Beyond Efficiency: A Unified Energy Survival Law for Road, Freight, and Marine Transportation

Abstract

Classical energy efficiency metrics systematically overestimate real-world performance across transportation, biological, and engineered systems. This discrepancy arises because efficiency isolates individual components under idealized conditions, while real systems operate through sequential absorption, transport, conversion, regulation, and dissipation stages, each subject to irreversible entropy production.

This study introduces a Unified Energy Survival–Absorption–Conversion Law, replacing efficiency with a physically grounded energy survival factor (Ψ) that explicitly accounts for irreversible thermodynamic losses. The survival factor is defined as

where AE is absorbed energy, TE represents recoverable transport and thermodynamic losses, and ε denotes irreversible entropy-generating losses.

To capture finite throughput and rate constraints, an internal conversion competency term (C_{int}) is introduced. The resulting governing law for useful energy production becomes:

Applied to electric vehicles, internal combustion vehicles, marine propulsion, and rail transport, the framework accurately predicts observed field-scale performance envelopes: ~60–75% wheel-level energy delivery in electric vehicles, ~20–30% in internal combustion transport, and ~40–55% shaft-to-thrust efficiency in marine systems.

By explicitly modeling energy survival rather than idealized conversion, the proposed law resolves long-standing efficiency paradoxes, enables cross-modal comparison, identifies dominant loss stages, and establishes hard thermodynamic upper bounds on transportation performance.