In this study, the utilization of waste coffee residue for biodiesel production, its solid byproduct after oil extraction for bioethanol production, as well as the second byproduct after bioethanol production for solid fuel and compost production was investigated. For the study, waste coffee residue sample was collected from TOMOCA PLC, Addis Ababa, Ethiopia. The oil was then extracted using n-hexane and resulted in oil yield of 19.73 %w/w. The biodiesel was obtained by a two-step process, i.e. acid catalyzed esterification followed by base catalyzed transesterification using catalysts sulfuric acid and sodium hydroxide respectively. The conversion, after esterification of waste coffee residue oil in to biodiesel, was about 80.4%. Various parameters that are essential for biodiesel quality were evaluated using the American Standard for Testing Material (ASTM D 6751- 09). The results obtained for kinematic viscosity (5.3 mm²/s), carbon residue (0.033%), flash point (222°C), ash content (0.0123%), water and sediment (<0.01%), iodine value (73.41 gI2/100g), acid value (0.78), copper striping corrosion (1a) and calorific value (38.4 MJ/kg) revealed that all quality parameters are within the range specified except for acid value. The fatty acid composition of the biodiesel was also analyzed by Gas chromatography and the major fatty acids found were linoleic acid (39.8%), palmitic acid (37.6%), oleic (12.7%), and stearic acid (7.6%). In addition, the solid waste remaining after oil extraction was investigated for possible use as a feedstock for the production of bioethanol. Hydrolysis of the spent was carried out using dilute sulfuric acid followed by fermentation using S. cereviciae, and resulted in bioethanol yield of 8.3 %v/v. Furthermore, the solid waste remaining after bioethanol production was evaluated for compost and solid fuel applications. The result indicated that the processed coffee residues could still be used as compost (21.9:1 C/N) and solid fuel (20.8 MJ/Kg). Therefore, the results of this work may suggest a new insight to production of biofuel from waste materials.
Keywords: Waste coffee residue, Biodiesel, spent of WCR, Saccharomyces cereviciae, Bioethanol, solid fuel, compost
Table of Contents
1. INTRODUCTION
1.1. Background and justification
1.2. Problem of the statement
1.3. Objectives
1.3.1. General objective
1.3.2. Specific objectives
1.4. Significance of the study
2. LITERATURE REVIEW
2.1. Overview of Ethiopia’s Energy Sector
2.2. Introduction to biodiesel
2.3. Biodiesel production
2.3.1. The Transesterification (alcoholysis) Process of Biodiesel
2.3.1.1. Catalytic transesterification
2.4. Variables Affecting the Transesterification Process
2.4.1. Effect of free fatty acids (FFA) and moisture
2.4.2. Effect of Alcohol/oil Molar Ratio and Alcohol Type
2.4.3. Type and Amount of Catalyst
2.4.4. Reaction Time and Temperature
2.5. Parameters which define the fuel quality of biodiesel
2.5.1. Density (15 °C)
2.5.2. Viscosity (40 °C)
2.5.3. Gross calorific value
2.5.4. Cloud point (CP)
2.5.5. Cetane Number
2.5.6. Iodine Value (IV)
2.5.7. Flash point
2.5.8. Water and sediment
2.5.9. Carbon Residue
2.5.10. Sulfated ash
2.5.11. Acid value
2.6. Coffee production and Waste coffee residues
2.6.1. Coffee production in Ethiopia
2.6.2. Waste Coffee Residues (WCRs)
2.6.2.1. Chemical composition of WCR
2.7. Advantages and Disadvantages of Biodiesel
3. MATERIALS AND METHODS
3.1. Materials and chemicals
3.2. Experimental
3.2.1. Waste coffee residue (WCR) Moisture content Determination
3.2.2. Waste coffee residue (WCR) oil extraction
3.2.3. Physicochemical parameters of WCRs oil
3.2.3.1. Determination of Saponification Value
3.2.3.2. Determination of Peroxide value
3.2.4. Two-Step Biodiesel Production Process
3.2.4.1. Acid-catalyzed esterification
3.2.4.2. Base-catalyzed transesterification
3.2.4.3. Purification
3.2.5. Biodiesel yield
3.2.6. Characterization of WCR Biodiesel
3.2.6.1. Determination of specific gravity/density (ASTM D1298) by hydrometer method
3.2.6.2. Determination of Kinematic Viscosity (40 °C)
3.2.6.3. Determination of Acid value
3.2.6.4. Determination of Gross calorific value
3.2.6.5. Determination of Cloud point (ASTM D 2500)
3.2.6.6. Determination of Water and sediment
3.2.6.7. Determination of Cetane number
3.2.6.8. Determination of Iodine Value
3.2.6.9. Determination of flash point by Pensky-Martens closed cup tester
3.2.6.10. Determination of conradson carbon residue
3.2.6.11. Determination of Ash content
3.2.6.12. Determination of Copper strip corrosion
3.2.6.13. Determination of distillation characteristics
3.2.7. Fatty acid composition of WCR methyl ester
3.2.8. Production of Bioethanol from the solid waste remaining after oil extraction of WCR (Spent of WCR)
3.2.9. Determination of the quality of the solid residue after Bioethanol production for compost and solid fuel
3.2.9.1. Calorific value
3.2.9.2. Proximate analysis
4. RESULTS AND DISCUSSION
4.1. Oil content of waste coffee residue (WCR)
4.2. Physicochemical characteristics of the extracted WCR oil
4.3. Biodiesel yield of WCR oil
4.4. Waste Coffee Residue methyl ester Fuel properties
4.4.1. Density (15 °C)
4.4.2. Kinematic viscosity (40 °C)
4.4.3. Gross calorific value
4.4.4. Cloud point
4.4.5. Acid value (AV)
4.4.6. Cetane number
4.4.7. Iodine Value
4.4.8. Water and sediment
4.4.9. Distillation Temperature
4.4.10. Ash content
4.4.11. The Conradson Carbon residue of waste coffee residue ester
4.4.12. Flash point
4.4.13. Copper corrosion
4.5. Fatty acid composition of WCR Biodiesel
4.6. Bioethanol yield from solid waste remaining after oil extraction of WCR (Spent of WCR)
4.7. Solid fuel and compost from the WCR after Bioethanol production
4.7.1. Solid waste remaining after Bioethanol production for solid fuel
4.7.2. Solid waste remaining after Bioethanol production for compost
5. CONCLUSION AND RECOMMENDATIONS
5.1. Conclusion
5.2. Recommendations
Objectives and Scope of the Study
This study aims to investigate the utilization of waste coffee residue as a sustainable raw material for the production of biodiesel, bioethanol, and secondary solid products, addressing the need for cost-effective, non-food-based feedstocks to reduce energy dependency and environmental impact.
- Extraction and optimization of oil from waste coffee residue.
- Physicochemical characterization and quality analysis of the produced biodiesel against international standards (ASTM D6751).
- Production and yield evaluation of bioethanol from the solid waste remaining after oil extraction.
- Assessment of the residual solid waste for potential applications as solid fuel and compost.
- Determination of the fatty acid composition to evaluate the potential for industrial fuel applications.
Excerpt from the Book
1.1. Background and justification
In recent times, the world has confronted with crises of increased demand for energy, price hike of crude oil, global warming due to emission of green house gases, environmental pollution, and fast diminishing supply of fossil fuels (Atadashi, et al., 2011; Miguel and Calixto, 2009). The indiscriminate exploration and consumption of fossil fuels has led to a reduction in petroleum reserves (Miguel and Calixto, 2009).
Our reliance on these energy sources threatens energy security and influence economic growth especially in fuel importing countries like Ethiopia. About all of Ethiopia’s liquid fuel requirements are imported in the form of refined petroleum products (Alemayhu, 2007). This external energy supply is unsteady and has become a burden to the rapidly growing national economy. In addition, diesel powered motor vehicles in the road transport sector are an important contributor to the total gas emissions in the urban cities (Christoffel, 2010). From the point of view of global environment protection and the concern for long-term supplies of conventional diesel fuels, it becomes necessary to develop alternative fuels comparable with conventional fuels. Alternative fuels should be, not only sustainable but also environmentally friendly (Miguel and Calixto, 2009). Some of the most notable alternative sources of energy capable of replacing fuels (Miguel and Calixto, 2009) include amongst others: water, solar and wind energy, and biofuels (Atadashi et al., 2011). A potential diesel oil substitute is biodiesel (Miguel and Calixto, 2009).
Biodiesel is a new energy source that has grown in importance over recent years. Nowadays, used vegetable oils are potential renewable sources for the production of biodiesel as an alternative to petroleum based diesel fuel, which is derived from diminishing petroleum reserves and which has environmental consequences caused by the exhaust gases from diesel engines (Maceiras et al., 2009). Biodiesel has several benefits such as a diminution in greenhouse gas emissions: it reduces emissions of carbon monoxide by about 50% and emissions of carbon dioxide by about 78% (Sheehan et al., 2008). In addition, biodiesel is produced from a variety of vegetable oils (such as soybean, rapeseed and sunflower) and animal fats, and can be used in diesel engines blended with petroleum diesel or on its own (Sánchez et al., 2012).
Summary of Chapters
1. INTRODUCTION: This chapter outlines the global energy crisis and justifies the need for alternative fuels, identifying waste coffee residue as a promising, sustainable feedstock for biofuel production in Ethiopia.
2. LITERATURE REVIEW: This section provides an overview of Ethiopia's energy sector and details the scientific principles of biodiesel production, including transesterification processes, catalyst types, and key parameters for fuel quality.
3. MATERIALS AND METHODS: This chapter describes the experimental setup, including the extraction of oil from waste coffee, the two-step biodiesel production process, and the analytical methods used to characterize the fuel properties and bioethanol yield.
4. RESULTS AND DISCUSSION: This chapter presents the experimental findings regarding oil yield, the physicochemical properties of the biodiesel produced, and the evaluation of residual waste for bioethanol, compost, and solid fuel applications.
5. CONCLUSION AND RECOMMENDATIONS: This chapter summarizes the successful conversion of waste coffee residue into biodiesel and bioethanol, concluding that it is a viable feedstock, while suggesting further research into commercial scalability.
Keywords
Waste coffee residue, Biodiesel, spent of WCR, Saccharomyces cereviciae, Bioethanol, solid fuel, compost, Transesterification, Feedstock, Fuel properties, Lipid extraction, Renewable energy, ASTM standards, Acid value, Calorific value.
Frequently Asked Questions
What is the primary focus of this research?
The research focuses on evaluating waste coffee residue (WCR) as a renewable, low-cost raw material for the production of biodiesel and exploring the potential for converting the remaining solid waste into bioethanol, solid fuel, and compost.
What are the central thematic areas of the study?
The central themes include renewable energy, waste management, biodiesel synthesis via transesterification, fermentation for bioethanol production, and the physicochemical characterization of waste-derived biofuels.
What is the main objective of the thesis?
The primary objective is to investigate the feasibility of using waste coffee residue as a sustainable feedstock for biodiesel production and to maximize resource recovery by converting the byproduct into other useful energy forms.
Which scientific methods were employed?
The study utilized chemical oil extraction (soxhlet), a two-step acid-catalyzed esterification and base-catalyzed transesterification process for biodiesel, hydrolysis and fermentation with S. cerevisiae for bioethanol, and various ASTM standard laboratory tests for fuel quality analysis.
What is addressed in the main body of the work?
The main body covers the literature on energy needs, detailed experimental procedures for oil extraction and conversion, analytical results of the produced biodiesel and bioethanol, and an analysis of the leftover solid waste for secondary applications.
What are the key terms that characterize this work?
Key terms include Waste coffee residue, Biodiesel, Bioethanol, Transesterification, Saccharomyces cerevisiae, Fuel properties, and solid fuel applications.
How did the author handle the high acidity of the coffee oil?
The author implemented a two-step production process, beginning with an acid-catalyzed esterification to reduce the high free fatty acid content before proceeding to base-catalyzed transesterification, ensuring better conversion efficiency.
What does the study conclude about the use of waste coffee residue for compost?
The study concludes that the solid waste remaining after bioethanol production possesses a carbon-to-nitrogen (C/N) ratio of approximately 21.9:1, which makes it a highly suitable feedstock for composting.
- Quote paper
- Mebrahtu Haile (Author), 2014, Biofuels. Sequential volarization of waste coffee grounds to Biodiesel, Bioethanol, and solid fuel, Munich, GRIN Verlag, https://www.grin.com/document/274372
