Gasification\nof Pruned Peach Tree Branches in a CO<sub>2</sub>/O<sub>2</sub> Atmosphere\nin the Presence or Absence of Steam:\nEffect of Gas Media Composition on Product Gas, Reactivity, and Kinetics

Pruned peach tree branches (PP) are widely and thinly\ndistributed\nin comparison to cedar, a typical planted forest species in Japan,\nmaking them a promising small-scale local energy source. However,\ntheir low carbon conversion rate restricts their use as fuel for small-scale\ngasification in combined heat and power plants. Moreover, kinetic\nstudies required to inform the design of gasifiers are lacking. Thus,\nin the current study, the gasification of PP using mixed CO<sub>2</sub> and O<sub>2</sub> gasifying media was evaluated using a laboratory-scale\ngasification apparatus. Thermogravimetric and differential thermal\nanalyses were performed to elucidate the characteristics of product\ngas and reaction kinetics. In the absence of steam, higher CO<sub>2</sub> or O<sub>2</sub> concentrations in the media led to higher\nCO yields and carbon conversion to gas (CCG) rates. However, when\nsteam was added, the H<sub>2</sub>/CO yield and CCG were higher under\nconditions with higher O<sub>2</sub> and lower CO<sub>2</sub> gasifiers.\nThis suggests that the char–O<sub>2</sub> and char–steam\nreactions do not compete. Moreover, analysis of the CO<sub>2</sub>/O<sub>2</sub> gasification reactivity of PP and timber waste (mainly\ncontaining cedar) chars revealed that the effect of O<sub>2</sub> was\nlow during the early reaction stages and increased as the reaction\nprogressed. Collectively, these results can be used to design gasifiers\nand gasification processes for PP char.