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Prospects and technological advancement of cellulosic bioethanol ecofuel production 215

Currently, most of the industrial countries are producing ethanol at a commercial
level because of its economic aspects, environmental benefits, and engine perfor-
mance. In 2005, Brazil produced about 4.2 billion gallons of ethanol and exported
approximately 100 million gallons to both India and the United States [20]. The
United States included “Renewable Fuels Standard (RFS)” as law in their energy pol-
icy in 2005. This strategic plan increased ethanol production to 4 billion gallons in
2006 and set a target to produce 36 billion gallons annually by 2022 [24].

8.3 Bioethanol feedstock resources

Typically, bioethanol is produced from the fermentation of various feedstocks that
contain mainly fermentable sugars or carbohydrates. The available feedstocks for
bioethanol can be categorized into four major types, as illustrated in Fig. 8.2. First-
generation bioethanol feedstock is mainly edible food crops such as rice, wheat,
barley, potato, corn, sugarcane, and vegetable oil, for example, soybean oil, sunflower
oil, olive oil, canola oil, mustard oil, etc. [25, 26]. Although first-generation bio-
ethanol has gained attention in a number of countries, the feasibility of production
is still questionable due to competition with the food supply and land utilization,
which increases the food cost [27].
A strategy has been made for producing bioethanol from nonedible second-
generation bioethanol feedstocks, including lignocellulosic biomass such as forest res-
idue, woody biomass, herbaceous biomass, etc.; nonfood crops; municipal solid waste;
and animal fat [25, 28, 29]. The second-generation bioethanol production has some
definite advantages over first-generation bioethanol production. For instance,
second-generation feedstocks can grow on poor quality marginal land with less water

4th generation
(Industrial waste CO )
2
3rd generation
(Algal biomass)
2nd generation
(lignocellulosic
biomass)

1st generation (kernels
and starchy crops
biomass)

Fig. 8.2 Bioethanol feedstocks classification [25].