Car engines, laptop computers, cellphones, and refrigerators all heat up with overuse. That heat can be captured and turned into energy using a method that produces electricity from heat. The technology uses a silicon chip, also known as a “device,” that converts more thermal radiation into electricity. This could lead to devices such as laptop computers and cellphones with much longer battery life and solar panels that are much more efficient at converting radiant heat to energy.
Researchers previously determined that there is a theoretical “blackbody limit” to how much energy can be produced from thermal radiation (heat). The new work shows that through a device that uses two silicon surfaces very close together, that limit can be extended. The team produced a 5 × 5-mm chip of two silicon wafers with a nanoscopic gap between them only 100 nanometers thick. While the chip was in a vacuum, one surface was heated and another surface was cooled, creating a heat flux that can generate electricity. The concept of creating energy in this manner is not unique; however, the new method fits the two silicon surfaces uniformly close together at a microscopic scale without touching each other. The closer they are to each other, the more electricity they can generate.
Such technology could be used to not only cool down portable devices like laptops and smartphones but also to channel that heat into more battery life, possibly as much as 50% more. A laptop with a six-hour charge could jump to nine hours, for example. The chips could be used to improve the efficiency of solar panels by increasing the amount of electricity from the Sun’s heat or in automobiles to take the heat from the engine to help power the electrical systems. They could also be designed to fit in implantable medical devices such as a pacemaker that would not require replaceable batteries.