1. Third World Electric Generator: Electricity from Excess Heat
Group 22
Sung Hoon Bae (BME)
Daniel Rim (ChBE)
Chris Zachara (ChBE)
Advisor: Dr. David Owens Owen Graduate School of Management
Bae, Rim, Zachara BME 273: Oral Report #3

2. Problem Statement Bangladesh Large population/high poverty rate
Population: 162 Million – 7th
GDP (PPP): $1,500 per capita – 153rd

3. Problem Statement Only 30% electricity distribution (2002)
25% in urban and 10% in rural (2000)
79% of population in rural (1999)
Government efforts
30% to 38% distribution from
Slow progression

4. Rural Bangladesh Families
Average family has 6 members
Typically 4 children
Earn $45 per month, spend $10 on fuel
~2$/month for lighting energy => 24$/yr
<50$ with life span >4 years => save 46$
Total literacy is only 48%
Considerably lower in rural areas
Poverty is major threat to primary education
Lighting is a Basic Need
Status Symbol
Needed for reading (above all else)
Total literacy only %48
Poverty is the major threat to primary education
Typical rural family has 6 people, about 4 children
Lighting in rural areas is a basic need (and status symbol). Above all else they want it for reading.

5. Objective Generate electricity Household scale generator
“Reasonable” retail price
Sufficient output electricity
LED light

6. Design Criteria Cost – cheap product and source of energy
Durability – long lasting materials
Reliability – no moving parts to minimize cause of failure
User friendly – simple design and simple operation
Efficiency – efficiency of converting source energy into light energy
Quality – quality of energy source (higher score for naturally occurring energy source)
Portability – device should be mobile
Flexibility – extent of dependency of the device on external environment

7. Determining Source of Light
Kerosene
Manual (Shake light)
Solar Panel
Biogas
TEG
Weight
Value
Product
Cost 5 4 20 25 3 15
Durability 16
Reliability 12 2 6 9
User Friendly
Efficiency 1
Quality
Portability 10
Flexibility
Total 84 91
101 83
115

8. Brainstorming Electric Generation Turbine system Solar panel
Keeps improving
Weather dependent
Well understood
Unlimited energy source
Low efficiency
Efficient only in large scale
Expensive
Relatively expensive
Sun as energy source
Emerging Technology
Turbine system
Expensive
Solar panel
Complicated design
Thermoelectric generation
Great flexibility
No moving parts
Electric Generation
Simple design
User friendly
Cheap
Manual
No moving parts
Stirling generator
Uses any kind of heat
Simple design
User friendly
Expensive
Complicated
But not user friendly

9. Thermoelectrics
Phenomenon: temperature difference creates electric potential or vice versa
Materials: specially doped semiconductors, most commonly made from Bismuth Telluride
Current Uses: portable refrigeration, electronics cooling

10. Advantages of TEG Less Expensive than Turbine Technology
Utilize Low Grade Heat
Small
Silent
Reliable
No moving parts
No maintenance

11. Challenges of Using TEG
TEG Only 10% Energy Efficient
Other design aspects will be very important
Significant Heat Gradient Needed
The “cold side” must be cooled
Cold side is just mm’s away from heat source

12. Uses of TEG Heat source  Electricity from TEG
Electricity from TEG  battery
Battery powers the LED light
Electricity from TEG has potential to be used elsewhere.

13. LED light Commercial white LED light  65 lm/W at 20mA
4 times as efficient as standard incandescent
Commercially available white LED light are very cheap (exp. $6/6LEDs)

14. Initial Design: Part 1 Heat Source Heatsink Generating Unit
Coated with black color for maximum heat absorption
Heat Source
Pressurized attachment
Thermal Grease
Pressurized attachment
Components
TEG
Heatsink
Thermal grease
Heatsink
Generating Unit

15. Initial Design: Part 2 Components LED Batteries Storage Unit Control
Probably Nickel Metal Hydride (NiMH) Batteries
Relatively constant discharged voltage
More current compared to other batteries
Various capacity available
Control
Current controller
For charging the battery
For powering the LED
LED
Storage Unit
Control
Battery
LED

16. Initial Design: Heat Source LED Storage Unit Heatsink Generating Unit
Thermal Grease
Rechargeable
Control
Battery
LED
Heatsink
Portable
Generating Unit
Convection

17. Current Work: testing Part 1 of our designV
Determine ideal operating temperature gradient
30mm
30mm
TEG Th ΔT I
Determine expected power generation Tc ΔT ΔT
Heatsink
Thermal Grease
Check heatsink performance
time

18. Possible Heat Sources Biogas Lamps Biogas Stoves
Efficiency only lm/W
Consume 120 to 150 L Biogas daily
Rely on incandescent metals heated to °C
Over 90% of energy emitted as heat
10% Efficient TEG could, theoretically, double performance
Biogas Stoves
Can be quite efficient, but still produce excess heat
Heat-to-electricity unit has no additional energy costs

19. Expected Cost and life span
TEG: ~20$/~200,000hrs = 22.8yrs*
Depends on individual TEG device
Heatsink: ~20$/indefinite
Batteries: 10-15$/~4years
Current controller: ???
Thermal grease: ~4$ for multiple uses/indefinite
Total: ~ (60+controller) + α $

20. Future Work
Test and characterize the prototype using different kinds of heatsink
Determine the ideal heat gradient
Determine heat source that can create the ideal temperature gradient
Determine whether a fan could be added to the prototype
Modify hot surface and heat source interface to optimize heat transfer
Contact the other group working on efficient LED light for their specs
Find an appropriate electric storage unit (probably NiMH batteries) along with a control unit – may need to contact EE professor for an advice ASAP
Determine final pricing point and determine economic feasibility

21. References
Department of Economic and Social Affairs Population Division (2009) (.PDF). World Population Prospects, Table A revision. United Nations. < Retrieved
"Bangladesh". <International Monetary Fund. Retrieved >.
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