The large amount of waste heat produced by power plants and automobile engines can be converted into electricity due to the thermoelectric effect, a physics effect that converts temperature differences into electrical energy. As long as you can maintain temperature difference, it will keep on generating electricity, for that one needs a material with low thermal conductivity. in the poster above, a method to reduce thermal conductivity is proposed which in turn increased the efficiency.

1. Single phase powders of CoSb3,
CoSb2.85Te0.15 and Yb0.075CoSb2.85Te0.15 were
obtained by mechanical alloying. Ceramic
disk of 20 millimetre diameter were
fabricated (relative density >97%) by
Spark Plasma Sintering.
Electrical Conductivity and seebeck
coefficient were measured using Namicro
thermoelectric measurement equipment,
under vacuum and thermal conductivity
were measured using LFA 457, DSC and
density measurement by Archimedes'
Principle.
The objective of our research is to
optimize thermoelectric properties of
CoSb3 by using Phonon Glass Electron
Crystal concept i.e. to reduce thermal
conductivity without affecting electrical
conductivity and seebeck coefficient.
Utilizing Waste Heat for Electricity Generation by
Thermoelectrics‡
Jibran Khaliq1
, Qinghui Jiang1
, Haixue Yan1,2
Kevin Simpson3
, and Michael J. Reece1,2∗
1
School of Engineering and Material Science, Queen Mary University of London, London, E1 4NS, UK
2
Nanoforce Technology Limited, London, E1 4NS, UK
3
European Thermodynamics Limited, Leicester LE8 0RX, UK
∗Email: m.j.reece@qmul.ac.uk, j.khaliq@qmul.ac.uk
3. Objective
6. Conclusion
A very low thermal conductivity of 2.19 W/m.K was observed in
Yb0.075CoSb2.85Te0.15 without affecting electrical conductivity and
seebeck coefficient of CoSb2.85Te0.15. A high zT value of ~0.7 is
reported for Yb doped and Te substituted CoSb3.
1. Motivation
5. Results and Discussions
Schematic of Spark Plasma Sintering (SPS) furnace
More than 60% heat is wasted while burning fuel. This waste heat can be utilized as a
source of free energy. Thermoelectric materials can convert this waste heat from different
sources directly into electricity. Thermoelectric materials are environmentally friendly, have
no moving parts and are light weight, which make them excellent energy harvesting
materials. Their efficiency is represented by dimensionless figure of merit zT which depends
on high electrical conductivity and seebeck coefficient and low values of thermal
conductivity.
School of Engineering and Materials Science
Mars Curiosity Rover: Powering itself
through thermoelectric generator (Photo
Credit: NASA/JPL-Caltech)
Acknowledgement
2. Applications
Cell phone charger: Uses heat from the feet Thermoelectric generator in car: Uses
heat from engine Thermoelectric Cooler
4. Materials and Methods
Sb was substituted for Te in CoSb3
(CoSb2.85Te0.15) to enhance electrical
conductivity and seebeck coefficient.
Two naturally formed cage in the crystal
structure of CoSb3 was filled by Yb
which ‘‘rattle’’ inside the cage to reduce
thermal conductivity only.
Decrease in thermal conductivity
with Yb addition in CoSb2.85Te0.15. No
effect on electrical conductivity and
seebeck coefficient. zT value
increased to ~ 0.7.
Co
Sb
Yb
‡ J. Khaliq et. al Scripta Mater 72-73 (2014) 63-66.