The AUSTEn project has mapped Australia’s tidal energy resource in unprecedented detail, assessed its economic feasibility and ability to contribute to the country’s future energy needs, and characterised in detail two potentially prospective tidal energy development sites to aid forthcoming developers. Project outcomes will aid the emerging tidal energy industry to develop commercial-scale tidal energy projects.
Australia is home to some of the largest tides in the world. Tidal energy systems are considered to have the highest technical maturity in the ocean renewable sector and several national and international tidal energy developers have been prospectively seeking opportunities for Australian tidal energy projects. However, knowledge of Australia’s tidal resource, its spatial extent and technical implementation remain insufficient for the tidal energy industry, regulators, policy makers and research community to make any assessment of their risks for investment in potential projects. The project was established to support prospective developers, financiers, regulators and policymakers, by providing critical baseline information, and establish what contribution tidal energy could make to Australia’s future energy mix.
The outcomes of this project provide considerable benefit to the emerging tidal energy industry, the strategic-level decision makers of the Australian energy sector, and the management of Australian marine resources by helping them to understand the resource, risks and opportunities available, and overcoming current barriers to investment by increasing the competitiveness of tidal energy against other forms of ocean renewables. Detailed field and numerical studies for the two sites have been delivered, providing tidal project developers a head start in commissioning their site prior to deployment of their technology. Further case studies were developed showing the potential of tidal energy in Australia’s energy mix.
Beyond mapping Australia’s national tidal energy resource, outcomes from the project extend to a range of purposes for other marine stakeholders, including marine spatial planning and environmental management, marine prediction for shipping and SAR, defence, oil and gas exploration and offshore wind and wave energy.
The AUSTEn project is a collaborative effort between research partners - the Australian Maritime College at the University of Tasmania, The University of Queensland and CSIRO; Industry partners - Mako Tidal Turbines, Sabella and SIMEC Atlantis Energy; and international collaborators – Bangor University, UK and Acadia University, Canada. The project is co-funded by the Australian Renewable Energy Agency (ARENA) Advancing Renewables Program.
Industrial partner involvement has brought valuable real project experience to deliver the outcomes. The broad collaborative research team has maximised domestic knowledge of both Australia’s marine estate and electrical systems and ensured strong international exposure. The project further benefitted from regular and sustained interaction with further project stakeholders (governmental bodies, regulatory bodies, grid and network experts as well as tidal and wave turbine engineering firms, developers and academia) throughout the project.
This Australian first project consists of three inter-linked components that have delivered:
- A National Australian high-resolution tidal resource assessment (~500 m resolution), feeding into the Australian Renewable Energy Mapping Infrastructure (online resource atlas).
- Focused case studies at the Banks Strait, Tasmania, and the Clarence Strait, Northern Territory for energy extraction, involving field based and high-resolution numerical site assessments, as well as in-situ environmental measurements and observations.
- Technological and economic feasibility assessment for tidal energy integration to Australia’s electricity infrastructure, including consideration of important issues such as grid integration, and competitiveness against existing and new sources of generation, intermittency and farm design. Case studies at six key sites also outlined opportunities for adding tidal generation to the energy mix.
A newly developed national Australian unstructured high-resolution hydrodynamic tidal model has identified the spatial extent of tidally energetic sites around Australia, and significantly enhanced understanding of Australia’s national tidal stream and range energy resources. The most energetic sites are predominantly distributed across the northern shelf of Australia, particularly on the North-West shelf, with sparse distribution to the south of Australia that include Banks Strait, NE Tasmania, and Port Philip Heads, Victoria. However, the tidal velocities of order 2-2.5 m/s, are lower than seen in other parts of the world (UK, Europe, Canada and the US), where Tidal Energy Converters (TECs) currently installed are deployed in sites with flows of approximately 4 m/s.
Extensive field campaigns were conducted to characterise promising sites at Banks Strait in NE Tasmania, and Clarence Strait in the Northern Territory. High-resolution numerical models of these two sites were successfully developed, calibrated and validated, with assessments of the tidal energy resource to international standards completed. These case studies located tidal velocities up to 2.8 m/s suggesting these sites are unlikely to be developed using current generation of TECs that seek flows greater than 4.0 m/s to be commercially viable. However, the moderate flows, suitable depth ranges and bottom compositions suggest these sites may be viable for TECs better suited to harnessing lower velocity flows. Although current speeds were lower than that found at promising sites internationally, for both the Banks and Clarence Strait sites, the potential area nationally for tidal turbine deployment was found to increase substantially when selecting sites with maximum flow speeds greater than 1.5 m/s, opening up new areas for potential TEC deployments. For both sites, the network capacity would need to be increased to take advantage of the substantial tidal energy resource.
Using power curves from off the shelf (OTS) TECs, the extractable power was determined from the national and regional resource assessments. Estimates of extractable power were also determined using TEC power curves adjusted for local conditions (flow speeds). As the amount of electricity produced depends not only on the resource, but also on the local electricity grid, studies of the electricity infrastructure at the most energetic sites around Australia were also performed. These included sites connected to Australia’s National Electricity Market (NEM), as-well as the Darwin Katherine Interconnected System (DKIS) and isolated grids including off-grid communities. The levelized cost of energy (LCOE) for tidal energy was determined at these sites using OTS and adjusted extractable p ower estimates. The LCOE estimates for Banks Strait, TAS and Clarence Strait, NT are in the range 1–1.75 $/kWh, indicating that tidal needs to achieve significant cost reductions, over and above those attributable to learning and those obtainable by modifying TECs, to better suit Australian conditions to be competitive with wind and solar PV. Levers to imitate these cost reductions were identified to guide developers in reducing these LCOE costs.
Six case studies are presented outlining examples where tidal energy may have application in Australia’s future energy landscape, exploiting reliability and cost advantages in a distributed energy system. Tidal energy can provide renewable energy plants with an additional level of power availability and security and could have particular application to aquaculture, emergency services, essential services, defence and energy/fuel export industries. Offshore applications could include supplying power for environmental monitoring and data acquisition installations, marine surveillance, weather stations and decommissioned oil and gas rigs where most of the necessary support and power management infrastructure is already in place.
Publicly Availability Resources
- The AUSTEn National Tidal Model hourly tidal elevation and velocity outputs are made openly available via CSIRO’s Data Access Portal. CSIRO Data Access Portal: http://hdl.handle.net/102.100.100/374951?index=1
- Tidal energy resource layers from both the AUSTEn National Tidal Model and the high-resolution Banks Strait, Tasmania and Clarence Strait, Northern Territory models are available via the Australian Marine Energy Atlas on the Australian Renewable Energy Mapping Infrastructure (AREMI) website. Australian Renewable Energy Mapping Infrastructure (AREMI) Link: https://nationalmap.gov.au/renewables/
- The data collected as part of the Banks Strait and Clarence Strait field campaigns are available on the Integrated Marine Observing System Australian Ocean Data Network (AODN) data repositories database, with the bathymetric surveys uploaded to Geoscience Australia’s Aus-seabed database to improve the national bathymetry dataset.
- Integrated Marine Observing System AODN Link: https://portal.aodn.org.au/
- Geoscience Australia Aus-Seabed Link: http://www.ausseabed.gov.au/
- Research from this project has also presented and published both nationally and internationally to highlight the emerging Australian tidal energy sector. http://www.austen.org.au
Recommendation 1: Technical improvements to tidal energy converter (TEC) design to increase capacity factors that are then competitive in relation to the Australian available tidal resource.
Recommendation 2: Tidal energy should primarily be reserved for applications where intermittency can’t be tolerated, for example high security / backup power in remote regions, or chemical processing for renewable fuels where tidal energy can save millions of dollars of capital expenditure, or for operating in environments on- or off- grid where tidal energy is the best resource to supply dispatchable power cost effectively.
Recommendation 3: The ability of hydrodynamic models to accurately resolve high flow currents is highly dependent on the quality of the bathymetry available. Ongoing collection of bathymetry for Australia’s marine domain provides broad benefits to many sectors in the blue economy, of which offshore renewable energy is an emerging participant.
Recommendation 4: Carry out detailed cost benefit analysis of hybrid solar/tidal and wind/tidal energy farms aimed at providing up to 30 percent dispatchable (continuously available) electricity for wind/tidal and 50 percent dispatchable electricity for solar/tidal energy farms.
Recommendation 5: Five potential sites should be assessed in further detail (Warrumiyanga, Yimpinari, Wadeye and Tharramurr, Ardyaloon and Derby and Banks Strait) due to having the strongest tidal resources in Australia together with communities that have ownership and ready access to regional areas associated with the sites, as well as a track record of
industrial and commercial development.
Recommendation 6: The north eastern corner of Tasmania where Banks Strait is located may have significant opportunities for development of green industries such as green steel and hydrogen production due to its tidal energy resource.
Recommendation 7: Development of a national Australian oceanographic modelling system capable of meeting Australia’s industry and governmental needs. For the offshore tidal energy sector, this will provide benefits of integrated knowledge of wave influence, and contribution of non-tidal flows (wind and density driven circulations) at prospective sites.
Recommendation 8: The available resource at small-scale high flow sites not identified by the national model requires targeted efforts to determine the resource viability.
Recommendation 9: The national tidal energy resources presented via Australia’s renewable energy mapping infrastructure present only the theoretical resource. Considerations of alternative uses of the marine domain must be addressed as this may limit the areas of development.
Recommendation 10: Perform full-scale ADCP measurements of flow field surrounding an operating TEC / TEC array, include near and far-field regions, to enable calibration and validation of numerical turbine models and to understand the impact of turbulence on the TEC device loads and performance.
Recommendation 11: Wave-current interactions, especially if prevalent for extended periods of time, can impact TEC device installations, operations and maintenance, and should assessed in the selection of sites for project development.
Recommendation 12: Existing technical guidelines (e.g. IEC) for site characterisation should be extended to include accurate procedures for turbulence measurements and parametrization in tidal energy sites.
Recommendations 13: Development of new numerical models that link the non-hydrostatic ocean models as used in this study with hydrostatic computational fluid dynamics turbine models that resolve the boundary layer flow over the turbine blades, allowing for the simulation of the entire flow field at all scales.
Recommendation 14: Instruments for site characterisation should be chosen such that they can accurately provide simultaneous measurements of currents, waves and turbulence (and other environmental parameters) over the required period. Data of this form can provide valuable information for a more targeted environmental impact assessment study and can minimize uncertainties surrounding in-stream tidal turbines.
Recommendation 15: As outlined as a core area for action in the UN Global Compact Sustainable Ocean Principles (UNGC, 2020); increased, ongoing mutual collection, sharing and standardised management of data from ocean based industries alongside Government, defence, academic and non-governmental communities; will enable development of best future decision making tools for emerging and current ocean industries.