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31 Critical Issues That Can Underpin the Drive for Sustainable Anaerobic Biorefinery

distiller’s waste, and glycerol). To date, biogas production is mainly affiliated with

the abatement of sewage sludge from municipal wastewater treatment plants.

Biogas as an energy carrier can play an essential role in the bioeconomy.

In comparison with fossil fuels, biogas production by AD can diminish green-

house gas (GHG) emission by using regionally available resources, and in contrast

with other bioenergy production techniques with GHG emission reduction bene-

fit, biogas production by AD is the least energy-consuming process [6]. In addition,

evaluations show that biogas production offers significant advantages over other

bioenergy production techniques because AD is a more energy-efficient and envi-

ronmentally friendly technology in terms of recovering energy and decreasing the

amount of organic waste [7, 8]. Moreover, current research activities aim to improve

AD efficiency, which indicates the growing economic potential of biogas produc-

tion in the coming decades over yet established bioenergy production techniques

[9]. This study grapples with several (bio)technological issues of AD and discusses

subtle perspectives of the biogas-based green economy by an updated consolidated

literature brief review.

31.2

Biogas – An Energy Vector

Although energy industry promulgates the gaseous fossil fuels over biogas, its

combustion for power and heat recovery is widely used in residential biogas plants.

Table 31.1 shows the properties of biogas compared with other gaseous fuels. The

biogas utilization consists of a mundane spectrum of industrialized applications.

The most common applications are electricity generation and heat recovery in the

combined heat and power (CHP) plants [12]. Electrical and thermal conversion

efficiencies of the CHP unit are around 40% and 50%, respectively. The physico-

chemical properties of biogas affect the choice of technology used for cleanup and

combustion; therefore, knowledge of these properties is useful to optimize the end

use of biogas [13]. To date, almost all the biogas produced worldwide is used for

heat and electricity production. Several countries contemplate biogas as a solution

Table 31.1

General properties of gaseous fuels [10, 11].

Low calorific

value (MJ/m³)

Specific

gravity

Boiling

point

(^∘C)

Ignition

temperature

(^∘C)

Flammability

limits on

air (% v/v)

Biogas

23.1

0.80

—

650

8–18

Carbon dioxide

—

1.52

−78.5

—

—

Methane

39.8

0.55

−161.4

590

5–15

Natural gas

38.7

0.65

−258.7

628

—

Ethane

60.8

1.048

−88.1

515

3–12

Propane

88.4

1.52

−43.4

470

2–9

Source: Park et al. [10].