1. Tidal In-Stream Energy Overview
Brian Polagye
EPRI PhD Fellow
University of Washington
Department of Mechanical Engineering
Presented: March 6, 2007 at People for Puget Sound

2. Agenda Tidal Energy Status TISEC Device Overview TISEC in Puget Sound
UW Research
Good Morning! My name is Roger Bedard. I am the Ocean Energy Leader at the
Electric Power Research Institute in Palo Alto California
EPRI performs R&D for the global energy industry. We span the breadth from
generation, all forms, through power delivery and use technologies and
include environmental effects and health and safety. We worry about keeping
the lights on 5, 10 and 20 years from now
As you can tell from m y name, I am of French Canadian descent. My grandparents
Immigrated to the US from Quebec in the 1920s.
I bring a message of hope about energy opportunities for the future – ocean energy
Three kinds of ocean energy 1) tidal, 2) wave and 3) hybrid wind-wave as illustrated
- Ocean energy is not as a silver bullet that will solve all energy problems, but
- It is an energy supply option to add to the provinces portfolio of energy
supply alternatives
Note that these all three of these ocean energy sources are indigenous sources
- Keeps the wealth in the province
- Increases your energy security
We have just completed a tidal power feasibility study for NSPI and the province
- I will explain the benefits and costs of Tidal Power in NS

3. Past development of the tidal resource has involved barrages
Status
Barrages
- Past Development -
Dam constructed across estuary requiring long construction time and large financial commitment
Power produced by impounding tidal waters behind dam
Drastically alters circulation of estuary in addition to attendant problems with conventional hydroelectric
Low-cost power production at very large scale
250MW barrage in La Rance, France
(constructed 1960)
001, ,AR.ppt

4. Present development interest is focused on free-stream turbines
Status
Tidal In-Stream Energy Conversion (TISEC)
- Present Development -
Turbines installed in groups allowing for more rapid, phased build-out
Power produced directly from tidal currents
Should be possible to generate power from tides with limited environmental impact
Moderate-cost power production at varying scales
1.5 MW TISEC Device
(Marine Current Turbines)
002, ,AR.ppt

5. TISEC looks like the wind industry about twenty years ago
Status
State of the Industry
- Device Developers -
More than a dozen device developers
Dominant design has yet to emerge
Most developers are UK based due to significant government investment in marine renewables
Many developers have tested small-scale models
Laboratory and field tests to verify expected performance
Difficult to address “big picture” questions in the lab
Full-scale testing just beginning
300 kW turbine in water in Devon, UK for three years (MCT)
1.5 MW turbine planned for Strangford, UK in 2006/2007 (MCT)
6 x 34kW turbine array permitted for East River, NY in 2007 (Verdant)
kW scale ducted turbine at Race Rocks, BC (Clean Current)
OpenHydro testing at EMEC (European Marine Energy Center) since December 2006
003, ,AR.ppt

6. Significant interest in developing this resource in Pacific Northwest
Status
State of the Industry
- Pacific NW Activities -
Many applications have been filed for preliminary permits from the FERC (Federal Energy Regulatory Commission)
Permit gives applicant three years to study site and precedence for application of full permit
Applications from utilities (municipal utilities given precedence) and site developers
Permit is needed to hook device up to grid, but does not authorize construction and installation. Subject to the same permitting requirement as any marine construction project.
A number of studies have been recently carried out, most notably, the ERPI North American Feasibility Study
8 prospective sites in US and Canada. For Washington, considered Tacoma Narrows
EPRI also recently produced a report on the in-stream resource in southeast Alaska
The FERC has recently awarded a number of preliminary permits in Puget Sound
Tacoma Power: Tacoma Narrows (awarded early 2006)
Snohomish PUD: Deception Pass, Agate Pass, Rich Passage, San Juan Channel, Spieden Channel, Guemes Channel (awarded February 2007)
Competing applications for development in Admiralty Inlet still pending decision
004, ,AR.ppt

7. Agenda Tidal Energy Status TISEC Device Overview TISEC in Puget Sound
UW Research
Good Morning! My name is Roger Bedard. I am the Ocean Energy Leader at the
Electric Power Research Institute in Palo Alto California
EPRI performs R&D for the global energy industry. We span the breadth from
generation, all forms, through power delivery and use technologies and
include environmental effects and health and safety. We worry about keeping
the lights on 5, 10 and 20 years from now
As you can tell from m y name, I am of French Canadian descent. My grandparents
Immigrated to the US from Quebec in the 1920s.
I bring a message of hope about energy opportunities for the future – ocean energy
Three kinds of ocean energy 1) tidal, 2) wave and 3) hybrid wind-wave as illustrated
- Ocean energy is not as a silver bullet that will solve all energy problems, but
- It is an energy supply option to add to the provinces portfolio of energy
supply alternatives
Note that these all three of these ocean energy sources are indigenous sources
- Keeps the wealth in the province
- Increases your energy security
We have just completed a tidal power feasibility study for NSPI and the province
- I will explain the benefits and costs of Tidal Power in NS

8. All turbines have a number of common components, but many variants
TISEC Devices
Turbine Overview
Gearbox
Increase rotational speed of shaft from turbine
80-95% efficient
Generator and Power Conditioning
Powertrain or Drivetrain
Generate electricity
Condition electricity for grid interconnection
Turns at high RPM
95-98% efficient
Rotor
Extracts power from flow
Turns at low RPM
Efficiency varies with flow velocity (45% max)
Foundation
Secure turbine to seabed
Resist drag on support structure and thrust on rotor
009, ,SNOPUD.ppt

9. Foundation selection is usually driven by site water depth
TISEC Devices
Foundation Types
Monopile
Gravity Base
Heavy foundation of concrete and low cost aggregate placed on seabed
Hollow steel pile driven or drilled into seabed
Pros:
Deep water installation feasible
Pros:
Small footprint
Established technology used in offshore wind
Cons:
Large footprint
Scour problems for some types of seabed
Decommissioning problems
Cons:
High cost in deep water
Installation expensive for some types of seabed
(10-40m)
Chain Anchors
Chains anchored to seabed and turbine
Tension Leg
Submerged platform held in place by anchored cables under high tension
Pros:
Small footprint
Deep water installation feasible
Pros:
Small footprint
Deep water installation feasible
Cons:
Problematic in practice
Device must have high natural buoyancy
Cons:
Immature technology now being considered for offshore wind in deep water
010, ,SNOPUD.ppt

10. Ducted turbines have been proposed to augment power production
TISEC Devices
Power Augmentation
Enclosing turbine in diffuser duct may boost power but a number of questions remain unanswered regarding this approach
Is it economically justified?
Ducts were never justified for wind turbines
Different set of circumstances for tidal turbines
Is there an increased hazard to marine mammals and fish?
Can a large fish or mammal become trapped in the duct?
Is screening of ducts feasible?
012, ,SNOPUD.ppt

11. Marine Current Turbines is furthest along in the development process
TISEC Devices
Marine Current Turbines (MCT)
Power train
Horizontal axis (2 bladed)
Planetary gearbox
Induction generator
Rated from 1.2 – 2.5 MW
Foundation
Monopile drilled or driven into seabed
Two turbines per pile
Maintenance
Lifting mechanism pulls turbine out of water for servicing
Development
3 years of testing prototype in UK
1.5 MW demonstration planned for installation in 2006/2007
Conceptual fully submerged units
Large Scale
(18 m diameter)
002, ,SNOPUD.ppt

12. Verdant is positioned to install the first array of TISEC devices in the world
Power train
Horizontal axis (3 bladed)
Planetary gearbox
Induction generator
Rated at 34 kW
Foundation
Monopile drilled or driven into seabed
Maintenance
Retrieval of power train by crane barge
Divers employed during installation
Small Scale
(5 m diameter)
Development
Installing 6 turbines off Roosevelt Island, NY City
First turbine in water producing power
002, ,SNOPUD.ppt

13. Lunar Energy Large Scale
Lunar Energy has adopted a different philosophy with an emphasis on a “bulletproof” design
TISEC Devices
Lunar Energy
Horizontal axis (ducted)
Hydraulic gearbox
Induction generator
Rated at 2 MW
Power train
Foundation
Gravity foundation using concrete and aggregate
Maintenance
Heavy-lift crane barge recovers “cassette” with all moving parts
Large Scale
(21 m diameter inlet)
Tank testing
Nearing end of design for first large scale unit
Development
001, ,SNOPUD.ppt

14. GCK is developing a vertical-axis turbine
TISEC Devices
GCK (Gorlov Helical Turbine)
Power train
Vertical axis (3 bladed)
Power train TBD
Rated at 7 kW
Foundation
TBD – neutral buoyant platform proposed for arrays, bottom mount for single units
Maintenance
TBD – divers?
Small Scale
(1 m diameter)
Development
Testing of single or multiple devices from fixed platforms
Power take-off has been problematic
005, ,SNOPUD.ppt

15. Agenda Tidal Energy Status TISEC Device Overview TISEC in Puget Sound
UW Research
Good Morning! My name is Roger Bedard. I am the Ocean Energy Leader at the
Electric Power Research Institute in Palo Alto California
EPRI performs R&D for the global energy industry. We span the breadth from
generation, all forms, through power delivery and use technologies and
include environmental effects and health and safety. We worry about keeping
the lights on 5, 10 and 20 years from now
As you can tell from m y name, I am of French Canadian descent. My grandparents
Immigrated to the US from Quebec in the 1920s.
I bring a message of hope about energy opportunities for the future – ocean energy
Three kinds of ocean energy 1) tidal, 2) wave and 3) hybrid wind-wave as illustrated
- Ocean energy is not as a silver bullet that will solve all energy problems, but
- It is an energy supply option to add to the provinces portfolio of energy
supply alternatives
Note that these all three of these ocean energy sources are indigenous sources
- Keeps the wealth in the province
- Increases your energy security
We have just completed a tidal power feasibility study for NSPI and the province
- I will explain the benefits and costs of Tidal Power in NS

16. Puget Sound Site Identification 700+ MW of tidal resources identified
A number of prospective tidal energy sites have been identified in Puget Sound
Puget Sound
Puget Sound Site Identification
Agate Passage
Spieden Channel
Guemes Channel
San Juan Channel
Deception Pass
Rich Passage
Point Wilson
Marrowstone Point
Tacoma Narrows
Bush Point
Large resource Strong currents
Small resource Weaker currents
700+ MW of tidal resources identified
006, ,SNOPUD.ppt

17. Deception Pass Narrows Preliminary Array Performance
Case 1: Deception Pass: Exceptional resource quality, small cross-section
Deception Pass Narrows
Siting
High Power Region
Feasible Array Layout
20 turbines (10 m diameter)
Average installation depth ~30m
Exceptionally strong currents may complicate installation and surveys
1 km
Preliminary Array Performance
3 MW average electric power
11 MW rated electric power
Power for 2000 homes
2 km
021, ,SNOPUD.ppt

18. Preliminary Array Performance
Case 2: Admiralty Inlet: Moderate resource quality, large cross-section
Admiralty Inlet
Siting
Feasible Array Layout
3 km
450 turbines (20 m diameter)
Average installation depth ~60m
Given lower power density can installation be economic?
0.9 km
Preliminary Array Performance
20 MW average electric power
68 MW rated electric power
Power for 15,000 homes
Key Next Step
Velocity survey of Admiralty Inlet to refine power estimates
022, ,SNOPUD.ppt

19. Case 3: Tacoma Narrows: High resource quality, moderate cross section
Siting
Bathymetry
Study Array Layout
64 turbines (2x18 m diameter)
Average installation depth ~56m
Point Evans Ref.
Study Array Performance
Dual Rotor Turbine Footprint
14 MW average electric power
46 MW rated electric power
Power for 11,000 homes
007, ,AR.ppt

20. The question of where to site turbines is a relatively complex one
Siting
Siting Decision Tree
Is there an in-stream resource? No
Is there a low-cost interconnection point? No
Yes
How deep is the water?
>60m
<10m
Yes
Are there marine construction facilities? No
Moderate Depth
Can seabed support foundation? No
Yes No
Are there other stakeholders?
Yes
Potential for multiple use?
Yes
Marine traffic in area?
How much of channel occupied?
Yes
Most/All No
Yes
OK to Build No
Limited
Large-scale turbulence?
Yes No
Environmental considerations?
001,3-6-07,UW.ppt

21. Environmental issues usually dominate the discussion and the key questions may be harder to identify, much less answer
Siting
Environmental Issues
Death of or injury to fish and marine mammals
Will a turbine make sushi in addition to electricity?
Fluidic impact of energy extraction
Will turbine operation alter sedimentation patterns?
Will flow rates in the estuary be reduced?
Will the tidal range be altered?
Will the rotor injure or harass fish and marine mammals?
Local environmental degradation
Toxicity of anti-fouling paints and lubricants?
Does turbine operation cause acoustic harassment?
Ecological implications of fluidic impacts
Mudflat ecosystems?
Oxygen levels in south Sound and Hood Canal?
How will turbine operation and installation affect salmon recovery?
015, ,UW.ppt

22. Agenda Tidal Energy Status TISEC Device Overview TISEC in Puget Sound
UW Research
Good Morning! My name is Roger Bedard. I am the Ocean Energy Leader at the
Electric Power Research Institute in Palo Alto California
EPRI performs R&D for the global energy industry. We span the breadth from
generation, all forms, through power delivery and use technologies and
include environmental effects and health and safety. We worry about keeping
the lights on 5, 10 and 20 years from now
As you can tell from m y name, I am of French Canadian descent. My grandparents
Immigrated to the US from Quebec in the 1920s.
I bring a message of hope about energy opportunities for the future – ocean energy
Three kinds of ocean energy 1) tidal, 2) wave and 3) hybrid wind-wave as illustrated
- Ocean energy is not as a silver bullet that will solve all energy problems, but
- It is an energy supply option to add to the provinces portfolio of energy
supply alternatives
Note that these all three of these ocean energy sources are indigenous sources
- Keeps the wealth in the province
- Increases your energy security
We have just completed a tidal power feasibility study for NSPI and the province
- I will explain the benefits and costs of Tidal Power in NS

23. Research Question: How much tidal energy can be extracted?
Extraction Limits
- Balancing Resource Against Fluidic Impact -
Case Study
UW Research
How much kinetic energy can be extracted by an array?
Current estimates are 15% of kinetic energy in a channel (little physical reasoning)
Preliminary results indicate limits are site specific, but also indicate it may be possible to “tune” turbines to site to minimize impact
Does the construction of one array preclude the construction of others?
Can 20+ MW arrays be built at Pt. Wilson, Marrowstone and Bush Point?
Can an array be built at Admiralty Inlet if one already operating in Tacoma Narrows?
Building an understanding with 1-D models
Validating 1-D results
2-D modeling work planned in conjunction with SnoPUD
Admiralty Head ?
Point Wilson ?
Marrowstone Point
Indian Island
Bush Point ?
003, ,SNOPUD.ppt