Co-Processing Agricultural Residues and Wet Organic Waste Can Produce Lower-Cost Carbon-Negative Fuels and Bioplastics

Scalable, low-cost biofuel and biochemical production can accelerate progress on the path to a more circular carbon economy and reduced dependence on crude oil. Rather than producing a single fuel product, lignocellulosic biorefineries have the potential to serve as hubs for the production of fuels, production of petrochemical replacements, and treatment of high-moisture organic waste. A detailed techno-economic analysis and life-cycle greenhouse gas assessment are developed to explore the cost and emission impacts of integrated corn stover-to-ethanol biorefineries that incorporate both codigestion of organic wastes and different strategies for utilizing biogas, including onsite energy generation, upgrading to bio-compressed natural gas (bioCNG), conversion to poly(3-hydroxybutyrate) (PHB) bioplastic, and conversion to single-cell protein (SCP). We find that codigesting manure or a combination of manure and food waste alongside process wastewater can reduce the biorefinery's total costs per metric ton of CO2 equivalent mitigated by half or more. Upgrading biogas to bioCNG is the most cost-effective climate mitigation strategy, while upgrading biogas to PHB or SCP is competitive with combusting biogas onsite.

Automated summary

Scalable and low-cost biofuel and biochemical production can contribute to a more sustainable carbon economy and reduced reliance on crude oil. Lignocellulosic biorefineries can serve as multifunctional hubs for fuel production, petrochemical replacements, and organic waste treatment. Strategies such as codigestion of organic waste and biogas upgrading can significantly reduce costs and emissions in corn stover-to-ethanol biorefineries. Upgrading biogas to bioCNG is the most cost-effective climate mitigation strategy, while upgrading to PHB or SCP can compete with onsite biogas combustion.