The article continues the discussion on modernisation and development of the national energy sector. This situation is stimulated by emission reduction requirements, concerning CO2 emission mainly. Taking into account some assumptions, findings of the simplified analysis of the CO2 emission reduction potential were presented and this reduction potential will come from power generation investments declared by the operators over the years 2012-2020. The number of the new investments was verified and limited to those ventures which seemed to be decided at that stage. All the proposed but not clearly defined investments using fossil fuels have been excluded (uncertainties about production technologies, rated thermal input or year of operating start). The verified number of new power generation investments was limited to 15.9 GWe foreseen in the energy and industrial sectors. Potential of the new investments was complemented by adding renewable energy sources, resulting as a complete technological outlook of the whole energy sector. The role of the district heating sub-sector was assumed asmarginal one because they are not allowed to sell "green certificates" of the ecological heat generation. The options of the nuclear energy from Ignalin power plant, introduced into national energy sector, and "0" scenario of neutral export/import balance of energy, were also considered. It would help to substantial improvement of reduction abilities of the energy sector against CO2 emission and other air pollutants. As a result of the analysis, taking into account adopted assumptions, the scenarios of power generation, fuel consumption and emission levels of SO2, NOx, CO2 and dust were projected for 2008-2020 period. Resulting fuel structure of energy production was also defined. This was the basis for calculation of the cost of additional allowances compared to the granted quota of CO2 emission, within the EU ETS over the years 2008-2012. The above mentioned option was taken into account. The analysis has not considered the costs of the increasing economical crisis, which are difficult to estimate. It might have a vital influence onto emission levels and they could be lower than projected. The potential costs of additional allowances of CO2 emission could be lower in next few years, too, because of possible decrease of energy demand.