Sustainable process design and synthesis of hydrocarbon biorefinery through fast pyrolysis and hydroprocessing

The process design and synthesis of hydrocarbon biorefinery, which is composed of fast pyrolysis, biocrude collection, hydroprocessing and hydrogen production sections, under economic and environmental considerations are concerned. A superstructure is developed that includes multiple process alternatives in each stage of the process flow diagram. A bi-criteria mixed integer nonlinear programming model is proposed to maximize the economic performance measured by the net present value and minimize the global warming potential according to life cycle assessment procedures. The bi-criteria mixed integer nonlinear programming model is solved with the ε-constraint method, and the resulting Pareto curve reveals the trade-off between the economic and environmental performance of the process. The two selected "good choice" optimal designs indicate net present values of 573 and 93.6 $MM (unit costs of $3.43 and $5.26 per gallon of gasoline equivalent), corresponding to global warming potentials of 100 and 53 kton CO₂ equivalent per year (unit greenhouse emissions of 1.95 and 2.04 kg CO₂ per gallon of gasoline equivalent), respectively.