Fish Friendly Micro-Hydropower: Centrifugal Screw Pump-as-Turbines

Abstract

Significant attention has been placed on the development of pump-as-turbines (PATs) for low-cost production of hydropower in the micro and pico scales. Research has focused on the modelling and prediction of the performance of mostly single stage centrifugal PATs for use in various micro-hydropower applications such as within existing hydraulic infrastructure and run-of-river schemes. However, while PATs address the important issue of equipment costs well in the micro-hydro setting, the financial impact of environmental consenting remains a barrier for many run-of-river schemes. This paper examines the potential for centrifugal screw PATs, which could provide a safe route for fish passage and meet some of the requirements for environmental protection measures such as fish protection, which can impact on the viability of run-of-river projects. Centrifugal screw pumps have been specifically developed for the pumping of live fish in the fisheries sector without injuring them. This paper demonstrates the theoretical applicability of Centrifugal Screw PATs to run-of-river micro-hydropower. Using analytical pump to turbine conversion methodologies, this paper outlines the flow and head application range and performance of the centrifugal screw PAT. Results highlight that the centrifugal screw PAT has the potential to generate energy from within head and flow ranges of 10-100m and 2-1650 l/s, efficiencies up to 82% and 2-750 kW power output per turbine. Even though results are promising, further work is required to confirm the power performance and fish-friendly nature of the device in turbine mode using laboratory testing and live or synthetic fish trials.