Ethanol, thermochemical biomass feedstock

When perfected, synthesis-gas-to-ethanol technology can be expected to have a large impact on fermentation ethanol markets. It is likely that thermochemical ethanol would then be manufactured at production costs in the same range as methanol from synthesis gas, which can be produced by gasification of virtually any fossil or biomass feedstock. Applying the advances that have been made for conversion of lignocellulosic feedstocks via enzymatically catalyzed options, it has been estimated that the production cost of fermentation ethanol... 

Ethanol is the key reactant in Eq. (1), and also in Eq. (2) because it is readily converted to acetaldehyde. The process based on Eq. 1 was developed in Russia and the process based on Eq. 2 was developed in the United States. The yield of butadiene for the Russian process is about 30-35%. It is about 70% if mixtures of ethanol and acetaldehyde are employed as in the U.S. process. Equation (3) represents a process that involves 2,3-butylene glycol, a product from the microbial conversion of biomass. The process is carried out in two sequential steps via the glycol diacetate in overall yields to butadiene of about 80%. The process of Eq. (4) starts with a biomass derivative, the cyclic ether tetrahydrofuran, and can be carried out at high yields. When this process was first operated on a large scale in Germany, acetylene and formaldehyde were the raw materials for the synthesis of intermediate tetrahydrofuran. It is manufactured today from biomass feedstocks by thermochemical conversion, as will be discussed later. 

The higher efficiency biomass case, again with biomass feedstock produced by the management-intensive system and no credit for ener co-products, is projected to be capable of dehvering about 3.4 times as much energy in the form of ethanol than the fossil-fuel inputs needed to operate the sj tem. The NEPRs ot each ol the thermochemical biomass cases would be higher still if low-grade feedstocks were used instead of those produced by the system described in Tables 14.8 and 14.9. 

TABLE 14.14 Net Energy Analysis of the Thermochemical Conversion of Natural Gas and Biomass to Ethanol in an Integrated Feedstock Production-Conversion System"... 

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