Economics and/or political intervention may one day dictate the conversion from oil or natural gas to coal in boilers that were originally designed to burn oil or gas. In recognition of this future possibility the US Department of Energy, Federal Energy Technical Center (DOE-FETC) supported a program led by ABB Power Plant Laboratories with support from the Energy and Fuels Research Center of Penn State University with the goal of demonstrating the technical and economic feasibility of retrofitting a gas/oil designed boiler to burn micronized coal. In support of the overall goal the following specific objectives were targeted: develop a coal handling/preparation system that can meet the technical and operational requirements for retrofitting microfine coal on a boiler designed for burning oil or natural gas; maintain boiler thermal performance in accordance with specifications when burning oil or natural gas; maintain NOx emissions at or below 0.6 lb NO2 per million Btu; achieve combustion efficiencies of 98% or higher; and determine economic payback periods as a function of key variables.