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Implications of Tidal Phasing for Power Generation at a Tidal Energy Site. Brian Polagye and Jim Thomson Northwest National Marine Renewable Energy Center University of Washington. Current: Resource Characterization April 11, 2013. Spatial Variability in Mean Currents.
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Implications of Tidal Phasing for Power Generation at a Tidal Energy Site Brian Polagye and Jim Thomson Northwest National Marine Renewable Energy Center University of Washington Current: Resource Characterization April 11, 2013
Spatial Variability in Mean Currents • Meaningful variations in flow characteristics on spatial scales as small as 100 m • Important implications for resource assessment and power estimates Admiralty Head 1.8±0.04 kW/m2 0.6±0.02 kW/m2 1.4±0.06 kW/m2 Polagye, B. and Thomson, J., 2013, “Tidal energy resource characterization: methodology and field study in Admiralty Inlet, Puget Sound, US,” Proc. IMechE Part A, J. Power and Energy, doi:10.1177/0957650912470081.
Phase Variations • If currents are out of phase between locations, this be theoretically exploited to reduce the intermittency of power generated • Investigated on a national scale in the UK • What about phase variations on a local scale (< 10 km)? Iyer, A. S., S. J. Couch, G. P. Harrison, and A. R. Wallace. "Variability and phasing of tidal current energy around the United Kingdom." Renewable Energy 51 (2013): 343-357.
Tidal Phase in Puget Sound Large phase changes across Admiralty Inlet and Tacoma Narrows Large power dissipation across these sills High velocity through narrow channels
Current Measurements Sites A & B Sites D & E Site F NNMREC Sea Spider Current Velocity Doppler profiler
Near-Headland Sites (A & B) A B 5-minute average to filter most turbulence
Turbine-Adjusted Power Density Ucut-in = 0.7 m/s Urated= 2.0 m/s
Array Phasing Potential Thyng, K.M., 2012, “Numerical simulation of Admiralty Inlet, WA, with tidal hydrokinetic turbine siting application,” PhD dissertation, University of Washington, Seattle, Washington (USA)
Conclusions • Large power density phase variations can occur over relatively short distances (< 10 km) • Exploiting these differences may be able to reduce the intermittency of power output from arrays at the same nominal “site” • To realize these benefits in practice, out of phase locations need to have similar power density and intermittency
Acknowledgements • This material is based upon work supported by the Department of Energy under Award Number DE-FG36-08GO18179. • Many thanks to Joe Talbert and Alex DeKlerk for maintaining the Sea Spider platforms over several years of deployments and to Captain Andy Reay-Ellers for helping us put them in the right place.