To evaluate the potential of carbon nanotube field effect transistors (CNFETs) to replace silicon CMOS technology, we develop a SPICE model of CNFET nanoelectronics. Our model is parameterizable, and it enables composition of models of various aspects of nanoelectronic behavior. Comparing CNFET nanoelectronics against current CMOS technology and future projections for CMOS, we demonstrate that CNFET nanoelectronics can achieve significantly greater performance at a fraction of the switching energy. ©2004 IEEE.