**2. Perspective view**

## **2.1 Diesel engine and its significance**

Diesel engines are imperative gear in open transportation, rock solid hardware, control age, agrarian and modern hardware attributable to their higher fuel-change profitability, higher power yield, higher torque limit, higher sturdiness, and higher trustworthiness than gas motors. Moreover they radiate lesser carbon monoxide

(CO), hydro carbons (HC) and carbon dioxide (CO2) floods than diesel motors [16]. The utilization of fossil diesel in diesel motors passes on high NOx (nitrogen oxides) and buildup radiation that are unpleasant to both regular and human prosperity [17]. Diesel fumes is named harm causing to people by the International association for research on infection (IARC) in perspective on satisfactory evidence that its presentation is connected with an extended peril of lung threatening development while:


Diesel engines are widely employed prime-movers for public transit systems, agricultural equipment, industrial implementations, power generation, construction and heavy machinery because of its un-matched fuel conversion efficiency, durability and torque capability [18]. The performance of diesel engines is usually higher than that of a gasoline engine of similar size. While the current state-ofthe-art diesel engines are typically turbocharged with cooled EGR, equipped with common rail direct injection (CRDI) and after-treatment for soot and NOx, a larger population of diesel engines sold in agricultural and construction equipment during the last few decades in India include naturally aspirated stationary diesel engines [19]. These engines are widely used in the Indian agricultural sector to drive siphon sets to supply water for water system purposes [20]. The present quantities of these diesel driven siphon sets in the nation is about 14.42 million. As indicated by a study completed by the Indian Petroleum Conservation Research Association (PCRA), the yearly generation of these diesel driven siphon sets is 1.5 million with a normal yearly development of 7%. It is important to note that Indian agricultural sector recorded a consumption of 6 million metric tons (MMT) of diesel, which is about 8.55% of India's total diesel consumption (69 MMT) in the year 2012–2013. This statistic implies that a large population of farmers in India is severely exposed to the toxic diesel exhaust from these engines.

#### **2.2 Crude oil and its demand**

The burgeoning population, rapid industrialization and higher mobility have increased the demand and consumption of crude oil every year. The **Figure 1** shows the crude oil consumption in the year 2014–2015 across the world. The International Energy Agency (IEA) has predicted that the global crude oil demand will rise to 99 million barrels per day by the year 2035. Diesel extracted from crude oil by fractional distillation faces depletion in future. There is an estimate that the reserves of crude oil are gradually depleting at the rate of 2.1% per annum. Hence it is imperative that alternative forms of diesel engine compatible fuels have to be identified to improve energy security by the way of bio-based renewable sources. Instability in crude oil prices has an impact on the economies of countries without oil reserves

*Alcohol Contribution over Conventional Fuel DOI: http://dx.doi.org/10.5772/intechopen.89084*

**Figure 1.** *Crude oil consumption in the year 2014–2015 [27].*

#### **Figure 2.** *Diesel consumption in India sector-wise [32].*

and is heavily dependent on import. In the past 10 years, India relied heavily on imports to meet its increasing fuel demands [21]. High crude-oil imports suggest payments in dollars and depletion of foreign reserves which affects economy. India's domestic crude oil production plummeted for the fourth straight year in 2015–2016 which escalated India's import dependence to 81% in the last year from 78.5% in 2015–2016. Thus substitution of even a fraction of fossil fuel with a renewable biofuel will have positive impact on both the economy and environment. It has to be noted that India's fossil diesel consumption accounted more than that of gasoline. For instance, in 2012–2013, India consumed 69 million tons of diesel oil which is four times than that of gasoline. This consumption is primarily in transportation, industry and agriculture as shown in the graphic in **Figure 2**. The consumption in agriculture sector comprises tractors 17%, pump-sets for 7.5% and agriculture equipment 9.5%. All this indicates that a huge population is constantly exposed to hazardous gaseous emissions from diesel engines.

#### **2.3 Hazards of diesel engine exhaust**

Diesel engines emits high levels of oxides of nitrogen (NOx) and particulate matter (PM) into the atmosphere which are proven to be harmful to both human and environmental health [22]. Smoke in diesel engine exhaust is carcinogenic and cause a cardio-respiratory diseases. The diesel exhaust is classified as carcinogenic and continuous exposure can increase the chances of lung cancer [23]. The nanosized particulate matter if inhaled is capable of trans-locating to the brain through olfactory nerves and can cause inflammation at deposition sites. In an experiment subjected 10 human volunteers to dilute diesel exhaust for an hour and showed that there is a functional effect in the human brain indicating a general cortical stress response [24]. Additionally, these smoke particles are also potential inducers of oxidative stress. The human brain is considered to be very sensitive to the damages caused by oxidative stress. Long term oxidative stress is found to be associated with diseases such as Alzheimer's and Parkinson's that leads to reduce cognitive function [25]. Further, when pregnant women are exposed to diesel fumes, adverse effect on fetal development is reported. NOx component present in diesel exhaust is a primary reason for smog, ground level ozone (1981), acid rain and sick building syndrome. NOx causes cyanosis and pulmonary diseases [26].

#### **3. Alternative source**

#### **3.1 Prospective diesel engine fuels**

Realizing a clean, affordable and safe energy future to address the growing concerns of fossil fuel dependence and the subsequent degradation of air quality by burning fossil fuels has been a challenge researchers relentlessly attempt to address [27]. Diesel engines could be perhaps fueled by a wide range of fuels like straight vegetable oil, biodiesel, biogas and bioalcohol adopting several strategies and modifications. The use of edible vegetable oils as diesel engine fuel threatens food security as the world community now embroiled in the "Fuel vs. Food" deliberation. Nonedible sources also have a concern. Their cultivation take up large land sources meant for food crop cultivation. Biodiesels are usually derived from edible and nonedible vegetable oils by transesterification which is a time consuming and expensive process. Biodiesels also presents the same concern as the vegetable oils because the feedstock they are derived from, takes up the acreage meant for the cultivation of food crop. Further the by-product of transesterification like glycerol poses another environmental challenge and has to be carefully disposed [28]. Biogas is typically a mixture of two potential greenhouse gases, methane and carbondioxide. Biogas is usually produced and used in as is where is basis because of the costs involved in its storage and distribution that require high pressure cylinders and safety measures to prevent leakage. Bioalcohols could be derived from both food and nonfood based feedstocks which makes them attractive [29]. Feedstock like lignocellulosic biomass which includes agricultural wastes (rice-straw, cornstalks and sugarcane-bagasse), forestry wastes (wood-pulp, saw-mill and papermill rejects) and energy crops (switch grass, elephant grass and agave) that can be subjected to gasification, pyrolysis, steam reforming and bacterial fermentation to yield platform chemicals. Valorization of biomass to esteem included items and vitality is set to occur in biorefineries which could be viewed as similar to the present oil refineries [30]. For a nation like India with huge prolific grounds thriven by ordinary regular precipitation through rainstorm, there is a monstrous open door for gathering enormous amounts of lignocellulosic biomass and to ubiquitous diesel

*Alcohol Contribution over Conventional Fuel DOI: http://dx.doi.org/10.5772/intechopen.89084*

engines. The present study utilizes two such bioalcohols namely cyclohexanol and n-octanol derived from nonfood based sources to power diesel engines. Low carbon bioalcohols like methanol and ethanol which are popularly researched in gasoline engines are incompatible with diesel engines owing to their low energy density and low cetane number. Higher carbon bioalcohols like n-butanol, n-pentanol, n-hexanol, cyclohexanol and n-octanol can be appropriate possibility for diesel engine innovation. These bioalcohols can be made from glucose by development using planned littler scale living things or by getting ready lignocellulosic biomass using enzymatic hydrolysis and maturing, anaerobic digestion, gasification, pyrolysis and biocatalysis. **Table 1** exhibits the properties of some bioalcohols in examination with diesel and low carbon alcohols. It will in general be considered that to be the alcohols move higher, its cetane number, low warming quality, streak point, thickness and consistency increases while its oxygen content, vapor weight, dissolvability in water and unconventionality diminishes [31]. Also, the less vapor weight and less hygroscopic nature of high carbon alcohols offer better handling and storage. As a blend component, longer alkyl carbon chains also offer better miscibility with fossil diesel without any phase separation over a period of time.
