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Keywords:

  • process synthesis;
  • optimization;
  • energy;
  • mathematical modeling

A method for synthesizing augmented biofuel processes, which improve biomass carbon conversion to liquid fuel (ηcarbon) using supplemental solar energy as heat, H2, and electricity is presented. For a target ηcarbon, our method identifies augmented processes requiring the least solar energy input. A nonconvex mixed integer nonlinear programming model allowing for simultaneous mass, heat, and power integration, is built over a process superstructure and solved using global optimization tools. As a case study, biomass thermochemical conversion via gasification/Fischer–Tropsch synthesis and fast-hydropyrolysis/hydrodeoxygenation (HDO) is considered. The optimal process configurations can be categorized either as standalone (ηcarbon ≤ 54%), augmented using solar heat (54% ≤ ηcarbon ≤ 74%), or augmented using solar heat and H2 (74 ≤ ηcarbon ≤ 95%). Importantly, the process H2 consumption is found to be close to the derived theoretical minimum values. To accommodate for the intermittency of solar heat/H2, we suggest processes that can operate at low and high ηcarbon. © 2014 American Institute of Chemical Engineers AIChE J, 60: 2533–2545, 2014