Effects of Long-Term Flow Variation on Microhydropower Energy Production in Pressure Reducing Valves in Water Distribution Networks

Abstract

Incorporating microhydropower (MHP) turbines within water supply networks has the potential to improve the economic and environmental sustainability of the sector. However, long-term flow and head variations in water networks are key risk factors that increase turbine performance uncertainty in the medium-to-long term, potentially impacting the investment payback period. Using high-resolution historical flow and head data across a number of pressure reducing valve sites in water networks in Ireland, this study presents an assessment of the impact of flow and head variations on turbine efficiency and power output over a 20-year period. Results indicated that pumps-as-turbines (PATs) represent a viable low-cost option over the long term at sites with smaller power output potential. Where flow and head rates displayed considerable fluctuation, the integration of a two-PAT configuration could improve operating efficiency and maximize power output. This design strategy opens up the opportunity to conduct energy recovery from sites that may previously have been considered unsuitable for MHP.