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This experimental-mixed methods investigates the impact of shifting from a traditional laboratory model to a hybrid laboratory model. The hybrid model consisted of (1) online instructions and pre-laboratory test, (2) compressed face-to-face laboratory time, and (3) post-laboratory data analysis. This study analyses whether student perceptions of a targeted intervention were correlated to a range of student performance indicators. Only a fractional improvement in student performance was observed, but evidence suggests that the use of online content led to more frequent student interaction with the learning material. The pre-laboratory tests encouraged a better preparation for the laboratory. Splitting the laboratory intervention into different phases was generally better perceived by students than the traditional style. The findings are expected to encourage course coordinators and developers to adopt concepts used in the delivery of hybrid solutions which is important due to the current emphasis on the use of online models of instruction.

Velocity fluctuations caused by unsteady flows substantially increase mechanical loads on tidal turbine blades and represent a major challenge to tidal energy converters. Overcoming the challenges posed by high levels of turbulence and large waves is a significant concern for turbine developers. Here we quantify turbulence and characterize wave-turbulence interaction in two prospective tidal energy sites in Australia: Banks Strait and Clarence Strait. Turbulence characterization was derived from deployments lasting up to 3 months. Our datasets represent the longest turbulence measurements at tidal sites published to date, setting a benchmark in tidal energy site characterization. Banks Strait data was affected by wave orbital velocities at mid-water column for nearly the entire period, whilst Clarence Strait data rarely presented significant wave-turbulence interactions. Turbulence intensities varied mostly between 12% and 17% in both sites. Higher turbulent kinetic energy density was observed in Banks Strait, although one of Clarence Strait stations revealed faster current speeds exceeding 2.8 m/s. Investigation of strong wind events suggests turbulence parameters were not majorly affected. Our findings are valuable to obtain more realistic turbine performance and loadings estimates from numerical models and considerably contribute towards efforts to establish best-practice turbulence assessment methods in tidal energy sites. [ABSTRACT FROM AUTHOR]

Banks Strait is a 15 km wide tidal channel in Tasmania, Australia, and has been identified as a prospective site for tidal energy extraction, however flow characteristics have never been investigated. We present detailed field measurements from campaigns which deployed multiple Acoustic Doppler Current Profiles (ADCPs) across Banks Strait to analyze energy resources. The deployment period lasted for almost a year including a rigorous technical assessment of tidal stream resource that exceeded IEC site characterisation standards. Our results reveal that the Banks Strait channel has sufficient depth but that tidal currents generally do not exceed 2.5 m/s at the mooring sites. Large areas reveal an active wave climate and significant wave current-interaction. Maximum values of in-situ tidal kinetic power densities were approximately 0.85 kW/m2 on the southern side of the channel. The northern side suggests even more energy potential although ADCPs could not be recovered due to strong currents and sediment movement. The results will feed into numerical models to further investigate the energy potential. Based on our in-situ estimates, a tidal turbine farm could bring significant advantages to the region by reducing intermittency and increasing constant energy extraction to support an already existing wind farm located in north eastern Tasmania. • Assessing Australia's tidal energy potential in a large tidal channel. • Detailed field measurements from several ADCPs. • Field data met and exceeded international guidelines (EMEC, IEA). • Insights for turbine installation, design and operation in Banks Strait, Australia. [ABSTRACT FROM AUTHOR]

Banks Strait, Tasmania, Australia, has been identified as a potential site for the deployment of tidal turbines. In this study, the characterization of sediment transport and large sand waves for this site is performed. Observations of bed level change collected from surveys in 2018 showed a migration of large sand waves over a period of nine months. Migration rates in an excess of one hundred meters for nine months were found, which are large compared to the rate reported at other coastal sites, by several meters per year. A validated hydrodynamic model is coupled with a morphodynamic model to perform sensitivity tests and identify what parameters influence migration to better understand sediment dynamic in the Banks Strait. Numerical analysis showed a constant shift of the sand waves profile in an eastward direction, consistent with the observations. This migration was strongly linked with tidal asymmetry, with a residual current flowing towards the east. The principal parameters driving the migration of sand waves in the Banks Strait were found to be sediment sorting, bed friction and residual current. This study gives new insights for the seabed of Banks Strait and provides an assessment of the natural variability of sediment for futures tidal farms deployments. [ABSTRACT FROM AUTHOR]

Tidal energy turbines are significantly impacted by surface gravity waves and high turbulence levels, which lead to increased blade loads and consequent device fatigue. Accurately describing turbulence quantities is a key factor to improve numerical models and ensure the minimum necessary device longevity. The application of an appropriate wave-turbulence decomposition technique substantially improves estimates and must be debated by the tidal energy community. This work analyses two wave-turbulence decomposition techniques: i) linear wave theory and ii) Synchrosqueezing Wavelet Transform (SWT) based on physical modelling. The experiments were conducted in a towing tank and the physical model used Froude scaling to simulate wave heights and frequencies based on field measurements from a tidal energy candidate site in Australia. Turbulence was generated using a grid with 47 mm openings replicating turbulence intensities of 17%, 23% and 25%. Both decomposition techniques present limitations in wave frequencies above 0.7 Hz. Our results suggest that the SWT technique is more versatile and more efficient under various conditions. Restrictions to the linear wave theory method are discussed with regards to ADCP geometry and possible non-linearity. The variability obtained from the wave-turbulence decomposition techniques emphasizes the importance of establishing guidelines for turbulence characterization in tidal energy sites. • Grid-generated turbulence is used in interaction with surface waves in a towing tank. • Impact of wave-turbulence decomposition on tidal energy site assessments is emphasized. • Wave-turbulence decomposition plays an important role in turbulence characterization. • SWT wave-turbulence decomposition technique proves to be satisfactorily versatile. • SWT decomposition is suitable in wave frequencies often observed in tidal energy sites. [ABSTRACT FROM AUTHOR]

The development of tidal energy in Australia is still a challenge with few studies performed on the characterisation of the resource, due to the difficulty to acquire data and uncertainties about the influence of this anthropogenic activity on the marine environment. Changes in flow could lead to alterations in sediment transport and have further influence on the marine habitat. A case study in a promising area, Banks Strait (Australia), was created using high resolution 2D and 3D models validated against in situ data to investigate changes to hydrodynamic conditions with two scenarios of tidal farms (100 and 300 turbines). Comparison between 2D and 3D is performed to find the best compromise between model accuracy and computational time for preliminary assessment. Changes to current speed and bed shear stress over a 35 day period were found to be localised around the tidal farms and did not extent more than 7 km from the farm (300 turbines) for both 2D and 3D. The results showed that for near field and far field, 2D models are sufficient to give a first approximation of the hydrodynamic influence of tidal farm deployment on its environment. [ABSTRACT FROM AUTHOR]

Experimental investigations measuring both bed elevation changes and near-structure flow velocities were undertaken to investigate wave scour processes around a model Oscillating Water Column (OWC) Wave Energy Converter (WEC) for a range of incident wave conditions at approximately 1:20 scale. The experiment design was informed by a proposed 200 kW OWC WEC deployment site at King Island, Australia. The measurements provide the first experimental data on scour around an OWC WEC structure, and one of the most comprehensive experimental studies of wave scour around a large rectangular cross-section structure. High resolution scour erosion and deposition patterns were measured using an above-water laser-based system. For normally incident waves, scour holes were observed to develop on all four corners, and the size of the scour holes at the four corners increased with the Keulegan-Carpenter (KC) number. An additional scour hole/trench also formed along the upstream face of the OWC WEC due to the flow in/out of the OWC WEC internal chamber. Changing the incident wave propagation angle by 20° has a significant effect on the observed scour patterns, with reduced scour on the front and back corners but significant scour holes remaining on the other two corners. It is found that if the model is not sufficiently embedded into the sediment bed, scour can undermine a significant area under the structure, with quadrant shaped scour holes underneath the back corners extending to approximately 25% of the total base area, suggesting a risk of differential settlement in field conditions. • Scour patterns measured experimentally around an Oscillating Water Column device. • Scour mechanism identified around a large bluff body structure. • Correlation found between scour depth and the Keulegan-Carpenter (KC) number. • Risk of differential settlement due to undermining scour identified. • Laser measurement system used for high-resolution 3D experimental scour study. [ABSTRACT FROM AUTHOR]

We present findings from a geotechnical survey for a gravity-based Wave Energy Converter (WEC) to be installed in King Island, Tasmania. The goal of this work was to assess the deployment location for a 200 kW Oscillating Water Column (OWC) and to identify possible challenges for the foundation of the structure to make it Australia's first operational offshore OWC for a remote offshore island. The proposed location for this OWC is the southeast coast of King Island, Tasmania, approximately in a depth of ~5.5 m LAT. The survey included sub-bottom profiling, sediment cores, surficial sediment strength by penetrometer drops, seabed imagery, as well as long-term deployment (>6 months) of pressure sondes and an acoustic wave current profiler (AWAC). Our findings demonstrate that the WEC can be installed in the proposed location with significant wave height Hs ~1–1.5 m and peak period Tp of 12–14 s, and that the site exhibits sufficient sand coverage and quasisteady bearing capacity. The period between the survey and prospective deployment is only one year, demonstrating the efficiency of the survey methods (in particular, the use of the penetrometer) and OWC design but also the suitability of the candidate site for this device design. [ABSTRACT FROM AUTHOR]

As the tidal energy industry grows, developers are interested in the influence that large scale arrays might have on their surrounding environment including hydrodynamic and sediment. Understanding of local and regional sediment dynamics is an important element for environment impact and site assessments, as changes in sediment processes could alter bed ecosystems. In Australia, the Banks Strait located in the Northeast of Tasmania has been identified as a promising site for tidal energy. Very large sand waves have been observed near the area suitable for tidal turbines installation and they may interfere with human activities. Building from previous work, a 2D regional scale model investigated the influence of different tidal farms on the morphology of Banks Strait and especially the sand waves. Results showed that tidal farm of more than 49 MW rated power will alter the circulation of residual currents in Banks Strait leading to significant changes in the sediment dynamics, and farms less than 24.5 MW will have negligible influence on the migration of sand waves. • Morphological impact assessment of Banks Strait with tidal farms. • Hydrodynamic and morphodynamic models including wave forcing are used due to the wave-current interaction in Banks Strait. • Tidal farms less than 24.5 MW (rated power) have negligible influence on the migration of sand waves. [ABSTRACT FROM AUTHOR]

Banks Strait, Australia has been identified as highly promising for tidal turbine deployments. To assess this site's feasibility, high-resolution unstructured mesh two-dimensional (2D) models were generated using the newly developed COMPAS hydrodynamic model. Model results were calibrated and validated against results from five Acoustic Doppler Current Profiler field datasets. Simulation results indicating that considerable tidal energy resources exist, with maximum tidal currents of almost 3 m/s found at depths suitable for both small and large-scale Tidal Energy Converters (TEC) array installations, making this region promising for tidal energy extraction for both on and off-grid energy demands. Two examples of tidal farms consisting of a 1.2 MW array of 3 m diameter TEC's in shallow water and a 60 MW array of twin-rotor 20 m diameter TEC's in deep water were then simulated. The study used two methods to determine farm power output using the 2D models: the first method estimated the output directly from current velocity predictions based on the developed resource model, whilst the second method simulated the TEC energy extraction using a bottom friction model. For both TEC arrays minimal changes in near and far-field mean current flow and surface elevations were found. • High-resolution tidal resource assessment of Bank Strait, Australia. • Currents speeds of almost 3 m/s at suitable water depths for tidal turbines. • Two tidal farms in shallow and deep water simulated. • Minimal influence of tidal farm arrays on hydrodynamic flow field. [ABSTRACT FROM AUTHOR]

The Clarence Strait, Northern Territory, Australia has been identified as a promising region for tidal energy, however little detail is known of the resource potential of the Strait. To assess the site feasibility, high-resolution two-dimensional (2D) unstructured mesh models were developed using the COMPAS hydrodynamic model, which were calibrated and successfully validated against results from five Acoustic Doppler Current Profiler field datasets. Results indicate that considerable tidal resources exist with maximum tidal currents of approximately 2.5 m/s found at water depths suitable for both small and large-scale Tidal Energy Convertors (TEC) array installations. Two arrays of 10 m and 20 m diameter TEC's were then simulated using the developed models using two methods to determine farm power output; the first derived directly from the current model velocity predictions from the developed resource assessment model, the second by directly simulating the TEC energy extraction using a 2D bottom friction model that was added to the hydrodynamic model. Results indicate an Annual Energy Production of up to 108 GWh using both models. Minimal change in near and far-field mean current flow of less than 0.03 m/s and little change in surface elevations were found, making the region suitable for tidal energy farm development. • High-resolution tidal resource assessment of Clarence Strait, Australia. • Currents speeds of over 2.5 m/s at suitable depths for large-scale tidal turbines. • Two tidal farms of 10 m and 20 m simulated. • Minimal influence of tidal farm arrays on hydrodynamic flow field. [ABSTRACT FROM AUTHOR]

As the tidal energy industry looks to expand into commercial-scale array installations, uncertainty in methodology and outcome for environmental impact assessments can encumber tidal energy developments. Incorporating environmental monitoring measures into site characterisation campaigns can provide baseline information about biophysical relationships and help recognise potential impacts to the marine environment early in the development process. Concurrent measurements of fish and tidal currents were taken at a tidal energy candidate site in Australia over ∼ 2.5 months during its tidal resource assessment. Fish aggregation metrics (density, abundance, centre-of-mass (CM), dispersion, %-water column occupied, evenness, and relative aggregation) were investigated for their relation to environmental conditions (current speed, shear, temperature, diel stage, and tidal stage). Diel stage was the most significant indicator for fish density, abundance, and %-water column occupied. Fish density and abundance were elevated during strong currents, with vertical fish distribution (CM and dispersion) also influenced by current speed. Environmental conditions were able to explain up to 25% of variation in fish aggregation metrics using linear models. This study shows that early-stage environmental monitoring can successfully provide baseline information about fish aggregation responses to prevailing environmental conditions, thus reducing uncertainty risks for stakeholders of tidal energy developments. • Environmental impact assessment was coupled with tidal resource characterisation in Australia. • Fish were more abundant, higher in the water column, and more dispersed at peak flows. • Fish were most influenced by diel stage with densities nearly two-times higher at night vs. day. • At high temperatures, fish were more abundant and closer to the bottom. • Environmental conditions explained 25% of variance in fish density using linear models. [ABSTRACT FROM AUTHOR]