The paper presents main organizational and economic factors influencing on the variability and costs of preparing agricultural biomass into pellets. Basic on case study there were data collected in the period July 2013 to June 2014. Investigation shows that capacity of plant varied between 509 to 1426 tons per month. The biggest part of processing costs were electricity – 43.8%. Next labour costs – 23.8%, maintenance and repairs – 16.6%, fuel costs-4.6% and depreciation – 11.6%. The cost of processing per one tone was 131 PLN.