Researchers at Michigan State University found a way to make efficient devices that convert heat into electricity using common minerals found in dirt. They process them by grinding and applying heat and pressure, which is far, far cheaper than the usual methods of creating thermoelectric devices. Because current technologies waste copious heat, thermoelectrics seem like a straightforward route towards higher efficiency energy use.
Read more about it in a news article:Energy savings—easy as dirt, heat, pressure.
Or in the original paper in Advanced Energy Materials, High Performance Thermoelectricity in Earth-Abundant Compounds Based on Natural Mineral Tetrahedrites