As part of a drive to replace energy derived from burning fossil fuels by energy from renewable sources, there is currently great interest in harnessing the energy in tidal currents. Though they vary in direction and current speed over a tidal cycle and through the seasons, tidal currents are assured and predictable. Electricity generated from tidal power will therefore take a premium place within the generation mix for those companies tasked with maintaining a continuous electricity supply.
However, there are concerns that devices such as rotating rotors placed within a tidal current will present an obstacle and collision risk to wildlife. These concerns relate most obviously to seals and cetaceans and deep-diving birds which forage within tidal channels, but there are also concerns about the potential collision risk to fish, particularly Atlantic salmon. While the risk presented by a single underwater turbine may appear minimal, there are proposals under development for large arrays of turbines whose combined frontal area represents a very significant proportion of the underwater cross-section (width x depth) of the channel1 in which they would be sited. For such arrays, it is important to understand the degree and extent of collision risks. Developers are therefore required to include an assessment of collision risks as part of their Environmental Statement / development application.
This guidance is written for developers and their consultants, and for regulatory bodies, with the aim of promoting approaches to collision risk assessment which are as far as possible standardised.
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