the energy and exergy efficiencies of
the product gas are in the ranges of 60.3%e85.1% and 50.7%e60.8%,
respectively. The exergy efficiency of the product gas is lower than
the corresponding energy efficiency, and the difference between
the two efficiencies increases with the reaction temperature. The
exergy and energy efficiencies of the product gas are mainly
determined by the corresponding exergy and energy values of the
product gas [12], respectively. In this study, the exergy and energy
values of the product gas are in ranges of 16,549.6e20,392.3 and
14,723.8 to 17,657.3 kJ/kg, respectively. The exergy values of the
product gas are lower than the corresponding energy values, and
the total energy and exergy rate of the feedstocks are close to each
other, making the exergy efficiency of the product gas lower than
the corresponding energy efficiency for the co-gasification of coal
and biomass in the autothermal fluidized bed gasifier.