carbonization, hydrothermal liquefaction (at subcritical conditions T, 250–374
C,
and P, 4–22 MPa), and hydrothermal gasification (at supercritical conditions
T > 374
C and P > 22 MPa). There has been significant research reported on the
hydrothermal conversion of lignocellulosic biomasses, algal biomasses, and also coutilization of these two with other waste materials. The interaction of water with the
biomass results in formation of various chemicals like acids, alcohols, cyclic
ketones, phenols, and methoxyphenols and more condensed structures like naphthols and benzofurans. This chapter focuses on the influence of the process parameters and types of biomass utilized on the hydrothermal conversion of biomass.
Additionally, the use of biomass as not only an energy source but also as a viable
source for value-added chemicals is discussed.
Keywords Biocrude, Biomass, Fine chemicals, Hydrothermal conversion
1 Introduction
Energy Alternatives India (EAI) estimates 450–500 million tons of biomass is
produced from various sources in that 31.2% of it is highly utilized for production
of bioenergy [1]. Bioenergy is one of the key renewable resources taken from
different sources that is awfully heterogeneous. Bioenergy is the most suitable
form of alternate energy that is derived from biological substances rich in organic
substance – biomasses. For each generation of feedstock, the compositions vary
broadly and are tedious to classify as most biomasses are wastes of various biochemical processes and are heterogeneous. The first-generation feedstocks are edible
crops like sugarcane, palm oil, and rapeseed that were used for thermochemical
conversion [2], whereas second-generation feedstocks are nonedible crops of lignocellulosic biomass like wood, straw, etc., used to avoid the shortage of food
compared to first-generation feedstock [3]. In both generations, the plants or crops
fix carbon through photosynthesis in the form of carbohydrates. When processed,
they leave out carbon dioxide (CO 2 ), and thus the vent gas can be recycled by other
plant. In the past few years, the third-generation feedstocks, i.e., algal biomasses,
emerges loudly and attract the researchers than the first- and second-generation
feedstocks [4]. They can be broadly classified into microalgae and macroalgae
based on its size, and like plants, algae store energy in the form of carbon-rich lipids
through photosynthesis.
In a crude point, the various classifications of biomass based on their primary
source are given in Table 1.
The two major categories of biomass that are going to be discussed are lignocellulosic and algal biomass. The lignocellulosic plants belong to the division
Spermatophyta of the subkingdom Phanerogame in the kingdom Plantae where the
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C. D. Venkatachalam et al.
C,
and P, 4–22 MPa), and hydrothermal gasification (at supercritical conditions
T > 374
C and P > 22 MPa). There has been significant research reported on the
hydrothermal conversion of lignocellulosic biomasses, algal biomasses, and also coutilization of these two with other waste materials. The interaction of water with the
biomass results in formation of various chemicals like acids, alcohols, cyclic
ketones, phenols, and methoxyphenols and more condensed structures like naphthols and benzofurans. This chapter focuses on the influence of the process parameters and types of biomass utilized on the hydrothermal conversion of biomass.
Additionally, the use of biomass as not only an energy source but also as a viable
source for value-added chemicals is discussed.
Keywords Biocrude, Biomass, Fine chemicals, Hydrothermal conversion
1 Introduction
Energy Alternatives India (EAI) estimates 450–500 million tons of biomass is
produced from various sources in that 31.2% of it is highly utilized for production
of bioenergy [1]. Bioenergy is one of the key renewable resources taken from
different sources that is awfully heterogeneous. Bioenergy is the most suitable
form of alternate energy that is derived from biological substances rich in organic
substance – biomasses. For each generation of feedstock, the compositions vary
broadly and are tedious to classify as most biomasses are wastes of various biochemical processes and are heterogeneous. The first-generation feedstocks are edible
crops like sugarcane, palm oil, and rapeseed that were used for thermochemical
conversion [2], whereas second-generation feedstocks are nonedible crops of lignocellulosic biomass like wood, straw, etc., used to avoid the shortage of food
compared to first-generation feedstock [3]. In both generations, the plants or crops
fix carbon through photosynthesis in the form of carbohydrates. When processed,
they leave out carbon dioxide (CO 2 ), and thus the vent gas can be recycled by other
plant. In the past few years, the third-generation feedstocks, i.e., algal biomasses,
emerges loudly and attract the researchers than the first- and second-generation
feedstocks [4]. They can be broadly classified into microalgae and macroalgae
based on its size, and like plants, algae store energy in the form of carbon-rich lipids
through photosynthesis.
In a crude point, the various classifications of biomass based on their primary
source are given in Table 1.
The two major categories of biomass that are going to be discussed are lignocellulosic and algal biomass. The lignocellulosic plants belong to the division
Spermatophyta of the subkingdom Phanerogame in the kingdom Plantae where the
202
C. D. Venkatachalam et al.