The material is fashioned from calcium, cobalt and terbium, which leads to a bio-friendly material that promises to be efficient in producing electricity via thermoelectric processes, and to be produced at a low cost. The discovery comes from the University of Utah, originating from a team led by Professor Ashutosh Tiwari.
The material works through a phenomenon called thermoelectric effect. This is where a temperature difference affecting a suitable material leads to the generation of an electrical voltage. When one end of the material is hot and the other end is cold, charge carriers located at the hot end move through the material towards the cold end. This leads to the generation of an electrical voltage. For electricity to be produced less than a one-degree difference in temperature is required.
A further advantage with the effect is that since the direction of the heating and cooling is determined by the polarity of the applied voltage this means that thermoelectric devices can be used as temperature controllers.
The effect overall is generally inefficient. The reason for this is because materials used for the thermoelectric effect are required to be good at conducting electricity, but not good at conducting thermal energy. Due to the considerable potential should a suitable material be created several science teams are investing time and resources searching for the right kind of material that makes the process more efficient and produces a suitable level of electricity. Additional concerns are with the material being suitable for the environment and not being toxic.
The issue of toxicity is why some materials with an effective thermoelectric effect are not used. Examples of toxic materials include cadmium-, telluride- and mercury-based materials. The new material is, what the research team term “bio-friendly” (a reference to its low toxicity) and “eco-friendly” (a reference to its low environmental impact). Possessing these properties as well as being very efficient at generating electricity makes it an ideal candidate substance. The green credentials of the material are important given that thermoelectric power generation stands as one of the most promising and emerging clean energy technologies for harvesting electricity from heat without producing any direct emission of greenhouse gases.
The central material, and the one that contributes most greatly to the thermoelectric properties, is terbium. Terbium is a chemical element; it is a silvery-white, rare earth metal that is malleable, ductile, and soft enough to be cut with a knife. Moreover it is an electropositive metal that reacts with water, evolving hydrogen gas, and it has good electrical properties. As an example of an everyday application, terbium oxide is used in green phosphors in fluorescent lamps and color television tubes.
As to what the new material can be used for these are multiple. For instance, body heat could be used to power implantable medical devices like blood-glucose monitors or heart monitors. Taking a different course the material could be used to charge mobile devices via cooking pans, or perhaps in cars, drawing power from the heat of an engine. Alternatively, aircraft could generate power by using heat from within the flight cabin (achieved by the temperature different between the air in the cabin and the cold air outside). As a final example, power plants could use the new material to generate electricity using the escaped heat the plant generates. This latter example could boost energy efficiency since 60 percent of energy is wasted and if this could be captured it would lower operating costs.
The research has been published in the journal Scientific Reports. The science paper is titled “Terbium Ion Doping in Ca3Co4O9: A Step towards High-Performance Thermoelectric Materials.”
Essential Science
This article is part of Digital Journal’s regular Essential Science columns. Each week Tim Sandle explores a topical and important scientific issue. Last week we weighed in on a new molecule that can be added to corn to prevent crop damaging fungal infections; these fungal infections also pose a risk to human health. The week before the subject was neuroscience and social media, looking at what happens to our brains when we decide whether or not to share an article or video. The results are illuminating in terms of why we share one article but decide not to share another.
