Tightening environmental regulations and the signing of the Kyoto protocol have prompted electric utilities to consider co-firing biomass with coal to reduce the levels of CO2, SO2, and NOx in stack emissions. This analysis examines the cost competitiveness of plantation produced woody biomass and waste wood with coal in electricity production. A case study of woody biomass production and co-firing in northern Indiana is presented. A Salix (willow) production budget was created to assess the feasibility of plantation tree production to supply biomass to the utility for:fuel blending. Go-firing with waste wood from primary and secondary wood processing activities and local municipalities also is considered. A linear programming model was developed to examine the optimal co-firing blend: of coal and biomass while minimizing variable cost, including the cost of ash disposal and material procurement costs. This model was used to examine situations where coal is the primary fuel and waste wood, willow trees, or both are available for fuel blending, The results indicate that co-firing woody biomass is cost-effective:for the power plant. Sensitivity analysis explored the effect of waste wood prices on co-firing cost. (C) 2000, Elsevier Science Ltd. All rights reserved.