sciencehabit writes: "Fossil fuels power modern society by generating heat, but much of that heat is wasted. Researchers have tried to reclaim some of it with semiconductor devices called thermoelectrics, which convert the heat into power. But they remain too inefficient and expensive to be useful beyond a handful of niche applications. Now, scientists in Illinois report that they have used a cheap, well-known material to create the most heat-hungry thermoelectric so far (abstract). In the process, the researchers say, they learned valuable lessons that could push the materials to the efficiencies needed for widespread applications. If that happens, thermoelectrics could one day power cars and scavenge energy from myriad engines, boilers, and electrical plants."