Methods for Calculating Energy Requirements for Processes in Which a Reactant Is Also a Fuel: Need for Standardization

When a process involves both endothermic chemical reactions and heat generation from the combustion of fuels, the choice of endothermic reactions to include in computing the energy requirement for the overall process is arbitrary and can be a source of confusion. It is shown that the essential question becomes whether the heat of combustion of a reactant, which can be used as a fuel, should be included in the energy requirement value. It is noted that the choice is a matter of convention, but it is important to clearly state what convention is followed in presenting the results of energy calculations. There is a need to select a standard approach because the presented value of energy requirement of a process depends on the choice. This problem is illustrated using the example of ironmaking by different processes including a novel flash ironmaking process under development at the University of Utah. The authors advocate using just the process energy requirement as the standard value of the energy requirement for a process in which a reactant is also a fuel.