**1. Introduction**

The global energy need has been confronting major challenges owing to population growth and industrialization [1, 2]. Green house gases and their emissions as well as developing energy safety mechanisms have perpetually turned the focus on research and technological development in this sector. The researcher community is applying renewable energy practices as an alternate to petroleum fuels with biodiesel, bioethanol, biomass, biogas, and synthetic fuels with the aim to curtail net CO2 emission, and improve air, soil, water and global warming [3]. The American Biodiesel Standard Specification (ASTM 6751) defines biodiesel (also named fatty acid methyl ester; FAMEs) as fuel comprising of monoalkyl esters of long-chain fatty acids acquired from vegetable oils or animal fats [4]. The International Energy Agency (IEA) provided the estimates about global market share of biofuels to be increased from 1% (2004) to 7% by 2030 [5]. The need for utilizing biodiesel is associated with its lower exhaust emissions (COx, SOx) and particulate matter [6]. Moreover, it possesses tremendous biodegradability [7], lubricity, storage [8], and higher flash point [6], oxygen content than diesel [9–11]. The higher oxygen content reflects the low carbon emissions, particulate emissions, CO, aromatic hydrocarbons, sulfur, smoke, and noise [12]. The major issues for biodiesel production and commercialization from vegetable oils comprise their availability and manufacturing cost [13].

The raw materials of biodiesel can be classified into three major groups including vegetable oil (edible or non-edible oil), animal fat, and edible waste oil [14]. These sources possess triglycerides [15] which carry great potential. Biodiesel obtained from vegetable oil has a viable market share in USA and European countries [16]. The scientific community is facing eminent challenge remains for suitable raw materials, their extraction and finally characterization for efficient and cost-effective biodiesel production. The transesterification [17] is a specialized method for biodiesel production from vegetable sources through conversion of one ester to another having low viscosity than the mineral diesel. The transesterification reaction involves catalyst between triglycerides, and short-chain alcohols, which produce monoesters, branched-chain, and long-chain triglyceride molecules that are further converted into glycerol and monoesters [18]. The three-step reaction forms monoglycerides and diglycerides as intermediates. As methanol contains lower charge, it is efficiently used for commercial production of biodiesel. Potassium hydroxide (KOH) as a predominate role in transesterification reaction [19]. The palm, sunflower, coconut rapeseed, soybean, and flaxseed are some of the raw materials being employed for commercialization [20]. Vegetable oil contains complex structure so it cannot be directly used in diesel engines and it will further aggravate the food supply chain through depletion of forests and wildlife destruction. Thus, impetus, toward non-edible sources, has been shifted for biodiesel production.

Feedstock has greater significance for ample availability of biodiesel [21]. The redeeming traits of non-edible sources include their toxicity, no utility in human food as it contains Erucic acid as major constituent of fatty acid; 56–66% [22], and its easy cultivation on poor soils [23], and cost-effectiveness. Moreover, it is very stable and possesses low melting point [24]. Biomass is a major energy source covering almost 10–14% of global need due to its easy combustion, less pollution and lower ash content [8]. However, it has equally low calorific value, thermal efficiency (10 to 15%), and comparatively large volume and transportation issues [8]. Chemically, biomass energy can be converted into liquid and gaseous forms [25].

*Optimization and Characterization of Novel and Non-Edible Seed Oil Sources for Biodiesel… DOI: http://dx.doi.org/10.5772/intechopen.97496*

Many studies have been conducted to explore the non-edible sources for biodiesel production comprising *Croton megalocarpus* [26], *Prunus dulcis* [27], *Prunus sibirica* [28], *Rhazya stricta* Decne [29], rubber seed oil [30], *Silybum marianum* L. [31], wild *Brassica juncea* L. [32], *Jatropha curcas* and Karanja [33–35], waste tallow [36], and notably, algae [37]. However, high-quality biodiesel production still remains to decipher from existing economical non-edible sources [38].
