Kinematic Self-Replicating Machines
© 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)  and each C-H bond in the final structure requires the dissipation of one C-H bond energy (~671 zJ)  to install, this implies a theoretical minimum replication energy of EC ~ 1112 zJ per carbon atom (half a bond energy, times four bonds per emplaced carbon atom) and EH ~ 671 zJ per hydrogen atom installed or Etheoret ~ EC NC,device + EH NH,device ~ 0.223 nJ for the entire device. However, the 14.2-56.8 pW device actually receives a total of Edevice ~ pdevice trepl ~ 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 erepl = Etheoret / Edevice ~ 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