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HOME > Useful Info > Interesting Stories About Thermoelectricity No.3

Number 3 "It has begun with a camp fire ! ----- Application of thermoelectricity to electric generation"

In this story, I compared early applications of thermoelectric generation with those of quite recent days.

There is thirteen years of time gap between the discovery of Seebeck effect in 1821 and the discovery

of Peltier effect in 1834. This may have affected for the resulting very many trials of thermoelectric

generation in the dawn era of thermoelectricity.

The development of practical device and equipment for thermoelectric generation mainly carried out in

Soviet Union since A.I.Ioffe, a Russian physicist, for the first time, theoretically explained in a book in

1929 that semiconductor thermoelectric material has high thermoelectric performance. The book,

"Semiconductor Thermoelectric Cooling" is called "The Bible of Thermoelectric Semiconductor".

Even if you used semiconductor materials Dr. Ioffe indicated, you could only get efficiency of 2 to 4 %,

however, compared to the conventional metallic material's efficiency of below 0.1%, the theory was

epoch-making !

See Figure 1. The equipment beside a fire cooking something with an odd-shaped pot is a wireless

communication gear. At the bottom of the pot, thermoelectric element couples made of zinc antimony

(ZnSb composite semiconductor) and constantan(CuNi alloy) are installed. The pot was called

"Partisan's canteen" that were used at the World War II(Russo-German War) in Soviet Union at around

1940. A canteen may not be popular for everyone, it is a portable cooking pot usually used by soldiers

or campers in the outdoors. The pot in the illustration is much like home cooking one, a bit different

from a typical curved canteen. The temperature at the bottom of the pot scorched by fire could have

reached to several hundred degrees centigrade, while the temperature of the content of the pot should

have been around 100C, the temperature difference possibly was kept above 200C. To call this

system "a thermoelectric generation" sounds a bit exaggerated, it rather appropriately be called "a

campfire electric generation". Any way, this can truly be admitted the very first practical beginning of

thermoelectric generation.

Page 1 of 5KELK Ltd. > Useful Info > Interesting Stories About Thermoelectricity No.3

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Fig.1 Partisan's Canteen: thermoelectric generation by campfire(ZnSb/constantan thermo-elements)

Fig.2 shows a home kerosene lamp having exhaust-gas pipe(right side illustration), installed with

ZnSb/constantan thermoelectric elements, is attached to the upper part of the lamp where combustion

exhaust gas is going out.

Large cooling fins are fit to this exhaust pipe so that a temperature difference is given to the thermo-

elements to generate electricity. I incidentally have seen this type of lamp like in Fig.2 in the showcase

of Leonardo da Vinci Museum in Milan, Italy.

At the time this lamp was used, Soviet Union introduced thermoelectric generation into their 5-year

plan in 1940s to effectively utilize domestic resources. In this activity, they operated 200-500W

thermoelectric generator as "a generator in the cold regions" using combustion heat of firewood,

gasoline and kerosene in the northern district. The Soviet Union was obviously an advanced country in

thermoelectric generation




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Fig.2 Model TGK-3 thermoelectric generator used for a radio

In 1970s, about 30years later since the practical use of thermo-electric generation in Soviet Union, a

thermo-electric generator such as shown in Fig. 3 was deployed as a battery charger for the United

States Army. This generator, could be operated with gasoline, jet fuel and diesel fuel, had an efficiency

of 3%. Previously mentioned " campfire generator should have had much lower efficiency.

In the structure of the generator in Fig.3, there were a lot of ideas in fuel injector, fan and burner mantle

to efficiently burn fuel and effectively transmit heat to the thermo-elements. As a result, it relatively had

a high efficiency. This generator obviously had advantages with the noise level of one fifth of a

gasoline engine generator and with no maintenance for 1500 hours.

It looks, however, that "campfire generator", should it work well, may be much better for a guerilla war

than the modern one. How about to refine "camp fire generator" to a modernized one ?




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Fig.3 500W portable generator using liquid fuel Lead telluride (PbTe)thermo-element

Fig.4 shows "candle radio" sold around 1990, using iron silicide (FeSi2) thermo-elements produced at

KELK Ltd. This product is undoubtedly an application of thermoelectric generation, but it features a

kind of amusement rather than usefulness. Compared to the previously mentioned "lamp generator", a




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difference of the necessity of the two products, which come from the background of the era and the

technological infrastructure, can be clearly found. Although the product in Fig.4 is almost a hobby,

local government such as city of Tokyo bought some for test use in the preparation for a Tokai Great

Earthquake expected to occur at that time. I have tried to hear the "candle radio" and found I really

could hear NHK program only if I were near the window in our building. But I didn't try to make a

coffee.

Fig.4 Candle Radio

(Note : Many part of this article were written by information referred to "Thermo-electric

Semiconductors and Their Applications" written by Kin-ichi Uemura and Isao Nishida published from

Nikkan Kogyo Shimbunsha in 1988. Fig.1 and Fig.2 are complimentary photos by Kin-ichi Uemura.)

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