Concept and Evolution of Pumped-Storage Plants.

The paper illustrates the criteria adopted in sizing pumped-storage stations, and determines the technical limit of the ratio between the capacity of these plants and the capacity of the thermal stations in the generating system. The economics are then discussed and the criteria adopted for a preliminary rough estimate are furnished. The role performed by the pumped-storage stations built in the last decade is illustrated, as well as the function that is expected to be assigned to the stations of the ENEL's medium-term construction program. A description is also given of the results of the investigation conducted by ENEL over the whole territory of Italy to locate potential pumped-storage station sites.