Pathways to Inherently Efficient System-Wide Thermal Energy Utilization

Abstract

Efforts at improving energy efficiency have typically involved component or device efficiency improvements, which limits energy use reductions to a few percent, for specific end uses. While such improvements are desirable, their impact on energy utilization at the national and global level is small. This talk will focus on revisiting the current global energy utilization paradigm, and suggest approaches to cascade primary energy utilization over several end uses across the temperature spectrum such that waste heat is minimized to the thermodynamically unavoidable levels. Such approaches yield substantial reductions in the carbon footprint of global energy utilization. In addition, techniques to not only harvest waste heat, but to upgrade it to produce power, cooling, and upgraded heat will be discussed. In the quest to "chase down the last Joule" from the source efficiently, a variety of technologies to harness, transform, store and transfer thermal energy will be presented. In particular, research being conducted at the Sustainable Thermal Systems Laboratory to exploit the advantages of microscale heat and mass transfer not only in small-scale devices, but also to extend them to Megawatt-scale applications will be presented. Thermally cascaded energy utilization systems for automotive, space-conditioning, electronics cooling, waste heat recovery, and portable cooling for the military, fire-fighting and other hazardous duty applications will be presented. The talk will demonstrate that improvements on the end-use side can have a significant impact on the supply, demand and intermediate stages of the energy spectrum.