An exergetic life cycle assessment (ELCA) and a classical environmental life cycle assessment (LCA) have been performed for three carbon dioxide low emission power cycles. The configuration of the power cycles are: a semi-closed gas turbine combined cycle with CO2 reduction from the exhausts by means of amine solution chemical absorption; an integrated gasification combined cycle with CO2 reduction from the synthesis gas by means of amine solution chemical absorption; and O-2/CO2 innovative cycle where, burning methane in oxygen, CO2 becomes the cycle working fluid, and the CO2 excess, produced in the combustion, is removed in liquid phase without any additional system. The LCA is mainly focussed on CO2 production during the three phases of construction, operation and dismantling of the plants. This is necessary to verify if the process is effective in terms Of CO2 reduction. Besides the classic LCA, also an ELCA was performed, whose aim is to assess the cost, in terms of exergy losses, of the life cycle of the plants. The CO2 reduction is effective during the lifetime, and a sort of classification of the studied plant is obtained.