Tidal energy extraction at one location affects the strength and timing (phase) of tidal elevation and currents elsewhere, with immediate implications for the resource and the environment. More holistically, it is apparent that the entire approach to tidal energy and related marine and energy policy should be informed by understanding of this interaction. We examine first the physical phenomena of interaction using a range of models and then consider the broader implications.
Studies using 2-dimensional or 3-dimensional hydrodynamic models and precise environmental and tidal stream array characteristics provide specific case studies of the effects of tidal stream arrays. These studies are reviewed here, but we demonstrate that a simpler “wiring diagram” approach gives more generic results and insights.
Previous studies have categorised effects of renewable energy extraction on the flow as near- field (<1 km), far-field (1-10 km) and regional (>1 0 km). Here, we concentrate on interactions spanning far-field and regional (>1km) and introduce the alternative categories of “systemic”, “inter-channel” and “intra-channel”. We show that in the case of both inter-channel and intra-channel interactions that “parallel is good, serial is bad”. Policy and governance should address this fundamental truth, encouraging the positive interactions associated with parallel developments.