Usage of Biofuels by Industrial Development and World Inhabitants

"Industrial development and world inhabitants are uninterruptedly increasing and this requests high energy consumption day in day out. As a matter of facts, the charge of crude oil, coal, and other natural gases is growing worst from time to time. Responsiveness of global climate alteration and the uncertainty of fossil fuel have thus led to the development of renewable energy. Biofuels are the major renewable dynamism that gets attention in this 21th century. Bioethanol, biodiesel, and biogas are the dominant energy of high demand (Asmamaw and Fassil, 2014).

Ethanol, which is an ancient organic solvent next to the water, is named as “Bioethanol”, after its production through fermentation process using microorganisms. Conversion of sugars into ethanol is one of the earliest anaerobic organic reactions employed by humanity, keeping global energy demand pathetic environment quality in view, it is dire need of renewable and sustainable liquid fuel and that can be achieved after the production of bioethanol (Memon et al., 2017). It is one of the oldest recreational drug and renewable product. Antoine Lavoisier defined ethanol as a compound of carbon, hydrogen, and oxygen. In 1808, Nicolas-Theodore de Saussure determined chemical formula. In 1908, Henry Ford has designed a fuel with a mixture of Gasoline and Alcohol and further it was referred as “The fuel of the future” in the year 1925 The Arabs and Romans learned to isolate the alcohol and to employ it industrially in the preparation of perfumes, cosmetics, and medicines (Zabed et al., 2014)

Two thousand years ago, even the Harappans appeared to have known the process of alcoholic fermentation reported (Wang et al., 2005). That ethanol (C2H5OH) which is pure in its colour, water free, and is a volatile and flammable. It has a molecular weight of 46.07, melting point of -115 0C, boiling point of 78 0C and specific gravity of 0.79 GM / ml at 20 0C. It has a high oxygen content, which burns completely and releases fewer pollutants. It can be produced in two forms like hydrated and anhydrous (Sembiring et al., 2014).

Ethanol is one of the best eco-friendly and advanced liquid fuel. Ethanol is anon toxic and renewable from the fermentation of the carbohydrate sor sugar fractions of plant biomass materials (Sembiring et al., 2014).

Bioethanol is a major component of alcoholic beverages such as beer, wine, whisky, brandy etc. It is also used as a solvent in syrups. Food and Energy security has been always key priorities, due to their limited availability and increasing demand with ever increasing population. During the last few years, an important effort has been made to enhance bioethanol production. Several authors reported that the attention has been devoted to the conversion of various substrates such as molasses, sugar cane, sorghum, potato, cassava, cashew, apple juice, fruit juices and corn, wheat, pearl millet, rice to fuel bio-ethanol (Asmamaw and Fassil, 2014).

Bioethanol is compatible with water and with many organic solvents such as pyridine, acetic acid, glycerol, acetone, benzene, carbon tetrachloride, chloroform, diethylether, ethylene glycol, nitromethane, and toluene. It is also mixable with light aliphatic hydrocarbons such as pentane and hexane and also with aliphatic chlorides like trichloroethane and tetrachloroethylene. The concentration of ethanol varies from the type of alcoholic beverage usually ranging from 5 % to 40 %. I t has been used as fuel for the lamp in the U.S.A since 1908 and it has an advantage of reducing greenhouse gas emissions, because it hasan oxygen content about 10 – 14 % (Karuppaiya et al., 2012).

Bioethanol is usually concentrated by distillation of aqueous solutions, but the composition of the vapor from aqueous ethanol is 96% ethanol and 4% water. Commercial ethanol contains 95 % by volume of ethanol and 5% of water. Dehydrating agents can be used to remove the remaining water and produce absolute ethanol. Dehydrated alcohol contains not less than 99.0 percent v/v or 99.0 % w/w, which is not more than 100.0 % v/v or 100.0 % w/w of ethanol and a gram of glucose can be converted to 0.511 grams of ethanol (Poulomi and Arthur, 2011). Currently, microorganisms such as yeast, fungi, and bacteria are playing a wide variety of roles in fermentation industry, pharmaceutical industry, and mining. However, most of the alcoholic fermentations are being carried out using yeast cells. Under anaerobic conditions, yeast can be converted one mole of glucose to two moles of ethanol, and the process can be described as anaerobic organic reactions by yeast cells (Kirdponpattara and Phisalaphong, 2013)

In Brazil alone, around 12 billion Litres of ethanol were produced per year from sugar cane, which is more than the Indian consumption of petrol. In the USA, about 8 billion litres of ethanol were produced per year, which is mostly from corn. Fuel prices are rising due to increase in demand by the populationin the world reported by (Dake et al., 2010).

In India, Government has been trying to add 10 % bioethanol for fullutilization and combustion of petrol and diesel and also to reduce carbon dioxide emissions by 90 % Vilela et al. (2013) reported that the economy bioprocess for the production of bio-ethanol from soybean molasses at laboratory, pilot and industrial scales.

In developed countries, there is a growing trend towards employing modern technologies and efficient bioenergy, which are computed with the fossil fuels in prices. The trend enables the developed countries to contribute towards meeting global reduction in carbon emission. The alternative method of reducing carbon dioxide emission, environment pollution and the dependence on fossil fuels is the renewable bioethanol production (Vilela et al., 2013) The fuels like bioethanol and biodiesel from edible sources replaces nonrenewable fuels (crude oil) are known as the first generation of biofuel and biofuel from non- edible sources are known as the second generation of biofuel. To overcome the obstacles such as environment, technology and cost issues needed introduction of energy policy for implementing and promoting the second generation of bioethanol. In India and in most of the world, ethanol is produced by using conventional batch fermentation under hostile environmental conditions without precise control over fermentation conditions (Bijender et al., 2010).

Fermentation is carried out by a variety of microorganisms such as fungi, bacteria, and yeasts. S. cerevisiae is one of the widely studied and used yeasts at both industry and household levels. S. cerevisiae has generated ethanol as its main fermentation product. S. cerevisiae is superior to bacteria, other yeasts, and filamentous fungi in various physiological characteristics regarding ethanol production in industrial context. It tolerates a wide range of pH (Lin et al., 2012). with acidic optimum (Ortiz-Mu˜niz et al., 2010), which makes its fermentation less susceptible to infection than bacteria. It also tolerates ethanol better than other ethanol producing microorganisms (Jutakanoke et al., 2012). S. cerevisiae is GRAS (generally regarded as safe) for human consumption which enhances its advantageous utilization more than other yeasts and microorganisms. This paper reviews the current trends of ethanol production using S. cerevisiae from different perspectives such as substrates, inhibitors reduction in biomass hydrolysates, growth variables, co-culturing it with other microbes, and different immobilization techniques."