Comparative thermodynamic assessment of plasma gasification and plasma pyrolysis of livestock‐derived agricultural waste for syngas production

Abstract

This study presents a thermodynamic assessment of the plasma conversion of livestock‐derived agricultural waste, represented by dried mixed manure, using the TERRA equilibrium program. Plasma gasification and plasma pyrolysis were compared within a unified modeling framework to evaluate carbon conversion, gas‐phase composition, condensed‐phase behavior, and specific energy consumption over 300–3000 K at 1 atm. The results showed that both routes are thermodynamically capable of producing a gas rich in H ₂ and CO, while complete carbon gasification is achieved at approximately 950 K. Based on the combined behavior of gas quality and energy demand, 1500 K was identified as the most suitable operating point for comparative assessment. At this temperature, the syngas fraction reached 65.2% for plasma gasification and 68.5% for plasma pyrolysis. The predicted condensed products were dominated by stable mineral phases, mainly tricalcium phosphate, magnesium oxide, and calcium sulfide. Overall, plasma pyrolysis favored preservation of reduced combustible species and yielded a slightly richer syngas, whereas plasma gasification showed a modest advantage in terms of lower specific energy demand. Because the difference between the two routes remained small, the results are interpreted cautiously as equilibrium‐level tendencies rather than statistically resolved performance margins.