          !" #$ %"&’ (# # Universidad Nacional Autónoma de México  Facultad de Ingeniería, México )# "*+&" Because of the importance of energy to sustainable development of Mexico, it is necessary to develop a tool that permits to make a comparative assessment of energy alternative options. This tool must take into a count their characteristics in terms of their economic, health, environmental and social impacts, both, positive and negative, local, regional and global. ,# *’ "- . +&+ !"/ ’0’ & 1&+" Demand for electricity in Mexico has increased steadily over the last decade. Mexican Energy Ministry has forecast demand to grow at a rate of 5.5% between 2005 and 2014. In 2004, Mexico's installed electric power generating capacity was 53,561 megawatts. In the same year, the country generated an estimated of 208.63 TWh of electricity, of which thermal (oil, natural gas, and coal) electricity generation accounted for 80.5% and only CO 2 free (hydro, nuclear, geothermal, and wind) electricity generation accounted for 19.5%. Oil fired power plants accounted for the 31.8% share of Mexico's thermal electricity generation, but many of these plants are being converted to natural gas. According to plans, fuel gas accounted for 36% of thermal feedstock in 2004 electricity generation. By 2014, natural gas is forecast to account for 52.6% of Mexico's power output while fuel oil's share is expected to drop to 13.4%. Table 1 shows the electricity generation mix of energy sources by 2004 and the forecast for 2014. [1]        +.""20 ,334 ,3)4 Natural Gas  CC 34.7% 52.5% Natural Gas Turbines 1.3% 0.1% Coal* 12.4% 11.0% Oil 31.8% 13.4% Diesel 0.3% 0.4% Nuclear 4.4% 2.5% Wind 0.002% 0.03 Geothermal 3.1% 2.47% Hydro 12.0% 8.9% Free 0% 8.7% Annual Generation GWh 208,634 348,170 * Coal units + Dual (Coal or Oil) units assumed to use coal. Nuclear energy and renewable energy sources are fundamentally different in terms of features, level of maturity, economic competitiveness, and public perception. However, they have, at least, one common feature. They offer contributions to climate policy aiming at control of greenhouse emissions. During the next ten years, there are plans to increase Mexico's renewable capacity with 2254 MW of Hydro, 592 MW of wind and 50 MW of geothermal, 0% of solar photovoltaic and 0% of biomass [1]. There is only one nuclear plant in operation in Mexico, with two BWR reactors of 654 MW each. Unit 1 went into commercial operation in 1990 and Unit 2 in 1995. In 1999, the installed capacity was increased by means of upgrading the power 5%. Today, there are no plans regarding new units before 2014 but there are plans to upgrade the power of each reactor 15%. According to a ranking based on Mexicanspecific generation costs [2], nuclear energy is the option with the lowest cost followed by wind, geothermal, natural gas, coal, oil and hydro (See Table 2).