Bioethanol costs

The reduction of the bioethanol cost and the increase of its competitiveness depend greatly on the production technology. Bioethanol technology consists of two phases the prodirction of raw ethanol and its further del dration. Azeotropic distillation, adsorption on molecular sieves and evaporation through the membrane are rrsed for ethanol delydration of [8]. 

Table 9.3 Energy values, costs and emissions per hectare in the comparison of the production of biodiesel by oilseed rape and bioethanol by wheat crops. (Adapted from [4]).

The compactness and complexity of (ligno)cellulose makes it much more difficult to attack by enzymes with respect to starch. Therefore, the cost of bioethanol production is higher [23], To be cost competitive with grain-derived ethanol, the enzymes used for biomass hydrolysis must become more efficient and far less expensive. In addition, the presence of non-glucose sugars in the feedstock complicates the fermentation process, because conversion of pentose sugars into ethanol is less efficient than conversion of the hexose sugars. 

Figure 9.8 summarizes the different possible conversion pathways and/or uses of bioethanol [83]. Notably, however, a decrease in ethanol cost may open the door to a large range of other possible applications, and there is interest in biorefineries to diversify the possible uses of ethanol so as to decrease dependence on market fluctuations. There is thus the need to rediscover, and improve as well, the catalytic chemistry of ethanol. 

Bioethanol upgrading and valorization is another area in which catalysis will be a key player. The decrease in ethanol production cost and the need to realize a transition to a society based more on renewables are two driving forces to develop new catalytic processes for bioethanol conversion. However, without improvements in the efficiency and selectivity of the various processes for ethanol, and in general biomass conversion, which are possible only by the introduction of better and/or new catalysts, this transition to a bio-based economy will probably not be possible. Research on catalysis will thus be the enabling factor for this change towards a more sustainable society. 

Biofuels such as bioethanol and biodiesel originate from cereal crops such as plant oils, and sugar beets. Today the production cost of bioethanol cereal crops is still too high, which is the major reason why bioethanol has not made its breakthrough as a fuel source yet. When producing bioethanol from maize or sugar cane the raw material constitutes about 40-70% of the production cost. 

The partial oxidation of ethanol was investigated, but with less intensity than in the case of steam reforming. The reason is that the use of the pure partial oxidation process is not advised for bioethanol reforming because bioethanol is an ethanol-water mixture in which removal of all the water entails a significant cost. Therefore, for bioethanol partial oxidation, the process is combined with steam reforming in autothermal schemes with the stoichiometry shown in Equation 6.18. 

In addition to the use of ethanol in cars and trucks, the chemicals industry, faced with daunting increases in petrochemicals costs, has a new appetite for bioethanol. In fact, bioethanol can be used to create plastics—an area that consumes vast quantities of oil in America and around the globe. Archer Daniels Midland is constructing a plant in Clinton, Iowa that will product 50,000 tons of plastic per year through the use of biotechnology to convert com into polymers. 

Bioethanol is one of the first and the largest markets to profit from cheap biomass feedstock. Ethanol is usually produced from dextrose, which in the USA tends to derive from corn. The first ethanol biorefmery based on waste biomass is already online. It is a Canadian venture operated by Iogen and receiving investment from Shell, Petro Canada, and the Canadian government. With an annual capacity of 700,000 liters it is semi-commercial in scale and not cost-competitive with conventional ethanol refineries. However, the technology is expected to improve quickly. 

The widespread use of papers has created an enormous amount of wastepaper however, it is not easy to recycle this resource because of the high cost of its utilization process. In the past, recycled wastepaper was used only two to three times before the fibers became unacceptably short (1). This wastepaper can be used in the bioethanol process as inexpensive... 

The main barrier to greater commercial success has been its historic high cost until recently. Some believe the solution is to extract zein as a by-product in the manufacturing process for bioethanol. From a high-value added perspective, Chinese researches have conducted intensive research on the use of zein as a biomedical material (Dong et al., 2004). 

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