Marine Hydrokinetic (MHK) systems: Using systems thinking in resource characterization and estimating costs for the practical harvest of electricity from tidal currents

Continuous and predictable shallow water tidal currents represent a promising renewable energy resource for investigation and additional exploitation. A systems thinking approach identifies aggregate properties of MHK systems such as turbine efficiency, transmission and power conditioning losses and leads us to propose that an overall project efficiency value (EEFF, the kW-hours of electricity effectively inserted into the grid) should be used for resource characterization and as an estimate of the practical extraction of energy from tidal currents. This project efficiency value can lead to better cost estimates and ultimately serve as a marker for decisions whether to proceed. By using a systems engineering approach we first determine the practical extraction of kinetic energy from Maine to Texas using National Oceanic Atmospheric Administration (NOAA) CO-OPS' Mapping and Charting Services Program data. Then, based on case studies of two generating stations and one discontinued station in the United States, we superimpose how those installed costs per kW compare to the resource characterization. This work identifies installed cost per kW for potential locations that exceed a kinetic power density of 100 kW for three array sizes with a goal of showing how the key attribute of cost might affect the decision making process when considering Marine Hydrokinetic (MHK) extraction systems.