At least two-thirds of the energy in gasoline used in cars and trucks is wasted as heat. Thermoelectrics, semiconductor materials that convert heat into electricity, could capture this waste heat, reducing the fuel needs of the vehicle and improving fuel economy by at least 5 percent. But the low efficiency and high cost of existing thermoelectric materials has kept such devices from becoming practical in vehicles. The DOE (Dept of Energy) is targeting getting 10% of more improvement in fuel efficiency.
BSST is using thermoelectrics—blends of hafnium and zirconium thave increased the generator efficiency by about 40 percent over Bismuth telluride.
BSST and GM researchers also need to find ways to make larger volumes of the new materials cheaply, but it might be at least another four years before thermoelectric generators make it into production vehicles.