The manufacture of Portland cement is an energy intensive process. It produces significant pollution and uses large amounts on nonrenewable resources. With increasing pressures to reduce greenhouse gas emissions due to cement manufacture, research and development of fuel alternatives and their effect on the manufacturing process has become an industry focus. The inherent properties of sintering cement in a rotary kiln allows for a large number of fuels to be burnt which are normally prohibited for use as fuel in other processes. To examine the suitability of a fuel, process modeling and simulation can be undertaken to predict the final impact of that fuel on kiln performance and greenhouse gas emission. With an accurate model and sufficient data, it is possible to conduct simulations for a wider range of alternative fuels. This paper discusses and summarizes the simulation results of three alternative fuels, namely spent carbon lining, used industrial lubricants and used tires, for identifying the most effective fuel source among these three. Among the selected fuels used, industrial lubricant is found to be the best option regarding the CO2 emission, while the spent carbon lining is the worst one. In contrast, feed material requirements can be reduced by up to approximately 15% by using spent carbon lining. Further research is recommended to justify the findings.