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 http://www.bme.vanderbilt.edu/srdesign/2009/group22/ BME 273: Oral Report #3

Problem Statement Bangladesh Large population/high poverty rate Population: 162 Million – 7th GDP (PPP): $1,500 per capita – 153rd http://en.wikipedia.org/wiki/File:Flag_of_Bangladesh.svg http://upload.wikimedia.org/wikipedia/en/f/f2/Bangladesh_(orthographic_projection).svg

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 2002-2008 Slow progression

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.

Objective Generate electricity Household scale generator “Reasonable” retail price Sufficient output electricity LED light http://www.ct.gov/opapd/lib/opapd/newsletter-pics/dollar2520squeezed.jpg http://image09.webshots.com/9/2/10/75/112721075ZEGbyv_fs.jpg http://www.odec.ca/projects/2007/sidd7g2/Images/appelectricty.gif

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

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

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

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

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

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

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.

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)

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

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

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

Current Work: testing Part 1 of our design V 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

Possible Heat Sources Biogas Lamps Biogas Stoves Efficiency only 1.2-2.0 lm/W Consume 120 to 150 L Biogas daily Rely on incandescent metals heated to 1000-2000°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

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 $

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

References Department of Economic and Social Affairs Population Division (2009) (.PDF). World Population Prospects, Table A.1. 2008 revision. United Nations. <http://www.un.org/esa/population/publications/wpp2008/wpp2008_text_tables.pdf>. Retrieved 2009-03-12. "Bangladesh". <International Monetary Fund. http://www.imf.org/external/pubs/ft/weo/2009/02/weodata/weorept.aspx?sy=2006&ey=2009&scsm=1&ssd=1&sort=country&ds=.&br=1&c=513&s=NGDPD%2CNGDPDPC%2CPPPGDP%2CPPPPC%2CLP&grp=0&a=&pr.x=35&pr.y=9. Retrieved 2009-10-01>. <http://web.worldbank.org/WBSITE/EXTERNAL/EXTABOUTUS/IDA/0,,contentMDK:21387765~menuPK:3266877~pagePK:51236175~piPK:437394~theSitePK:73154,00.html>. <http://www.geni.org/globalenergy/library/national_energy_grid/bangladesh/index.shtml>. . http://www.malmberg.se/module.asp?XModuleId=14085 http://www.stefanv.com/electronics/using_nimh.html http://www.tegpower.com/products.html