Most of the utility boilers do not use reburn with natural gas due to high cost of natural gas and development of conventional low NOX burners where the difference between total air and primary air is split into swirling secondary air and tertiary air; i. e. air is introduced in stages to reduce O2 availability thus reducing NOX. A 30kWt LNB facility has been built and tested for cofiring coal:DB blends; the reader is referred to Lawrence et al. (2012) and Lawrence (2013) for more details on facility, experiments and results from cofiring in LNB. However this LNB facility used overfire air as tertiary air. Dairy biomass is evaluated as a cofiring fuel with Wyoming Powder River Basin subbituminous coal in a small scale 30kWt burner boiler facility equipped with air staged combustion for low NOX control. The cofiring experiments were performed with 90:10 (by mass percent) coal: dairy biomass blended fuels as well as pure coal. Standard emissions from solid fuel combustion (O2, CO2, CO, NOX, and SO2) were measured in addition to the temperature profile along the axial length of the furnace. In addition to these emissions measurements, NOX on a heat basis (g/GJ) was calculated. Figure 3.42 shows the preliminary results on variation in NOX emission with % tertiary air; when compared to PRB, only about 12% reduction in NOX was obtained.