Coal plants that reburn with catttle biomass (CB) can reduce CO2 emissions and save on coal purchasing costs while reducing NO, emissions by 60-90% beyond levels achieved by primary NOx controllers. Reductions from reburning coal with CB are comparable to those obtained by other secondary NOx technologies such as selective catalytic reduction (SCR). The objective of this study is to model potential emission and economic savings from reburning coal with CB and compare those savings against competing technologies. A spreadsheet computer program was developed to model capital, operation, and maintenance costs for CB reburning, SCR, and selective non-catalytic reduction (SNCR). A base case run of the economics model, showed that a CB reburn system retrofitted on an existing 500 MW, coal plant would have a net present worth of -$80.8 million. Comparatively, an SCR system under the same base case input parameters would have a net present worth of +$3.87 million. The greatest increase in overall cost for CB reburning was found to come from biomass drying and processing operations. The profitability of a CB reburning system retrofit on an existing coal-fired plant improved with higher coal prices and higher valued NOx emission credits. Future CO2 taxes of $2S tonne(-1) could make CB reburning as economically feasible as SCR. Biomass transport distances and the unavailability of suitable, low-ash CB may require future research to concentrate on smaller capacity coal-fired units between 50 and 300 MW. (C) 2009 Elsevier Ltd. All rights reserved,