© 2004 Robert A. Freitas Jr. and Ralph C. Merkle. All Rights Reserved.

Robert A. Freitas Jr., Ralph C. Merkle, Kinematic Self-Replicating Machines, Landes Bioscience, Georgetown, TX, 2004.

B.4.5 Energy Efficiency and Energy Cost of Molecular Manufacturing

The overall energy efficiency of the proposed molecular assembler is very low. If each C-C bond in the final structure requires the dissipation of one C-C bond energy (~556 zJ) [208] and each C-H bond in the final structure requires the dissipation of one C-H bond energy (~671 zJ) [208] to install, this implies a theoretical minimum replication energy of E_C ~ 1112 zJ per carbon atom (half a bond energy, times four bonds per emplaced carbon atom) and E_H ~ 671 zJ per hydrogen atom installed or E_theoret ~ E_C N_C,device + E_H N_H,device ~ 0.223 nJ for the entire device. However, the 14.2-56.8 pW device actually receives a total of E_device ~ p_device t_repl ~ 14,200-56,800 nJ of acoustic energy during each replication cycle (0.073-0.291 pJ per carbon atom), so replication energy efficiency is only e_repl = E_theoret / E_device ~ 0.001%. If energy is delivered efficiently to the onboard acoustic transducer, the energy cost of manufacturing could be as low as 3.8 x 10¹² J/kg for an energy cost of ~$100,000/kg (cf. ~$6,880,000/kg for the active surfaces of computer chips and $28,000,000/kg for gemstone quality diamond at wholesale; Table 6.1) assuming a raw energy cost of ~$0.10/KW-hr (2.78 x 10^-8 $/J). These high costs and poor efficiency may be significantly improved in successor designs.

Last updated on 13 August 2005