In this study the economic feasibility of using alternative fuels in a mass burn boiler for a chemical plant in northeastern Missouri is analyzed. The key consideration is whether biomass (switchgrass and crop residues) is economically preferred to other available fuels. Research reveals an abundance of alternative fuels for which the plant would receive a tipping fee, including municipal solid waste and used tires. Since the plant would have to pay for biomass, it does not appear in the optimal solution. An economic optimization model shows the marginal cost to the plant of using biomass would increase as more biomass is used, displacing quantities of more valuable (in terms of tipping fees per BTU) waste materials. (c) 2005 Elsevier Ltd. All rights reserved.