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Design of Scalable Biogas Digester for the Developing World. By: Tiffany Cheng, Thomas Davis Dawn Schmidt, Kyle Schroeder, Andrew Wu BME 272- Senior Design Project 12/1/09 Advisors: Dr. Dave Owens – Owen Graduate School of Management - PowerPoint PPT Presentation
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Design of Scalable Biogas Digester for the Developing
World
By: Tiffany Cheng, Thomas DavisDawn Schmidt, Kyle Schroeder, Andrew Wu
BME 272- Senior Design Project12/1/09
Advisors:Dr. Dave Owens – Owen Graduate School of Management Dr. Paul King – Vanderbilt University School of Engineering
Current Issue• In Bangladesh and other third-world countries:
– Poor waste management• Human health• Environment destruction
– Costly energy resources
• Potential solution: Biogas– HOWEVER, currently not
affordable for these countries
http://water1st.org/waterlog/wp-content/uploads/2009/05/hanging-latrine-480x480.jpg
Objective
• Design a scalable biogas digester that is an appropriate technology for Bangladesh in order to:– Improve human health– Protect environment– Provide affordable and accessible energy
Design Requirements
• Two primary foci– Biogas instrument design – Target population
Biogas Instrument
• Materials– Long life span
• At least 5 years
– Durability• Pressure • Temperature
– Gas permeability– Affordability and availability
Biogas Instrument
• Structure– Size
• Location • Gas capacity
– Simplistic design• Little or no training required• Simple repairs and installation
Target Population Considerations
• Cultural perspectives– Human waste– Risk averse population (needs proof)
• Socioeconomic status– Average income/family = ~$60/month
• Size of average family– 6 people (4 children)
• Degree of education– Related to ability to build and maintain digester
Goals
• Overall Goal is to provide cheap energy to the people of Bangladesh– Create a viable energy source
• One meal
– Provides economic incentive for waste management
• Pathogen free high quality fertilizer
Factors
• Economical Issues will be determining factors for the success of the product– Cost of labor, cost of materials, cost of energy
produced
• Environmental factors will affect the energy produced– Temperature, soil condition, location
Performance Metrics
• The main goal is to create a viable working product– Therefore economics will be the governing
theory in determining the success of the product
• Cost vs. benefits
Past Work
• Weekly meetings with Dr. David Owens and business students from Owen
• Met with Dr. Musaazi to learn about appropriate design for developing world
• Created survey to verify and refine current design specifications
• Researched current biogas digester solutions
Fixed-dome Plant Size: 5-200 m3
• Pro:– Potential underground construction– Low cost– No moving parts– Long life spans – Compact
• Con:– Challenging construction – Frequent gas leaks– Fluctuating gas pressure – Gas production not immediately
visible
http://www.gtz.de/de/dokumente/en-biogas-volume2.pdf
Floating Drum Plant
Size: 5-15m3 for small to mid size farms
• Pros: – Constant pressure – Visible gas volume– Generally gas-tight
• Cons:– More expensive– High level of maintenance– Short expected lifetime
http://www.gtz.de/de/dokumente/en-biogas-volume2.pdf
Digester Shapes
• Egg-shaped vessel – Expensive
• Cylinders w/conical covers and bottom – Less favorable
surface-volume ratio
http://www.water-technology.net/projects/reading_sewage/images/Island-Road-2.jpg
http://www.gtz.de/de/dokumente/en-biogas-volume2.pdf
Digester
• Material – Steel
• Pro: Gas-tight; Con: Corrosion
– Concrete • Pro: Unlimited Useful Life, Cheap; Con: Gas-tight
– Plastic • Pro: Gas-tight; Con: Mechanical Stress, UV
radiation
– Masonry• Pro: Easy to Build; Con: Gas-tight
Gas Piping
– At least 60% of failure biogas digester is due to defect in gas piping
– Galvanized Steel Pipe• Standardized
– Plastic Tubing • Inexpensive
– No ferrous metal • biogas is 100% saturated with water vapor and
hydrogen-sulfide
Current Work
• Continuing research of current biogas solutions
• First ideation cycle of potential solutions specific to Bangladesh
Future Work
• Analyze results of survey in Bangladesh to determine true price point and product specifications
• Design sketch prototypes of digester (Dec. 10th – Jan. 14th)
• Select design and begin construction of functional prototype (Jan. 14th – Feb. 15th)
• Test and refine functional prototype (Feb. 15th – Mar. 15th)
• Finalize prototype and collect data (Mar. 15th – Apr. 1st)
Reference Human Development Index, United Nations, 2009
Project Pyramid, Information gathered during 2009 trip to Bangladesh
Van Nes, Wim J. Asia hits the gas. Renewable Energy World. 1:102-111 (2006).
http://www.gtz.de/de/dokumente/en-biogas-volume1.pdf
http://www.gtz.de/de/dokumente/en-biogas-volume2.pdf
http://www.gtz.de/de/dokumente/en-biogas-volume3.pdf
http://www.gtz.de/de/dokumente/en-biogas-volume4.pdf