viz., sorbitol, 5-HMF, glucaric acid, succinic acid, and lactic acid. Furthermore,
furfural and xylitol can be produced using hemicellulose as a source, whereas
levulinic and glutamic acids derived from both cellulose and hemicellulose of
biomass (Ge et al. 2018). However, the process technologies used in the biorefineries
are still under the research stage. This chapter delves about the broad outline of
biorefineries and also discusses challenges faced in commercialization.
6.2
Potential and Availability of Agro-Residues
Generally, the agro-residues are mainly classified into primary residues and secondary residues. Primary residues are collected at the time of crop harvesting, whereas
secondary residues are collected from the processing of agro-produce. The agroresidues are made of three major constituents such as cellulose, hemicellulose, and
lignin. The composition of selected agro-residues is listed in Table 6.1. The biomass
compositions vary with biomass species, environmental conditions, and even in the
same variety grown in different seasons. The cellulose content of selected residues is
in the range of 24–53%, and variation in the values is due to their biomass types and
other factors. Lignin is another vital constituent of agro-residue, which offers more
resistance for biological conversion. Generally, the percentage of lignin content in
these residues ranges from 6 to 29, and lignin content can be used as the chemical
platform to produce biochemicals.
The cultivation of crops is mostly region-specific, and a variety of crops is grown
in different parts of the world. Generally, the quantity of agricultural residues
generated per annum is directly linked with the residue to grain ratio of the individual crop. The details of the residue to grain ratio for most of the crops are already
available in the literature. Therefore, we can use the individual crop yield data to
predict their respective residue, and summing up the individual crop residue would
give the total crop residue availability for a region or nation. The cereal and
sugarcane crops are contributing a significant share in global residue production
(Tripathi et al. 2019). Annual agro-residues produced in India is estimated as
500 million tonnes (Mt), which includes sugarcane (141 Mt), wheat (110 Mt),
paddy (122 Mt), maize (71 Mt), millets (26 Mt), fibre crops (8 Mt), and pulses
(28 Mt) (Saroj Devi et al. 2017).
6.3
Biorefinery Methods
The biorefinery is a platform used to produce biofuels, bioenergy, and biochemicals
from single/multiple biomass feedstocks by applying a group of selected biomass
conversion methods with their appropriate equipment/machinery. The group of
selected biomass conversion methods used in the biorefineries could be operated
by one by one in a sequential order. In the case of biorefinery, the raw material can be
converted to main products in the first process, and their intermediate products
further converted into secondary products through the second conversion process.
6 Sustainable Biorefinery Technologies for Agro-Residues: Challenges and. . .
103
furfural and xylitol can be produced using hemicellulose as a source, whereas
levulinic and glutamic acids derived from both cellulose and hemicellulose of
biomass (Ge et al. 2018). However, the process technologies used in the biorefineries
are still under the research stage. This chapter delves about the broad outline of
biorefineries and also discusses challenges faced in commercialization.
6.2
Potential and Availability of Agro-Residues
Generally, the agro-residues are mainly classified into primary residues and secondary residues. Primary residues are collected at the time of crop harvesting, whereas
secondary residues are collected from the processing of agro-produce. The agroresidues are made of three major constituents such as cellulose, hemicellulose, and
lignin. The composition of selected agro-residues is listed in Table 6.1. The biomass
compositions vary with biomass species, environmental conditions, and even in the
same variety grown in different seasons. The cellulose content of selected residues is
in the range of 24–53%, and variation in the values is due to their biomass types and
other factors. Lignin is another vital constituent of agro-residue, which offers more
resistance for biological conversion. Generally, the percentage of lignin content in
these residues ranges from 6 to 29, and lignin content can be used as the chemical
platform to produce biochemicals.
The cultivation of crops is mostly region-specific, and a variety of crops is grown
in different parts of the world. Generally, the quantity of agricultural residues
generated per annum is directly linked with the residue to grain ratio of the individual crop. The details of the residue to grain ratio for most of the crops are already
available in the literature. Therefore, we can use the individual crop yield data to
predict their respective residue, and summing up the individual crop residue would
give the total crop residue availability for a region or nation. The cereal and
sugarcane crops are contributing a significant share in global residue production
(Tripathi et al. 2019). Annual agro-residues produced in India is estimated as
500 million tonnes (Mt), which includes sugarcane (141 Mt), wheat (110 Mt),
paddy (122 Mt), maize (71 Mt), millets (26 Mt), fibre crops (8 Mt), and pulses
(28 Mt) (Saroj Devi et al. 2017).
6.3
Biorefinery Methods
The biorefinery is a platform used to produce biofuels, bioenergy, and biochemicals
from single/multiple biomass feedstocks by applying a group of selected biomass
conversion methods with their appropriate equipment/machinery. The group of
selected biomass conversion methods used in the biorefineries could be operated
by one by one in a sequential order. In the case of biorefinery, the raw material can be
converted to main products in the first process, and their intermediate products
further converted into secondary products through the second conversion process.
6 Sustainable Biorefinery Technologies for Agro-Residues: Challenges and. . .
103