Butanol Production from Lignocellulosic Biomass

As the worldwide demand for fuels and chemicals surges and petroleum deposits are depleted, producers of ethanol fuel are increasingly looking beyond corn, potatoes, and other starchy crops for substrates for ethanol fuel production. Ethanol is currently the most important renewable liquid biofuel, but it has problems ranging from lesser energy content than gasoline, blending limitations with gasoline, potential for corrosion of pipes, and subsequent inability to be transported using existing pipeline infrastructure, to requiring modifi cation of car engines with increasing ethanol concentrations such as E85 or 100% ethanol. Attempts are underway to produce alternative renewable liquid biofuels and chemical feedstocks that are superior to ethanol. Butanol is one such biofuel because it has greater energy content, is more miscible with diesel, is less corrosive, and has a lesser vapor pressure and fl ash point than does ethanol. Butanol can also be used at greater blend amounts with gasoline or even at 100% concentration in car engines with little or no engine modifi cation, and because of its solubility characteristics, it can be transported in existing fuel pipelines and tanks. One of the major problems associated with bio - based production of butanol is the cost of substrate. The cost of substrate has led to recent interest in the production of butanol from alternative, inexpensive materials. However, much of the proposed alternative substrates, such as corn stover, corn fi ber, wheat straw, rice straw, or dedicated energy crops such as switchgrass and Miscanthus , present challenges that need to be overcome before they can be used as commercial substrates for butanol production. This chapter, therefore, details the (1) pretreatment and hydrolysis of various lignocellulosic biomass; (2) generation of lignocellulosic degradation products during pretreatment of biomass; (3) effects of degradation products on growth and butanol production by fermenting microorganisms; and (4) strategies for improving lignocellulosic hydrolysates utilization for butanol production.