Techno-Economic Analysis and Life Cycle Assessment of Waste Lignin Fractionation and Valorization Using the ALPHA Process

Techno-Economic Analysis (TEA) and Life Cycle Assessment (LCA) were performed on the Aqueous Lignin Purification with Hot Agents (ALPHA) process, which is being investigated for the fractionation and purification of raw, bulk lignins recovered from cellulosic ethanol biorefineries or Kraft pulp mills. Here, ALPHA is proposed for the isolation of lignin from a corn stover-to-ethanol plant into purified low, medium, and high molecular weight (MW) fractions for producing polyurethane foam, activated carbon, and carbon fiber, respectively. A scenario analysis was conducted to determine the effect of ALPHA solvent choice on process economics and environmental performance. Solvent choice was found to have a significant impact on ALPHA, with a minimum selling price of $838/tonne with use of acetic acid vs $463/tonne with ethanol. Conversion of the lignin, processed with ethanol solvent, to high-value products yields $151 million/year in profit, which over 30 years results in a total net present value of $533 million. A life cycle assessment was conducted to determine the gate-to-gate greenhouse gas emissions and energy consumption of the lignin-based products compared to fossil-based equivalents. A value allocation scenario was conducted and it was determined that products generated using the ALPHA process with ethanol have similar or lower greenhouse gas emissions than the same products from fossil feedstocks.

Automated summary

The Techno-Economic Analysis and Life Cycle Assessment of the ALPHA process demonstrate the economic benefits and environmental advantages of using different solvent choices to extract lignin and produce high-value products.