Heat can be directly and cost-effectively converted to electricity through a process called thermionic energy conversion (TEC). Thermionics has a long history, with the original idea for a converter dating back to the early 1900s. We are working towards improving TEC devices by making them more compact and efficient through standard microfabrication techniques.
Image 1: Experimental apparatus
1. "Microbead-separated thermionic energy converter with enhanced emission current.” Karl A. Littau, Kunal Sahasrabuddhe, Dustin Barfield, Hangyuan Yuan, Zhi-Xun Shen, Roger T. Howe and Nicholas A. Melosh. Physical Chemistry Chemical Physics 15, pp. 14442-14446 (2013)
2. “Optimal emitter-collector gap for thermionic energy converters.” Jae-Hyung Lee, Igor Bargatin, Nicholas A. Melosh and Roger T. Howe. Applied Physics Letters 100, pp. 173904 (2012)