Renewable energy sources are an important component of energy economy. One of its most popular types is plant-based biomass. Among its various types, grass plant straw in form of dried stems and leaves calls for particular attention. Its main source is the cultivation of grains for fodder and consumption. The use of biomass as an energy source requires mechanical processing which entails fragmentation of the material followed by compaction to form briquette which may be used as fuel in boilers. The fragmentation process is mostly breaking and cutting. The Chair of Machine Design Basics of the Poznań University of Technology has taken up work to analyze the energy consumption of the biomass fragmentation process with utilization of a drum-type cutting system. This article presents the preliminary study of cutting triticale straw, allowing to identify any possible problems arising during that process. The forces required for shearing grain stems will be established and utilized to design a mathematical model for the cutting process of similar materials. The obtained material characteristics for the course of the cutting process will be employed in the formulation of the physical model. The end result of such work shall be the analysis of process energy consumption for the drum type cutting system.