Economics fermentation ethanol

Ethylene. Where ethylene is ia short supply and fermentation ethanol is made economically feasible, such as ia India and Bra2il, ethylene is manufactured by the vapor-phase dehydration of ethanol. The production of ethylene [74-85-1] from ethanol usiag naturally renewable resources is an active and useful alternative to the pyrolysis process based on nonrenewable petroleum. This route may make ethanol a significant raw material source for produciag other chemicals. 

Enzymatic hydrolysis of cellulose appears to be more economically attractive than chemical hydrolysis. [59]. Regardless of hydrolysis method, cellulose opens up the possibility to use of all kinds of farm wastes, straw, sawdust, wastepaper, etc., to produce sugars for fermentation ethanol. 

Often the coupling of the membrane unit with the bioreactor results in significant synergy as in the study of O Brien et al. [6.15] on the application of PVMBR to ethanol production, which we discussed in Chapter 3. The required bioreactor volume for the PVMBR system was smaller than that of the conventional system by a factor of 12. Nevertheless, it turns out that the PVMBR-based process is still 25 % more expensive than the classical batch fermentation process in terms of capital costs despite the substantial reduction in the required reactor volume. This cost differential is not only due to the membrane costs, which are, themselves, substantial, but also due to the cost of the additional hardware associated with membrane operation. The application of MBR for the ethanol production by fermentation faces marginal economics, since ethanol is a relatively cheap commodity chemical. 

Liquefaction. Siace the 1970s attempts have been made to commercialize biomass pyrolysis for combiaed waste disposal—Hquid fuels production. None of these plants were ia use ia 1992 because of operating difficulties and economic factors only one type of biomass Hquefaction process, alcohohc fermentation for ethanol, is used commercially for the production of Hquid fuels. 

Other L-amino acids are manufactured much more economically ia thousands of tons per year ia Japan by simplified fermentations direcdy from glucose, ethanol, acetic acid, glycerol, or / -paraffin, by means of selected auxotrophic, regulatory, and analogue-resistant bacterial mutants (94,95). 

Use of biofilm reactors for ethanol production has been investigated to improve the economics and performance of fermentation processes.8 Immobilisation of microbial cells for fermentation has been developed to eliminate inhibition caused by high concentrations of substrate and product, also to enhance productivity and yield of ethanol. Recent work on ethanol production in an immobilised cell reactor (ICR) showed that production of ethanol using Zymomonas mobilis was doubled.9 The immobilised recombinant Z. mobilis was also successfully used with high concentrations of sugar (12%-15%).10... 

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