Scientists Find New Way to Harvest Waste Heat
PALO ALTO, Calif.—Researchers at Stanford University and the Massachusetts Institute of Technology (MIT) have found a new alternative for low-temperature waste-heat conversion into electricity—that is, in cases where temperature differences are less than 100°C (180°F). The system is based on the principle known as the “thermogalvanic effect,” which states that the voltage of a rechargeable battery is dependent on temperature. First, an uncharged battery is heated by waste heat. While the battery is still warm, a voltage is applied. Once fully charged, the battery is allowed to cool. Because of the thermogalvanic effect, the voltage increases as the temperature decreases. When the battery has cooled, it actually delivers more electricity than was used to charge it. The study is published in the May 21 issue of the journal Nature Communications
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