As more countries consider alternative, renewable sources for energy, the need for accurate methods to assess the impacts of these new technologies is growing.Dr. Len Zedel is the associate dean of Science (graduate and research) and a professor in Memorial University of Newfoundland’s Department of Physics and Physical Oceanography.
He is investigating an alternative use for a popular tool for measuring water velocity to see if it can also be used to evaluate the effects of in-stream tidal turbines on fish in channels being used for power generation. “The turbine is similar to a windmill, only underwater,” he said. “So, depending on the model, it can have big blades rotating around.
If it is blocking the flow of water, or creating large pressure differences, what is that doing to the fish? How are they reacting to the presence of the turbine?”Currently, Doppler profilers are already in use in many of these testing areas to measure the impact the currents will have on the turbines and how much force the structure will have to withstand. Profilers use Doppler sonar, where a pulse of sound is transmitted into the water and is scattered by items being carried along by the water.
The frequency difference between the signal sent out and the returned signal can tell how fast the object is moving; in other words, the speed of the water. However, when the signal is “contaminated” by a fish swimming through the acoustic beam at a different rate of speed, that data is often thrown out. Dr. Zedel is hoping to prove this information can actually be used to count the number of fish present and monitor fish behaviour, which usually requires other types of expensive fish-finding equipment. READ MORE