THE IMPORTANCE OF THE SIZE OF THE RESERVOIR´S USEFUL VOLUME FOR CONSUMPTION AND COST DECREASE IN ELECTRICITY

Abstract

Current paper analyzes the reservoir´s useful water volume for hydropower efficiency in water supply systems. Data, retrieved from the Guanabara Water Supply System of the municipality of Ananindeua, state of Pará, Brazil, were analyzed. Two useful volume sizes were determined following recommendations by NBR 12.217/1994 “Project on the water distribution reservoir for public supply”. The former featured the time curve of water consumption and the latter the rate of maximum daily discharge. The latter stage assessed the most adequate useful water volume from the point of view of hydropower efficiency by Epanet 2.0. Dimensions with or without water consumption curve provided useful volumes of 838 m3 and 2.043 m3, respectively. In the case of the lowest volume, 47 hours/day of CMB functioning and 987 kWh/day of electric power consumption in EAT were detected. Volume increase to 2,043 m3 was positive, followed by 30 hours/day of functioning of CMB and consumption at 818 kWh/day in EAT. Hydropower costs were reduced by R$ 35,903.00/year, from R$ 143,108.00/year, with a useful volume of 838 m³, to R$ 107,205.00/year with 2,043 m³. Research revealed the importance of computerized simulation in decision-taking and the need for the updating of NBR 12.217/1994 by criteria of hydropower efficiency in the preparation of projects involving water supply reservoir systems.