Local And Non-Local Geomorphic Effects Of Hydrokinetic Turbines In Rivers: From A Single Turbine To A Power Plant Array

Abstract
With mounting scientific evidence and growing social awareness of climate change, governments around the world are investing resources in the advancement of all forms of renewable energy technologies with the main goal of decarbonizing energy production. Hydrokinetic Energy is an emerging form of waterpower technology that can play a significant role in this transition. Hydrokinetic energy devices harness the natural movement of water flows such as tides, rivers, and ocean currents, without the need of stream impoundments. Rivers are currently overlooked sources of local and continuous kinetic energy that can be utilized close to population centers around the world, especially for remote and underserved regions. 

In this talk, I will present research on the interaction between hydrokinetic turbines and the surrounding physical environment. Combining experiments with analytical modeling, I will show the local and non-local effects of hydrokinetic turbines on the river morphology and dynamics. Locally, operating turbines create a remarkable localized erosion-deposition pattern significantly larger than those observed by in-river constructions such as bridge piers. The erosion was first characterized experimentally and then modelled theoretically applying the phenomenological theory of turbulence to predict the scour magnitude. Non-local geomorphic effects (i.e., far from the array location) can arise when turbines are installed asymmetrically within the channel cross-section. The asymmetric obstruction of the flow triggers alternating scour-deposition patterns that resemble the typical signature of forced fluvial bars. Forced bars are steady mesoscale features believed to be the onset of river meandering. A physical model of a 12-turbines staggered array demonstrated that we could minimize this effect by minimizing the lateral obstruction while proving its resiliency to intense flooding conditions. Power distribution and turbines wake evolution were also measured through the array. Results reveal similar trends already observed in experimental wind farm models, despite the complexity added by the evolving bathymetry. 

Biography
Mirko Musa, research scientist within the Water Resource Science and Engineering Group at Oak Ridge National Laboratory (ORNL), focuses on hydropower research, building on his expertise in experimental hydraulics. He supports technology advancement and testing, resource characterization, and environmental compatibility, continuing his work on the interactions between renewable energy systems and riverine environments. Mirko received his PhD in civil, environmental, and geo- engineering from the University of Minnesota, where his research focused on the experimental investigation of the interaction between hydrokinetic turbines and the surrounding physical environment. Specifically, Musa conducted physical modelling at St. Anthony Falls Laboratory to study the effects of operating turbines on the local erodible bathymetry (local erosion-deposition) and non-locally on river morphodynamics (forced river instabilities). He also received a BS and MS in environmental engineering at the University of Trento (Italy).