ClearStack Combustion Corporation has developed a three-stage combustion technique that is called the Stage3CycloneTM; see Figure below. The technology is based on the use of three stages of oxidation air, the third of which is overfire air (OFA). Limestone is added with the coal to maintain good slag fluidity. This staged combustion technique will effectively reduce NOX emissions from cyclone units at very low capital and operating costs, offering the performance of Selective Catalytic Reduction (SCR) at a substantially reduced cost. This simple three-stage combustion technique will reduce NOX emissions to < 0.15 lb /106 Btu. ClearStack has limited resources so it has not been pushing this technology much to date. A decision was made to market the multi-pollutant AG-CS technology, get it commercialized, then move to its other technologies.