Utilizing a CO2 Carrier Gas in a Plasma Assisted Waste Conversion Test Cell for Space Applications

As space exploration expands beyond Low Earth Orbit, and environmental sustainability becomes an increasing issue, alternative technologies for the reuse of human generated waste become essential. One such technology available to convert waste-to-gas is the implementation of plasmas. Low power plasma-assisted waste conversion under 1 kilowatt of electrical consumption has not been fully explored for viability in terrestrial or space applications. Presented in this report is a plasma torch operating under 400 Watts and utilizing feedstock gases such as compressed air, and now, carbon dioxide (CO2). Materials of interest for waste conversion in this report are typical items of astronaut generated waste such as cloth, food packaging, plastics, and vibrational packing foam. For the work reported here, when the feedstock gas for plasma generation was air, a combustion-dominated process was observed, whereas a pyrolysis dominated process was observed when utilizing CO2. The average waste conversion from solid to gas for air plasma was approximately 87% and for CO2 plasma it was 74%. The by-product gases were captured and analyzed using a GC and FTIR system that showed generation of CO2, CO, C2H4, CH4, H2O, and other hydrocarbons. This work reports on the plasma characteristics, reaction mechanisms, and viability of a low power plasma torch for waste conversion.