Microwave heating technique has gained widespread popularity in pyrolyzing biomass feedstocks due to its
several unique features over the conventional furnace heating method. Accordingly, the present work aimed at
finding the optimal operating conditions of a microwave reactor applied to pyrolyze horse manure from the
exergetic, exergoeconomic, and exergoenvironmental viewpoints. The effects of two process variables, i.e., reaction temperature and catalyst:biomass ratio, were thoroughly investigated on the considered exergy-based
methods. Three more key exergetic indicators “viz. exergy efficiency of the process, unitary exergoeconomic
cost of the product”, and unitary exergoenvironmental impact of the product were taken into account to select
the most efficient, productive, and sustainable process conditions. The reaction temperature significantly
affected the exergy efficiency of the process. Interestingly, the exergy dissipation due to mass loss and thermodynamic irreversibilities accounted for over 50% of the total input exergy of the process. The quantity of
activated carbon catalyst is a determinant factor in exergoeconomic and exergoenvironmental analyses. The
optimum operating conditions were the reaction temperature of 350 ◦C and the catalyst:biomass ratio of 1:2.
Under these conditions, exergy efficiency of the process, unitary exergoeconomic cost of the product, and unitary
exergoenvironmental impact of the product were 49.2%, 487 USD/GJ, and 151 mPts/GJ, respectively. Overall, it
could be concluded that the applied exergetic approaches could be appealing complements to the chemical
evaluation for analyzing and optimizing various bioenergy systems.
