Environmental Projects
| Environmental Studies - Physical Interactions |
| Environmental Studies - Physical Interactions |
Strike and other MHK Fish-Device Interactions Fish and other aquatic organisms may have a variety of physical interactions with MHK devices, including attraction to or avoidance of project structures and strike by rotors or other moving parts. ORNL has refined a model used to predict rotor strike rates and probabilities of injury or mortality to fish in riverine and tidal deployments of MHK devices. We have conducted studies on the effects of blade encounter on larval and juvenile fish survival in laboratory flume. Information on the distributions of aquatic organisms in large rivers, likely behavioral responses to MHK structures, and strike, injury, and mortality estimates for small fish are used to estimate the potential impacts of MHK devices on fish populations. |
Fields (EMF) on Behavior Effects of Electromagnetic |
Among the potential issues that must be resolved in order to deploy these projects safely are the effects on aquatic organisms of EMF created by the underwater generators and transmission cables. We are examining the behavioral responses of common freshwater fish and invertebrates to electromagnetic fields that may be emitted by hydrokinetic projects. These laboratory studies quantify changes in swimming behavior, activity levels, and distribution relative a sources of static (DC-generated) and variable (AC-generated) magnetic fields. |
| Effects of Noise on Fish Behavior |
ORNL scientists are working with MHK developers and acoustic experts to reproduce realistic operational levels of noise in order to assess behavioral effects on aquatic animals. Field measurements of sound signatures are analyzed to provide estimates of acoustic “dose” for organisms in the vicinity of an MHK device, and then reproduced as a waveform that considers the characteristics of the acoustic source and the location of the test organisms from the acoustic source. Experiments will be conducted to expose candidate organisms to realistic levels of acoustics in a confined field setting (experimental mesocosm) in order to create a dose/response curve for noise for each species of interest. Endpoints of interest include behavioral responses, changes in distribution relative to the noise source, and hearing threshold shifts. |
Toxic Effects of MHK Device Coatings |
Critical to the success of MHK devices are the materials and coatings that are resistant to corrosion, biofouling, and fatigue, while remaining affordable, easy to manufacture, and exhibiting low toxicity to the environment. Chemicals that are accidentally or chronically released from MHK installations could have toxic effects on aquatic organisms. ORNL researchers are carrying out 1) leaching studies to determine whether toxic chemicals enter the environment from materials and coatings used in MHK systems and 2) toxicity tests with representative aquatic organisms to determine whether there could be environmental impacts from these chemicals. |
Effects of Benthic and Open Water Habitat Alterations |
MHK project-caused alterations of current flow, wave structure, water quality, and substrate structure and composition have the potential to not only alter aquatic habitats but also displace or eliminate biota in those habitats. Changes in water velocities and sediment transport processes caused by the presence of MHK structures will alter benthic habitats, at least on a local scale, and any such alterations, in turn, would likely result in changes in the benthic communities of those habitats. We are identifying the nature and extent of benthic habitat alterations and are developing protocols for monitoring ecological responses to predicted habitat changes. ORNL has developed field techniques and protocols for characterizing the distribution of different sediment types in large rivers using a combination of hydroacoustics (sonar) and video imaging. The techniques are being used to characterize the sediments at a future MHK site on the Mississippi River site. |
| Environmental Studies - EMF |
| Effects of Electromagnetic Fields (EMF) on Fish and Invertebrate Behavior |
Among the potential environmental issues that must be resolved in order to deploy MHK projects safely are the effects on aquatic organisms of electromagnetic fields created by the underwater generators and electrical transmission cables. We have evaluated the behavioral responses of common freshwater fishes and invertebrates to static and variable electromagnetic fields that may be emitted by HK technologies. Static (DC) fields were created by a permanent bar magnet placed outside of the aquaria, and changes in activity levels and distribution of fathead minnows, redear sunfish, striped bass, channel catfish, snails, and clams relative to the magnet were tracked over a 48-h period. In nearly all cases there were no observable changes in distribution or level of activity in response to a strong static magnetic field (Cada et al. 2011, Cada et al. 2012). Variable (AC-generated) magnetic fields were created by a switched electromagnet; rapid behavioral responses to the onset of the AC field were recorded with high-speed video. Paddlefish did not react to a variable, 60-Hz magnetic field comparable to that which would be emitted by an AC generator or cable. However, lake sturgeon consistently responded to the AC-generated magnetic field with a variety of altered swimming behaviors, many of which suggested a momentary attraction to the field (Cada et al. 2012). The EMF studies are being expanded to include experiments in larger, outdoor ponds. The ponds (mesocosms) allow the behavioral responses of larger fish to be studied in more natural settings, yet still provide experimental control of sample sizes, replication, and other factors that are not possible in a strictly field study. The movements of radio-tagged fish relative to energized submerged electrical cables are quantified to determine whether the EMF emitted from the cables cause changes in fish behavior (e.g., attraction, repulsion, and changes in activity levels).
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