Researches regarding evaluation of energy consumption for manufacturing of pellets from vine pruning residues

Abstract

Renewable energy resources represent real prospects for replacing fossil fuels. Compared to other combustible materials (coal, oil etc.), biomass is widespread and can be found in various forms (wood, woody plants, aquatic, agricultural, waste etc.). Any country on the globe has the possibility and obligation to produce green energy from biomass. Biomass contributes with 14 % to global primary energy consumption, and for three quarters of the world's population living in developing countries it is the most important source of energy. The researches of the present paper were aimed to evaluate the potential of biomass resulting from dry cutting of varieties of vines on the fruit and the energy consumed during the operations of milling, drying and manufacturing of pellets derived from it. All the operations were carried out with equipment designed and realized within the Laboratory of Mechanization of Agriculture, from the University of Agricultural Sciences and Veterinary Medicine "Ion Ionescu de Brad" from Iasi. Following the analyses performed, it was found that the higher calorific value of the vine pruning residues harvested and taken in the study was between 14.49-18.31 MJ•kg -1 , and the lower calorific power varies between 13.08 ... 16.88 MJ•kg -1 , depending on the variety. Considering the specific nature of the vineyard plantation, it turns out that the energy potential of the biomass harvested from one hectare has values between 8746.39 MJ•(kg•ha) -1 and 13603.94 MJ•(kg•ha) -1 , equivalent to one quantity of firewood between 696.37 kg and 812.18 kg. Also, within this work, the energy requirements for conversion of vine pruning residues into densified biomass, as pellets, were evaluated. Thus, a total average electricity consumption of 0.5215-3.4959 MJ•kg -1 was recorded, of which, for coarse chopping 0.0236-0.0306 MJ•kg -1 , for grinding particles larger than 4 mm, 0.0587 MJ•kg -1 , for drying 2.692 MJ•kg -1 and for pelletizing 0.4392 MJ•kg -1 .

Sustainability of Briquettes Production Based on Biomass from Vineyard Winter Pruning

“…These remain as dust residues into the combustion place. Consequently, the ash content is an important quality index, leading to problems during the processing and combustion of biomass [38,39,40]. In solid biofuels, ash diminishes the calorific value and impedes the diffusion of air into the hotbed, forming plastic conglomerates that include large quantities of fuel, which thus becomes unavailable for combustion.…”

“…The importance of the chemical composition of the briquettes has been largely analyzed in another paper [38]. The chemical composition of the briquettes was analyzed according to the requirements of the respective standards (ISO 16948 for nitrogen; ISO 16994 for Sulphur and chlorine; ISO 16968 for arsenic, cadmium, chrome, copper, mercury, nickel and zinc).…”

“…In order to densify the collected tendrils, the biomass had to be dried, thus reducing its humidity ratio from 44-46% to 10-12% [16,23,38]. Two drying procedures were used in our experiments: natural and artificial drying.…”