Congratulations to Prof. Kay Park!  He recently received a National Science Foundation grant for $299,998 on “Fundamental Studies of Near-field Enhancement in Thermionic Energy Conversion”.

In 2014, Unites States consumed more than 97 quadrillion Btu of energy. This is equivalent to the amount of energy in 3.5 billion tons of coal or 776 billion gallons (US) of gasoline. However, almost 59% of such energy consumption is being lost as waste heat. It is thus imperative to find an innovative way of recycling energy from a waste heat source as an emission-free and less-costly energy resource. The objective of this project is to explore the near-field enhancement of thermionic emission for renewable energy recycling. Conventional thermionic energy conversion (TEC) generally requires a high cathode temperature over 1500K to thermally excite enough electrons from the cathode overcoming its binding potential, or work function, for power generation. Low efficiency is another challenging issue of TEC power generation. Park’s group will address this challenge by implementing a low bandgap semiconducting material as a cathode and placing it a subwavelength distance away from a thermal emitter. They hypothesize that the near-field enhancement of thermal radiation will boost the photoexcitation of electrons in the low-bandgap semiconductor cathode, significantly increasing the thermionic current density. In addition, the energy conversion efficiency will be substantially improved because the most radiation absorbed in the cathode will benefit thermionic emission, i.e., photoexcitation from the photon energy slightly above the cathode bandgap and thermalization from the excess photon energy and sub-bandgap photon energy. The success of this project will make a transformative impact to thermionic power generation as a possible way of renewable energy recycling. The project will also promote training and learning by involving students in micro/nanofabrication, thermal and infrared characterization of nanodevices, nanoscale heat transfer measurements, and nanoscale instrumentations.