General Electric - Energy & Environmental Research Corporation (GE-EER) proposes to develop and commercialize an innovative method for controlling NOx emissions from coal-fired boilers, while improving byproduct characteristics. The proposed method is called Fuel-Flexible Reburning (FFR). In conventional reburning, a portion of the total fuel is diverted from the main burners to a downstream location, thereby establishing a fuel-rich zone in which NOx emissions are reduced. Overfire air is then added to burn out remaining combustible material. Economically, it is ideal to use an inexpensive material such as coal as the reburn fuel (coal reburning). However, due to limitations in reburn zone gas temperatures and residence times, combustion of the reburn coal is typically incomplete. This can lead to excessive carbon-in-ash, turning the ash from a saleable commodity into a waste product. The FFR concept solves this problem. The technology increases the efficiency of NOx reduction in coal reburning and decreases carbon-in ash. FFR can achieve the same efficiency as conventional gas reburning, about 60%, while using inexpensive solid fuel. Carbon-in ash can be reduced below 5%. While preliminary proof-of-concept tests have demonstrated the basic feasibility of the concept, further research and development work is needed to commercialize the technology. This two-year project will include a series of analytical and experimental tasks that will optimize the FFR process. The work will provide a design methodology for full-scale applications. The development work will be integrated with GE-EER's forthcoming full-scale reburning installations to provide fast-track demonstrations at coal-fired boilers, which will be directly followed by process commercialization.