Abstract
The study was conducted in North Wollo, Mersa-Chekorsa village, Ethiopia in 2006/2007, where animal dung for biogas production is available. The overall objective of the study was to introduce economically feasible, technically acceptable and environmentally friendly biogas plant to the farming community and other potential users in Ethiopia. The research was carried on two types of biogas plants of 3m3 capacity (1) geo-membrane plastic (two single and two double layered) biogas plants constructed below and above the ground surface and (2) fixed-dome biogas plant. Each bio-digesters was fed with a mixture of 75Kg of cow-dung and 75Kg pure water at equal volume and proportion. Amount of gas and slurry were measured using calibrated biogas burner and weight balance respectively. The quality of the slurry (i.e. total-N and organic matter content) were analyzed in the laboratory using Kjeldahl and ash method respectively. The bio-digesters were compared after gas has completely produced at the end of 40 days of fermentation with respect to amount of gas and slurry produced, quality of slurry in terms of total-N and organic matter content. Economic analysis of the bio-digesters was carried out using cost-benefit analysis. The social aspect of using biomass and biogas technologies and environmental impact assessment of the new geo-membrane plastic biogas technology was also assessed. The emissions of CO2 and CH4 were computed by measuring the production of biogas in the two models of bio-digester. Fermented slurry contained larger nitrogen content than fresh cow dung in both models of bio-digester. The geo-membrane plastic biogas plant gave higher net benefit than fixed-dome biogas plant. So, from this, investment on geo-membrane plastic bio-digester is economically feasible. Environmental impact assessment of the technology was studied and found that 360.04 m3 of CO2 and 600.06 m3 CH4 was prevented from emitting in to the atmosphere and save 0.562 hectare of forest per year. Generally, it was found that, the geo-membrane cylindrical film bio-digester technology was found cheap and simple way to produce gas in the study area and it was recommended to introduce the technology into the rural areas having even and high temperature which is similar to the study area more preferably to an area having mean daily temperature greater than 20 OC.
Key words:Geo-membrane ,fixed-dome bio-digester, biogas, quality of fermented slurry,economical feasibility
Table of Contents
1 Introduction
1.1 Background
1.2 Problem Statement
1.3 Purpose of Study
1.4 Hypothesis
1.5 Objective of study
1.5.1 General objective
1.5.2 Specific objective
2 Literature Review
2.1 Fuel Consumption in Ethiopia
2.2 Biomass and Biogas Energy Technologies in Ethiopia
2.3 Theory of Biogas Technology
2.4 Benefits of low-cost Plastic Biodigester Technology
2.4.1 Environmental Benefites of Biogas Technology
2.4.2 Social Benefits of Biogas technology
2.4.3 Economic Advantages of Plastic Biogas Technology
2.4.4 Beneficiaries of Biogas Production
2.5 Input materials of Bio-Gas production
2.6 Biogas Production Process
2.7 Theory of Biogas Burner
2.8 The Slurry after Digestion
2.9 Measurement of Biogas Production
2.10 Designing of Digester
2.11 Working of Fixed-Dome Biogas plant
2.12 Selection and Layout of Pipeline and Biogas Accessories
2.13 Transfer of the plastic film Bio-digester Technology
2.14 Promotion of Fixed and Floating Dome Biogas Plant
2.15 Economic Evaluations of Biogas Plants
2.16 LDPE Geo-membrane Plastic
2.17 Theory of Environmental Impact Assessment (EIA)
3 Materials and Methods
3.1 Description of the Study area
3.1.1 Location
3.1.2 Socio-economic activity
3.1.3 Climate
3.1.4 Land Use
3.1.5 Livestock population
3.2 Experimental Design and Layout
3.3 Geo-membrane plastic construction and methodology
3.4 Data collection procedures
3.4.1 Input to the digester
3.4.2 Measurement of gas production
3.4.3 Temperature of the air and Slurry
3.4.4 Total-Solids(DM) content
3.4.5 The organic dry matter(ODM)
3.4.6 pH of the fresh Cow Dung and Digested Slurry
3.4.7 Quality of output Slurry
3.4.8 The efficiency of Bio-digester
3.4.9 Social aspect of biomass and biogas technologies
3.4.10 The economic Visibility of a plastic and fixed Dome biogas plant
3.4.11 The Environmental Impact of the plastic biogas plant
3.5 Statistical Analysis
4 Result and Discussion
4.1 Operation of Plastic Bio-digester
4.2 Biogas production
4.3 Temperature of the Air and Slurry
4.4 Characteristics of Bio-digested Slurry (Effluent) and the Influent
4.5 Characteristics of Total-N in the Slurry and Influent
4.6 Characteristics of Organic Matter in the Slurry and Substrate
4.7 Characteristics of pH of Fermented Slurry
4.8 Efficiency of the Bio-digester
4.9 Economic Evaluation
4.9.1 Market price of inputs
4.9.2 Market price of inputs
4.9.3 Cost-Benefit analysis of Biogas Plants
4.10 Social aspect of biogas technology
4.10.1 Income generation through increased crop production
4.10.2 Income generation through Cost saving
4.10.3 Perceptions of Habru Woreda People regarding the use of Biomass & Biogas Technology
4.11 Technological aspect of geo-membrane plastic bio-digester
4.11.1 Sustainability
4.11.2 Simple technology
4.11.3 Replicability
4.11.4 Demand driven
4.12 Technical problems with the geo-membrane plastic digester
4.13 Environmental Impact Assessment of the Plastic Bio-digester
4.13.1 Reduction of green house gas emissions
4.13.2 Reduction of rate of deforestation
5 Conclusions and Recommendation
5.1 Conclusions
5.2 Recommendation
Research Objectives and Focus
The primary research objective of this study is to introduce economically feasible, technically acceptable, and environmentally friendly biogas plants, specifically using geomembrane plastic technology, to the farming community in North Wollo, Ethiopia, as an alternative to traditional, cost-intensive biogas systems.
- Evaluation of gas and slurry quantity/quality produced by geomembrane plastic versus fixed-dome biogas digesters.
- Economic viability assessment of different biogas plant models through cost-benefit analysis.
- Environmental impact assessment, focusing on greenhouse gas emission reductions and deforestation mitigation.
- Analysis of social implications, including income generation potential and rural community perceptions of biogas technology.
- Technological performance evaluation of geomembrane plastic digesters in terms of sustainability, replicability, and ease of use.
Excerpt from the Book
3.3 Geomembrane Plastic Construction methodology
The plastic biodigester was constructed with the use of materials like geomembrane plastic, PVC pipes, GI pipes, gate valves, reducers, GI caps, sockets, nipples, neoprene rubber hose and biogas stoves with the help of electrical geomembrane welding machine from Ambasel trading company and CM-43 adhesive with other mixtures from one technician working in North Wollo,GARDO. Three rolls of geomembrane plastic material, was bought from North Wollo, Mersa town. Each rolls of plastic has a dimension of 13 meter width and 13.5 meter length.
The plastics were taken and placed carefully to the work shop of Mersa agricultural T.V.E.T College after the floor has been cleaned. The plastics were cut at a dimension of 7meter length and 4.50meter width. Then, it was welded with the help of electrical plastic welding machine across the length and the circular part of the cylinder was fitted with the help of CM-43 adhesive and with other chemical mixtures. Few number of small openings found in the plastic were closed with the help of vehicle inner tube and the CM-43 chemical mixtures. In this manner two double layered and two single layered cylindrical geomembrane plastic biodigester were made.
Summary of Chapters
1 Introduction: Provides background on energy dependency in rural Ethiopia, highlights the environmental challenges of biomass reliance, and outlines the research objectives for alternative biogas technology.
2 Literature Review: Discusses Ethiopia's energy consumption patterns, theoretical aspects of biogas, and summarizes the environmental, social, and economic benefits of low-cost plastic biodigesters.
3 Materials and Methods: Details the study area characteristics, experimental design including the construction of different geomembrane plastic and fixed-dome biodigesters, and the methodologies for data collection.
4 Result and Discussion: Presents findings on gas production rates, slurry quality, economic evaluation, and environmental impact assessments, comparing plastic biodigesters with traditional fixed-dome systems.
5 Conclusions and Recommendation: Summarizes the study’s findings, confirming the economic and technical superiority of plastic biodigesters, and provides recommendations for policy-driven adoption and further research.
Keywords
Biogas, Geomembrane Plastic, Fixed-dome Digester, Slurry Quality, Fermentation, Cost-Benefit Analysis, Renewable Energy, Ethiopia, Deforestation, Greenhouse Gas Reduction, Rural Development, Sustainable Agriculture, Economic Feasibility, Anaerobic Digestion, Organic Fertilizer.
Frequently Asked Questions
What is the core focus of this thesis?
The thesis focuses on evaluating the viability of low-cost geomembrane plastic biodigesters as a sustainable alternative to traditional fixed-dome biogas plants in rural Ethiopia.
What are the primary thematic areas covered?
The core themes include technical construction, gas production performance, quality analysis of organic fertilizer (slurry), economic viability (cost-benefit analysis), and environmental impacts regarding deforestation and greenhouse gas mitigation.
What is the main objective of the research?
The objective is to introduce and prove the feasibility of an economically accessible, technically efficient, and environmentally friendly biogas technology to farming communities in North Wollo, Ethiopia.
Which scientific methods were employed?
The study used field experiments, laboratory analysis (Kjeldahl and ash methods for nutrient content), and cost-benefit analysis, complemented by open-ended interviews with local farmers.
What is addressed in the main chapters?
The main chapters cover the background and problem statement, a comprehensive literature review, detailed experimental materials and methods, results and technical discussion, and final conclusions with recommendations for future implementation.
What are the primary keywords characterizing this work?
Key terms include geomembrane plastic, biogas, slurry, economic feasibility, renewable energy, rural energy sources, and environmental impact assessment.
How does the geomembrane plastic digester compare to fixed-dome systems?
The study finds the geomembrane plastic model to be more cost-effective, easier to install, and capable of producing a higher amount of gas and better quality fertilizer than fixed-dome systems due to better heat absorption.
What are the environmental impacts mentioned in the research?
The research concludes that these biodigesters significantly reduce reliance on firewood and dried cow dung cakes, thereby preventing deforestation and minimizing greenhouse gas emissions by capturing methane for energy use.
- Quote paper
- Bezabih Yimer (Author), 2008, Biogas Production using Geomembrane Plastic Digesters as Alternative Rural Energy Source and Soil Fertility Management, Munich, GRIN Verlag, https://www.grin.com/document/211838
