Estimativa das emissões de gases de efeito estufa (CO2 e CH4) pela hidrelétrica de Balbina, Amazônia Central, Brasil.

Abstract

The relatively constant temperature of the Earth is due to the presence of gases in the troposphere, which retain solar energy and thus regulate the global climate, a natural phenomenon called the greenhouse effect. The construction of new hydroelectric reservoirs has contributed to the recent increase in two of these greenhouse gases: CO2 and CH4. In reservoirs, these gases are produced by the anaerobic and aerobic decomposition, principally, of pre-existing terrestrial. The site with one of the largest potentials for generating greenhouse gases (GHGs) in the Brazilian Amazon is the Balbina dam. Created in 1987, the Balbina reservoir inundated over 3.000 km2 of upland tropical forest. The objective of the present study was to estimate the emissions of CO2 e CH4 from Balbina complex both upstream and downstream from the dam. Diffusive emissions were estimated with static chambers. Bubble fluxes were estimated with submerged inverted funnels in the reservoir and from the difference in methane concentrations at the entrance and outflow of the turbines downstream from the dam. Detailed bathymetric and habitat maps were used together with a hydrological model for the temporal and spatial interpolation of emission measurements in the reservoir. The sum of annual emissions upstream and downstream of the dam for CO2 and CH4 were estimated as 2554 and 485 Gg CO2 equivalent C, respectively. The study should help us to evaluate the contribution of this and other Amazonian reservoirs to global atmospheric pollution and contribute to the development of ecologically sustainable strategies for energy generation at the regional and national levels.