Space Applications of Torrefaction Processing
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Abstract
A recent study addressed the technical feasibility of a torrefaction (mild pyrolysis) processing system that could be used to sterilize feces and related cellulosic biomass wastes (food, paper, wipes, and clothing) in space, while simultaneously recovering moisture, producing additional water, and small amounts of other useful products (e.g., CO2, CO, and CH4). This work was done using bench scale torrefaction processing units and examined different modes of heating (conventional and microwave). The amounts of solid vs. gas plus liquid products could be controlled by adjusting the torrefaction conditions, especially the final temperature and holding time. The solid char product from a fecal simulant was a dry, free flowing powder that did not support bacterial growth and was hydrophobic relative to the starting material. The proposed torrefaction approach has potential benefits to NASA in allowing for solid waste sterilization and stabilization, planetary protection, in-situ resource utilization (ISRU) and/or production of chemical feedstocks and carbon materials. In particular, the torrefaction char residue has several potential applications in space. These include production of activated carbon, a nutrient-rich substrate for plant growth, construction material, radiation shielding, storage of elemental carbon, hydrogen, or oxygen, and fuel gas (CH4, CO, and H2) production. The current paper provides additional torrefaction data and analysis. It also addresses the potential space applications of torrefaction processing, how it compares to other approaches to solid waste management, its applicability to a range of cellulosic biomass materials, and how the technology could be integrated with existing advanced life support technologies, such as the Heat Melt Compactor (HMC) or the Universal Waste Management System (UWMS).
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Michael A. Serio, Advanced Fuel Research, Inc, USA
Joseph E. Cosgrove, Advanced Fuel Research, Inc, USA
Marek A. Wójtowicz, Advanced Fuel Research, Inc, USA
Jeffrey Lee, NASA Ames Research Center, USA
Kanapathipillai Wignarajah, NASA Ames Research Center, USA
John Fisher, NASA Ames Research Center, USA
The 45th International Conference on Environmental Systems was held in Bellevue, Washington, USA on 12 July 2015 through 16 July 2015.