Third World Electric Generator: Electricity from Excess Heat

Group 22Sung Hoon Bae (BME)Daniel Rim (ChBE)Chris Zachara (ChBE)Advisor: Dr. David OwensOwen 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://upload.wikimedia.org/wikipedia/en/f/f2/Bangladesh_(orthographic_projection).svghttp://en.wikipedia.org/wiki/File:Flag_of_Bangladesh.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)

Objective

Generate electricity Household scale generator “Reasonable” retail price Sufficient output electricity

LED light

http://www.odec.ca/projects/2007/sidd7g2/Images/appelectricty.gifhttp://image09.webshots.com/9/2/10/75/112721075ZEGbyv_fs.jpghttp://www.ct.gov/opapd/lib/opapd/newsletter-pics/dollar2520squeezed.jpg

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 Value Product Value Product Value Product Value Product

Cost 5 4 20 5 25 3 15 4 20 4 20

Durability 4 4 16 5 20 4 16 4 16 5 20

Reliability 3 4 12 4 12 2 6 3 9 5 15

User Friendly

3 3 9 5 15 5 15 3 9 5 15

Efficiency 3 2 6 2 6 3 9 2 6 1 3

Quality 3 2 6 1 3 5 15 1 3 4 12

Portability 2 5 10 5 10 5 10 5 10 5 10

Flexibility 5 1 5 0 0 3 15 2 10 4 20

Total 　 　 84 　 91 　 101 　 83 　 115

Brainstorming

Electric Generation

Turbine system

Thermoelectric generation

Solar panel

Manual

Stirling generator

Efficient only in large scale Expensive

Emerging Technology

Well understoodLow efficiency

Keeps improving

Relatively expensive

Great flexibility

Unlimited energy source

Sun as energy source

Weather dependent

Expensive

Cheap

Uses any kind of heat

ExpensiveComplicated

Simple design

No moving parts

User friendly

No moving parts

But not user friendly

Simple design

User friendly

Complicated design

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

Thermal Grease

Pressurized attachment

Coated with black color for maximum heat absorption

Components• TEG• Heatsink• Thermal grease

Pressurized attachment

Initial Design: Part 2

LED

Control

Batte

ry

Storage Unit

Components Batteries

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

Initial Design:

LED

Heat Source

Control

Batte

ry

Heatsink

Generating Unit

Storage UnitThermal Grease

Rechargeable

Portable

Convection

Current Work: testing Part 1 of our design

Tc

Th

30mm

30m

m

Thermal GreaseHeatsink

TEGΔT

V

ΔT

time

ΔT

I

Determine ideal operating temperature gradient

Check heatsink performance

Determine expected power generation

Possible Heat Sources Biogas Lamps

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