Investigations on pump running in turbine mode: A review of the state-of-the-art

In remote communities where it is not economical and practically possible to take the grid connection, stand-alone small hydro systems can be used to fulfill the energy requirement. Small-scale hydroelectric power systems are emerging as a promising source of renewable energy generation, but they require low cost hydraulic and electric equipments to make them economically feasible. In such plants, pumps can be used in turbine mode considering various advantages associated with pump e.g. ease of availability, proven technology, low initial and maintenance cost, availability for a wide range of heads and flows, etc. The efficiency of pump as turbine (PAT) is usually lower than that of conventional hydro turbines. However, efficiency is not the primary selection criterion for such machines and it is recommended to operate such machines around maximum efficiency point.