1.2
Feedstock
1.2.1 Vegetable Oils
The main feedstock for first-generation biodiesel production worldwide includes oils
from energy crops (such as soybean, rapeseed, canola, sunflower, corn, palm
kernels, animal fats) and recycled oil. Jatropha curcas L. oil has also been used
for biodiesel production in tropical areas such as India and Africa.
Vegetable oils from energy crops (which are also often commercialized in the
food sector) are considered high-quality materials for biodiesel production because
they have a high triglyceride content (92–99%) and low FFA content (<2%).
Vegetable oils produced from soybean and rapeseed are the most commonly used
feedstock for biodiesel production in the United States and Europe, respectively.
Waste oil is recycled cooking oil used in restaurants, food industry, and
households. It contains usually more free fatty acids and water and less triglycerides
than fresh vegetable oils. The typical composition of waste oil includes linoleic acid
(53%), oleic acid (28%), and palmitic acid (11.73%) (Shah et al. 2007). Because of
its high FFA concentration and water content, waste oil usually needs a pretreatment
to remove water and transform FFAs to esters. The production of waste oils
worldwide is significant; in 2007, in fact more than 15 million tons have been
generated in the world (Gui et al. 2008). Vegetable oils composition and main
characteristics are proposed in Table 1.2 (Leung et al. 2010).
1.2.2 Starch and Sugars
Ethanol derived from biomass has the potential to be a sustainable transportation fuel
that can replace gasoline (Wang 2000; Kim and Dale 2004). Ethanol can be
produced from sugar- or starch-containing crops (see Table 1.3) and lignocellulosic
biomass (such as agricultural residues, herbaceous crops, forestry wastes, wastepaper, and other wastes) (Wyman 1996). The production of bioethanol from lignocellulosic biomasses is still under development. The composition of lignocellulosic
biomasses is presented in the next paragraph.
1.2.3 Lignocellulosic Biomass
Lignocellulosic biomass composition derives directly from the composition of the
plant cell wall (Caffall and Mohnen 2009). The lignocellulosic feedstock is
represented by the agricultural and forest residuals, which are mainly composed by
the cell wall tissue, which remains after the plants have died. Plant cell wall biomass
contains mainly cellulose, hemicellulose, and lignin. Different species of plants have
significant differences in the proportions of the main components and important
differences in the types of hemicellulose which are contained and the ratios of
1 Biofuels: Types and Process Overview
5
Feedstock
1.2.1 Vegetable Oils
The main feedstock for first-generation biodiesel production worldwide includes oils
from energy crops (such as soybean, rapeseed, canola, sunflower, corn, palm
kernels, animal fats) and recycled oil. Jatropha curcas L. oil has also been used
for biodiesel production in tropical areas such as India and Africa.
Vegetable oils from energy crops (which are also often commercialized in the
food sector) are considered high-quality materials for biodiesel production because
they have a high triglyceride content (92–99%) and low FFA content (<2%).
Vegetable oils produced from soybean and rapeseed are the most commonly used
feedstock for biodiesel production in the United States and Europe, respectively.
Waste oil is recycled cooking oil used in restaurants, food industry, and
households. It contains usually more free fatty acids and water and less triglycerides
than fresh vegetable oils. The typical composition of waste oil includes linoleic acid
(53%), oleic acid (28%), and palmitic acid (11.73%) (Shah et al. 2007). Because of
its high FFA concentration and water content, waste oil usually needs a pretreatment
to remove water and transform FFAs to esters. The production of waste oils
worldwide is significant; in 2007, in fact more than 15 million tons have been
generated in the world (Gui et al. 2008). Vegetable oils composition and main
characteristics are proposed in Table 1.2 (Leung et al. 2010).
1.2.2 Starch and Sugars
Ethanol derived from biomass has the potential to be a sustainable transportation fuel
that can replace gasoline (Wang 2000; Kim and Dale 2004). Ethanol can be
produced from sugar- or starch-containing crops (see Table 1.3) and lignocellulosic
biomass (such as agricultural residues, herbaceous crops, forestry wastes, wastepaper, and other wastes) (Wyman 1996). The production of bioethanol from lignocellulosic biomasses is still under development. The composition of lignocellulosic
biomasses is presented in the next paragraph.
1.2.3 Lignocellulosic Biomass
Lignocellulosic biomass composition derives directly from the composition of the
plant cell wall (Caffall and Mohnen 2009). The lignocellulosic feedstock is
represented by the agricultural and forest residuals, which are mainly composed by
the cell wall tissue, which remains after the plants have died. Plant cell wall biomass
contains mainly cellulose, hemicellulose, and lignin. Different species of plants have
significant differences in the proportions of the main components and important
differences in the types of hemicellulose which are contained and the ratios of
1 Biofuels: Types and Process Overview
5