Excerpts from the report Introduction: Can BIOCO save coal power plants? BIOCO (BIOmass CO-firing with COal) is an approach that extends the life of coal-fired plants by rejuvenation (retrofitting to co-firing coal with biomass). The idea is to consider an investment in a coal plant with the possibility of a future BIOCO retrofit. If desired, government programs could be established to promote BIOCO. The underlying foundation for determining these programs is a theoretical understanding of the interplay of costs between the existing coal plant prior to retrofitting and post-retrofitting costs. Our objective is to develop such a theoretical understanding. Our aim is to study the conditions under which rejuvenation of coal-power plants with BIOCO can become an economically efficient path for society to transition from a high-to a low-emission power system. For BIOCO to become feasible, current policies and government incentive programs may require modification or new programs to be adopted. The theoretical developed model for investigating the conditions required for BIOCO can serve as a foundation for policy analysis.