A thermodynamic model for a hybrid thermo-solar externally fired gas turbine power plant fueled with biomass is presented. This technology represents a fully renewable way of obtaining electr ic power relying mainly in biomass with an extra advantage of decreasing its consump tion at good radiative conditions. A concentrated solar power plant is implemented considering the Sol ugas project situated in Abengoa’s Solúcar Platform near Seville. To predict its behavior two models were im plemented and compared with experimental data. Typical daily evolution of the output power, biomass mass flow, overall effi ciency and biomass convers ion efficiency for a typical Uruguayan year is presented. In addition, global results are presented leading to a 1.5% biomass saving increasing the economic efficiency a 0.34% what denotes the solar field and thermal power of receiver seem to be undersized.