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Ceramics is the oldest human technology, with pottery artifacts as old as 30,000 years found in archaeological digs (Vandiver et al., 1989). In recent decades, this prehistoric technology has rapidly progressed to give rise to a new generation of “advanced ceramics”, thanks to significant steps forward in our understanding of ceramic chemistry and crystallography, and ceramic production and manufacture (AZom, 2017).
Some of these new uses found for ceramics exploit their thermoelectric properties or ability to convert heat energy into electric energy. This is achieved in materials with a large Seebeck coefficient (ZT), low-resistivity, and low thermal conductivity. The Seebeck effect occurs when one side of the material is heated and the other kept cool. Therefore, thermal energy passing through the material can be converted into electricity.
With numerous applications being developed, especially in the clean technology fields of renewable energy, waste energy capture, and energy efficiency, thermoelectric ceramics will play an increasing role in modern life. Interest in thermoelectric materials is growing, and the market is expected to be worth $750 million USD by 2022.
Clean technology
Clean technology is defined as:
“[A] set of technologies that either reduces or optimizes the use of natural resources, while at the same time reducing the negative effect that technology has on the planet and its ecosystems.” (Pirolini, 2015)
Thermoelectric ceramics, as described above, are increasingly playing an important role in a number of these technologies.
Thermoelectric ceramics in clean technology
For instance, thermoelectric ceramics have been developed in the automotive industry to capture 75% of energy created in internal combustion engines that is usually lost in exhaust and convert it into electricity (Cuffari, 2019). This will enable hybrid electric vehicles (HEVs) to “achieve more fuel efficiency and lower carbon emissions”, a key part of the definition of eco-cars (Pilkington, 2019).
Not only vehicles with internal combustion engines, but also many other modern processes produce waste heat. Industrial and manufacturing facilities, inefficient space heating, air conditioning outputs and even computers can become miniature energy generators with the application of thermoelectric generators.
Thermoelectric ceramics can also be used in conjunction with photovoltaic materials (which convert high-frequency light energy from the sun into electricity) to capture more of the sun’s energy. Photovoltaics alone waste the majority of solar energy, which reaches the earth in the form of thermal energy. Combining solar panels with photovoltaics and thermoelectric ceramics can produce solar energy with much more efficiency than photovoltaics alone (Walker, 2013).
Ceramic thermoelectric generators are solid-state, meaning they contain no moving parts. They are very simple to install and maintain, and are, therefore, installed in places where high reliability is an important factor. Their use in space stations is testament to the usefulness of these properties.
The ruggedness of thermoelectric generators makes them especially useful in several clean technology applications. Delivering power to remote, inaccessible sites where solar radiation is low means that, for instance, environmental science laboratories can be possible. One example is the deep-sea thermoelectric generator developed by the Marine Applied Physics Corporation in Baltimore, US, which exploits temperature differences in the sea caused by hot water vents interacting with cold seawater (Liu, 2014).
Due to the high scalability of thermoelectric generators like these, they can be applied to any size of heat source. From the sun to the tailpipe, the large amounts of heat that are either emitted through other energy generation processes or that occur naturally from the sun or earth’s core can be captured and converted to usable electricity without causing environmental harm. As such, thermoelectric ceramics (and other thermoelectric materials) will continue to play an important role in clean technology.
Sources
- AZoM (2017). Advanced Ceramics – The Evolution, Classification, Properties, Production, Firing, Finishing and Design of Advanced Ceramics. [online] AZoM.com. Available at: https://www.azom.com/article.aspx?ArticleID=2123.
- Azure Technology (2009). Innovative Solar Energy System for Domestic Power, Heating and Cooling, Azure ALI Technology from Azure Energy. [online] AZoCleantech.com. Available at: https://www.azocleantech.com/article.aspx?ArticleId=199.
- Cuffari, B. (2019). What are Thermoelectric Ceramics? [online] AZoM.com. Available at: https://www.azom.com/article.aspx?ArticleID=18413.
- Liu, L. (2014). Feasibility of large-scale power plants based on thermoelectric effects. New Journal of Physics, 16(12), p.123019.
- Pilkington, B. (2019). The Different Types of Eco Cars. [online] AZoCleantech.com. Available at: https://www.azocleantech.com/article.aspx?ArticleID=958.
- Pirolini, A. (2015). What is Clean Technology? [online] AZoCleantech.com. Available at: https://www.azocleantech.com/article.aspx?ArticleID=532.
- Vandiver, P.B., Soffer, O., Klima, B., and Svoboda, J., The Origins of Ceramic Technology at Dolni Vestonice, Czechoslovakia. Science, Vol. 246, Nov. 24, 1989, pp. 1002-1008.
- Walker, K. (2013). How Can Thermo Electrical Generators Help the Environment? [online] AZoCleantech.com. Available at: https://www.azocleantech.com/article.aspx?ArticleID=361.
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