In this series of two articles, the concepts and approaches of environomic (thermodynamic, economic and environmental) performance ‘Typification’ of power generation technologies (Part I) and of combined heat and power (CHP) cogeneration technologies (Part II) in the context of CO2 abatement are introduced. A methodology is then proposed for a flexible and fast project based power or CHP cogeneration system design evaluation though post-optimization integration of the operating and capital costs. This allows to effectively deal with the uncertainty of the project specific design and operation conditions (fuel, electricity and heat selling prices, project financial conditions such as investment amortization periods, annual operating hours, etc). Furthermore, the uncertainties linked to the external cost such as the CO2 tax level under a tax scheme or the CO2 permit price in the emission trading market can be assessed. Application examples, including gas turbine and combined cycles are treated with the proposed methodology, by using the superstructure based generic environomic models and a multi-objective optimizer. Furthermore an extension of the methodology using statistical approach is also presented and illustrated with different generation technologies.