Nearly 70% of the energy requirement of China is satisfied by burning coal; therefore, economy development is tangled with atmospheric pollution. Coal still takes half energy duty of the world for the near future, therefore, the radical energy solution to against climate change is to change coal green. Greening of coal is stop to burn coal, but burn hydrogen that obtained from water in assistance of coal. As consequence, the fast knot between development and pollution is untangled.

The technical route of greening coal is to produce hydrogen from water via a FeO/Fe3O4 cycle, and CO keeps the cycle running. The source of CO is carbon, which is renewable if it comes from biomass, or nonrenewable if it comes from coal. A theoretical mass and energy balance tells that each mole water and carbon produces one mole hydrogen and one mole carbon monoxide, and 62% of the produced carbon monoxide is enough to satisfy the energy requirement of the process and 38% left for by-product. The CO2 produced in consuming CO can be favorably disposed: 1. Injected into natural gas reservoirs to increase natural gas output; 2. Injected into petroleum fields to increase oil recovery; 3. Injected into flammable ice sediments to release methane. According to the proposed strategy, hydrogen is a practical alternative fuel wherever coal is usually burnt, and most CO2 emission is avoided.