanced

Eddy Viscosity

Abbott, M B & Larsen, J (1985) Modelling Circulations in Depth-integrated Flows. Journal of Hydraulic Research, 23, pp 309-326 and 397-420.

Aupoix, B (1984) Eddy Viscosity Subgrid Scale Models for Homogeneous Turbulence. In Macroscopic Modelling of Turbulent Flow, Lecture Notes in Physics, Proc. Sophie-Antipolis, France.

Falconer, R A & Mardapitta-Hadjipandeli (1987) Bathymetric and Shear Stress Effects on an Island's Wake: A computational Study. Coastal Engineering, 11, pp 57-86.

Horiuti, K (1987) Comparison of


Mechanics of Fluids, Wiley, New York.

Schlichting, H (1960) Boundary Layer Theory, McGraw-Hill, New York.

Streeter, V L (1961) Handbook of Fluid Dynamics, McGraw-Hill, London.

Svendsen, I A & Jonsson, I G (1976) Hydrodynamics of Coastal Regions, Technical University of Denmark.

U.S. Army Coastal Engineering Research Center (1984) Shore Protection Manual.

Computational Hydraulics

Abbott, M B (1979) Computational Hydraulics, Elements of the Theory of Free Surface Flows, Pitman, London.

Abbott, M B & Basco, D R (1989) Computational Fluid Dynamics, an Introduction for Engineers, Longman, London, and Wiley, New York.

Abbott, M B & Cunge, J A (1982) Engineering Applications of Computational Hydraulics, Pitman, London.

Abbott, M B, McCowan, A D & Warren, I R (1981) Numerical Modelling of Free-Surface Flows that are Two-Dimensional in Plan. Transport Models for Inland and Coastal Waters, edited by Fischer, H.B., Academic Press, New York.

Conservative and Rotational Forms in Large Eddy Simulation of Turbulent Channel Flow. Journal of Computational Physics, 71, pp 343-370.

Leonard, A (1974) Energy Cascades in Large-Eddy Simulations of Turbulent Fluid Flows. Advances in Geophysics, 18, pp 237-247.

Lilly, D K (1966) On the Application of the Eddy Viscosity Concept in the Inertial Subrange of Turbulence. NCAR Manuscript No. 123, National Center for Atmospheric Research, Boulder, Colorado.

Madsen, P A, Rugbjerg, M & Warren, I R (1988) Subgrid Modelling in Depth Integrated Flows. Coastal Engineering Conference, 1, pp 505-511, Malaga, Spain.

Smagorinsky, J (1963) General Circulation Experiment with the Primitive Equations. Monthly Weather Review, 91, No. 3, pp 99-164.

Wang, J D (1990) Numerical Modelling of Bay Circulation. The Sea, Ocean Engineering Science, 9, Part B, Chapter 32, pp 1033-1067.

Tidal Analysis

Doodson, A T & Warburg, H D (1941) Admiralty Manual of Tides, Her Majesty's Stationary Office, London.

Dronkers, J J (1964) Tidal Computations, North-Holland Publishing Company, Amsterdam.

Godin, G (1972) The Analysis of Tides, Liverpool University Press.

Wind Conditions

Duun-Christensen, J T (1975) The Representation of the Surface Pressure Field in a Two-Dimensional Hydrodynamic Numerical Model for the North Sea, the Skagerak and the Kattegat. Deutsche Hydrographische Zeitschrift, 28, pp 97-116.

NOAA, National Weather Service (1972) Revised Standard Project Hurricane Criteria for the Atlantic and Gulf Coasts of the United States, Hurricane Research Memorandum


Pugh, D T (1987) Tides, Surges and Mean Sea-Level, A Handbook for Engineers and Scientists, Wiley, UK.

Schwiderski, E W (1978) Global Ocean Tides, Part I-X, Naval Surface Weapons Center, Virginia, USA.

HUR 7-120.

Smith, S D & Banke, E G (1975) Variation of the Sea Drag Coefficient with Wind Speed. Quart. J. R. Met. Soc., 101, pp 665-673, 1975.

US Weather Bureau (1968) Meteorological Characteristics of the Probable Maximum Hurricane, Atlantic and Gulf Coasts of the United States, Hurricane Research Interim Report, HUR 7-97 and HUR 7-97A.

J121/R01, October 2004, Rev 1 Page D-1

APPENDIX D – TIDAL POWER MAPS

J121/R01, October 2004, Rev 1 Page D-2



Bass StraitKing Island

Flinders Island

CornerInlet

Westernport

Port Phillip

145

144

-40

-39

-38

-41

143

142

141

146

147

148

149

150

Figure D - 1 Wave Power – Bass Strait

wave and tidal power assessment for the victorian …/media/resources...wave and tidal power...

Documents