Navigating the Kinetic‐Transport Trade‐Off in Transient Water Electrolysis via Physics‐Informed Impedance Analysis

Coupling offshore renewable energy with water electrolysis is critical for sustainable hydrogen production, yet power intermittency challenges system stability and efficiency. Existing control methods often fail to account for rapid microscopic changes at the electrode interface during dynamic operation. Here, we develop a dynamic equivalent circuit model derived from electrochemical impedance spectroscopy to resolve these transient behaviors under fluctuating loads. Our approach quantitatively separates kinetic factors from transport losses induced by bubble shielding and pore occlusion. This distinction allows for the precise identification of catalyst degradation and membrane performance mechanisms that are typically obscured during unsteady states. By leveraging these descriptors, we construct a dynamic regime map to guide the system from transport‐limited zones toward an optimal operational window. Consequently, we achieve a reduction in specific energy consumption of 8 to 15 percent and a 12 percent decrease in carbon intensity without requiring hardware modifications. These insights facilitate the deployment of physics‐based control protocols that turn renewable intermittency from a stability risk into an optimization parameter for industrial hydrogen production.