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Power variability of tidal-stream energy and implications for electricity supply

Lewis, Matt, McNaughton, James, Márquez-Dominguez, Concha, Todeschini, Grazia, Togneri, Michael, Masters, Ian, Allmark, Matthew ORCID:, Stallard, Tim, Neill, Simon, Goward-Brown, Alice and Robins, Peter 2019. Power variability of tidal-stream energy and implications for electricity supply. Energy 183 , pp. 1061-1074. 10.1016/

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Temporal variability in renewable energy presents a major challenge for electrical grid systems. Tides are considered predictable due to their regular periodicity; however, the persistence and quality of tidal-stream generated electricity is unknown. This paper is the first study that attempts to address this knowledge gap through direct measurements of rotor-shaft power and shore-side voltage from a 1 MW, rated at grid-connection, tidal turbine (Orkney Islands, UK). Tidal asymmetry in turbulence parameters, flow speed and power variability were observed. Variability in the power at 0.5 Hz, associated with the 10-min running mean, was low (standard deviation 10–12% of rated power), with lower variability associated with higher flow speed and reduced turbulence intensity. Variability of shore-side measured voltage was well within acceptable levels (∼0.3% at 0.5 Hz). Variability in turbine power had <1% difference in energy yield calculation, even with a skewed power variability distribution. Finally, using a “t-location” distribution of observed fine-scale power variability, in combination with an idealised power curve, a synthetic power variability model reliably downscaled 30 min tidal velocity simulations to power at 0.5 Hz (R2 = 85% and ∼14% error). Therefore, the predictability and quality of tidal-stream energy was high and may be undervalued in a future, high-penetration renewable energy, electricity grid.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Engineering
Additional Information: This is an open access article under the terms of the CC-BY Attribution 4.0 International license.
Publisher: Elsevier
ISSN: 0360-5442
Date of First Compliant Deposit: 20 August 2019
Date of Acceptance: 29 June 2019
Last Modified: 05 May 2023 12:26

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