A Probabilistic Model for Hydrokinetic Turbine Collision Risks: Exploring Impacts on Fish

Abstract

A variety of hydrokinetic turbines are currently under development for power generation in rivers, tidal straits and ocean currents. Because some of these turbines are large, with rapidly moving rotor blades, the risk of collision with aquatic animals has been brought to attention. The behavior and fate of animals that approach such large hydrokinetic turbines have not yet been monitored at any detail. In this paper, we conduct a synthesis of the current knowledge and understanding of hydrokinetic turbine collision risks. The outcome is a generic fault tree based probabilistic model suitable for estimating population-level ecological risks. New video-based data on fish behavior in strong currents are provided and models describing fish avoidance behaviors are presented. The findings indicate low risk for small-sized fish. However, at large turbines (≥5 m), bigger fish seem to have high probability of collision, mostly because rotor detection and avoidance is difficult in low visibility. Risks can therefore be substantial for vulnerable populations of large-sized fish, which thrive in strong currents. The suggested collision risk model can be applied to different turbine designs and at a variety of locations as basis for case-specific risk assessments. The structure of the model facilitates successive model validation, refinement and application to other organism groups such as marine mammals.

Habitat Connectivity of Fish in Temperate Shallow-Water Seascapes

“…Subsequently, abundances were calculated (m −2 ) based on fish activity. This was defined as the number of instances fish entered the field of view divided by the recording area, which therefore corrects for the variation in visibility among sites (Hammar et al, 2015;Perry et al, 2017). Field of view is defined by the maximum distance at which a recorded fish is identified for each specific film.…”

Long‐term effect of a tidal, hydroelectric propeller turbine on the populations of three anadromous fish species

“…During turbine passage aquatic organisms can be affected by mechanical strike, shear, pressure flux and cavitation (Von Raben, 1957;Čada, 1990;Dadswell & Rulifson, 1994;Deng et al, 2005;Stokesbury & Dadswell, 1991). Unfortunately, many of the instream hydrokinetic machines installed or planned worldwide are also large propeller turbines (Gill, 2005;Lewis et al, 2015;FORCE, 2017) and the same physical phenomena will be encountered by organisms that pass through them (Bucklund et al, 2013;Hammer et al, 2015;Zangiabadi et al, 2016).…”

“…These resources sustain the economic viability of many coastal communities and their loss will affect the livelihoods of their human populations (Dadswell & Rulifson, 1994;Gill, 2005). Because the instream propeller turbines operate without a barrage the chance of fish encounters are considered to be reduced (Shen et al, 2016;Bevelhimer et al, 2017), however, because of their size and the fact most operate on both ebb and flood tide means they will pass huge amounts of water through their draft tube (c. 1,200 m 3 s −1 for a 16 m diameter machine; FORCE, 2017) potentially affecting large numbers of fishes and capable of impacting cetaceans (Tollit et al, 2011;Hammer et al, 2015). Is it wise and justifiable to replace one renewable resource with another when alternate forms of electric generation are possible?…”

Hydroacoustic Assessment of Behavioral Responses by Fish Passing Near an Operating Tidal Turbine in the East River, New York

“…One of the most important environmental issues facing the marine and hydrokinetic energy industry is whether fish and marine mammals that encounter these devices are likely to be struck and possibly injured by moving components, primarily rotating turbine blades. For hydrokinetic devices (e.g., tidal turbines) that generate energy from flowing water, this concern is greatest for large organisms because their increased length increases the probability that they will be struck as they pass through the blade-swept area (Schweizer et al 2011;Hammar et al 2015) and because their increased mass means that the force absorbed if they are struck is greater and potentially more damaging (Amaral et al 2015). Key to addressing this issue is understanding whether aquatic organisms encountering a hydrokinetic device change their swimming behavior in a way that decreases their likelihood of being struck and possibly injured by the device.…”