Proximate, Ultimate, and Energy Values Analysis of Plum Biomass By-products Case Study: Croatia s Potential

In many European countries, residues from agricultural products represent a considerable potential for development of bio-energy industry. A significant part of these biomass materials come from the fruit-growing business, i.e., primary fruit production and fruit processing plants. The EU directives require that the disposal of such residues should be environmentally sustainable. The objective of this study was to determine proximate (moisture content, ash, fixed carbon, volatile matter), ultimate (carbon, hydrogen, nitrogen and sulphur) and energy values (higher, lower) of biomass, as well as the Croatian total energy potential generated after the pruning (pruned residues) and processing of plum fruit (stone). Five different plum varieties (Bistrica, Cacanska ljepotica, Cacanska rodna, President, and Stanley), most commonly grown in the territory of Croatia, were analyzed and compared. The analyzed data were compared with the norm CEN/TS 14961 (2005) for solid biofuels and the data from the relevant literature. Both types of investigated biomass proved to be highly valuable sources of energy; and no significant difference between investigated plum varieties were found. Lower heating value, as one of the fundamental parameters of the biomass energy efficiency, averaged in the studied samples: 15.2 MJ kg^-1 for plum pits and 17.12 MJ kg^-1 for pruned biomass, which classifies plum biomass as a valuable energy raw material. Also, the calculations show that the potential production of the biomass available in Croatia could reach up to 292.13 MJ of renewable green energy annually.