Economic and sustainability prospects for wet waste valorization: The case for sustainable aviation fuel from arrested anaerobic digestion

Valorizing wet wastes to sustainable aviation fuel (SAF) can be achieved through sequential arrested anaerobic digestion (AAD) to volatile fatty acids (VFAs) and thermochemical catalytic upgrading. Alternatively, conventional anaerobic digestion (AD) can use wet waste to produce biogas (for electricity generation), biomethane, or green hydrogen. To assess the VFA-SAF pathway, we conducted a comprehensive techno-economic analysis (TEA) of each approach using Aspen Plus and discounted cash flow models, coupled with life cycle assessment (LCA) to estimate fuel carbon intensity (CI) and evaluate the implications of policy incentives for carbon emissions reduction. First, we calculated the minimum fuel selling price (MFSP) required to meet a 10 % internal rate of return (IRR) for each product without policy incentives. In this scenario, all pathways faced challenges in meeting the market values of equivalent fossil-based products. Next, we examined projected costs for alternative sustainable technologies and found that SAF and biomethane from wet waste were competitive, while electricity and hydrogen costs were significantly higher. Finally, we incorporated current policy incentives; with incentives, all pathways exceeded a 10 % IRR using fossil-equivalent selling prices. Among all the options considered, VFA-SAF produced the most profitable carbon-negative fuel that was economically competitive with alternative sustainable technologies. [Display omitted]