Integrated Microalgae Biorefinery for the Production of Biodiesel and Value Added Products

CARLA V. GARCÍA PRIETO; VANINA G. ESTRADA; MARIA SOLEDAD DIAZ

San Francisco

Congreso; AIChE Annual Meeting 2013; 2013

AIChE (American Institute of Chemical Engineers)

The production of biofuels has been studied in the last years as a solution for the increased demand of crude based fuels. Firstgeneration biofuels appear unsustainable because of the potential stress that their production places on food commodities, resulting in the development of second and third generation biofuels, where lignocellulosic and algae biomass are considered as raw materials. Microalgae perform oxygenic photosynthesis and live in freshwater, marine and terrestrial environments while showing a wide diversity of morphologies, metabolisms and cell structures. They have several features that make them attractive to obtain products in farmaceutical, nutraceutical, biofuels, and other industries. Microalgae reach high cellular densities in culture and have simple growth requirements: light, carbon dioxide, and other inorganic nutrients to grow. Carbon dioxide can be obtained from waste streams from other plants. Many researchers have focused their investigations on improving productivity of algae culture for ethanol, hydrogen and biodiesel, based on control of the environmental conditions such as light intensity, salinity, temperature, pH (Christy, 2007; Estrada et al., 2012) and on metabolic engineering (Deng and Coleman, 1999; Paulo et al., 2011). However, for costeffective production of biofuels, value added coproducts need to be considered. In this work, we formulate a mixedinteger nonlinear programming model for the design of an integrated microalgaebased biorefinery for the production of biodiesel and coproducts that include nutritional supplements, omega3 fatty acids, carotenoids, fertilizers, etc., depending on the particular microalgae species considered. The production of biogas by anaerobic digestion of the oil cake together with liquid waste streams is also included in the superstructure. The model has been implemented in GAMS (Brooke et al., 2011) and solved with DICOPT. Numerical results provide useful insights on the design of integrated biorefineries that use carbon dioxide as carbon source, as well as quantitative information on economical benefits.