Wave-Turbulence Decomposition Methods Applied to Tidal Energy Site Assessment

Larissa Perez, Remo Cossu, Camille Couzi and Irene Penesis
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Larissa Perez: School of Civil Engineering, University of Queensland, Brisbane 4072, QLD, Australia
Remo Cossu: School of Civil Engineering, University of Queensland, Brisbane 4072, QLD, Australia
Camille Couzi: Australian Maritime College, University of Tasmania, Hobart 7250, TAS, Australia
Irene Penesis: Australian Maritime College, University of Tasmania, Hobart 7250, TAS, Australia

Energies, 2020, vol. 13, issue 5, 1-21

Abstract: High levels of turbulence have been proven to substantially increase the blade loadings on tidal turbines, outlining the need of properly characterizing turbulence parameters in tidal energy sites. The presence of long surface gravity waves may cause a significant bias on the estimation of these parameters, which requires wave-turbulence decomposition methods that are currently missing from guidelines. Here, three techniques of decomposing wave and turbulence are tested: the stopband filter (SB), moving average filter (MA), and synchrosqueezing wavelet transform (SWT). The study site, Banks Strait, Tasmania, is a 16 km wide channel that presents high potential for tidal energy generation. Wave peak periods at the study site were found to vary mostly between 7 and 12 s, with maximum exceeding 15 s. Turbulence intensities (TI), turbulent kinetic energy (TKE), and integral scales are quantified. Our results indicate differences between the estimates obtained from each method. The MA highly underestimates turbulence, resulting in TI values which were nearly 50% lower than those obtained from other decomposition methods. While TI and TKE estimated from the SB and the SWT techniques are quite similar, integral length scales are considerably underestimated by the SB. These findings reveal that the SWT is a more reliable method because of the more accurate estimates of turbulence parameters and indicate the need of establishing guidelines which address wave-turbulence decomposition in tidal stream energy site assessments. Despite having shown to be quite a versatile technique, further investigation of its applicability in data from other prospective tidal energy sites is necessary to fully assess the generality of the SWT technique.

Keywords: tidal energy; site assessment; wave-current interaction; turbulence; integral length scales; wave-turbulence decomposition (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2020
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (8)

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