Laura Bartley,* Tao Xu, Chengcheng Zhang,
Hoang Nguyen and Jizhong Zhou

Introduction

Compared with current commercial biofuel production from sugars, starch, and oils in food commodities, future generation biofuel production has potential to improve energy yields and reduce green house gas emissions (Farrell et al. 2006; Fargione et al. 2008; Schmer et al. 2008). The polysaccharides and lignin in plant vegetative tissues, i. e., leaves and stems, are an abundant source of chemical energy for biofuel production. This so-called lignocellulosic material includes dedicated energy crops as well as agricultural and industrial waste products, such as corn stover, wheat straw, and paper mill waste. Economists estimate that grass biomass represents ~55% of the biomass that can be sustainably produced in the United States, with about half of this from agricultural residues and half from perennial crops (US-DOE 2011). Among candidate bioenergy grasses, switchgrass (Panicum virgatum L.) has received the most attention due to its relatively high yield even under low-input conditions (Thomason et al. 2004), among other factors. The two major approaches for production

Department of Microbiology and Plant Biology, University of Oklahoma, Norman, OK 73019.

Corresponding author: lbartley@ou. edu

of biofuels from lignocellulosic biomass are biochemical conversion and thermochemical conversion. With ground-breaking on a handful of lignocellulosic biochemical conversion production plants in the U. S. in 2012, biochemical conversion is close to commercialization and will be the main focus of this chapter. Thermochemical conversion is briefly discussed here and thoroughly covered in other chapters of this volume.