Synergies between geological sequestration and microalgae biofixation for greenhouse gas abatement: Life cycle design of carbon capture, utilization, and storage supply Chains

We address the integration of two greenhouse gas (GHG) abatement options, namely, geological sequestration and microalgae biofixation, using a supply chain optimization approach. A multiscale, multiperiod, mixed-integer nonlinear programming (MINLP) model is proposed, which accounts for CO₂ transportation pipeline network design, algae processing route, and product selection, as well as the seasonality in CO₂ source availability and algal biomass productivity. The model allows for pipeline transportation of both supercritical CO₂ and feed gas. By using the Life Cycle Optimization framework, we simultaneously optimize the economic and environmental performances. We employ an improved branch-and-refine algorithm for efficient global optimization of the resulting nonconvex MINLP problems. We consider a case study on the optimal design of potential CO₂ capture, utilization, and storage infrastructures in the state of Texas. By taking advantage of the synergies between these two GHG abatement options, the CO₂ emissions can be sequestrated and utilized at an average cost of $45.52/tCO₂, and about 64% of the GHGs can be avoided from entering the atmosphere.