In this study, wild-type microalgae species isolated from Porsuk river (Central Anatolia, Turkey) investigated as energy production feedstock and carbon dioxide sink. The obtained experimental data have been used for energy evaluation of the whole process and size estimation of large scale microalgae plant. Growth rate, CO2 mitigation rate, lipid, carbohydrate and protein content and natural settling behavior of the isolated species were investigated. The microalgae Gleocystis ampula had the highest growth rate equal to 0.138 +/- 0.008 g l(-1) d(-1) which also was observed to fix carbon dioxide with the highest rate of 0.281 +/- 0.025 g l(-1) d(-1). The highest measured lipid content of 47.32 +/- 0.40 wt% belonged to Scenedesmus quadricauda (I) with an estimated lipid production rate of 51.9 +/- 0.4 mg l(-1) d(-1). The species Kirchneriella lunaris showed the highest carbohydrate proportion being 72.43 +/- 6.40 and Micrococcus sp. had the highest protein content of 58.11 +/- 8.5 wt%. Promising large scale application of microalgae was concluded for biodiesel production and carbon dioxide mitigation just when efficiency of processes improved substantially. An Energy Efficiency of 1.62 was estimated following an ideally designed cultivation and dewatering approach.