Unconventional Impacts from Unconventional Hydropower Devices: The Environmental Effects of Noise, Electromagnetic Fields, and other Stressors

Conventional dam-based hydropower production produces a variety of environmental stressors that have been debated and confronted for decades. In-current hydrokinetic devices present some of the same or analogous stressors (e.g., changes in sediment transport and deposition, interference with animal movements and migrations, and strike by rotor blades) and some potentially new stressors (e.g., noise during operation, emission of electromagnetic fields [EMF], and toxicity of paints, lubricants, and antifouling coatings). The types of hydrokinetic devices being proposed and tested are varied, as are the locations where they could be deployed, i.e., coastal, estuarine, and big rivers. Differences in hydrology, device type, and the affected aquatic community (marine, estuarine, and riverine) will likely result in a different suite of environmental concerns for each project. Studies are underway at the U.S. Department of Energy's national laboratories to characterize the level of exposure to these stressors and to measure environmental response where possible. In this presentation we present results of studies on EMF, noise, and benthic habitat alteration relevant to hydrokinetic device operation in large rivers. In laboratory studies we tested the behavioral response of a variety of fish and invertebrate organisms to exposure to DC and AC EMF. Our findings suggest that lake sturgeon may be susceptible to EMF like that emitted from underwater cables, but most other species tested are not. Based on recordings of various underwater noise sources, we will show how the spectral density of noises created by hydrokinetic devices compares to that from other anthropogenic sources and natural sources. We will also report the results of hydroacoustic surveys that show how sediments are redistributed behind pilings like those that could be used for mounting hydrokinetic devices. The potential effects of these stressors will be discussed in the context of possible fish population- or community-scale impacts. Results from these studies will be useful to hydrokinetic developers for designing systems and operations that minimize environmental impact and to environmental regulators for assessing potential impacts and proscribing effective mitigation.