A torrefied biomass polygeneration system (TBPGS) composed of a torrefied biomass gasification process, a combined cycle system, a water-gas-shift reactor (WGSR) process, and a CO methanation process, is developed to produce electricity, hydrogen, and synthetic natural gas (SNG) simultaneously. To cope with the daily energy patterns of power/SNG grid demands, three frameworks are addressed. The TBPGS is directly connected to power/SNG grids as the first framework (FW1). It is found that FW1 cannot cope with the SNG/power demand patterns due to SNG shortages appeared in some time intervals. To increase the operational flexibility of TBPGS, the TBPGS is connected to a combination of compressed hydrogen tank and PEM fuel cell stack as the second framework (FW2) and the TBPGS is connected to an SNG tank as the third framework (FW3). Based on the optimal allocation strategy for minimizing the daily net operating costs of FW2 and FW3, the comparative results show that (i) the total capital cost (TCI) of FW3 is lower than FW2 by 36.9%, (ii) the total operating cost (TOC) of FW3 is lower than FW2 by 5.4%, and (iii) the levelized cost of energy (LCOE) of FW3 is lower than FW2 by 31.7%.
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