Dynamic Transmission of Steam Coal Prices Under Energy Transition: Evidence from Inventory, Logistics, and Cross-Energy Substitution in China

The stability of coal prices is of vital importance to national energy security and macroeconomic stability. Against the backdrop of Supply-side Structural Reform and the deepening strategy of “Carbon Peaking and Carbon Neutrality” (Dual Carbon), the coal price formation mechanism has evolved into a complex system incorporating intertemporal inventory adjustment, external energy substitution, and logistics constraints. Based on monthly data from May 2016 to August 2025, this paper constructs a six-dimensional Vector Error Correction Model (VECM) comprising coal prices, raw coal production, port inventory, ocean freight rates, international oil prices, and import volumes to analyze the long-term equilibrium and short-term dynamic transmission mechanisms among these variables. The research results indicate that: First, a stable long-term cointegration relationship exists among the core variables of China’s coal market, and the long-term equilibrium mechanism remains effective despite the market volatility experienced in 2021. Second, port inventory exerts a significant negative intertemporal lag effect on prices, validating the convenience yield mechanism within the theory of storage. Third, ocean freight rates and international oil prices exhibit significant cost compounding effects and energy substitution effects, respectively, with oil price shocks demonstrating greater persistence. Fourth, compared with nominal production, the “effective supply”—integrating inventory and logistics—better explains pricing, though logistics constraints significantly amplify price volatility. Policy implications suggest establishing a dynamic early-warning mechanism based on port inventory thresholds and implementing flexible import quotas to buffer domestic supply shocks.