Page 128 - Advances in Eco-Fuels for a Sustainable Environment

100 Advances in Eco-Fuels for a Sustainable Environment

is unique. It is between 45 and 55wt% and it is in the form of long esters of fatty acids
and alcohols. Therefore, it is more appropriately called a wax ester. The jojoba wax
ester mainly consists of fatty acids such as eicosanoic acid, erucic acid, and oleic acid
with cis-11-eicosen-1-ol and cis-13-docosen-1-ol. The methanolysis of the unique
composition of jojoba wax results in the production of FAME and large chain alco-
hols, and their separation is problematic [17]. Canoira et al. [42] reported that around
79% methyl esters of jojoba oil have been obtained from crude jojoba oil for a meth-
anol to oil molar ratio of 7.5:1, at a temperature of 60°C, in a reaction time of 4h using
1% (wt of oil) NaOH as catalyst. The properties of methyl esters of Jojoba oil include a
2
kinematic viscosity of 9.0mm /s and a cold filter plugging point of 14°C after the
reduction of the alcohol component through laborious purification [42].
4.2.1.4 Potential nonedible oils

The following are the potential nonedible oils used for the production of biodiesel.

Tobacco seed oil (Nicotiana tabacum)
Tobacco (Nicotiana tabacum) belongs to the Solanaceae family, and is an annual her-
baceous plant grown worldwide for its leaves, which are used to produce tobacco
products such as cigarettes, cigars, or snuff. The tobacco seeds are small in size,
but the number of seeds per plant is extremely large. The number of seeds in tobacco
plant vary between 0.6 and 1.2tonnes seeds/ha and 5tonnes seeds/ha for varieties used
in leaf production and improved to produce tobacco seed oil, respectively. For biodie-
sel production, the tobacco seeds contain 36–41wt% of nicotine-free oil, giving oil
yields per hectare (0.2–2tonnes/ha) similar to other nonedible oils such as Jatropha
or Karanja used for biodiesel production [43]. The free fatty acid content in tobacco
seed oil is 17wt%. Tobacco seed oil contains linoleic acid (69.5wt%) in high quantity
and other fatty acids such as oleic acid (14.5wt%) and palmitic acid (11.0wt%) in
significant quantities [17]. Garcia-Martinez et al. [43] stated the maximum conversion
of tobacco oil to its corresponding methyl esters obtained has been around 93% at a
reaction temperature of 300°C in a reaction time of 90min for a methanol to oil ratio of
43:1 via the noncatalytic transesterification method. The methyl esters of tobacco seed
2
oil exhibit properties such as a kinematic viscosity of 3.5mm /s, cetane number of 51,
and an acid value of 1.44mgKOH/g [17, 43].

Coffee oil (Coffea arabica)
The world’s largest coffee producer is Brazil. The oil content in the spent coffee gro-
und (organic residues from brewed coffee) is approximately 10–15wt%. Roughly
1.3L of biodiesel from the coffee oil could be added to the world fuel supply from
approximately 8 million tonnes of coffee produced globally each year. The instant cof-
fee powder is mixed with hot water or steam to prepare instant coffee and accounts for
half the world’s coffee consumption. The solid waste of spent coffee ground (SCG)
after extraction of coffee with hot water amounts for 2kg per kg of instant coffee pow-
der (ICP) [44]. Because of high antioxidant content in coffee oil, the coffee-based
biodiesel is more stable than traditional biodiesel. The fatty acids present in coffee