Energy demand continuously increases what contributes to higher emissions of GHG. Moreover, the primary energy sources like coal, natural gas and oil are depleting. To manage this problem, the scientists have worked on the different possibilities of renewable energy conversion technologies in order to get the most useful and cleanest type of energy. In this work, there are investigated possible biomass conversion technologies in order to satisfy energy demand for Poznan, the city in Poland. Actually, the energy demand is met by coal combined with heat and power plant (CHP). There is an interest of changing actual coal CHP plant with biomass to minimize emissions. The aim of this work is to choose the best thermo-chemical biomass conversion option in the concept of minimum investment cost. To achieve this goal, the thermo-economic analysis and optimization of different biomass conversion technologies have to be conducted. First, on the basis of the literature review, the models of biomass conversion processes are modeled in Belsim Vali software. Then, from 2008, two different scenarios of energy demand are defined for the city. In the next step of this work, there is conducted energy integration in order to find an optimal set of designed boundary conditions through maximizing the units of performance for the most promising types of biomass conversion processes. Finally, an optimal configurations and sizes of the equipments are found by thermo- economic optimization.