THERMOELECTRIC POWER FOR OCEANOGRAPHIC RESEARCH 
by MELVIN BARMAT, Manager, Thermoelectric Division 
General Instrument Corporation 
Newark, New Jersey 
The utility of thermoelectric generators in 
oceanographic research is outlined. The 
history and basic technology of thermoelec- 
tricity are briefly reviewed and generators 
currently being developed for oceanographic 
service are mentioned. 
Much of modern oceanograp.iic research is 
conducted by the collection and transmission 
of data over long periods of time from 
unmanned stations. Furthermore, it appears 
that this trend is increasing in use. There 
are many potential missions in this category, 
but to mention a few--- 
1. anchored buoys with weather and 
oceanographic instrumentation 
2. bottom mounted instruments for 
current measurement and recording 
3. freely moving buoys for following 
currents 
One of the most critical components of 
these systems is the source of power. A 
power supply for these missions must have: 
long life 
high reliability 
low volume 
freedom from environment 
low cost 
oannowpn 
Thermoelectric generators now being 
developed for various government agencies 
give great promise towards fulfilling these 
requirements. Before describing these new 
developments I would like to briefly provide 
some background in thermoelectricity. 
In 1823, Johann Seebeck reported to the 
Prussian Academy of Sciences his discovery 
of a magnetic field when a temperature dif- 
ference was applied tc the junctions of dis- 
similar metals. This magnetic field was, of 
course, due to the current developed by the 
generated voltage. Eleven years later, in 
1834, Peltier announced his discovery that 
heat was developed or removed at a similar 
junetion when a direct current electrical 
potential was applied. These have been 
classified as "thermoelectric" effects 
(See figures 1 and 2) For over fifty years 
these phenomena remained only laboratory 
curiosities, the physicist had too many other, 
more promising phenomena to explore. How- 
ever, in this first half of the present 
century the thermcelectric phenomena was 
widely applied for temperature measurement, 
in fact it remains today the most important 
method for scientific and industrial temp- 
erature measurement. 
It had been recognized for many years 
that these thermoelectric effects could be 
used for electrical power generation if a 
temperature difference were maintained 
between the junctions, or as a heat pump if 
electrical energy was applied to the system. 
However, it was not until the pioneering 
work of Maria Telkes in the U.S.A. and A.F. 
Ioffe in the U.S.S.R. that intermetalic 
semiconductor materials were utilized, 
resulting in the potentiality of achieving 
useful efficiency levels. It has been the 
growth of knowledge of semiconductors that 
has given the impetus tc an even more wide- 
spread scientific and industrial interest in 
thermoelectricity. In this country there is 
considerable government supported research 
in the field of material and device develop- 
ment, due to potential applications as 
diverse as submarines and satellites. 
Why has this later work been so fruitful 
as compared to the earlier 130 years? It is 
the result of a happy coincidence; the 
previously mentioned development of solid 
state physics and semiconductor technology 
coupled with a genuine industrial, commer- 
cial and military need for the kind of 
devices thermoelectricity makes possible. 
Understanding of the reasons for the sreatly 
advanced thermoelectric utility of semi- 
conductors will enable us to obtain insight 
into thermoelectric material requirements. 
The properties of a thermoelectric mater- 
ial that govern its performance are: 
©f Seebeck Coefficient - expressed as 
volts per unit temperature differ- 
ence, usually microvolts/°C. 
© Electrical resistivity, usually ohm-cm 
K Thermal conductivity, usually watts/ 
om°C. 
A thermoelectric generator, schematically 
shown in Figure 3 consists of a heat source, 
a cold dump, and a thermocouple (in normal 
practice, a number of thermocouples in 
series). This device, to be efficient, 
requires a high output voltage, therefore 
