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

Integrated microalgae biorefinery for the production of biodiesel and value added products

Carla Valeria García Prieto, Vanina Estrada, María Soledad Díaz, Chemical Engineering, Planta Piloto de Ingeniería Química (PLAPIQUI), CONICET- Universidad Nacional del Sur, Bahía Blanca, Argentina.

The production of biofuels has been studied in the last years as a solution for the increased demand of crude based fuels. First-generation 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 cost-effective production of biofuels, value added co-products need to be considered.

In this work, we formulate a mixed-integer nonlinear programming model for the design of an integrated microalgae-based biorefinery for the production of biodiesel and co-products that include nutritional supplements, omega-3 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.

References

Brooke, A., Kendrick, D., Meeraus, A., Raman, R. (2011), GAMS, A User Guide. Washington, DC, USA.

Christi, Y. (2007). Biodiesel from Microalgae. Biotechnology Advances. 25: 294-306

<>Deng M., Coleman, J. (1999). Ethanol synthesis by genetic engineering in cyanobacteria. Applied & Environmental Microbiology. 65: 523-528.

Estrada, V., Vidal Vidal, R., Florencio, F. J., García Guerrero, M. and Díaz, M.S. (2012). Parameter estimation of bioethanol production model by a genetic engineered cyanobacterium. AIChE Annual Meeting, Pittsburg, USA.

Paulo, C., Di Maggio, J., Estrada, V., Díaz, M.S. (2011). Optimizing cyanobacteria metabolic network for ethanol production. Computer Aided Chemical Engineering. 29, 1366-1370.

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