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Capturing the heat of the moment

Energy -- its sources, uses, and impact to the environment are perhaps the most significant scientific and technical challenge faced by modern society.

On the supply side of the equation, many are focused on the development of greener energy sources such as wind, solar, and hydrogen power. On the demand side, others seek ways to increase the efficiency of existing energy sources and usage, thereby curtailing overall demand.

Lehigh engineer Nelson Tansu, assistant professor of electrical and computer engineering, seeks to develop technologies that will achieve both of these goals at once.

Tansu and his research group within Lehigh’s Center for Optical Technologies (COT) study the properties of Indium gallium nitride (InGaN), a semiconductor material best known for illuminating LED displays in devices such as digital watches, cell phones and laptop backlighting. Tansu says that InGaN shows promise in converting solar energy more efficiently into electricity, and in generating thermoelectricity – the capturing of wasted heat energy for conversion into electric power.

A thermoelectric material converts heat into electricity when variations in its temperature generate voltage differences. This so-called as Seebeck effect triggers a flow of electrons. The challenge, according to Tansu, is to develop a thermoelectric material with a large Seebeck voltage that conducts electricity well without readily transferring heat.

“The standard incandescent light bulb converts electricity into 5% light, and the rest is dissipated as heat,” says Tansu. “Consider how hot the hood of a car becomes after even a short drive, or the temperature of the vents on the back of a refrigerator. And then, think about industrial facilities that rely on producing high temperature for fabrication or synthesis. The fact is, a tremendous portion of global energy usage is lost as heat dissipation – literally, it vanishes into thin air.”

The challenge, he continues, is to develop materials and technologies that can capture heat energy and recycle it into electricity.

“We’re investigating InGaN and other classes of nitride semiconducting materials,” says Tansu. “We think they could make viable thermoelectric materials because of their high electric conductivity and low thermal conductivity.”

Tansu’s investigation of solar cells and thermoelectric materials is supported by the Pennsylvania Infrastructure Technology Alliance as well as the PA Department of Community and Economic Development.


To learn more about this project and other aspects of nanotechnology research at Lehigh, see “Bridging the “green” LED gap” in Resolve® magazine (volume IV) – a publication devoted to Lehigh engineering research and educational innovation, highlighting exciting partnerships, projects and academic programs within and around Lehigh's engineering community.

 
NANOTECHNOLOGY AND APPLICATIONS