This report reviews information on impacts of conventional hydropower turbines that can be used to evaluate potential impacts of hydrokinetic turbines on fish. The report discusses design and operational differences between conventional and hydrokinetic turbines as well as differences in the magnitude or potential for fish injury and mortality. This report will be valuable to industry, resource agencies, non-governmental environmental organizations, and universities involved in research, management, and protection of aquatic ecosystems.
Hydrokinetic generation is an emerging technology for producing electricity from flowing water. This form of generation differs from conventional and pumped storage hydropower generation in that it does not employ dams or other structures to impound water and create hydraulic head. Rather, hydrokinetic turbines are placed in natural, free-flowing water courses and man-made channels. Because hydrokinetic generation is a new form of power generation, relatively little information is available regarding potential impacts on fish individuals and populations. A substantial body of information exists, however, pertaining to the effects of turbine passage at conventional hydropower projects. Useful information can be obtained from the literature on turbine passage at conventional hydropower projects, despite important differences between conventional and hydrokinetic power generation.
Objectives and Approach
This report reviews existing information on injury mechanisms associated with fish passage through conventional hydro turbines and the relevance and applicability of this information to fish passage through hydrokinetic turbines. Available information includes probability of blade strike, blade strike survival rates, and criteria for shear levels and pressure regimes that can damage fish.
Fish passing through the blade sweep of a hydrokinetic turbine experience a much less harsh physical environment than do fish entrained through conventional hydro turbines. The design and operation of conventional turbines results in high flow velocities, abrupt changes in flow direction, relatively high runner rotational and blade speeds, rapid and significant changes in pressure, and the need for various structures throughout the turbine passageway that can be impacted by fish (e.g., walls, stay vanes, wicket gates, flow straighteners). Most, if not all, of these conditions do not occur or are not significant factors for hydrokinetic turbines. Furthermore, compared to conventional hydro turbines, hydrokinetic turbines typically produce relatively minor changes in shear, turbulence, and pressure levels from ambient conditions in the surrounding environment. Injuries and mortality from mechanical injuries will be less as well, mainly due to low rotational speeds and strike velocities, and an absence of structures that can lead to grinding or abrasion injuries. While information pertaining to conventional hydro turbines is useful for assessing the potential for adverse effects of passage through the swept area of hydrokinetic turbines, additional information is needed to rigorously assess the nature and magnitude of effects on individuals and populations, and to refine criteria for design of more fish-friendly hydrokinetic turbines.
This report will provide hydrokinetic device and project developers, fisheries resource managers, and regulators with improved understanding of the potential for hydrokinetic turbines to adversely affect individual fish and fish populations. The information contained in this report can also be used by researchers and potential research funders to identify areas for future, productive research.