Water-current MHK turbines are receiving a growing interest in many parts of the world with available hydrokinetic resources. Because of potentially reasonable investment and maintenance costs, reliability, and environmental friendliness, this technology is considered worthy of research investment. Furthermore, small-scale MHK energy from river or tidal currents can be a solution for power supply in remote areas. However, little is known about the potential effects of MHK device operation in coastal embayments, estuaries, or rivers, or of the cumulative impacts of these devices on aquatic ecosystems over years or decades of operation. This lack of knowledge affects the actions of regulatory agencies, the opinions of stakeholder groups, and the commitment of energy project developers and investors. For example, the power generating capacity of water-current MHK turbines will depend on the turbine type, number, and current flow velocities, among other factors. In other words, each MHK-device array’s footprint and performance will depend on the type of turbines and the characteristics of the local system. There is an urgent need for practical, accessible tools and peer-reviewed publications to help industry and regulators evaluate environmental impacts and mitigation measures and to establish best siting and design practices.
This study focuses on the initial development of a hydrodynamic model of Cobscook Bay, ME. This is the first deployment location of the Ocean Renewable Power Company (ORPC) TidGenTM units. One unit is currently deployed with 4 more to follow in the coming years. Potential changes to the physical environment imposed by operation of a five-MHK turbine array are evaluated using the modeling platform SNL-EFDC (James et al., 2011; James et al., 2012; James et al., 2006a; James et al., 2010a; James et al., 2010b; James et al., 2006b). Model results with and without an MHK array were compared to facilitate an understanding of how this small 5-MHK turbine array might alter the Cobscook Bay environment. These simulations can assist cost-effective planning before proceeding to detailed siting, engineering designs, and deployment of devices.