The subject of the research in this article is the analysis of operational modes of a wood chip-powered cogeneration plant in terms of fuel consumption. The data set for analysis comprises the data measured on an hourly basis at the cogeneration plant. The volume of the data set is 720 modes. It can be observed that the specific fuel consumption increases along with a part of the condensation modes (α value increases). The correlation analysis of data has been carried out, and an equation linking the specific fuel consumption to the changes in the ratio of power generation to heat energy has been obtained. The average value of the specific fuel consumption of the plant's cogeneration mode is 1.19 ± 0.1 loose m3/MWh and power-to-heat ratio is 0.48 ± 0.03. The uncertainty in the average measurement is defined for a 95% confidence interval. Along with the increase in the power- to-heat ratio value by 0.1, the increase in the specific fuel consumption is 0.19 loose m3/MWh.