**2. Types of biomass**

Biomass, which is sourced from organic matter from the biosphere (animal or plant origin) and through transformation of wastes, is a promising source of energy. This renewable energy source can be classified into three: (1) forestry biomass, (2) energy crops and (3) biomass from wastes and residues. These three forms of biomass will be discussed in the following sections.

#### **2.1 Forestry biomass and residues**

Forests as terrestrial ecosystems store and generate biomass, which justifies their applicability as energy sources since time immemorial [8, 9]. This biomass form differs based on topography, stand structure, site and management systems. Irrespective of the variations, forest is a primordial energy source due to its uniformity and availability globally as well its carbon neutrality [10, 11]. Forest biomass is removed as harvests or in silvicultural activities. Forest biomass is classified into two categories: (1) energy plantations and (2) timber systems where energy is produced as forest residues. Energy plantations are distinguished from agricultural crops from the ability to enhance their biodiversity, their variability globally,

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*The Potential of Biomass in Africa and the Debate on Its Carbon Neutrality*

harvest flexibility, economic variability, low risk and their capacity to perform phytoremediation [12, 13]. Some countries such as China, Canada, USA and Europe have some of these plantations as documented by Goncalves et al. [14] and compared to developing countries. A number of factors such as the management practices, harvest cycle, rotation, density and the selection of species are considered in the growth of energy crops [14]. Forest residues include stumps, stems, limbs and tops of trees and their production depends on tree species, stem quality and stand

The current share of forest biomass use is limited despite the known advantages of its use in energy production including the ability to convert it to transportation fuels, heat and electricity. The use of bioenergy and renewable wastes for energy supply accounted for 9.4% compared to all sources in 2015 [15]. Among these biomass supplies, 63.7% was from solid biofuels such as renewable municipal waste, biogas and liquid biofuels while other renewable biomass took the remaining share. Wood, wood fuel and wood residues produce heat and electricity and can be used indirectly by power plants combined with heat and power or directly by end users. Forest biomass contributed to 87% of biomass feedstock while 3 and 10% was from municipal waste and agricultural feedstock, respectively [16]. Examples of forest biomass sources include wood pellets, pine wood chips, pine bark, beech woos, willow wood, poplar and eucalyptus wood [17]. In sub-Saharan Africa, woody biomass is the main source of energy at domestic level and 81% of the population use it for economic, household and cooking activities [7]. This rate is by far higher compared to higher income developing countries of India and China. Although projections by the IEA as noted by Stecker et al. [18] claimed that wood biomass use for energy would reduce globally by 2035, it is noted that in Africa, this form of biomass will contribute to 51–57% of energy consumption. Wood biomass use in Africa varies with some countries such as Central African Republic, Burundi and Rwanda having

Energy crops are wild and cultivated crops, which produce biomass for various purposes. They exist as woody, herbaceous, perennial, or annual and generate raw materials for gaseous or liquid biofuels in addition to solid biomass. A number of factors including maintenance of land productivity, improved soil fertility, use of crop rotation systems, climate change adaptation and crop characteristics influence the successful production of energy crops [19]. Energy crops are used for three main purposes: 1) biodiesel, 2) bioethanol and 3) electric and thermal production [20]. Some of the crops used to produce biodiesel include *Cynara cardunculus,* cotton, *Glycine max, Helianthus annuus* and *Brassica napus*. Energy crops used in bioethanol production include *Beta vulgaris*, *Zea mays* and *Sorghum bicolor*, wheat among other cereals. *Miscanthus giganteus*, *Eucalyptus globulus* and *Arundo donax* are used in electric and thermal production. According to Lynd et al. [21], energy crops occur in four categories: (1) cellulosic such as trees, grass and a variety of wastes, (2) oil rich such as palm oil, soy, rapeseed and sunflower, (3) sugar rich including sugar beet and sugarcane and (4) starch rich crops such as sorghum, wheat and maize. A number of conversion technologies transform the crops to energy. These technologies include biological processes such as fermentation, lignocellulose hydrolysis and anaerobic digestion as well as non-biological processes such as transesterification, pyrolysis, gasification and combustion. African countries such as Kenya, Zimbabwe, South Africa, Tanzania, Ghana and Ethiopia have embraced the use of these biomass crops as energy sources in addition to the use of forest

*DOI: http://dx.doi.org/10.5772/intechopen.93615*

a percentage use rate of 90% and above [18].

biomass, residues and other forms of wastes [21].

structure [8].

**2.2 Energy crops**

#### *The Potential of Biomass in Africa and the Debate on Its Carbon Neutrality DOI: http://dx.doi.org/10.5772/intechopen.93615*

harvest flexibility, economic variability, low risk and their capacity to perform phytoremediation [12, 13]. Some countries such as China, Canada, USA and Europe have some of these plantations as documented by Goncalves et al. [14] and compared to developing countries. A number of factors such as the management practices, harvest cycle, rotation, density and the selection of species are considered in the growth of energy crops [14]. Forest residues include stumps, stems, limbs and tops of trees and their production depends on tree species, stem quality and stand structure [8].

The current share of forest biomass use is limited despite the known advantages of its use in energy production including the ability to convert it to transportation fuels, heat and electricity. The use of bioenergy and renewable wastes for energy supply accounted for 9.4% compared to all sources in 2015 [15]. Among these biomass supplies, 63.7% was from solid biofuels such as renewable municipal waste, biogas and liquid biofuels while other renewable biomass took the remaining share. Wood, wood fuel and wood residues produce heat and electricity and can be used indirectly by power plants combined with heat and power or directly by end users. Forest biomass contributed to 87% of biomass feedstock while 3 and 10% was from municipal waste and agricultural feedstock, respectively [16]. Examples of forest biomass sources include wood pellets, pine wood chips, pine bark, beech woos, willow wood, poplar and eucalyptus wood [17]. In sub-Saharan Africa, woody biomass is the main source of energy at domestic level and 81% of the population use it for economic, household and cooking activities [7]. This rate is by far higher compared to higher income developing countries of India and China. Although projections by the IEA as noted by Stecker et al. [18] claimed that wood biomass use for energy would reduce globally by 2035, it is noted that in Africa, this form of biomass will contribute to 51–57% of energy consumption. Wood biomass use in Africa varies with some countries such as Central African Republic, Burundi and Rwanda having a percentage use rate of 90% and above [18].
