If, for example, you place a piece of metal on a hot plate, the heat quickly spreads through the material. Associate Professor Per Eklund at Linköping University is developing materials where this does not happen; his aim is a material that can be hot at one end and cold at the other. If he achieves a stabile temperature difference in the material, he can use this to generate electricity. That is called a thermoelectric material.
However, the development of thermoelectric materials has proven difficult. At the same time as they are insulating against heat, they need to be able to conduct electricity efficiently. When researchers develop these materials, they calculate a value called ZT that determines the efficiency. The best ones currently have a value of 2, but they have to achieve 4 for the material to be broadly applicable.
Per Eklund uses nanotechnology to develop thermoelectric materials. He builds the material layer by layer, where structures that are only a few millionths of a millimeter thick can reduce heat conduction. If he succeeds in producing a material that can make use of the heat from machines and equipment, as well as from the sun, this could contribute to a much more energy-efficient society.
Photo: Markus Marcetic