*3.2.1 Ethanol from cane and other sugar plants*

Fermentation is the fundamental method to synthesize the ethanol used in industries. Sugarcane molasses was the important raw material for ethanol production, which is byproduct of sugar industry [3]. Also, in fermentation process grain starches (wheat and corn), potato mashes, fruit juices, non-sugar lignocelluloses fractions of crops such as grasses and plants used as raw materials. Generally, molasses contain up to 50% simple sugar that can be easily fermented into ethanol and it is an ideal raw material for ethanol production with high availability and low cost. However, once the raw materials are delivered to the ethanol production plant, it is stored in the warehouse and conditioned to prevent from early fermentation and contamination [12]. Moreover, an enzyme such as microscopic yeasts plays a vital role in the fermentation process to convert carbohydrates to ethanol in the absence of oxygen. The possible equations in the process of fermentation by yeast in the absence of Oxygen are shown here under [13]. The synthesis route of ethanol [14] is represented in **Figure 3**.

$$\text{C}\_{12}\text{H}\_{22}\text{O}\_{11} + \text{H}\_{2}\text{O} \rightarrow 2\text{C}\_{6}\text{H}\_{12}\text{O}\_{6} \tag{3}$$

$$\text{2C}\_6\text{H}\_{12}\text{O}\_6 \rightarrow \text{2CH}\_3\text{CH}\_2\text{OH} + \text{2CO}\_2\tag{4}$$

**Figure 3.** *The schematic representation of ethanol production [14].*

### **3.3 Usage of alcohol fuels as gasohol**

Traditionally, after the production of industrial methanol or ethanol, it has been used for alcohol fuel blending to manufacture gasohol. However, after fermentation and distillation process, it can be blended with petrol/gasoline in distinct proportion. The 10% ethanol was blended with 90% gasoline is considered as Low-level ethanol blends like E10, it can be used in conventional vehicles. Moreover, 85% ethanol was blended with 15% gasoline is considered as high-level blends, such as E85, it can be used in specially designed motorized vehicles like flexible fuel vehicles [15].

Alcohol fuel effectively used as an alternative liquid transportation fuels by varying their properties by the addition of certain additives, which must be physically and chemically compatible with the base alcohol fuel and have the same or higher specific energy content. Especially, both MeOH and ethanol are poorly miscible in gasoline containing traces of water, but completely miscible with water. The alcohols are blended with gasoline in presence of water, which may leads to a phase separation problem. In this situation to avoid the phase separation problem, few additives was added to alcohol fuel like higher alkanols such as 1-butanol, n-decanol, iso-propanol, different anionic fatty acid surfactants and various commercial non-ionic surfactants. Here, the avoidance of phase separation would have exact benefits for overall drivability, as well as in corrosion of water-sensitive components such as aluminum. In spark ignition engines, alcohol fuel can run at a much higher exhaust gas recirculation rates and with higher compression ratios [16].

The combustion MeOH:

$$\text{2CH}\_3\text{OH} + \text{3O}\_2 \rightarrow \text{2CO}\_2 + \text{4H}\_2\text{O} + \text{Heat} \tag{5}$$

The combustion ethanol:

$$\text{C}\_2\text{H}\_5\text{OH} + \text{\textdegree\text{O}}\_2 \rightarrow \text{2CO}\_2 + \text{\textdegree\text{H}}\_2\text{O} + \text{Heat.} \tag{6}$$

The properties of gasoline, MeOH and ethanol such as air–fuel ratio, density, combustion energy, Percentage of oxygen, Reid Vapor Pressure (RVP), Research Octane Number (RON) and Motor Octane Number (MON) [17, 18] were listed in **Table 2**.

*Alcohol Fuels as an Alternative Fuels - Bringing New Heights in Sustainability DOI: http://dx.doi.org/10.5772/intechopen.86626*


**Table 2.**

*Properties of liquid fuels [17, 18].*

**Table 2** illustrates that, alcohols having lower air–fuel ratio compared with gasoline, which helps to alcohol fuel to produce more power inside of an engine when these fuels are burned. However, the efficiency and quality of fuel are expressed in terms of difference between Research Octane Number (RON) Motor octane number (MON). Generally, RON is greater than MON in most of the fuel components. The RON and MON of alcohol fuel were measured in test engines at a relatively low speed (600 rpm) to simulate city driving speed with frequent acceleration and at a higher speed (900 rpm), which simulates highway driving respectively. The maximum octane sensitivity value defined as the difference between RON and MON of gasoline. While, methanol has the highest percentage of oxygen, its sensitivity is 30 when compared with ethanol, having a sensitivity of 15. Moreover, the percentage of oxygen and Reid vapor pressure (RVP) of ethanol was less than that of methanol. In this regard, ethanol has more advantages when comparing with sensitivity, % of O2 content and RVP with those other fuels.
