exploring optimal locations for underwater turbine emplacement near marine navigation passageways

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Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways Steps to a “go” or “no” answer. With Thanks to: MIT Sea Grant , the Chewonki Foundation , Mass Maritime Academy, Town of Hull, MA USGS, Falmouth Scientific Inc. Geoff Cowles , Dorothy Kelly, Peter Arnold, Stanley King, Tom Pham, Herman Gustafson, Jim Manning, Kurt Bornheim, Andy Stern, Neil Ganju, ….

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Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways Steps to a “go” or “no” answer. With Thanks to: MIT Sea Grant , the Chewonki Foundation , Mass Maritime Academy, Town of Hull, MA USGS, Falmouth Scientific Inc. - PowerPoint PPT Presentation

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Page 1: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation

Passageways

Steps to a “go” or “no” answer.

With Thanks to:MIT Sea Grant, the Chewonki Foundation, Mass Maritime Academy, Town of Hull, MAUSGS, Falmouth Scientific Inc.

Geoff Cowles, Dorothy Kelly, Peter Arnold, Stanley King, Tom Pham, Herman Gustafson, Jim Manning, Kurt Bornheim, Andy Stern, Neil Ganju, ….

Page 2: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Studies Done at Three Sites

Page 3: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

The Three Sites

Mass. Maritime/Cape Cod Canal

Page 4: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

The Three Sites

The Hull Gut

Page 5: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

The Three Sites

The Sheepscot River

Page 6: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Site #3

The Sheepscot River

Page 7: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways
Page 8: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

FERC Permit Area

Page 9: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Step 1

Hydrodynamic Modeling

Page 10: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways
Page 11: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

The Island Tidal Node

Page 12: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways
Page 13: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Tidal Power Distribution

Page 14: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Tidal Power Distribution

Page 15: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Step 2

Spatial Velocity Survey

Page 16: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Surveyed Areas

Our sampling focused on five areas, indicated by the sampling sites (green dots) shown here. These areas were identified as high energy locations by a numerical model and by the data from a preliminary survey conducted on September 28.

Page 17: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

The Surveying Equipment

Acoustic Doppler Current Profiler

(ADCP)R/V Seagull and Capt.

Stanley King

Page 18: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Surveyed Areas

The Best Area

Page 19: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Under the Bridge

The focus here will be on the tidal flows and tidal power near the Westport Island bridge.

Page 20: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Capturing the Tidal Cycle

Observations out of the Nav. Channel, but with bottom depth > 7m

Page 21: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

The Tidal Cycle

The tidal velocity nicely follows a sinusoidal cycle, with maximum ebb (positive) and flood (negative) currents of slightly greater than 1 m/s. Velocities were somewhat higher directly underneath the bridge (by about 10 %), but this is a minor point.

Page 22: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Not the Strongest Tides of the Year

But wait! The timing of our survey was based on boat and personnel availability. Unfortunately, this availability did not coincide with a time of strong tides. In fact, our survey was conducted during unusually weak neap tides, as seen by highlighting the time of our survey (in red above) on a plot of tidal height at Wiscasset.

Page 23: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Extending the Analysis to Other Tides

With a little math, we can relate the maximum tidal velocity, Vmax, to the mean power density over the half tidal cycle. The formula is:

<F> = 2ρVmax3

Assuming that Vmax is proportions to the height range, Hdiff, of a particular tide

Vmax = Hdiff*Vmax(Sept 30) 7 ft

Allows for the computation of the expected velocity and power distribution under the bridge.

Page 24: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

For Vmax(Sept 30) = 1 m/s ; <F>year = 623 W/m2

Page 25: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Step 3

Evaluating the Bottom Conditions

-Side Scan Surveying

Page 26: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Maine DMR Side-Scan Survey April 5,2011

Page 27: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Refining the “Best Spot” Assessment

Page 28: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Step 4

Installing a Moored Velocity Profiler (e.g. ADCP) Near the Best Spot

Page 29: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

ADCP

Page 30: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways
Page 31: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Conclusion

Page 32: Exploring Optimal Locations for Underwater Turbine Emplacement near Marine Navigation Passageways

Conclusion

A four-step process:

1. Hydrodynamics modeling

2. Ship-board velocity surveying

3. Side-scan sonar surveying

4. Moored velocity profiling

Offers a cost-effective way to evaluate the tidal resource in a estuarine environment, with a “go” or

“no” assessment at each step