Is there any way to convert thermal energy to electricity?

Pavi98 · Jun 13, 2021

Hello,

Currently I'm working on a project to convert thermal energy to electricity and store on a battery. I found it on the internet that Peltier Module can be used for this energy conversion? Is that possible in the long term use or is there any other possible way for this energy conversion?

Thank You

Les Jones · Jun 13, 2021

A lot depends on the temperature and the temperature difference available from the source of thermal energy. I think in Iceland they use heat from volcanic activity to turn water into steam to drive turbines. (See https://en.wikipedia.org/wiki/Geothermal_power_in_Iceland )With other temperature differences it may be possible to use the same principle but with different working fluids. The Peltier module will work. A lot depends on the scale on the project.

Les.

rjenkinsgb · Jun 13, 2021

Pavi98 said:
I found it on the internet that Peltier Module can be used for this energy conversion? Is that possible in the long term use or is there any other possible way for this energy conversion?

It's possible to convert heat FLOW (ie. the difference in temperature between to parts) to electricity or, with a suitable mechanism, to mechanical energy.

A peltier module with a heat source at one side and a heat dissipator at the other will produce electricity.

A "heat engine" such as a Stirling engine, with the appropriate part heated and heat dissipated from another part, will produce mechanical energy or run a generator.

For sunlight as a source, you can use curved reflectors to focus more light and heat on to pipes to get high temperature water or other liquid & transfer that to a heat engine, or heat a low boiling point liquid and use it to run a turbine - then feed it through a condenser (heat dissipator) to allow it to change back to liquid; a refrigerator in reverse.

You can also use "heat pipes" for transferring heat in and out of devices - tubes lined with a porous material that acts as a wick for the transfer liquid (eg. alcohol) while the hot vapour travels the opposite way down the open centre.

Or just a closed loop pipe with gravity return for liquid in the lower part and vapour in the upper.

Pavi98 · Jun 13, 2021

rjenkinsgb said:
It's possible to convert heat FLOW (ie. the difference in temperature between to parts) to electricity or, with a suitable mechanism, to mechanical energy.

A peltier module with a heat source at one side and a heat dissipator at the other will produce electricity.

A "heat engine" such as a Stirling engine, with the appropriate part heated and heat dissipated from another part, will produce mechanical energy or run a generator.

For sunlight as a source, you can use curved reflectors to focus more light and heat on to pipes to get high temperature water or other liquid & transfer that to a heat engine, or heat a low boiling point liquid and use it to run a turbine - then feed it through a condenser (heat dissipator) to allow it to change back to liquid; a refrigerator in reverse.

You can also use "heat pipes" for transferring heat in and out of devices - tubes lined with a porous material that acts as a wick for the transfer liquid (eg. alcohol) while the hot vapour travels the opposite way down the open centre.

Or just a closed loop pipe with gravity return for liquid in the lower part and vapour in the upper.

Is the peltier module reliable to use? One module will produce maximum of 1V and is it possible to use two modules in series to gain much voltage to recharge a small battery?

Thank you.

rjenkinsgb · Jun 13, 2021

A peltier effect generator, aka thermoelectric generator (TGR), will have a voltage defined by the size and number of junctions, and the load.

Example, an evolution of wartime "tea kettle" thermoelectric generators which gives around 20V off load (which would be DC, not AC as the description claims). The flame would pass through the centre, the fins are the heat dissipators.

THERMOGENERATOR - TGK THERMO ELECTRO GENERATOR TGK made in USSR | #1913408303

THERMOGENERATOR - TGK ; THERMO ELECTRO GENERATOR TGK ; made in USSR between 1950 -1960, before the electrification of the villages. It has been designed to suply with electricity a radio receptor, usi

www.worthpoint.com

I can't find any pictures of tea kettle type TGRs, but there is a reference to those and the above TGK-3 here:

Status Report on Thermoelectricity

books.google.co.uk

A better example of the TGK-3

Thermoelektrogenerator TGK-3 {ТГК-3} Power-S Metallamp, Moscow |Radiomuseum.org

Thermoelektrogenerator TGK-3 {ТГК-3} Power-S Metallamp, Moscow, build 1953, 18 pictures, 3 schematics, Soviet Union, tubes, semiconductors, Power supply

www.radiomuseum.org

Diver300 · Jun 13, 2021

It is possible to put thermoelectric modules in series. Most thermoelectric modules already have multiple junctions in series as each junction only creates a few millivolts

You can buy ready-made thermoelectric modules with power bank:- https://uk.bioliteenergy.com/products/campstove-2-plus

Pommie · Jun 13, 2021

You may find this thread informative.

Mike.

Pavi98 · Jun 14, 2021

Pommie said:
You may find this thread informative.

Mike.

Thank you very much. That was quite iinformative.

danadak · Jun 14, 2021

Solar cells have a spectral response that includes infrared -

Not sure how effective/efficient it is though.

Regards, Dana.

KeepItSimpleStupid · Jun 16, 2021

The peltier technology is very inefficient, but it does have applications. Power source for space probes. A radiation heat source and a thermoeletric module.

Delta T is the big issue. The max I have seen is 60 degrees C. They can melt.

Pommie · Jun 16, 2021

KeepItSimpleStupid said:
Delta T is the big issue. The max I have seen is 60 degrees C. They can melt.

This is true, especially if inadequate heat-sink is used. If you keep below 250°C then they tend to be OK, if you then keep the cold side at 50°C with an adequate heat-sink and fan then a decent amount of power can be generated. So, delta T can be (much) higher than 60°C. How much self heating will happen if you draw a large current is anyone's guess. I've always intended to getting around to working this out but it's another project waiting for me to get around to doing. My guess is that a much higher voltage will be produced and the same current can be drawn as at delta T of 50°C.

Mike.

KeepItSimpleStupid · Jun 16, 2021

I only worked with them in the cooling mode, but I had a book by Cambion about their modules.

Is there any way to convert thermal energy to electricity?

Pavi98

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Les Jones

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rjenkinsgb

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Pavi98

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rjenkinsgb

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THERMOGENERATOR - TGK THERMO ELECTRO GENERATOR TGK made in USSR | #1913408303

Status Report on Thermoelectricity

Thermoelektrogenerator TGK-3 {ТГК-3} Power-S Metallamp, Moscow |Radiomuseum.org

Diver300

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Pommie

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Pavi98

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danadak

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KeepItSimpleStupid

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Pommie

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KeepItSimpleStupid

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