7 Microalgae-based Systems for Carbon Dioxide Sequestration and Industrial Biorefineries Eduardo Jacob-Lopes 1 and Telma Teixeira Franco 2 1 School of Agricultural Engineering, Federal University of Pelotas, UFPel, 96010-900, Pelotas-RS, 2 School of Chemical Engineering, State University of Campinas, UNICAMP, P.O. Box 6066, 13083-970, Campinas-SP, Brazil 1. Introduction The bulk of the evidence indicating that global climatic alterations occur as a result of increasing concentrations of greenhouse gases in the atmosphere has created pressure to develop strategies to reduce these changes (IPCC, 2001). Carbon dioxide is considered to be the main gas of the greenhouse effect, both in terms of emission and its climate-altering potential. In 1997, the signatory countries of the Kyoto Protocol agreed to reduce CO 2 emissions in an agreement that established the need to develop carbon dioxide sequestering processes. Thus the various technologies available for carbon capture and storage need to be evaluated from the point of view of obtaining carbon credits, aiming to stabilize emissions of this pollutant (UNFCCC, 1997). In addition to technologies available for immediate use, other CO 2 capture methods are being developed for application in the near future. The choice of these methodologies will depend on factors such as cost, capture capacity, environmental impact and the speed with which the technology can be introduced in addition to social factors such as public acceptance (IPCC, 2007a). In this context, the use of biotechnological processes for carbon dioxide biofixation is considered viable for reducing emissions of this pollutant. These processes are based on the use of reactors used to develop photosynthetic reactions in which microalgae are used as biocatalysts in a series of biochemical reactions responsible for the conversion of CO 2 into photosynthetic metabolic products (Jacob-Lopes et al., 2010). With this in mind, the objectives of this present chapter are to present an overview of a potential technology for carbon dioxide transformation into biomolecules and to describe the current state of the art in the biological conversion of CO 2 in photobioreactors thereby facilitating worldwide advances in this research area. 2. Carbon dioxide emissions Global monitoring of atmospheric CO 2 concentration during the last century indicated an increase in carbon dioxide concentration from 295ppm in 1900 to 377ppm in 2004, Source: Biomass, Book edited by: Maggie Momba and Faizal Bux, ISBN 978-953-307-113-8, pp. 202, September 2010, Sciyo, Croatia, downloaded from SCIYO.COM www.intechopen.com