Evolution of Storage Capacity in the Brazilian Hydropower System

Abstract

In Brazil over the last 12 years, on average 90% of energy consumed has come from hydropower generation. The hydro system includes 150 medium and large hydropower plants. Among these 150 plants, 135 are in operation today and 15 are planned to be operational by the end of 2017. The Brazilian hydro system is completely interconnected. About half of the hydropower plants have large storage capacities to regulate flows. The system is linked with the power grids in Paraguay, Argentina, Venezuela, and Uruguay. Brazil also receives natural gas imports from Bolivia. Each month hydropower generation must be determined. This is a complex decision-making process. The objective is to optimize the entire system operation, which depends on the inflows, storages, forecasts of demands, fuel prices for thermal units, and expansion of the system over a given planning horizon, typically looking ahead five years. Environmental, technical, social, and economic constraints have made it increasingly difficult to project and build new reservoirs with large storage capacities. As a result, newly built hydropower plants are mostly the run-of-river type. To better understand the process, this paper presents a historical survey of the installed capacity of hydropower and storage capacity of the system since 1908 and extends to the planned expansion over the next four years, through 2017. The storage capacity is represented by the concept of maximum stored energy in each reservoir and subsystem. The paper also presents the history of operation over the last 12 years. Data from 2000 and projections through 2017 indicate a significant reduction of relative regulating capacity, represented by the ratio of maximum storage and installed capacity. This reduction has a direct impact on decisions regarding operation and expansion of the complementary thermal system.