1 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION Tidal In-Stream Energy Overview Brian Polagye Research Assistant University of Washington Department of Mechanical Engineering March 6, 2007

2 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION Agenda Tidal Energy Status TISEC Device Overview TISEC in Puget Sound UW Research

3 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION Past development of the tidal resource has involved barrages Status Barrages - Past Development - 001, ,AR.ppt 250MW barrage in La Rance, France (constructed 1960) 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

4 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION Present development interest is focused on free-stream turbines Status Tidal In-Stream Energy Conversion (TISEC) - Present Development - 002, ,AR.ppt 1.5 MW TISEC Device (Marine Current Turbines) 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

5 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION TISEC looks like the wind industry about twenty years ago Status State of the Industry - Device Developers - 003, ,AR.ppt 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

6 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION Significant interest in developing this resource in Pacific Northwest Status State of the Industry - Pacific NW Activities - 004, ,AR.ppt 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

7 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION Agenda Tidal Energy Status TISEC Device Overview TISEC in Puget Sound UW Research

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

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

10 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION Ducted turbines have been proposed to augment power production TISEC Devices Power Augmentation 012, ,SNOPUD.ppt 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?

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

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

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

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

15 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION Agenda Tidal Energy Status TISEC Device Overview TISEC in Puget Sound UW Research

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

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

18 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION Case 2: Admiralty Inlet: Moderate resource quality, large cross-section 022, ,SNOPUD.ppt Admiralty Inlet Siting Feasible Array Layout Preliminary Array Performance 450 turbines (20 m diameter) Average installation depth ~60m Given lower power density can installation be economic? 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 3 km 0.9 km

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

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

21 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION 015, ,UW.ppt 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 Local environmental degradation Toxicity of anti-fouling paints and lubricants? Does turbine operation cause acoustic harassment? How will turbine operation and installation affect salmon recovery? Will a turbine make sushi in addition to electricity? Will the rotor injure or harass fish and marine mammals? 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? Ecological implications of fluidic impacts Mudflat ecosystems? Oxygen levels in south Sound and Hood Canal?

22 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION Agenda Tidal Energy Status TISEC Device Overview TISEC in Puget Sound UW Research

23 L ABORATORY FOR E NERGY AND E NVIRONMENTAL C OMBUSTION Research Question: How much tidal energy can be extracted? 003, ,SNOPUD.ppt Case Study Extraction Limits - Balancing Resource Against Fluidic Impact - UW Research Admiralty Head Point Wilson Bush Point Marrowstone Point Indian Island 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 ? ? ?