PRODUCTION OF BIOETHANOL FROM ELEPHANT GRASS (PENNISETUM PURPUREUM) STEM

1.1 Introduction

Bioethanol is an alcohol produced by fermenting the sugar components of renewable plant biomass (Keith, 2009). It is made mostly from sugar and starch crops such as sugar cane and corn among others. Bioethanol feedstock can contain either sucrose, starch or a lignocellulosic material (Macedo et al., 2008). The chemical properties of lignocelluloses components make them of enormous biotechnological values for the production of affordable fuel ethanol. Also, it is less expensive than starch and sugar crops and is also renewable and available in large quantities (Aiyejagbara, 2015). Bio-ethanol is ethanol derived from the process of fermentation of biological materials. This is accomplished by the action of micro organism like yeast. Since the micro organism utilizes only simple sugars, starchy and cellulosic materials are first converted into simple sugars by a process of hydrolysis before they are subjected to fermentation.

As a prelude to other parts of this study, this chapter will discuss the background upon which this study was initiated, the statement of problems that led to this study, the Aim and Objectives of the study. Others are Significance of the study, Scope of work, Limitations of the Study and Definition of technical terms.

1.2 Background of Study

The bioconversion of lignocelluloses to biofuel from cheap non-edible materials such as corn cob for renewal energy is imperative. Thus, by varying temperature conditions during the fermentation process, maximum productivity of biofuel on an industrial scale can be optimized. In the brewing industry, production of biofuel is carried out by the fermentation of starchy materials, in which case, sugars are converted into bioethanol with carbon dioxide and water (Hongguang, 2006) as byproducts. For waste plant materials to be valuable, it must be converted to fuel as a sustainable substitute to fossil fuel. Therefore, there is a need for renewable energy resources from non-edible agricultural sources such as corn cob to replace fossil forms. This is because gas emissions from plant feedstock fuel are less than those emitted by fossil forms and thus beneficial to the environment and global warming (Demirbas, 2005; Hongguang, 2006). Bioethanol produced from corn uses only a small part of the plant material, whereby only the starch from the kernel is transformed into bioethanol (Cao et al., 1996).

Several research studies have been carried out on the production of bioethanol from elephant grass through simultaneous saccharification and fermentation of lignocelluloses agricultural wastes by Kluyveromyces marxianus 6556 (Zhang et al., 2009), using Aspergillums Niger and Saccharomyces cerevisae in simultaneous saccharification and fermentation (Zakpaa et al., 2009) and from Lignocellulosic Biomass (Kumar et al., 2009).

Greenhouse gases balance also seems to shift as the production of bio ethanol involves more and more food crops. Some environmental concern shows that bio ethanol production from crops might affect the biodiversity and water preservation. The quest for alternative energies has provided many ways to produce electricity, such as wind farms, hydropower, or solar cells. However, about 40% of the total energy consumption is dedicated to transports and in practice requires liquid fuels such as gasoline, diesel fuel, or kerosene. These fuels are all obtained by refining petroleum. This dependency on oil has two major drawbacks, burning fossil fuels such as oil contributes to global warming and importing oil creates a dependency on oil producing countries (Sadler, 2004).

Again, ethanol produced from biomass would be of great benefit to the transportation sector where it is assumed that two-third of Nigeria's gasoline is consumed. Globally, fossil fuels are being threatened out of dominance over other fuels by the negative effects of fossil fuels products on the environment e.g. The release of greenhouse gases like carbon dioxide that contribute to global warming.

The pollution of air, water, and soil by fossil fuels products (carbon dioxide from fossil fuel combustion accounted for nearly 80% of global warming in the 1990s) (Hileman, 1999). The greatest proportion of the world's energy requirements comes from petroleum exports especially in the Middle East, a region of high political tension, the reasons that necessitate efforts at finding alternatives to fossil fuels. Lignocellulose wastes refer to plant biomass wastes that are composed of cellulose, hemicellulose, and lignin as well as other minor components. Both the cellulose and hemicellulose fractions are polymers of sugars, and are thereby potential sources of fermentable sugars, which can be converted into other products (Ndukwe et al., 2013). Hemicellulose can be readily hydrolyzed under mild acid or alkaline conditions.

Furthermore, the use of lignocellulosic waste offers a possibility of geographically distributed and greenhouse-gas-Favourable sources of products (Rubin, 2008). The Energy Commission of Nigeria reported that the fuel-wood resource constitutes 2.8% of the total renewable energy resources in Nigeria. Biomass reserve in Nigeria is put at 80 %, which equals to an equivalence of 1.645 billion tonnes of energy which is predicted to be potentially available for the next 100 years (Umar et al., 2000). Nigeria started the importation of ethanol from Brazil, and thereafter there was a call to mass produce cassava as a raw material for cellulosic ethanol production.

Therefore, in Nigeria where the research was carried out, the activities that was conducted is to know the Production of Bioethanol from Elephant Grass (Pennisetum Purpureum) Stem used as Fuel for Generating Power.

1.3 Statement of Problems

Investigation reveals that bioethanol include its lower energy density than gasoline (but about 35% higher than that of methanol), its corrosiveness, low flame luminosity, lower vapor pressure (making cold starts difficult), miscibility with water, increase in exhaust emissions of acetaldehyde, and increase in vapor pressure. Ethanol can be produced from biomass by the hydrolysis and sugar fermentation processes. Biomass wastes contain a complex mixture of carbohydrate polymers from the plant cell walls known as cellulose, hemi cellulose and lignin. In order to produce sugars from the biomass, the biomass is pre-treated with acids or enzymes in order to reduce the size of the feedstock and to open up the plant structure (Esru, 2021).

1.4 Aim and Objectives of Study

The aim of the study is to determine the Production of Bioethanol from Elephant Grass (Pennisetum Purpureum) Stem used as Fuel for Generating Power. In achieving this aim, the following specific objectives were laid out as follows:

1. To assess the yield of bioethanol produced from elephant grass
2. To evaluate the effects of process parameters on the yield of bioethanol.
3. To produce ethanol through the fermentation of reducing sugars resulting from the hydrolysis of pretreated elephant grass

1.5 Research Questions

The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:

• Are there effects of process parameters on the yield of bioethanol?
• What is the yield of bioethanol produced from elephant grass?
• What are the fermentation of reducing sugars resulting from the hydrolysis of pretreated elephant grass?

1.6 Significance of Study

Ethanol produced from elephant grass can provide a cleaner environment, environmentally friendly fuel and stimulate community based jobs for our teeming youths and economic growth. Lignocellulosic biomass such as elephant grass, poplar wood, sugar cane bagasse, herbaceous grasses, and municipal wastes provide a unique and sustainable resource for environmentally safe organic fuels and chemicals.

This study will be of immense benefit to other researchers who intend to know more on this study and can also be used by non-researchers to build more on their research work. This study contributes to knowledge and could serve as a guide for other study.

1.7 Scope of Study

The scope of the research is focused on the Production of Bioethanol from Elephant Grass (Pennisetum Purpureum) Stem used as Fuel for Generating Power.

1.8 Limitations of the Study

During the course of this study, many things militated against its completion, some of which are:

1. Time Constraint: The time frame given to accomplish this project was very short due to school academic calendar and it was carried out under pressure which made the researcher not to implement some necessary features.
2. Research material: availability of research material is a major setback to the scope of the study.
3. Frequent power failure: This made the researcher append more money on fuel to ensure sustainable power.
4. Financial Constraint: Insufficient fund tends to impede the efficiency of the researcher in sourcing for the relevant materials, literature or information and in the process of data collection (internet, questionnaire and interview).