Sugar-to-What? An Environmental Merit Order Curve for Biobased Chemicals and Plastics

The chemical industry aims to reduce
its greenhouse gas
emissions
(GHGs) by adopting biomass as a renewable carbon feedstock. However,
biomass is a limited resource. Thus, biomass should preferentially
be used in processes that most reduce GHG emissions. However, a lack
of harmonization in current life cycle assessment (LCA) literature
makes the identification of efficient processes difficult. In this
study, 46 fermentation processes from literature are harmonized and
analyzed on the basis of their GHG reduction compared with fossil
benchmarks. The GHG reduction per amount of sugar used is defined
as Sugar-to-X efficiency and used as a performance metric in the following.
The analyzed processes span a wide range of Sugar-to-X efficiencies
from −3.3 to 6.7 kg of CO2 equiv per kg of sugar
input. Diverting sugar from bioethanol production for fuels to the
fermentation and bioconversion processes with the highest Sugar-to-X
efficiency could reduce the chemical industry’s GHG emissions
by an additional 130 MT of CO2 equiv without requiring
any more biobased feedstocks.