The use of bioethanol can reduce our dependence on fossil fuels while reducing net emissions of carbon dioxide, the main greenhouse gas [1]. The feedstock used for biofuels has been categorized into three major groups, cellulose biomass, sugar, and starchy crops, and oil-producing plants. Interest is currently focused on the first group also referred to as a biofuel of the second generation. This is because there are conflicts between food production for human and animal consumption in the second and third groups [2].
Brazil and the US together accounted for about 60.0% of the world ethanol production exploiting sugarcane and corn, respectively [3]. However, using these food crops for ethanol production may raise concerns about food security environmental degradation debate, and other issues. Fortunately, there is a growing interest worldwide to develop new and cheaper carbohydrate sources for the production of bio-ethanol [4]. The most attractive feedstock source is the lignocellulosic biomass, from which ethanol or other chemical agents can be produced via scarification and fermentation [5].
Lignocellulosic biomass is the primary and most abundant organic material on the earth which makes it the most promising resource for alternative energy. Among the available lignocellulosic feedstocks, Sugarcane Bagasse s are receiving a renewed interest due to their high growth rate and better reduction of carbon footprint compared to an equivalent area of woody plants [6].
The high overall cost of the cellulosic biofuel supply chain (CBSC) is the principal explanation for this enormous difference between the target and actual output. Researchers and industrial societies have made efforts to reduce the cost of industrialization of cellulosic biofuels using different approaches to tackle this issue, including supply chain optimization and management. A well-planned supply chain can help to promote the adoption of cellulosic biofuel since it has the great potential to enhance economic viability. A typical CBSC consists of five entities: biomass collector, biomass inventory, biorefinery, biofuel storage, and end-product distributor [7]. Many studies have investigated CBSC design and optimization considering multiple aspects, including location selection, feedstock uncertainty, economic performance, transportation, financial risk, and energy consumption [8]– [10].
A number of lignocellulose pre-treatment technologies existed in both laboratory scales and as pilot plants, such as dilute acid, flow-through, ammonia fiber explosion, ammonia recycle percolation, lime, steam explosion, and organosolv (OS) pre-treatment which have suffered from relatively low sugar yields, severe reaction conditions, large capital investment, or high processing costs. Recently, a novel fractionating recalcitrant lignocellulose technology under modest reaction conditions was developed. Based on this technology, three components that existed in lignocellulosic materials will be separated for further use. The cellulose component will be used for ethanol via enzyme scarification and fermentation [11]–[13].
Another barrier or challenge is the absence of robust organisms for ethanol production. Currently, different recombinant strains have been engineered to produce ethanol from lignocellulosic biomass, such as genetically engineered Saccharomyces cerevisiae, Escherichia coli, Klebsiella oxytoca, and Zymomonas mobilis, which provide a basis for constructing an industrially suitable engineered strain on cellulose ethanol industrialization. Among all these strains, Z. mobilis used historically in tropical areas to make alcoholic beverages from plant sap, showed fast growth rates and high specific ethanol production compared with S. cerevisiae. The advantages that Z. mobilis holds over traditional yeast processes have led to more economical methods of producing ethanol. However, its narrow spectrum of fermentable carbohydrates has limited its use, especially for fuel ethanol production from lignocellulosic materials [14], [15].
The exploitation of natural energy resources and the increasing cost of raw materials drive the search for renewable energy sources. Bioethanol is known as an important renewable bioenergy source that may be used to reduce greenhouse gases (GHG) and dependency on fossil fuels. Thus, bioethanol is regarded as a more environmentally friendly fuel than gasoline. Sugarcane bagasse (SCB) is a potentially renewable resource that may be used to produce bioethanol, which is one of the largest cellulosic agro-industrial by-products. Over the last decade, many efforts have been made to achieve maximum hydrolysis and saccharification efficiency to obtain higher yields of fermentable sugar and ethanol from SCB [16].
Therefore, this study investigates Sugarcane Bagasse as the source of carbon and the optimization of the medium for ethanol production. The design expert was employed to screen the effects of different medium ingredients on ethanol yield in order to perform this study and further optimization of the medium was carried out using the response surface methodology.