As clean energy moves into the limelight, demand for tellurium is on the rise. Leading the pack is the solar energy industry, which has been monopolizing tellurium headlines with companies like FirstSolar (NASDAQ:FSLR) using cadmium telluride as a semiconductive layer in its thin film solar panels. But solar panels only scratch the surface of tellurium’s electrical capabilities. What about tellurium’s long-standing demand in thermoelectrics?
What are thermoelectrics?
Thermoelectrics, or “thermoelectric effect,” is defined as the conversion of temperature differences into electricity and vice versa. The two most important “thermoelectric effects” are the Peltier effect and the Seebeck effect, named for 19th century scientists who discovered early-stage thermoelectrics.
The Peltier effect, named after Jean Peltier, identified that when a current passes through two different electrical conductors, connected at two junctions, one junction would create heat while the other absorbed it. The Peltier effect is commonly used in thermoelectric cooling systems where a solid state heat pump is used to transfer heat from one side of the pump to the other, consuming electrical energy. These cooling systems are highly efficient and can be used in refrigeration systems; however, it typically is sidelined due to its high cost.
Thomas Seebeck (the Seebeck effect) found that a closed loop of two metals, joined in two places, was able to convert temperature differences into an electrical current. The thermoelectrics industry takes advantage of the Seebeck effect through exploiting the power created from heat differentials.
What do thermoelectrics have to do with tellurium?
Thermoelectric devices need materials with strong thermoelectric capabilities to work. Tellurium is a semiconductor that, when coupled with bismuth (bismuth telluride), an efficient thermoelectric material with high electrical conductivity is created . Tellurium can also be alloyed with lead (lead telluride) to create a similar alloy.
According to Resource Investor, bismuth and lead telluride have been the subject of many studies due to their “ability to generate electricity from an applied temperature gradient such as waste heat source.”
Thermoelectric generators in vehicles
As industries strive to find clean energy solutions, it is no wonder that the automotive industry is looking to thermoelectric power generation to help increase fuel economy and electrical efficiency.
Technology Review reported that wasted heat energy accounts for nearly two-thirds of the energy in gasoline engines in vehicles. Through the use of a thermoelectric generator, fuel economy has the potential to be increased by at least five percent in the short term.
In a September 2010 presentation, the US Department of Energy (DoE) calls vehicular thermoelectrics “the new green technology” and outlined the potential fuel economy increases that integrating thermoelectric generators (TEG) in vehicles can achieve. Together with the National Science Foundation NSF, the DoE speculated that over a six to 15-year-period, the integration of TEGs in diesel or gasoline engines can increase efficiency in heavy-duty trucks by 55 percent and in light trucks and cars by 50 percent.
Drawbacks to tellurium in thermoelectrics
The use of thermoelectric generators are still in the developmental stage. The main factor impeding the use of tellurium in these applications is its cost. Trading in a range of $100-132 per kilogram, it is difficult to justify the use of tellurium in thermoelectrics, despite its efficiency.
Another drawback of tellurium in some thermoelectric applications is its heat restriction. Leading thermal technology firm Gentherm (formerly BSST), stopped using bismuth telluride thermoelectric materials o other metals, like hafnium and zirconium, which can reach higher temperatures. Bismuth telluride units are only able to reach temperatures up to 250°C.
What about demand?
In a recent interview with Deer Horn Metals (TSXV:DHM) Chairman Tony Fogarassy commented that tellurium has a base market, that beyond thermoelectrics, extends to “alloys and other uses such as blu-ray disks and pretty much any memory storage device.” Fogarassy goes on to say that “the newest user of tellurium, the phase-change memory devices being developed by Intel and Samsung and Numonyx.” For the phase-change memory devices, Fogarassy states tellurium is absolutely necessary.
Securities Disclosure: I, Vivien Diniz, hold no investment interest in any of the companies mentioned in this article.