Environmental concerns, both at the local and global levels, have been present in Mexico＇s energy planning and national and international commitments. However, deregulation policies and financial constraints in the public sector seem to come in conflict with respect to greenhouse gas emissions in the development of the Mexican energy system. This is specially noticeable in the power sector where expansion of non fossil fuel generation has been essentially postponed at present and only the substitution of fuel oil and diesel by natural gas is contemplated.