Exploring the Practicality of Iron as a Sustainable Replacement to Coal

The negative and long-lasting effects of carbon dioxide within our atmosphere has set the clock for the rapid decarbonization of energy. While carbon-free technologies have been developed, many of these solutions require new infrastructure and supply chains to be formed which slows transition away from carbon-based fuels. One modern fuel source that has garnered interest in hastening adoption of carbon-free energy is iron. This solid fuel has comparable ignition and flame temperatures to coal, which would allow iron to assimilate into preexisting infrastructure with minimal modifications. Instead of producing carbon dioxide, iron powder forms various oxides during combustion which resolidify into byproducts that can be recycled back to its original form, completing the “iron fuel cycle”. For iron to be a realistic alternative to coal the practicality and details of this “iron fuel cycle” need to be better understood. Current work on iron integration into coal plants has been based on thermodynamic calculations and does not assess how iron combustion would work in real-world application. Characteristics of iron in various furnace environments needs to be collected to update current predictions of iron fuel ignition and combustion to understand how iron particles will interact with each other and how to best utilize the reaction’s nanoparticle byproducts. Through scanning electron microscopy and x-ray diffraction we have examined the effects of various temperatures, flow rates, and oxygen concentrations on the byproducts of iron particle combustion within a drop tube furnace. Within this work, we present experimentally grounded recommendations for optimal particle morphologies and furnace environments, which can be used to further analyze the cost of transitioning from coal to iron in specific industries.