Application of hydrokinetic turbines in microtidal rivers: The Misa River test site

The present study focuses on the potential application of Archimedes screw turbines in microtidal rivers. The Misa River, a 48-km long Italian course flowing into the Adriatic Sea, is taken as the reference test. Since hydrokinetic turbines operate with low discharges and require little engineering facilities, an Archimedes turbine was recently tested both in laboratory and numerically, showing performance coefficients up to 23.8%. To investigate its functioning within the Misa River, observed river stages are statistically analyzed and then used at the upstream boundary of a hydraulic model. The flow results are analyzed to evaluate the potential energy production of turbine configurations built upon a range of: (i) potential installation zones along the river, (ii) turbine radii, (iii) streamwise inclinations of the turbine axis. The energetic analysis of each configuration is performed accounting for one or more turbines installed along selected river cross-sections. A direct dependence is found between generated power and turbine size, especially for the inclined configurations. The optimal size and number of devices to be deployed at specific cross-sections are identified. The total annual energy for the best configurations is around 1MWh, which may find application to supply energy to community buildings, like schools or kindergartens