Energy saving does not yield CO2 emissions reductions: the case of waste fuel use in a steel mill

Carbon dioxide is a major source of the green house effect and, therefore, fuel saving techniques are expected to reduce emissions. Yet, in some cases, energy saving techniques may result in higher CO2 emissions. For instance, when natural gas is mixed with waste blast furnace gas, energy savings are associated with higher CO2 emissions. To confirm this proposition we have constructed a model of a furnace by using energy-object network that consists of modules of convective heat exchangers, combustion and stream mixing.