3. Results
3.1. Impact of hydraulics on head and tower mass
In order to predict the head mass of the proposed hydraulic turbine, the baseline conventional head mass is estimated for a range of rotor ratings. Industry data [15] and NREL scaling models [10], [16] and [17] are used to estimate how the head mass scales with the rated rotor power for conventional turbines. A power regression is plotted as a solid curve in Fig. 6 to best fit the data. The exponent in the fit equation is about 1.3, suggesting that conventional turbine technology will yield increasingly unsustainable growth in head mass as rotor power ratings approach extreme scales. Thus, this scaling relationship demonstrates the need for novel technology that allows a reduction in head mass; and the present hybrid hydraulic-electric turbine has potential to alleviate this concern.