Cableless Power Transmission System: Problems and Prospects

Cableless power transmission—the transfer of electrical energy through free space rather than a conductor—now spans commodity near-field chargers, standardized electric-vehicle (EV) charging, kilometre-scale microwave and laser beaming, and in-orbit tests of space-based solar power. Existing reviews usually treat one mechanism, quote peak efficiencies without their geometric conditions, and rarely connect performance to exposure regulation or cost. This paper develops a unified framework covering inductive, resonant, capacitive, microwave and laser links. A generalized three-layer system architecture (power, control–communication, safety) is defined. Near-field links are modeled from the Neumann integral to the closed-form bound η max = F/(1 + √(1 + F)) 2 with F = k 2 Q 1 Q 2 ; far-field links through the Goubau relation η b = 1 − exp(−τ 2 ); optical links through Gaussian-beam propagation with Beer–Lambert extinction; and all mechanisms through a common end-to-end efficiency cascade and a levelized cost of transmission (LCOT). Simulations show that coupling decays approximately as d −3 , that 90% coil-to-coil efficiency at Q = 300 is limited to gaps of about 22 cm for a 20-cm-radius pad, that a 10-km, 5.8-GHz link needs apertures of about 36 m at each end for 98% beam capture, and that a well-engineered microwave chain delivers about 51% end to end. A 1-MW, 10-km island case study gives an LCOT roughly twice that of a submarine cable, offset by a much shorter repair time. The problems are classified as fundamental, engineering, regulatory and economic, and a staged prospect roadmap is proposed.