Production of first generation biofuels using food crops is under criticism over sustainability issues on food security. Tanzania is showing active interest in developing second generation biofuels to deal with some of such issues, especially from the feedstock point of view. This project work determine energy characteristics of rice and coffee husks blend in Nigeria. The results show that coffee husks have better energy quality than rice husks, while heating values of coffee are 18.34 MJ/kg and 13.24 MJ/kg for rice husk. Thermogravimetric analysis made for coffee husks blended rice husks at a ratio of 75 : 25% vol. show better material degradation characteristics yielding low residual mass of 23.65%, compared to 26.50% of char and ash remaining in pure rice husks. Derivative thermogravimetric analysis shows comparable hemicellulose degradation peak values of −11.5 and −11.2 and cellulose −3.20 and −2.90 in pure coffee and rice husks, respectively. In coffee and rice husks blends, substantial reductions of hemicellulose and cellulose peaks were observed. Use of coffee and rice husks blends applying high temperature gasification would reduce the latter’s flammability, while increasing its flame retention characteristics, hence offering opportunities for production of clean syngas in a sustainable manner.
For many years, we have consumed fossil fuels with no worries about possible shortages, but, now, those same oil fields are running dry, while use of coal as a source of energy is also facing criticisms due to its contribution on environmental pollution, D. A. Mwakipesile (2012). In view of this situation, there has been a growing impetus looking for alternative sources of energy for the future. Biomass based second generation biofuels could partly assist to resolve some of these issues, especially from the feedstock point of view for energy production applying various conversion methods to improve the combustion efficiency, Tyebkhan G (2002). The advantages of using biomass are obvious as this material, is generally left to rot or burnt in an uncontrolled manner, producing CO2 as well as smoke.
Most African countries are facing problems of inadequate access to modern sources of energy, P. J. Haines (2002). The United Republic of Tanzania being one of the sub-Saharan African countries is showing active interest in the development of the second generation biofuels, especially from the feedstock point of view to address criticism over sustainability issues as well as arguments on food security arising from the production of 1st generation biofuels derived from food crops materials to replace the current use of petroleum products, P. J. Haines (2002).
Use of biomass materials, referred to as the second generation biofuel, derived from agricultural wastes and forest residue and a number of fast growing trees, and grown specifically for energy purposes, could provide opportunities for nonfood based feedstock materials. Tanzania is endowed with biomass potential for energy production originating from forest plantations and agricultural wastes supported by the already existing infrastructure for their deployment, Tyebkhan G (2002).
The conversion of biomass materials to gaseous or liquid form of energy is known to be easier to handle and make applications. Varied schemes of processes for converting biomass into valuable fuels also exist. These include biological processes to make ethanol or methane and thermal processes to make heat, gaseous fuels, liquid fuels, and solid fuels. During the process, a variety of secondary products can also be produced from the liquid and gaseous fuels. In this form, because of added value, the derived fuels can be used to produce electricity.
This paper reports on work done to determine the energy characteristics of selected agricultural residues originating from rice and coffee husks. The study conducted thermogravimetric analysis to obtain information on thermodegradation behaviour of the biomass materials and their main components (hemicellulose and cellulose). Use of the derivative thermogravimetric (DTG) analysis has also been made in order to establish materials suitability for the production of clean syngas for electricity generation in a sustainable manner applying high temperature gasification technology.
1.2 AIMS AND OBJECTIVES
This main aim and objectives of this study is outline below:
1. Production of bio-fuel from rice and coffee husk
2. The energy characteristics of selected agricultural residues originating from rice and coffee husks
3. The study conducted thermogravimetric analysis to obtain information on thermodegradation behaviour of the biomass materials and their main components (hemicellulose and cellulose)
4. Use of the derivative thermogravimetric (DTG) analysis in order to establish materials suitability for the production of clean syngas for electricity generation in a sustainable manner applying high temperature gasification technology.
1.3 STATEMENT OF PROBLEM
As wood fuel supplies diminish, the people who depend on wood fuels are suffering increase in physical or economic burdens in maintaining even a minimal dailyfuel supply. The use of firewood and misuse of the existing energy resources (agricultural residues) is creating human and environmental crisis in developing countries which is resulting in deforestation. Traditionally, wood in form of fuel wood, twigs and charcoal has been the major source of renewable in Nigeria, accounting for about 51% of the total annual energy consumption; the other sources of energy include natural gas (5.2%), hydroelectricity (3.1%), and petroleum products (41.3%) (Akinbami, 2001).
1.4 SCOPE OF THE STUDY
The study is focus on the analysis of energy characterization of rice and coffee husk blend in Nigeria. The project will be guided by both objective and analysis of literature review on survey and experimental research conducted on the characterization of rice and coffee husk.
1.4 SIGNIFICANCE OF THE STUDY
The study is significance because it shows that:
• Rice and coffee husk is a widely available agricultural waste India produces around 25 million tons of Rice Husk
• It is largely used as a fuel—in small scale, and in large scale for electrical power generation and thermal needs
• Rice husk contains 20 % ash and leaves large amount of residue (about 25 %) after it is burnt causing a disposal problem
• Silica is the main constituent of the Rice and coffee husk ash (~ 90 %)
• Precipitated silica is a high value product (Rs. 40 per kg) having applications in rubber, cosmetics, tooth paste and many other industries
• Production of precipitated silica from rice husk thus solves the disposal problem ash and provides additional revenue stream
• This process is cheaper – production cost about Rs. 22 – 24/kg of silica
Finally, students of chemical engineering will also find the work useful as it touches on their area of specialization.
1.5 LIMITATION OF THE STUDY
The major handicap of this study is that of time factor. The time under which this study was carried out was too short for the researcher to do a thorough and more comprehensive research work. This study was done coupled with academic stress and this may have resulted in some minor faults in the study. Financial problem, Ability to raise money for the project work was a big challenge.