Fact Checked

What is a Thermal Converter?

T.F. Johnson
T.F. Johnson

A thermal converter, also known as a thermocouple converter or a thermoelectric generator, is an electronic device that is capable of converting heat energy into electrical energy. Although there are several thermal converter types, they are all based upon the Seebeck effect. The Seebeck effect is a phenomenon in which differences in temperature can be harnessed to generate an electrical current. It was first discovered by Thomas Johann Seebeck in 1826, when he observed that two dissimilar metals can generate an electrical charge as long as the connecting points of the two metals are at different temperatures. It has since been found that the thermoelectric effect generated by these circumstances increases as the difference in temperature does.

One common misconception is that a thermal converter is the same thing as a heat engine. A heat engine converts differences in temperature into mechanical output, while a thermal converter turns temperature differences directly into electrical energy. Also, while heat engines often are more efficient than thermal converters, thermal converters may be preferable in some situations as they are smaller and more compact than most heat engines. The key difference between thermal converters and heat engines is that, unlike most generators, a thermal converter generally has no moving parts, with the exception of a possible cooling fan.

Thermocouples generate voltage that is proportional to the heat they are measuring or monitoring.
Thermocouples generate voltage that is proportional to the heat they are measuring or monitoring.

Thermal converters can be applied to a number of different situations. Apart from being used to replace heat engines, research is also being done to harness the use of waste heat from combustion engines, such as those used in cars and airplanes. If this can be done, the fuel efficiency of these machines could be increased by a fairly large amount. Thermal converters are also used in far-ranging space probes to generate a constant source of electrical power.

There are some issues with thermal converter use, however. For example, is the converters usually only produce a 5-10% efficiency unless the voltage is increased significantly. In order to create a large enough output for the thermal converter to compete with the efficiency of a combustion engine, the number of dissimilar elements used to generate the electric current have to be increased. The end result is that the thermal converter ends up becoming too large to be efficient. Research is being done, however, to increase the generative capacity of thermal converters, so in time these temperature differences may be harnessed more efficiently without making them so large that they lose their effectiveness.

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Discussion Comments


@hamje32 - It never ceases to amaze me how many of our modern electrical concepts date back to experiments conducted back in the 1800s. The Seebeck effect is one such example.

What’s interesting however is that while the principle may have been observed for quite some time, the technology to exploit thate principle was not yet around.

So that’s the difference between two scientists, one living in the 1800s and one living now. Today’s scientists can find immediate applications to their discoveries in my opinion.


@David09 - I would vouch for solar electricity as being the technology of choice in that regard. As pointed out in the article the thermal converter is not terribly efficient. I personally believe solar power is a lot more efficient.

Solar power is also used in space probes too and would probably generate more electrical current per square foot, as it were. I know that it’s used to power the Hubble Space telescope. Maybe thermal converters are used there too but I would doubt it.

As to the perpetual motion machine question, I don’t know if you were being rhetorical, but no, this would not qualify. A perpetual motion machine continues in motion, once initially set in motion, without any additional supply of power. The thermal converter needs a constant input to keep working. It is an engine in that sense of the term.


So do we have the basis for a perpetual motion machine in the thermal voltage converter then? Perpetual motion machines just keep going and going without dying down.

Of course those systems are usually mechanical in nature. But it appears that the thermal converter can keep generating electricity as it does in outer space with space probes, described in the article. It will keep satellites going forever.

For that matter, would the electricity generated be more efficient with the thermal converter, or with a direct conversion from solar light? In other words, forget about using temperature variances. Just convert solar light to electric current off right off the bat.

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    • Thermocouples generate voltage that is proportional to the heat they are measuring or monitoring.
      By: Alexandar Iotzov
      Thermocouples generate voltage that is proportional to the heat they are measuring or monitoring.