Page 78 - Biofuels Refining and Performance

Photosynthetic Plants as Renewable Energy Sources 61

Woody and herbaceous species are the ones used most often by biomass
researchers and industry. Several parameters are important in the biomass
conversion process. The principal considerations in terms of the material
type are moisture content, calorific value, fixed carbon and volatile pro-
portion, ash/residue content, alkali metal content, and cellulose–lignin
ratio. In a wet-biomass conversion process, the moisture content and
cellulose–lignin ratio is of prime concern, while in a dry-biomass conver-
sion process, it is the alkali metal content and cellulose–lignin ratio. The
Laticiferous plant species of Apocyanaceae, Asclepiadaceae, Convolvulaceae,
and Euphorbiaceae have been analyzed for use as renewable energy
sources. Analysis of oil and hydrocarbon contents of 15 different plant
species tested has revealed that Carissa carandas L., Ceropegia juncea
Roxb., Hemidesmus indicus R. Br., and Sarcostemma brunourianum W. A.
are the most suitable species [16]. In another study, five different plant
species Plumeria alba, C. procera, Euphorbia nerifolia, Nerium indicum,
and Mimusops elengi have been evaluated as potential renewable energy
sources. Whole plants and plant parts (leaf, stem, and bark) have been ana-
lyzed for oil, polyphenol, hydrocarbons, crude protein, -cellulose, lignin,
ash, and mineral content. The barks of these plants were identified to have
greater hydrocarbon content than the leaves. Based on the dry-biomass
yields, hydrocarbon content, and other properties, these plant species most
suitable for renewable energy sources have been identified [17]. In a study
conducted on 51 plant species in Tennessee, in the United States, an exam-
ination of the oil, polyphenol, hydrocarbon, protein, and ash content reveals
that Lapsana communis yields the maximum oil (6.1% dry, ash-free plant
sample basis). Chrysopsis graminifolia, Solidago erecta, and Verbesina
alternifolia have been identified as rubber-producing species with 0.4–0.7%
hydrocarbon [18].

2.6 Products
Several processes similar to petroleum refining are involved in the con-
version of biomass into different products. Biorefineries convert biomass
into different products in different stages. The different stages involved
in the conversion of biomass to products are depicted in Fig. 2.11.

Enzymatic or Solid,
Agricultural acid liquid, and
residues and
waste hydrolysis gaseous
Biological products

Figure 2.11 Different products from biomass.