In this article the Bio economy of power plants connected to the national interconnected system of Nicaragua is analyzed, through the study of environmental effects of greenhouse gases emissions from the use of solid biomass from sugarcane bagasse and oil to generate electricity. In addition, an analysis of Cost - Benefit of investments to the electricity generation using fossil fuel and bagasse is done. The Methodology EX-Ante Carbon-balance Tool (EX-ACT) was used; this methodology was proposed by the United Nations Organization for Food and Agriculture (FAO) to determine the overall greenhouse gases (GHG) emission balance. Additionally, the WinDASI program, also developed by FAO, was used for the Cost - Benefit Analysis of investment in power plants. Furthermore, we performed marginal costing GHG reduction. The results show, that all plants are sources of GHG emissions, however the impact of sugar mills is partially positive by reforestation components and annual crops. However, the component inputs had negative environmental and socially impact. In the case of thermal power generation plants based on petroleum connected to the national grid, they were found to be sources of greenhouse gases. The analysis of the Benefit Cost in their investment indicates that there is a positive financially impact except in ALBANISA power plant and sugar Mills power plants.