Low head pico hydro turbine selection using a multi-criteria analysis

Turbine types suit specific ranges of head, flow rate and shaft speed and are usually categorised by specific speed. In the pico range, under 5 kW, the requirements are often different to that of larger scale turbines and qualitative requirements become more influential in selection. Pico hydro turbines can be applied beyond these conventional application domains, for example at reduced heads, by using non-traditional components such as low speed generators. This paper describes a method to select which turbine architecture is most appropriate for a low-head pico hydro specification using quantitative and qualitative analyses of 13 turbine system architectures found in the literature. Quantitative and qualitative selection criteria are determined from the particular requirements of the end user. The individual scores from this analysis are weighted based on the perceived relative importance of each of the criteria against the original specification and selects a turbine variant based on the total weighted score. This methodology is applied to an example of a remote site, low head and variable flow requirement, leading to the selection of a propeller turbine variant or single-jet Turgo turbine for this specification.

► Limitations with specific speed selection methodology at pico hydro level discussed. ► Method to select a pico hydro turbine for a low head site is presented. ► Quantitative and qualitative criteria developed from the specification. ► These criteria are used to give tangible evidence for the design choice of turbine. ► Propeller or single-jet Turgo design shown suitable for low head pico specification.