But recently, I have found that scientists discovered an interesting and new method how to transform thermal energy into electricity! The new method is called lead telluride thermo-electrical device.
Although it is not a new idea at all and many researches had done these devices before, they had never overcome a magical 10% line of efficiency whereas material scientists at the university of Illinois created a 14% one!
That means that dirty factories could recycle 14% of their overall waste heat! And it was calculated that it IS definitely worth of it. Simply imagine that we could use waste energy, which is, without doubt, present in many industrial fields - varying from glass and steel production to coal plants and paper mills!
Moreover, we could reduce amounts of carbon dioxide released in the atmosphere as well as green house effect in consequence.
Before describing the new method to you, can you even imagine how does a thermo-electrical device work?
Well, I think it's not so obvious, so let's start with it.
From wikipedia, there is a nice definition, so I'll quote it from there:
''The thermoelectric effect is the direct conversion of temperature differences to electric voltage and vice-versa. A thermoelectric device creates a voltage when there is a different temperature on each side. Conversely, when a voltage is applied to it, it creates a temperature difference. At the atomic scale, an applied temperature gradient causes charged carriers in the material to diffuse from the hot side to the cold side, similar to a classical gas that expands when heated; hence inducing a thermal current.''
Moreover, we can measure quite precise temperature with these devices.
On the other hand, there is a problem of electron-scattering, which means that electrons are deflected from their original trajectories and the efficiency of such machines is lowered.
It is due to several facts:
- In thermoelectronic devices, there is also a certain magnetic field created and thanks to the ''theory of quantum electrodynamics'' it influences electrons' trajectories (or we can refer to Lorentz force)
- Secondly, electrons hold charges and due to their electrostatic Coloumb forces they repulse each other
Nevertheless, the breakthrough in using these devices will be probably caused by the new method!
Let's describe it:
In general, you put nanocrystals of rock salt into lead telluride (lead an tellurium on a lattice).
On one hand, lead telluride has been part of past experiments with thermoelectric devices and NU researchers were not the first to attempt a nanoscale inclusion in bulk material in order to improve the thermoelectric properties of a material, but they did their job better than others. Their new material reduces the phenomenon called “electron scattering,” (I tried to describe above) an enemy of thermoelectric conversion efficiency.
Hope it was understandable :-)
So we can use our waste energy far more efficiently now, but will our politicians give financial incentives for electricity produced by these devices with high price for purchase?
But definitely, I must admit that new opportunities with nanomaterials are vast and I am looking forward to future inventions :-)
sources:
http://www.greenoptimistic.com/2011/01/22/lead-telluride-thermoelectric-record/
http://cleantechnica.com/2011/01/20/14-nanomaterial-breakthrough-in-waste-heat-electricity-could-turn-dirty-industries-in-us-into-electric-power-generators/
http://www.nature.com/nchem/journal/v3/n2/full/nchem.955.html
http://www.instructables.com/community/Help-Thermo-Elecetric-Generator/
http://en.wikipedia.org/wiki/File:Peltierelement_16x16.jpg
http://www.webelements.com/compounds/lead/lead_telluride.html
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