The document describes the design and testing of a simple and low-cost thermoelectric generator made of aluminum and graphite strips. The generator is based on the Seebeck effect to convert heat directly into electricity. Testing showed that increasing the temperature difference between the hot and cold junctions and the number of couples increased the generated voltage. Wider and taller strips also led to higher voltages. Future work could introduce better cooling and new materials to minimize heat transfer and make the design more portable.

1. AAlluummiinnuumm –– GGrraapphhiittee
TThheerrmmoo--eelleeccttrriicc GGeenneerraattoorrss
Charith S Suriyakula
Faculty of Applied Sciences
Rajarata University of Sri Lanka

2. Simple theory
Simple technology
Low cost
Robust

3. FFoorr wwhhaatt..........??
• Fossil fuel is a limited resource of Earth. Fossil fuels are non-renewable
and is a finite resource.
• To meet the power demand of the world, people have to
discover renewable energy sources.
• Using fossil fuel is damaging the environment and also it is
expensive

4. 2012 world electricity generation pie chart, from BP Statistical Review of
World Energy 2013

5. RReenneewwaabbllee eenneerrggyy ssoouurrcceess
• Main source is sunlight. Also known as Solar energy
o Can directly use to light, heat homes and other buildings.
o Can be used to generate electricity
o Hot water heating
• Wind energy is captured by wind turbines to generate
electricity
• Hydro power is used to rotate turbines and generate
electricity
• Some alternative energy generation method
o Geo-thermal energy
o Thermo-electricity

6. WWhhaatt wwee nneeeedd…………??
HHeeaatt eenneerrggyy ffrroomm aannyy ssoouurrccee………………
• Mechanical engines, computers
• Stoves, lamps
• Sun light
• Radio active elements…….

7. HHeeaatt  EElleeccttrriicciittyy ??
• Seebeck effect is the phenomenon
of inducing electricity from heat
• It was first discovered by Thomas
Seebeck in 1821
• Modern technology use
semiconductor materials to design
TEG devices

8. • To design and develop a low-cost and low-tech
thermo-electric generator module.
Glass slides
plastic
Copper wires
wood
aluminum
adhesives
paper

9. Seebeck coefficients ooff ssoommee ccoommmmoonn mmeettaallss
Metal / Alloy Seebeck Coefficient (μV/K)
compared to Platinum
Semiconductor Seebeck Coefficient
(μV/K) compared to
Platinum
Antimony 47 Se 900
Nichrome 25 Te 500
Cadmium 7.5 Si 440
Gold 6.5 Ge 300
Silver 6.5 n-type Bi2Te3 -230
Copper 6.5 p-type Sb2te3 185
Lead 4.0 PbTe -180
Aluminum 3.5 Pb06Ge39Se58 1670
Carbon 3.0 Pb15Ge37Se58 -1990
Mercury 0.6 PbBi4Te7 -53
Platinum 0 SnSb4Te7 25
Sodium -2.0 SnBi4Te7 120
Bismuth -72 SnBi2Sb2Te7 151

12. • The following factors were considered when designing
o Minimized Heat conductivity from “hot” junction to “cold” junction.
o Maximized temperature difference between “hot” and “cold”
junctions
o The contact points of two materials needs to be clearly specified.
o More couples = more power

13. • More couples in a single glass slide.
• Still the contact points were not clearly visible.

14. • The aluminum and graphite strips are
connected using “L” shaped contact area.

17. RReessuullttss

20. DDiissccuussssiioonn Strip width comparison
Cell # Aluminum Graphite Number
of
junctions
Hot
Junction
Temp.
(0C)
Cold
Junction
Temp.
(0C)
Room
Temp.
(0C)
Generated
voltage
(mV)
Total
resistance
(kΩ)
Width
(cm)
Height
(cm)
Width
(cm)
Height
(cm)
05 0.5 3 0.5 3 4 37 22 29 0.24 45.6
0.5 3 0.5 3 4 45 24 29 0.52 50.4
0.5 3 0.5 3 4 54 26 29 0.78 55.2
0.5 3 0.5 3 4 67 28 29 1.27 60.1
13 1.0 3 1.0 3 4 43 23 28 0.26 39.7
1.0 3 1.0 3 4 54 27 28 0.58 47.6
1.0 3 1.0 3 4 98 42 28 2.1 48.1

22. Cell # Aluminum Graphite Number
of
junctions
Hot
Junction
Temp.
(0C)
Strip height comparison
Cold
Junction
Temp.
(0C)
Room
Temp.
(0C)
Generated
voltage
(mV)
Total
resistanc
Width Height
Width
Height
e (kΩ)
(cm)
(cm)
(cm)
(cm)
13 1.0 3 1.0 3 4 43 23 28 0.26 39.7
1.0 3 1.0 3 4 54 27 28 0.58 47.6
1.0 3 1.0 3 4 98 42 28 2.1 48.1
15 1.0 2 1.0 2 4 82 38 28 2.01 21.6
1.0 2 1.0 2 4 90 39 28 2.1 54.8
1.0 2 1.0 2 4 103 46 28 2.52 62.9
1.0 2 1.0 2 4 114 51 28 3.0 92.8

24. • Generated per couple voltage increases with the
temperature difference between two junctions.
• Theoretically this is a linear relationship.
• Some reasons for the variation with the practical graph
o Unevenly distributed graphite powder
o Contact between the tow materials
• Temperature difference between the ‘hot’ and ‘cold’
junctions play an important role in generating a higher
voltage.

25. FFuuttuurree ddeevveellooppmmeennttss
• Introducing a proper cooling mechanism for the ‘cold’
junction.
• Experimenting on different materials to make the design
more portable and to minimize the heat conductivity
between the two junctions.
• Making the module more durable.

26. AAcckknnoowwlleeddggeemmeenntt
• Dr. Deepal Subasinghe of Institute of Fundamental Studies,
Kandy for the opportunity given to conduct the project.
• Senior colleagues of Department of Earth Sciences,
Institute of Fundamental Studies, Kandy for the continuous
support and guidance given throughout the project.
• Dr. T. M. W. J. Bandara of Faculty of Applied Sciences,
Rajarata University of Sri Lanka for the constant advice
given to make this project a success.

27. RReeffeerreenncceess
• 1. Van Herwaarden, A. W., & Sarro, P. M. (1986). Thermal sensors based on the Seebeck
effect. Sensors and Actuators, 10(3), 321-346.
• 2. Harman, T. C., Cahn, J. H., & Logan, M. J. (1959). Measurement of thermal conductivity
by utilization of the Peltier effect. Journal of Applied Physics, 30(9), 1351-1359.
• 3. Iue.tuwien.ac.at. 2013. 3.5.12 Seebeck Coefficient. [online] Available at:
http://www.iue.tuwien.ac.at/phd/mwagner/node47.html [Accessed: 20 Sep 2013].
• 4. Douglas-self.com. 2013. Thermo-Electric Generators. [online] Available at:
http://www.douglas-self.com/MUSEUM/POWER/thermoelectric/thermoelectric.htm
[Accessed: 20 Sep 2013].
• 5. Thermoelectrics.caltech.edu. 2013. History of Thermoelectrics. [online] Available at:
http://www.thermoelectrics.caltech.edu/thermoelectrics/history.html [Accessed: 20 Sep
2013].
• 6. Kasap, S. (2001). Thermoelectric effects in metals: thermocouples. Canada: Department
of Electrical Engineering University of Saskatchewan.