Accurate estimation model for small and micro hydropower plants costs in hybrid energy systems modelling

In last decades, more and more complex models have been developed to investigate hybrid energy systems in order to define optimal size and management strategies. However, the results accuracy of these analyses is strictly related to the accuracy not only of the models but also of the input data, among which one of the most important is a proper assessment of investment costs. Even though small deviations from real investment costs are expected due to the peculiarities of each energy system, the meaningfulness of optimization analyses is affected by the availability of cost correlations characterized by sufficient accuracy. Although some technologies are characterized by standardized costs, other ones, as small hydro power plants, are characterized by investment costs that cannot be properly estimated with too simplified models, based on power and net head. This paper proposes a new approach for the estimation of the electro-mechanical equipment cost, according to which the final cost is divided into three terms with a distinct dependence not only on power and net head, but also on design flow rate. The resulting cost estimation correlations for Pelton, Francis and Kaplan turbines were characterized by mean errors smaller than those of the best performing literature correlations.