For many systems, more energy is lost as heat than is used. If this were not the case, we likely would not need advanced cooling systems in computers, as a passive cooler could potentially keep a modern CPU cool. Some researchers are focusing on improving the efficiencies of these systems, so less heat is lost, but others are instead focusing on ways to reclaim this heat, including those at Northwestern University and Michigan State University. These researchers have recently made the most efficient thermoelectric material ever known.
What makes a material good at converting heat into electricity is a high ratio between the thermoelectric power and thermal conductivity, as well as its electrical conductivity. An ideal thermoelectric material is a poor heat conductor, as it is a temperature differential that creates the electric current. Thus being a good electrical conductor is also useful. Sadly the thermoelectric power and conductivity are typically linked, making it difficult to manipulate only one. However the researchers achieved this by scattering a wide spectrum of phonons, the quantum of vibrational energy, which also carry heat energy.
The researchers expect this material to achieve between 15% and 20% efficiency, but perhaps more important than these numbers is how they did it. Their method of affecting the scattering of phonons could be applied to all thermoelectric materials and can also be improved to increase the efficiency values even more.