The object of this work is a study on the application of biomass co-firing in an existing Greek lignite power plant. The Meliti - Florina Power Plant in Western Macedonia has been used as areference station for all the case study investigations. After a brief reference to the biomass potential of Western Macedonia, an analysis of the proposed technical solutions of biomass transportation and storage system and a technical solution for the actual scenario of co-firing biomass in the concerned station is given. For the different scenarios of feeding and combustion examined, computer simulations using computational fluid dynamics code havebeen performed The presentation of those technical solutions is followed by the techno-economic analysis and evaluation of the extension of the power station through implementing the biomass feeding and co-firing system. Thus, despite the difficulties encountered, mainly relating to a lack of necessary quantities of biomass and the need for greater organization in the field of biomass production, the prospect of implementing co-firing biomass in existing lignite-fired power stations is presented as a realistic and feasible scenario from a technical and economic point of view.