Effects of simulated flue gas on growth of microalgae

Abstract

Studies have demonstrated that the atmospheric carbon dioxide level is increasing on a global scale due to the emissions from increased combustion of fossil fuels. Current CO{sub 2} emissions due to combustion of fossil fuels are estimated to be 2 x 10{sup 10} tons/yr. These emissions are implicated as a major contributor to the 1-2 ppm annual increase in atmospheric CO{sub 2} concentration; the present level of atmospheric CO{sub 2} is 360 ppm. Efforts are now under way to develop possible methods to minimize CO{sub 2} emissions. One method proposed for minimizing the CO{sub 2} emissions from power plants is to grow microalgae in flue gas streams, converting CO{sub 2} to algal biomass which could then be converted to fuels, chemicals, and foods. Algae can utilize CO{sub 2} efficiently, yielding three to five times more biomass per land area than typical crops and terrestrial plants. Flue gas contains not only CO{sub 2} but also oxides of sulfur and nitrogen that may be toxic to algal growth either by lowering the pH of solutions or by direct inhibition. High levels of CO{sub 2} (10-15 %) found in flue gas could also be inhibitory to algal growth.