This article aims to demonstrate how electricity generation, through renewable sources of energy, can contribute to mitigate the current trend of increasing the emissions of greenhouse gases in the supply to Brazilian electric market. The supply is analyzed taking into account the two big national subsystems: national grid and the isolated systems, which supply electricity to the Amazonian Region, including big cities such as Manaus and Porto Velho. The former is mostly supplied by hydropower generation and with an increasing role played by natural gas while the latter is basically supplied by diesel and fuel oil generation. Preliminary analysis signalize that the introduction renewable energy projects on the national grid will create small impact on the economic performance of the projects. By the contrary, the impact can be significant on the internal rate of return. of projects in the two other markets.