© 1999 Robert A. Freitas Jr. All Rights Reserved.

Robert A. Freitas Jr., Nanomedicine, Volume I: Basic Capabilities, Landes Bioscience, Georgetown, TX, 1999

6.5 Design Energetics Assessment

6.5.1 Power in Biological Cells

Table 6.8 summarizes the total power outputs and power densities of various cells in the human body, adapted from numerous experimental studies on tissue metabolism using assumed cell volumes as listed. Relatively inactive red cells produce only ~0.01 pW, while thermogenic fat cells may release 8 million times more energy during shivering. Muscle cells and platelets have very low basal rates, but are capable of brief bursts of high power density. The typical human tissue cell operates at ~30 pW and at this power level has ~2000 sec of free glucose energy available solely from internal stores without requiring external resupply, assuming ~50% energy conversion efficiency. Biological power densities range from 10²-10⁶ watts/m³, with the typical tissue cell operating at about 3800 watts/m³. The active flight muscle of the honeybee has the highest known power density in biology (3.4 million watts/m³).

Last updated on 18 February 2003