Today you can drive your car down Commonwealth Avenue as your vehicle emits tons of exhaust into the atmosphere, continuing humanity's onslaught on the earth's environment. In the future, due to recent efforts by a joint research team from Boston College and the Massachusetts Institute of Technology, that exhaust might be used to power your car's battery.

In more technical terms, these researchers have demonstrated a huge increase in thermoelectric efficiency - effectively introducing a new standard for the creation and use of heating, cooling, and power. Though the technology has been around for years, this specific advancement is important because it has paved the way for commercial application - ranging from refrigerators and air conditioners to solar technology to automobiles to semiconductors. The primary ramifications are that the products will be cleaner and will run more efficiently.

The team is composed of Zhifeng Ren, a BC physics professor and co-leader of the project, six researchers from Ren's lab, Gang Chen, a mechanical engineering professor from MIT and the project's other co-leader, Mildred S. Dresselhaus, an MIT physics professor, Bed Poudel of GMZ Energy, Inc., and Junming Liu, a physicist from Nanjing University in China and a visiting professor at BC. The research was funded by the Department of Energy and the National Science Foundation. The team's results were published on Thursday, March 20 in the online edition of Science, a world-renowned journal for scientific research. The team approached the project with a novel low-cost strategy, which consists of producing minute alloy nanostructures approximately one one-thousandth the width of human hair that can act as power generators or micro-coolers. Besides being economical, this technique can be adopted by many product manufactures so their products will either recapture energy that would otherwise be wasted or simply consume less energy.

The research is based on the thermoelectric effect, which is the conversion of temperature differences into electric voltage and electric voltage into temperature differences. There are several useful applications of the thermoelectric effect: measuring temperature, generating electricity, and the cooling or heating of objects. On one hand, a thermoelectric device can create a voltage when there is a temperature difference between its sides. On the other, when a voltage is applied to a thermoelectric device, the result is a temperature difference. Such devices make great temperature controllers because the direction of the heating or cooling is determined by the applied voltage's sign (positive or negative). The thermoelectric effect, however, is not the same as Joule heating - the heat that is produced when a voltage difference is used on a resistive material. The thermoelectric effect is reversible, while Joule heating is not. The team's achievement is important because it is a successful attempt to utilize the applications of the thermoelectric effect, which has stymied researchers since the 19th century after French physicist Jean Charles Athanase Peltier and Estonian-German physicist Thomas Johann Seebeck each independently discovered it. In the 1950s, scientists tried to improve thermoelectric efficiency using all kinds of materials such as silicon wires and expensive, complex lattices. The main problem is that many materials conduct both electricity and heat, which makes their temperatures equalize quickly. The team has used materials that conduct electricity without also conducting heat.

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