The quality of biomass and fuel pellets from Jerusalem artichoke stalks and wheat straw

Abstract

In recent years, the biomass market has constantly increased. The densification of plant biomass would contribute to improving its efficiency as a fuel by increasing its homogeneity and allowing a wider range of lignocellulosic materials to be used as fuel. The eco-friendly solid fuels, such as pellets, have become rapidly a viable alternative to fossil fuels, due to their high energy content, which makes them suitable for use by small households and by industrial consumers. The knowledge of the physical and mechanical properties of biomass is important for the design and efficient operation of equipment for handling, storing and processing such materials. Jerusalem artichoke, Helianthus tuberosus, is native to North America. Its tubers were previously used as raw material, food, folk remedy and animal fodder. Its potential yield and low requirements meant that it could be of interest in the renewable energy sector, tubers can be used for biogas or ethanol production, and the aboveground parts – for pellets and briquettes. The objective of this research was to evaluate some physical and mechanical properties of dry biomass and pellets from Jerusalem artichoke stalks and wheat straw collected from the experimental field of the National Botanical Garden (Institute), Chişinău. The physical and mechanical properties were determined according to the European standards accepted in the Republic of Moldova; the production of solid fuels, pellets – by the equipment developed in the Institute of Agricultural Technique "Mecagro", Chişinău. The pellets were produced from Jerusalem artichoke biomass and mixture of Jerusalem artichoke and wheat straw with a percentage: 0%, 30%, 50%, 70% and 100%. It was determined that the bulk density of the chaffs milled by a 6 mm sieve ranged from 163 to 231 kg/m3 , the ash content – from 2.12 to 4.93%, the gross calorific value - from 17.4 to 19.1 MJ/kg. The biomass of the species Helianthus tuberosus was characterized by high gross calorific value and moderate ash content. The physical and mechanical properties of fuel pellets varied depending on the mixture ratio: the moisture content ranged from 13.8 to 14.1%, the bulk density - from 582 to 685 kg/m3 , the specific density - from 880 to 1008 kg/m3 and the net calorific value - from 15.6 to 17.71 MJ/kg.