The potential energy that could be produced from solid wastes in Brazil tops 50 TWh. Equivalent to some 17% of the nation's total power consumption at costs that are competitive with more traditional options, this would also reduce greenhouse gases emissions. Moreover, managing wastes for energy generation purposes could well open up thousands of jobs for unskilled workers. Related to power generation and conservation, energy use requires discussions on the feasibility of each energy supply option, and comparison between alternatives available on the market. Power conservation is compared to projects implemented by the Federal Government, while power generation is rated against thermo-power plants fired by natural gas running on a combined cycle system. Although the operating costs of selective garbage collection for energy generation are higher than current levels, the net operating revenues of this scheme reach some US$ 4 billion/year. This underpins the feasibility of garbage management being underwritten by energy uses and avoided environmental costs. The suggested optimization of the technical, economic, social and environmental sustainability of the expansion of Brazil's power sector consists of compatibilizing the use of fossil and renewable fuels, which is particularly relevant for hybrid thermo-power plants with null account on greenhouse gases emissions. (C) 2002 Elsevier Science Ltd. All rights reserved.