California-based Alphabet Energy plans to begin selling a new type of material that can turn heat into electricity. Unlike previous thermoelectrics, as such materials are known, it is abundant, cheap, and nontoxic.
Thermoelectric materials can turn a temperature difference into electricity by exploiting the flow of electrons from a warmer area to a cooler one. Thus, they can theoretically turn waste heat into a power source. But an efficient thermoelectric material has to conduct electricity well without conducting heat well, because otherwise the temperature across the material would soon equalize. Most materials that are good electrical conductors are also good thermal conductors, and the few materials researchers have been able to develop with good thermoelectric properties have been rare, expensive, or toxic. Alphabet Energy’s solution is tetrahedrite: an abundant, naturally occurring mineral that also happens to be more efficient on average than existing thermoelectric materials.
Ali Shakouri, a professor of electrical and computer engineering at Purdue University, says that tetrahedrite has promise because it doesn’t require the expensive up-front manufacturing that other materials require. “I think that’s kind of quite unique in thermoelectrics,” Shakouri says. “People look at so many materials, but the starting point has always been pure materials that they synthesize together.”
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