(80b) Process Modeling, Techno-Economic and Life-Cycle Assessments of Producing Potentially Carbon-Negative Building Material from CO2 and Waste Lignin or Lignite

Many technologies have been developed to capture CO₂ from point sources and convert it into fuels or chemicals, which typically emit CO₂ at the end of their life. However, there are limited studies of technologies that convert CO₂ into materials that can retain atmospheric carbon in a sequestered form for a long duration. To address this gap, the project team at Pacific Northwest National Laboratory developed an emerging two-step technology to produce a potentially carbon-negative building material from CO₂. In the first step, CO₂ captured from point sources is reacted with waste lignin or lignite to form CO₂-loaded lignin/lignite (CO₂LIG) material via carboxylation, forming durable carbon-carbon bonds. Then CO₂LIG filler is mixed with commodity polymers (i.e. high density polyethylene) to produce CO₂LIG-polymer composites via injection molding. A CO₂ loading up to 5 wt.% in CO₂LIG and a CO₂LIG loading up to 70-80% in the polymer composite have been achieved in the experimental study, which leads to a CO₂ loading up to 4 wt.% in the final product. In addition, water-lean solvents developed by PNNL will be used to capture CO₂ from point sources. Compared with the industrial benchmark, aqueous amines, the energy consumption, and carbon capture cost of water-lean solvent are roughly 22% and 15%, respectively. In this talk, we present process models developed in Aspen Plus based on lab-scale experimental data, techno-economic and cradle-to-gate life-cycle GHG emission assessments for both lignin and lignite cases and assess their viability as a carbon-negative approach. We also detail comparisons with commodity materials in the present market, and examine the sensitivity of how key economic and environmental measures are impacted by feedstock resources and logistics, reactor performance and mixing ratio between CO₂LIG and polymer.