(444b) Synthesis of Processing Paths Fot the Valorization of Specialty Chemicals in Microalgae Biorefineries

Over the last years, biorefineries are gaining ground and numerous studies have been developed with main focus on the exploitation of lignocellulosic feedstock for biofuels and bioproducts. Advances on synthesis, design and integration of such biorefineries are well established and continue to evolve. Third generation biorefineries are currently in the spotlight, especially due to the plethora of chemicals that can be incorporated in the portfolio of products. Microalgae constitute a very promising feedstock with the ability to utilize CO₂ and convert it to specialty chemicals. Thus, challenges arise as to the probe of such an incentive, which does not only include the synthesis and design of a microalga biorefinery, but also its integration with other types of biorefineries.

The study addresses the challenges in the synthesis of microalgae biorefineries by developing a combinatorial approach, in order to simultaneously screen for potential processing paths and formulate the desired product portfolio. The approach enables high-throughput screening with focus on securing the feasibility and profitability of the incentive. The selection of processes and the formulation of the product portfolio are treated as degrees of freedom. The model takes into consideration feedstocks, processes, intermediate fractions and products in a conceptual form and employs economic criteria for the selection of the optimal path. The study takes into account the stages after cultivation and harvesting of the microalgae, where screening paths of candidate technologies and product portfolios is a matter of necessity due to the numerous available options. Competitive chemistries characterizing microalgae as well as the lack of thermodynamic properties regarding involved chemicals add to the complexity of such designs. Extensive knowledge about the use of suitable technologies and required specifications is imperative, thus the need for experimental data becomes indispensable. The methodology deals with these limitations and practicalities, which derive mainly from the lack of industrial applications to draw knowledge from. Therefore, extensive collaboration with practitioners is of vital importance.

For the purpose of this study, the methodology is applied to a real-life case of a microalga biorefinery undertaken by the D-Factory, an FP7 collaborative project, which is relative to the valorization of high-value chemicals from the microalga Dunaliella. This particular microalga is considered a great candidate for mass outdoor cultivation especially because of its extraordinary tolerance to salt stress and potential environmental contaminants. The addressed methodology deals with encountered limitations and constitutes a stepping stone to the development of a systematic approach for the design of integrated microalgae biorefineries. It provides flexibility due to the high profit of specialty chemicals and guidelines of vital importance for future design analysis.