Micro hydro power generation from water supply system in high rise buildings using pump as turbines

Water supply is of vital importance for urban development, so the overall pressure in urban fresh water pipeline is usually very high to ensure consistent water supply throughout the urban area. Currently, pressure reducing valves (PRVs) are widely used to reduce water pressure in the water supply system (WSS) of high rise buildings to avoid water leakage and other danger in Hong Kong. The application of pump as turbine (PAT) appears as an ideal way for water head reduction as well as hydropower generation in water pipelines. In the present paper, the feasibility and performance of PAT used in WSS for electricity generation was investigated. In the research process, a PAT was first selected by empirical equations based on the given working conditions in one typical high rise building. After selection, CFD simulation and laboratory tests were carried out to study the performance of the selected PAT. Both the simulated and measured results show that the selected PAT is feasible for power generation and water head reduction. The comparison between numerical and experimental results indicate that the simulation outcomes could be used for performance prediction of PAT although the deviation exists. A PAT installation and control strategy was designed and tested in the hydraulic test rig, and the results show that the proposed PAT installation and control strategy performed well for avoiding excessive water head reduction at higher flow rates.