A Short History of Thermoelectrics 

With every discussion of old and new emerging concepts, theories, and technologies within the STEM field, comes an introduction of the figures behind them. Thomas Johann Seebeck is certainly not the only scientist that had a lasting influence upon the development of thermoelectric technologies, but he is just one among many who catalyzed research into this energy source. In 1821, Seebeck made the discovery that different temperatures had the ability to move a compass magnet.^[1]  Although he had initially thought that this was caused by magnetism created by the temperature difference and the “Earth’s magnetic field”, he later discovered that the temperature difference produced electric potential (voltage)  which can generate electric current in a closed circuit, now known as the Seebeck Effect. ^[1] 

How Thermoelectric Materials Generate Electricity

Essentially, thermoelectricity is formed when heat is converted into energy. What makes a material have the ability to create thermal electricity is “both high electrical conductivity and low thermal conductivity.^[2]  To simplify this idea: electrons flow back and forth on what is called a temperature gradient. ^[2]  Since we generally know that metal is a good energy conductor, electrons that are responsible for creating the thermoelectric energy can flow easily through metal. (CITATION 2)  Now, to add the next component which is the temperature gradient we had just mentioned; If one end of a metal pipe is heated and the other is left cold what do you think will happen? This causes the electrons to move from the hot end of the pipe to the cold end (CITATION 2). The figure below demonstrates what this looks like.

Thermoelectric Modules: How it Creates More Efficient Energy

A thermoelectric module is the primary component that produces usable energy as an end-product. Since thermoelectric modules need to produce a constant flow of energy, it must be able to maintain a large energy gradient and house a large number of protons moving back and forth in order to produce usable, reliable energy. Thermoelectric modules, experience what is called mechanical fatigue which demonstrates that a lot of work is being put into producing thermoelectric energy as well. ^[2]   The physical composition of thermoelectric models is what provides for its unique properties; it must be composed of two types of semi-conductors which are materials that are “intermediate in electrical conductivity between a conductor and an insulator.” ^[3]  One type of semi-conductor is positively charged or p-type and the other is negatively charged or n-type. ^[4] Just like how thermoelectric technologies need a balance between hot and cold temperature on a gradient, the variance must be maintained between positive and negative semi-conductors. ^[4] The figure below shows how thermoelectric modules can look. Note the loops that the energy have to go through.

Where Thermoelectricity is Used

Thermoelectricity is used in a variety of technologies in many parts of our lives, from laboratory settings, to the  military, and telecommunications, this energy is used to power many things that we are familiar with. ^[5]  A common use for thermoelectric modules is in liquid-cooled PC’s. If you own a computer of any brand, you may be familiar with the sound of a fan after you have been using the computer for an extended period of time or just finished downloading a new software. In order to keep the computer from overheating, liquid-cooling is used. ^[6]  You may be wondering why a piece of expensive technology would use water to cool itself, but just take a second to think about how cars need anti-freeze to keep it running efficiently during winter months – this is a similar idea. Both pieces, make use of thermodynamics, which you may recall as being the idea that heat moves from warm areas to cooler areas. As this process takes place it cools down the computer – or the car. Similar applications of thermoelectric coolers are water coolers and dehumidifiers ^[5] Can you think of any other ways that thermoelectricity or thermoelectric coolers are used? Surely, when Thomas Seebeck made his initial discovery in the 1800’s he did not foresee these concepts being applied to so many things that we used today.

 

Sources:

1. Brief History of Thermoelectrics. History of Thermoelectrics. [accessed 2018 Feb 28]. http://www.thermoelectrics.caltech.edu/thermoelectrics/history.html
2. How Thermoelectric Generators Work. Alphabet Energy. [accessed 2018 Feb 28].https://www.alphabetenergy.com/how-thermoelectrics-work/
3. The Editors of Encyclopædia Britannica. Semiconductor. Encyclopædia Britannica. 2017 Dec 28 [accessed 2018 Feb 28]. https://www.britannica.com/science/semiconductor
4. How Do Thermoelectrics Work? Power Practical. [accessed 2018 Feb 28]. https://powerpractical.com/pages/how-do-thermoelectrics-work
5. Thermoelectric Technical Reference . Ferrotec. [accessed 2018 Feb 28]. https://thermal.ferrotec.com/technology/thermoelectric-reference-guide/thermalref03/
6. Wilson TV. How Liquid-Cooled PCs Work. HowStuffWorks. [accessed 2018 Feb 28]. https://computer.howstuffworks.com/liquid-cooled-pc.htm