Document Type
Article
Publication Date
6-3-2025
Department
Department of Chemical Engineering
Abstract
Lignin valorization is limited by both impurities and broad molecular weight (MW) distributions. The Aqueous Lignin Purification using Hot Agents (ALPHA) process exploits the novel liquid–liquid equilibrium that exists between lignin and hot, one-phase solutions of aqueous renewable solvents to simultaneously purify and fractionate raw bulk lignins. Our analysis considered the valorization of lignin recovered from two ethanol biorefinery waste streams, black liquor and lignin cake. By applying sequential ALPHA stages, distinct lignin fractions of controlled MW and purity were isolated suitable for producing carbon fibers, polyurethane foams (PUF), and activated carbons (ACs). Surprisingly, only a single extraction stage was required to split lignin cake into two useful fractions: a purified, low MW lignin for PUFs and a ‘dirty’, cellulose-contaminated lignin that proved to be effective for AC production. Using inputs generated in lab, an ASPEN Plus simulation was developed to model a 130 000 metric tons lignin (dry)/yr plant for valorizing the lignin by-product from a lignocellulosic ethanol biorefinery. Economic results generated using a 30 yr discounted cash flow table show an annual profit of $25.7 million yr−1 and a net present value of $238 million for the best-performing scenario. Accounting for net unfavorable uncertainties through a Monte Carlo simulation, the ALPHA process has a 92% chance of being profitable over the 30 yr lifespan. Environmental impacts were calculated using a life cycle assessment methodology and the software SimaPro. The fractionated lignin products have GHG emissions and cumulative energy demand equivalent to or lower than their fossil precursor equivalents. Considering the sequestration of carbon by the final products lowered the GHG emissions for all scenarios by 40%–50%. Coupling the economic and environmental results indicate that the ALPHA process is a promising emerging technology for valorizing lignin, aiding in fulfilling the UN Sustainable development goal of using sustainable raw materials.
Publication Title
Sustainability Science and Technology
Recommended Citation
Kulas, D. G.,
Handler, R.,
Tindall, G.,
Lynn, B.,
Thies, M.,
&
Shonnard, D.
(2025).
Economic and environmental impact of recovering and upgrading lignin via the ALPHA process on an ethanol biorefinery.
Sustainability Science and Technology,
2(3).
http://doi.org/10.1088/2977-3504/adda4d
Retrieved from: https://digitalcommons.mtu.edu/michigantech-p2/2190
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 International License.
Version
Publisher's PDF
Publisher's Statement
© 2025 The Author(s). Published by IOP Publishing Ltd. Publisher’s version of record: https://doi.org/10.1088/2977-3504/adda4d