Coordinated planning of hydrogen refuelling stations and distribution networks considering two-phase hydrogen storage and carbon emission flow

Hydrogen refuelling stations (HRSs) are essential infrastructure for hydrogen-powered transportation. However, their planning faces coupled challenges arising from high-pressure hydrogen storage risks and the indirect carbon emissions caused by grid-connected electrolysis. To this end, this paper proposes a coordinated planning model for HRSs and distribution networks (DNs) considering gas-solid two-phase hydrogen storage and carbon emission flow. First, the explosion energy of hydrogen storage tanks is quantified by leveraging the TNT equivalent approach, and storage-safety constraints are established based on the blast-overpressure consequence criterion. A hybrid gas-solid two-phase configuration is then introduced for hydrogen storage, and a metal-hydride-based storage model is formulated using hydrogen absorption/desorption kinetics. Second, the carbon emission flow theory is employed to trace nodal and time-dependent carbon intensity in the DN, thereby allocating the carbon responsibility of HRS electricity consumption along power-flow transmission paths. Third, traffic assignment is utilized to determine the spatial distribution of hydrogen-powered vehicle (HPV) refuelling demand, based on which an HRS location model is established incorporating HPV driving-logic rules to guarantee refuelling accessibility. On this basis, a two-layer coordinated planning framework is constructed. The upper layer optimizes DN reinforcement and renewable energy deployment, while the lower layer determines HRS siting, equipment sizing, and hydrogen-production scheduling under nodal carbon responsibility and storage-safety constraints. The updated HRS demand is fed back to the upper layer to update DN operating states and carbon-intensity distribution. Case studies show that the carbon-responsibility signal, gas-solid storage safety mechanism, and two-layer feedback jointly improve low-carbon performance, storage safety, and planning economy. Compared with the cost-oriented benchmark, the proposed model reduces carbon emissions by 30% and improves safety performance by 87.32%, with only a 1.56% increase in total cost.