This work develops a theoretical extension of the Theory of Dynamic Resonant Ether (TDRE), introducing the concept of Cold Current as a non-Maxwellian, longitudinal mode of energy propagation. Within the TDRE 1+8 manifold, a coherent longitudinal mode (λL = 9) is shown to decouple from transverse lattice-interaction modes. We formalize Cold Current (Jc) as a phase-gradient flow of an underlying plenum field Φ, governed by nonlinear wave dynamics. The transition from Jc to observable electrical current (Je) is described as a phase-transduction process at nonlinear boundaries. The model yields testable predictions regarding low-thermal energy transport and non-linear coupling to classical systems.