(394c) Optimization of Macroalgae Based Biorefinery Producing Fuel and Chemicals with Zero Carbon Emissions Potential

Process
flowsheet optimization of seaweed-based biorefinery was performed to find the
optimal processing route to produce bioethanol, protein rich solids, succinic
acid, and microalgae. Biochemical processes such as fermentation produce considerable
amount of carbon dioxide as a byproduct. This immense amount of carbon dioxide
is a threat for global warming. Products like succinic acid and microalgae use
carbon dioxide as a precursor, which may reduce the greenhouse gas emissions
from biorefineries. Most promising industrial design alternatives were selected
to build a superstructure. The proposed superstructure contains thirty design
alternatives (including different pretreatment steps, fermentation, carbon
dioxide mitigation alternatives, and different separation technologies).
Furthermore, four design alternatives with respect to products and chemicals
were also considered. A techno-economic model was formulated by considering mass
and energy balances, capital and manufacturing constraints. The resulting model
was mixed integer nonlinear programming (MINLP) and solved in GAMS software. Global
optimization was performed by using LINDO solver. The aim was to determine
optimal biorefinery design which produces minimum amount of carbon dioxide as
well as high economic potential. Numerical results were computed for three separate
optimization objective functions namely maximize NPV, maximize yield, minimize carbon
emissions. Sensitivity analysis was performed to identify the major cost
drivers to process.  The proposed framework can be utilized to investigate a
range of important questions: what is the best process design for minimum
carbon dioxide emissions? What is the best manufacturing strategy of biofuel
and chemicals to maximize NPV?

Acknowledgements

This research was respectfully supported by
Engineering Development Research Center (EDRC) funded by the Ministry of Trade,
Industry & Energy (MOTIE). (No. N0000990).