The challenge of enzyme cost in the production of lignocellulosic biofuels

TLDR

The study builds a techno‑economic model to quantify how enzymes contribute to the cost of lignocellulosic biofuels. The authors constructed this model and performed a sensitivity analysis on feedstock prices and fermentation times to assess enzyme cost impact. They found that enzyme production costs are much higher than assumed, contributing $0.68/gal at theoretical yields and $1.47/gal at reported yields to ethanol from corn stover, and that further effort is needed to reduce this contribution.

Abstract

With the aim of understanding the contribution of enzymes to the cost of lignocellulosic biofuels, we constructed a techno-economic model for the production of fungal cellulases. We found that the cost of producing enzymes was much higher than that commonly assumed in the literature. For example, the cost contribution of enzymes to ethanol produced by the conversion of corn stover was found to be $0.68/gal if the sugars in the biomass could be converted at maximum theoretical yields, and $1.47/gal if the yields were based on saccharification and fermentation yields that have been previously reported in the scientific literature. We performed a sensitivity analysis to study the effect of feedstock prices and fermentation times on the cost contribution of enzymes to ethanol price. We conclude that a significant effort is still required to lower the contribution of enzymes to biofuel production costs.