Development of a Material-Driven Phase III Lignocellulosic Feedstock Biorefinery System

Abstract

The present status of operational biorefineries confronts an array of technological and economic hurdles, encompassing challenges related to product diversification, environmental impacts, and efficient waste management. In this study, a highly streamlined and techno-economically viable material-driven phase III lignocellulosic feedstock biorefinery system is delineated, aiming to sequentially extract non-structural and structural components from diverse lignocellulosic biomass and pretreatment chemicals such as nitrogen-, potassium-, and phosphorus- (NPK) containing materials. To construct the biorefinery system, a thermo-pressurized sequential phosphoric acid-potassium hydroxide pretreatment method was employed on extractives-free lignocellulosic biomass, effectively fractionating numerous non-wood and hardwood samples into their structural components. Applying the pretreatment process, the primary structural components, i.e., hemicellulose (77 to 98%), cellulose/pulp (77 to 93%), and lignin (75 to 85%), were separated. The pretreatment chemicals were also recovered (around 100%) as valuable NPK fertilizers in crystalline and liquid forms from the spent liquors by using ammonium hydroxide. A techno-economic analysis was performed on the biorefinery system (small-scale plant; lignocellulosic biomass used: 7300 t/y; production capacity: 19,568 t/y; estimated capital cost: 31.00 million USD; operating cost: 23.48 million USD) by developing a deterministic model that showed a payback period of 6.69 years. Local sensitivity and uncertainty analyses were also performed using the deterministic model, and changes in the return on investment were evaluated. Additionally, a superstructure was developed for the biorefinery, showing potential downstream operations. Overall studies, including cradle-to-gate lifecycle assessment, demonstrated that the biorefinery is a green and sustainable technology for the conversion of lignocellulosic biomass with greater than 95% atom economy.