Author : Yajie Wu
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (144 download)
Book Synopsis Lignin Valorization in Lignocellulosic Biorefineries Through Biological Upgrading by : Yajie Wu
Download or read book Lignin Valorization in Lignocellulosic Biorefineries Through Biological Upgrading written by Yajie Wu and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation digs into the lignin valorization biorefinery system, focusing on biological upgrading, within the context of the global shift towards a sustainable economy and achieving carbon neutrality. As the world increasingly moves away from fossil-based resources towards renewable lignocellulosic materials for energy and chemical production, lignin--an abundant but underutilized biomass polymer--emerges as a key player in the creation of value-added biochemicals. Yet, the valorization of lignin has been a complex challenge, primarily because of technical barriers, leading to its main use in power generation. With technological advancements in the field of lignin valorization, it is essential to conduct a comprehensive assessment of these technologies, considering their economic viability and environmental impact, to fully make use of lignin's potential in a sustainable manner. This dissertation aims to bridge the gap in current studies by developing optimization models tailored for evaluating biorefinery processes in lignin valorization with biological upgrading to identify economically viable and environmentally beneficial process pathways. It starts with a bibliometric study, shedding light on current research trends and identifying gaps within the field of lignin valorization, particularly noting the limited systems analysis on the developing technologies for lignin valorization. The following section presents an optimization framework to identify economically viable pathways. The economic potential for converting lignin from hardwood, softwood, and herbaceous plants into valuable bioproducts is evaluated. The result indicates that the production of 2-pyrone-4,6-dicarboxylic acid (PDC) from hardwood is the most economically promising, with an estimated net present value (NPV) of $771.41 million and an internal rate of return (IRR) of 19.73%. Capital costs represent a significant portion of the total expenses across all scenarios. Revenue from woody feedstocks is largely derived from lignin-based products, while for herbaceous plants, co-products such as sugars are the main revenue contributors. The study then employs a stochastic optimization model via Monte Carlo simulation to evaluates the optimal process route in the face of uncertain parameters such as market prices, costs, and process yield, while also considering the impact of technology learning on operating costs. The findings reveal a non-negligible risk of unprofitability: 18.86% for hardwood, 21.78% for softwood, and 19.34% for herbaceous plants. Hardwood emerges as the preferred feedstock due to its high selection frequency (3,690 times/10,000 times) and lower risk profile, supporting the result of deterministic models and underscoring its reliability in uncertain environments. Optimal processes identified for hardwood and herbaceous plant, including milling, dilute acid pretreatment, base catalyzed depolymerization, and PDC fermentation, stand out as economically favorable, showing both high frequency of selection and the highest average NPV with consistent risk levels. Conversely, while these processes also rank highly for softwood in terms of selection frequency, the associated average NPV and variability suggests the need for careful balance between achieving high returns and ensuring economic viability. The last section of the dissertation incorporates a life cycle assessment within a multi-objective optimization framework, employing the epsilon constraint method to simultaneously maximizing NPV and minimizing global warming potential (GWP). This approach provides a comprehensive analysis of both economic and environmental considerations in lignin valorization processes, extending the biorefinery system to include the upgrading of fermentable sugars into ethanol. Findings indicate that the primary source of greenhouse gas emissions is from utility consumption, with the lowest GWP achieved when directing lignin towards combustion. In scenarios where lignin undergoes upgrading, the process pathway of steam explosion, base catalyzed depolymerization and PDC fermentation is consistently favored for minimizing GWP. The study uncovers a crucial trade-off between enhancing NPV and reducing GWP, suggesting that a carefully managed distribution of lignin between combustion and upgrading can align economic gains with environmental benefits. Although hardwood and softwood are identified as viable for profitable investments, herbaceous plants do not demonstrate economic potential. When evaluating methods for the best NPV to GWP ratio, steam explosion is identified as more effective than dilute acid pretreatment, highlighting its role in optimizing both financial and environmental outcomes in lignin valorization. Overall, this dissertation underscores the importance of applying advanced optimization techniques in evaluating lignin valorization biorefinery system and highlights the necessity of a rigorous, multi-faceted approach to developing sustainable bioeconomy solutions. Through an exploration of economic impacts, uncertainty analysis, environmental considerations, and the trade-off between economic and environmental impacts, this research contributes valuable insights into the sustainable valorization of lignin, marking a significant step towards innovative and environmentally friendly process and bioproducts.
