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Tidal In-Stream Energy Overview

Tidal In-Stream Energy Overview. Brian Polagye Research Assistant University of Washington Department of Mechanical Engineering. March 6, 2007. Agenda. Tidal Energy Status TISEC Device Overview TISEC in Puget Sound UW Research.

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Tidal In-Stream Energy Overview

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  1. Tidal In-Stream Energy Overview Brian Polagye Research Assistant University of Washington Department of Mechanical Engineering March 6, 2007

  2. Agenda • Tidal Energy Status • TISEC Device Overview • TISEC in Puget Sound • UW Research

  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) 001,09-18-06,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) 002,09-18-06,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 003,09-18-06,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 004,09-18-06,AR.ppt

  7. Agenda • Tidal Energy Status • TISEC Device Overview • TISEC in Puget Sound • UW Research

  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 009,09-07-06,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 010,09-07-06,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? 012,09-07-06,SNOPUD.ppt

  11. Marine Current Turbines is furthest along in the development process TISEC Devices Marine Current Turbines (MCT) Horizontal axis (2 bladed) Planetary gearbox Induction generator Rated from 1.2 – 2.5 MW Power train Monopile drilled or driven into seabed Two turbines per pile Foundation Lifting mechanism pulls turbine out of water for servicing Maintenance 3 years of testing prototype in UK 1.5 MW demonstration planned for installation in 2006/2007 Conceptual fully submerged units Development Large Scale (18 m diameter) 002,09-07-06,SNOPUD.ppt

  12. Verdant is positioned to install the first array of TISEC devices in the world TISEC Devices Verdant Horizontal axis (3 bladed) Planetary gearbox Induction generator Rated at 34 kW Power train Foundation Monopile drilled or driven into seabed Retrieval of power train by crane barge Divers employed during installation Maintenance Small Scale (5 m diameter) Development Installing 6 turbines off Roosevelt Island, NY City First turbine in water producing power 002,09-07-06,SNOPUD.ppt

  13. 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 Heavy-lift crane barge recovers “cassette” with all moving parts Maintenance Large Scale (21 m diameter inlet) Tank testing Nearing end of design for first large scale unit Development 001,09-07-06,SNOPUD.ppt

  14. GCK is developing a vertical-axis turbine TISEC Devices GCK (Gorlov Helical Turbine) Vertical axis (3 bladed) Power train TBD Rated at 7 kW Power train TBD – neutral buoyant platform proposed for arrays, bottom mount for single units Foundation TBD – divers? Maintenance Small Scale (1 m diameter) Testing of single or multiple devices from fixed platforms Power take-off has been problematic Development 005,09-18-06,SNOPUD.ppt

  15. Agenda • Tidal Energy Status • TISEC Device Overview • TISEC in Puget Sound • UW Research

  16. A number of prospective tidal energy sites have been identified in Puget Sound Puget Sound Puget Sound Site Identification Agate Passage Guemes Channel Spieden Channel San Juan Channel Deception Pass Rich Passage Point Wilson Marrowstone Point Tacoma Narrows Bush Point Large resource Strong currents 700+ MW of tidal resources identified Small resource Weaker currents 006,09-18-06,SNOPUD.ppt

  17. 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 021,09-07-06,SNOPUD.ppt

  18. 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 022,09-07-06,SNOPUD.ppt

  19. Case 3: Tacoma Narrows: High resource quality, moderate cross section Tacoma Narrows 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 007,09-18-06,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? Potential for multiple use? Yes Yes Marine traffic in area? How much of channel occupied? Yes Most/All No Yes OK to Build No Limited Large-scale turbulence? Yes Environmental considerations? No 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? 015,1-22-07,UW.ppt

  22. Agenda • Tidal Energy Status • TISEC Device Overview • TISEC in Puget Sound • UW Research

  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 ? 003,09-07-06,SNOPUD.ppt

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