Overview of Iron Energy Utilization: Update Status and Prospective Development

Under the vision of carbon neutrality, the global energy system urgently requires storable, transportable, and tradable zero-carbon carriers. Iron, due to its high crustal abundance, low cost, environmentally friendly reaction products, and ease of closed-loop cycling, is being reconsidered as a potential “metallic energy” alternative to fossil fuels. This paper systematically reviews the conceptual evolution, scientific lineage, and paradigm shift logic of iron-based energy within the framework of dual pathways: combustion and electrochemistry. On the combustion front, a multi-level understanding has been established—ranging from microscopic reaction mechanisms to macroscopic flame propagation, and from unit combustors to diversified thermal power systems—laying a methodological foundation for an integrated “solid fuel–thermal–power” approach. In parallel, the electrochemical pathway has developed both liquid and solid routes, integrating energy storage, pollution control, and resource recovery within a single device through multi-valent redox reversibility, thereby expanding the concept of generalized energy storage under the “battery-as-factory” paradigm. Current research is shifting its focus from single performance metrics toward synergistic optimization of efficiency, lifespan, cost, safety, and environmental impact, marking a transition in technological paradigm from “material trial-and-error” to “mechanism design.” Looking forward, to advance iron energy beyond the experimental validation stage, it is imperative to establish a cross-scale, closed-loop scientific characterization system, develop recycling strategies with low entropy and low energy consumption, and deeply integrate with renewable electricity, hydrogen, and high-temperature heat sources to form spatiotemporally transferable zero-carbon energy systems. In this way, iron may integrate into global energy trade as a “metallic energy in specific scenarios like ports/islands,” offering a scalable, hydrocarbon-independent technological option for achieving carbon neutrality.