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Enhanced CO2 concentration in exhaust gas is regarded as a potentially effective method to reduce thehigh electrical efficiency penalty caused by CO2 chemical absorption in post-combustion capturesystems. The present work evaluates the effect of increasing CO2 concentration in the exhaust gas of gasturbine based power plant by four different methods: exhaust gas recirculation (EGR), humidification(EvGT), supplementary firing (SFC) and external firing (EFC). Efforts have been focused on the impacts oncycle efficiency, combustion, gas turbine components, and cost. The results show that the combined cyclewith EGR has the capability to change the molar fraction of CO2 with the largest range, from 3.8 mol% toat least 10 mol%, and with the highest electrical efficiency. The EvGT cycle has relatively low additionalcost impact as it does not require any bottoming cycle. The externally fired method was found to have theminimum impacts on both combustion and turbomachinery.