Page 260 - Fundamentals of Ocean Renewable Energy Generating Electricity From The Sea

Optimization Chapter | 9 249

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FIG. 9.7 Mean power density (≥1kW/m ) in the Pentland Firth over a spring tidal cycle. There
are four leased tidal energy sites in this region, including the MeyGen project in the Inner Sound
of Stroma. (Reproduced from S.P. Neill, A. Vögler, A.J. Goward-Brown, S. Baston, M.J. Lewis, P.A.
Gillibrand, S. Waldman, D.K. Woolf, The wave and tidal resource of Scotland, Renew. Energy 114
(2017) 3–17, under the Creative Commons Attribution License (CC BY).)

Pentland Firth. How, for example, would large-scale tidal energy extraction in
the Inner Sound influence the tidal energy resource within the Pentland Firth
itself (Fig. 9.7)? In addition, for scenarios where there is a fairly equal channel
division, devices could be strategically installed on one side of an island, leaving
the opposite side clear for navigation [16]. Polagye and Malte [17] simulated a
range of channel networks, including a split tidal channel (which they call a
multiple-connected network). They found that transport in the impeded channel
reduced, at maximum power, to around 50% of its magnitude compared with its
undisturbed state. This is agreement with Cummins [18], who found, using an
electric circuit analogue, that the transport in the impeded channel was reduced
to 50–71%: a similar range to the much reported 58% calculated by Garrett
and Cummins [19] for a single channel in the resistive limit. Polagye and Malte
[17] found that maximum dissipation (P max ) was 20% higher when extraction
was evenly distributed between the two branches (Fig. 9.8), and that an even
distribution minimizes far-field impacts. However, such an optimal arrangement