3.4 Tidal Resource Assessment Techniques

Tidal resource assessment is crucial for harnessing ocean energy. It involves measuring sea levels, analyzing currents, and modeling tidal patterns. These techniques help identify prime locations for tidal energy projects and estimate their potential power output.

Site evaluation goes beyond just finding strong currents. It considers environmental impacts, conflicts with other ocean users, and practical aspects like grid connection. This holistic approach ensures sustainable and feasible tidal energy development.

Measurement Techniques

Tide Gauge Measurements

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Top images from around the web for Tide Gauge Measurements

• 

  Frontiers | Wave Measurements From Radar Tide Gauges View original

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• 

  ESurf - Precise water level measurements using low-cost GNSS antenna arrays View original

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• 

  Frontiers | A Regional Frequency Analysis of Tide Gauges to Assess Pacific Coast Flood Risk View original

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• 

  Frontiers | Wave Measurements From Radar Tide Gauges View original

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• 

  ESurf - Precise water level measurements using low-cost GNSS antenna arrays View original

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• Tide gauges measure sea level variations over time to determine tidal range and patterns
• Pressure sensors or float systems are commonly used in tide gauges to record water level changes
• Tide gauge data is essential for understanding local tidal characteristics and validating numerical models (Bay of Fundy)
• Long-term tide gauge measurements provide insights into seasonal and interannual variability of tidal resources

Acoustic Doppler Current Profiler (ADCP) Surveys

• ADCPs use sound waves to measure current velocities throughout the water column
• Vessel-mounted or bottom-mounted ADCPs can be deployed to collect spatial and temporal variations in tidal currents
• ADCP surveys help identify regions with high tidal current velocities suitable for energy extraction (Pentland Firth)
• Repeated ADCP measurements at different tidal phases are necessary to capture the full tidal cycle and spring-neap variations

Harmonic Analysis and Exceedance Curves

• Harmonic analysis decomposes tidal signals into constituent harmonic components with specific amplitudes and phases
• Tidal constituents obtained from harmonic analysis can be used to predict tidal elevations and currents at any given time
• Exceedance curves represent the percentage of time a particular tidal current speed or tidal range is exceeded
• Exceedance curves help assess the available tidal energy resource and inform the design of tidal energy converters

Modeling and Mapping

Numerical Modeling Techniques

• Numerical models simulate tidal hydrodynamics by solving governing equations of fluid motion
• Two-dimensional depth-averaged models (TELEMAC-2D) are commonly used for large-scale tidal resource assessments
• Three-dimensional models (Delft3D) provide detailed information on vertical variations in tidal currents
• Numerical models require accurate bathymetry, boundary conditions, and calibration against measured data

GIS Mapping and Resource Characterization

• Geographic Information Systems (GIS) integrate spatial data to create maps of tidal energy resources
• GIS maps combine information on tidal range, current speeds, water depths, and proximity to infrastructure
• Resource characterization involves estimating the theoretical, technical, and practical tidal energy potential of a region
• GIS tools facilitate site selection by identifying areas with high energy density and favorable environmental conditions (Minas Passage)

Site Evaluation

Site Selection Criteria

• Tidal range and current speeds are primary factors in determining the suitability of a site for tidal energy development
• Water depth, seabed geology, and proximity to electrical grid infrastructure are important considerations
• Shipping routes, fishing activities, and marine protected areas should be avoided to minimize conflicts
• Site accessibility, distance to ports, and local supply chain capabilities influence project feasibility and costs

Environmental Impact Assessment

• Environmental impact assessments (EIAs) are conducted to identify potential effects of tidal energy projects on marine ecosystems
• EIAs consider impacts on sediment transport, water quality, marine habitats, and wildlife (marine mammals, fish, and seabirds)
• Baseline surveys and monitoring programs are established to assess pre-construction conditions and detect changes
• Mitigation measures, such as marine mammal observers and acoustic deterrents, are implemented to minimize adverse impacts (SeaGen project)
• Stakeholder engagement and public consultations are integral parts of the EIA process to address concerns and incorporate local knowledge