Fabrication of Thermionic Device using Advanced Ceramics

Project innovation

This project created a working prototype of a device called a thermionic energy converter, which directly converts the heat generated by concentrated sunlight into electricity. The device uses advanced ceramic materials that are able to operate at high temperatures thereby providing a greater conversion efficiency that reduces the cost of solar electricity.

The thermionic energy converter is attached to a reflective parabolic dish that concentrates sunlight onto the device using mirrors. The temperatrue (or thermal energy) of electrons in the ceramic material becomes high enough for them to break away from the surface of the material, similar to water evaporating from a boiling kettle. The electrons that travel across a small vacuum gap are then condensed on a collector surface that is maintained at a lower temperature. The movement of electrons from the hot-to-cold surfaces generates the electrical energy.

This research differs from other projects by using ceramics that can withstand very high temperatures (called refractory materials) in a thermionic energy converter. Materials used for other devices are not capable of withstanding elevated temperatures, whereas this device is made of materials used to propel spacecraft and can operate at 1400 degrees Celcius.

The ability of these materials to operate at such high temperatures increases the amount of energy available for conversion to electricity and makes thermionic energy conversion ideal for concentrated solar thermal (CST) applications.

Benefit

This device simplifies the harvesting of solar energy by converting heat directly into electricity and eliminates the need for conventional steam-driven generators typically used in this type of solar energy technology.