Sustainability Metrics for Biomass-Based Carbon Chemicals

The application of biomass-based resources for the production of chemicals could slow the depletion rate of fossil reserves and enable the development of a sustainable chemical industry. Three sustainability metrics, the sustain- ability value of resource replacement (SVrep), the sustainability value of the fate of waste (SVwaste), and the sustainability indicator (SUSind), were defined for biomass-based carbon chemicals by using the ethanol equivalent (EE) as a common currency. These sustainability metrics were calculated for ethylene, propylene, toluene, p-xylene, styrene, and ethylene oxide in the U.S.A. for 2008 and 2014. Our calculations are based on the initial chemical dehydration of corn-ethanol to ethylene followed by its conversion by existing chemical processes. These basic chemicals cannot be produced sustainably at this time primarily due to the limited availability of bioethanol. Consequently, bioethanol-based carbon products should only be labeled “sustainable” when the necessary biomass is available to produce the required bioethanol, independently of social and economic changes. The waste management of the processes shows much better sustainability values than the resource management, due to the successful greening of petrochemical processes