Document Type : Review Paper
Department of Process Engineering, Stellenbosch University, Private Bag X1, Matieland 7602, South Africa.
Biobased fuels, chemicals, and materials can replace fossil fuel products and mitigate climate change. Sugarcane mills have the potential to produce a wider range of biobased chemicals in a similar approach to bioethanol production, including adipic acid. Multiple alternative pathways for converting simple sugars into adipic acid have been described, with the potential for integration into a sugar mill. The economics and expected greenhouse gas emissions reductions compared to fossil-based adipic acid were investigated in the present study to identify preferred pathways for implementation in sugarcane biorefineries. Nine biobased pathways for adipic acid production were screened for technical performances, resulting in the selection of four preferred options for rigorous comparison, i.e., direct microbial conversion of sugars, and production via cis,cis-muconic acid, glucaric acid, and glycerol as intermediate, obtained from sugars. The minimum selling prices of adipic acid for an attractive return on investment were determined for these pathways, using either A-molasses or a combination of A-molasses and pretreated sugarcane lignocelluloses in biorefineries designed to be energy-self-sufficient. Adipic acid production from A-molasses via cis,cis-muconic acid was the best overall performing scenario with the lowest minimum selling price of USD 2,538/Mt and lowered greenhouse gas emissions (2,325 g CO2 eq/kg wet) compared to fossil-based adipic acid production. The scenarios with combined A-molasses and lignocellulosic feedstock had increased minimum selling prices by 29 to 101% compared to adipic acid production from A‑molasses via cis,cis-muconic acid.
- Biobased adipic acid (ADA) production has great potential to revitalize the sugarcane industry.
- Compared to fossil-based, biobased ADA production can lower GHG emissions up to 80%.
- Biobased ADA production from A-molasses is only 15% more expensive compared to fossil-based ADA.
- The intermediate cis,cis-muconic acid found the best route for ADA production.
- The adoption of biobased ADA faces competition from the petrochemical market.