Page 399 - Refining Biomass Residues for Sustainable Energy and Bioproducts

362 Refining Biomass Residues for Sustainable Energy and Bioproducts

16.2 Feedstocks used in agroindustries

Biomasses from agriculture are used as feedstocks in agroindustries. This includes
plant biomass (food and nonfood), biomass from livestocks and fisheries. Both the
aquatic and terrestrial plants are used as feedstocks. Likewise, unused biomass gen-
erated as waste from agriculture, forest, and municipality is also potent feedstocks
for agroindustries (Naik et al., 2010). Broadly, agroindustrial feedstocks are catego-
rized as food and nonfood feedstocks based upon their usage as food for animals.
Moreover, there are other three classes of feedstocks, where the first group is classi-
fied based on the form of yield they provide, for example, sugar, starch, and
oil-yielding crops.
Sugar yielders such as sugarcane, sugar beet, and sweet sorghum contain higher
amount of fermentable sugar (Kim and Day, 2011). Various grain crops such as
wheat, corn, barley, rye, millet, and sorghum are used as feedstocks in agroindus-
tries. Sugar beets and sugarcanes are the sources of monomeric sugars and can be
directly converted to ethanol. Edible oil plants such as rapeseed, soybean, palm oil,
sunflower, canola, mustard, flax, coconut, hemp, and pennycress are the efficient
feedstocks for biooil industries (Naik et al., 2010; Smith et al., 2007). Recently,
emphasis has been paid on the use of macaw palm as feedstock in agroindustries.
The excellent adaptability of this plant in adverse climate (especially temperature)
and the absence of any toxic compounds make them suitable as feedstock for feed
industries apart from using in biodiesel production (Chew and Bhatia, 2008).
Another halophyte, that is, dwarf saltwort, is also an emerging feedstock for biodie-
sel industries. Some other halophytes such as Halopyrum mucronatum,
Desmostachya bipinnata, Phragmites karka, Typha domingensis, and Panicum
turgidum have also identified as bioethanol crops (Abideen et al., 2011).
Castor bean and agricultural residues such as waste biomasses from sugar, oil,
and starch-yielding crops are used extensively as feedstocks (Bateni and Karimi
2016; Naik et al., 2010; Cabral et al., 2016; Oyeleke and Jibrin, 2009). Wastes from
wheat, corn, rice, coconut, sugarcane, and sugar beet are good sources of biofuels.
For example, residue generated from food biomass such as corn oil is a powerful
feedstock for methanol production. Recently, the use of energy cane (a hybrid sug-
arcane) is gaining momentum in ethanol industry due to the higher (three times
than sugarcane) fermentable sugar (Wei et al., 2009). Lignocellulose (hemicellulose
and lignin) is continuously generated by photosynthetic plants and microbes and
existing in large numbers. A wide variety of lignocelluloses is obtained starting
from the forest to the sea. With the help of enzyme cellulase, glucose is obtained
from cellulose and can be used in food/feed industries (Rathna et al., 2014). Some
lignocellulosic energy crops such as Miscanthus has very high biomass yield and
can be grown with limited inputs. Giant reed grass is another energy crop with
long-time yield potential from a single plantation. Some more species from family
Poaceae such as Napier grass, switchgrass, and elephant grass are efficient feed-
stocks for biofuel production (Wei et al., 2009). Animal and poultry manures, sew-
age, and municipal solid wastes can be converted to energy. Agricultural crop