PROCESS AND TECHNO-ECONOMIC MODELING FOR WASTE-TO-ENERGY PROCESSES TO IDENTIFY EFFECTIVE FACILITY SCALING

Abstract

This dissertation presents a techno-economic analysis (TEA) of waste-to-energy (WTE) biofuel production using hydrothermal liquefaction (HTL). The study focuses on facility scaling, feedstock dynamics, unpiling strategies, and cost modeling to evaluate how process conditions and supply constraints influence the minimum fuel selling price (MFSP) of biocrude. Unlike traditional studies that assume static conditions, this research considers the dynamic nature of feedstock availability, storage, and biomass properties over time.Feedstock availability fluctuates seasonally and geographically, influencing both biomass properties and overall process performance. Unlike conventional studies that assume a constant or simplified feedstock supply, this work models how fluctuations in waste wood availability impact storage pile size and inventory dynamics. To better understand the role of inventory management, this study evaluates different unpiling methods, including first-in, first-out (FIFO), last-in, first-out (LIFO), and homogeneous (HG) mixing. Each method determines how long biomass remains in storage before processing, leading to differences in drying, degradation, and conversion efficiency. Facility scaling presents a further challenge, as HTL remains a relatively new technology with limited data on scale-based economics. While previous studies often rely on single scaling factors or focus on specific cost components in isolation, this dissertation evaluates interconnected factors such as equipment scaling, site-specific resource costs, and feedstock procurement strategies. By exploring a range of facility sizes and economic conditions, this research assesses how these factors impact MFSP and overall feasibility. Additionally, this work also examines the role of contracts in securing a stable feedstock supply. Agreements with municipalities or private suppliers that dictate wood procurement affect both operations and cost. The economic trade-offs of different contract structures are analyzed, focusing on how contract duration, seasonal variations, and supply guarantees influence viability. While contracts are often treated as secondary to facility design, this study incorporates them as a key modeling component. By integrating fluctuating feedstock availability, inventory dynamics, facility scaling, and contractual agreements, this dissertation provides a comprehensive framework for assessing the economic feasibility of WTE biofuel production. The findings contribute to a more nuanced understanding of biofuel economics and offer insights to inform future research, industrial applications, and renewable energy development.