We develop a novel superstructure of algal biorefinery processes for biological carbon sequestration and utilization, encompassing off-gas purification, algae cultivation, harvesting and dewatering, lipid extraction, remnant treatment, biogas utilization, and algal oil upgrading stages. Based on the superstructure, we propose a mixed-integer nonlinear programming (MINLP) model to minimize the unit carbon sequestration and utilization cost and apply a tailored branch-and-refine algorithm based on successive piecewise linear approximation to globally optimize the resulting nonconvex MINLP problem efficiently. The minimum unit carbon sequestration and utilization cost of $1.48/ton of CO2 is obtained when the diesel price is $3.91/gal and feed gas is delivered to the biorefinery only during daytime at a flow rate of 5003.46 ktons/year corresponding to the carbon dioxide emission rate of a 600 MW coal-fired power plant. The resulting algal biorefinery design reuses all the CO2 produced within the process, leading to zero direct greenhouse gas emission of the entire process.
ASJC Scopus subject areas
- Chemical Engineering(all)
- Industrial and Manufacturing Engineering