Despite the efficacy of thermal treatment being well studied, research on the relative sustainability of novel OPs is limited. A report from 2012 explored the general themes of OPs and the types of treatment processes these systems could leverage. However, this early-stage study highlighted biological processes (e.g., anaerobic digestion) as a core treatment strategy and argued thermal conversion (e.g., pyrolysis) was too complex with no systems available for fecal sludge management at the time. Although biological treatment is common for community-scale treatment, greenhouse gas emissions (i.e., CH4 and N2O) can be substantial, as deviation from optimal operation conditions commonly occurs. Significant innovation has made thermal treatment of excreta feasible, with several of OPs having gone through multi-year pilot studies, and limited publicly available information suggests promising technical viability. For example, a laboratory study of the Biogenic Refinery (a pyrolysis-OP from Biomass Controls PBC) showed this system could support its steady state electrical and heating needs when paired with a combined heat and power system (i.e., it does not require any energy inputs). The development of OPs as part of a portfolio of technologies to address global sanitation needs presents a timely opportunity to investigate their relative sustainability.