Assessment of Quality Characteristics of Briquettes Produced From Selected Wood Waste

The paper presents evaluation of the quality characteristics of briquettes produced from selected wood waste, whose use is part of a sustainable farming policy. The following types of wood waste were used in the study: poplar sawdust, poplar bark, oak shavings and oak bark. In order to crush the poplar and oak bark, a beater shredder was used. Briquettes were made using hydraulic piston briquetting machine. During the briquetting process, the working pressure was 8 MPa. Depending on the type of waste used, the briquettes produced differed in their qualities. Based on the analysis of the obtained results, it was found that the characteristics of produced briquettes were influenced by such factors as the type of raw material, its humidity and fragmentation. The best quality features characterized briquettes made of oak bark and the least advantageous of oak shavings. INTRODUCTION The Sustainable Agriculture Strategy fosters environmental protection in rural areas, which is linked to increased use of renewable energy sources. Wood waste is a valuable energy resource and they fit in this strategy. It can be used to produce electricity, heat, and liquid and gaseous fuels. Remnants of the trees, waste from sawmills or branches of orchards can be burned in the form of sliced wood, chips, and processed into pellets or briquettes (Hejft & Obidziński, 2015; Niedziółka et al., 2016). This allows full use of the raw material. This type of fuel is not harmful to the environment. Carbon dioxide, which is emitted to the atmosphere during combustion, is completely absorbed by plants reproducing biomass in the process of photosynthesis. In addition, wood is the fuel that leaves the minimum amount of ash after burning (Kachel-Jakubowska et al., 2013; Mc Kendry, 2002; Panwar et al., 2011). Wood, which is a major part of biomass, is the most widely used renewable energy source in Europe. It occurs in the form of shavings from perennial trees (e.g. willow, poplar) as well as chips, sawdust and wood dust (Ivanova et al., 2014). The popular way to use wood fractions is to produce pellets and briquettes for energy purposes. In addition, the generation of energy from wood waste is profitable, because prices of these fuels on the market are competitive relative to fossil fuels (Frączek, 2010; Shawa et al., 2009). Besides wood waste, straw and specially developed energy crops can be used for the production of heat. These raw materials are the biomass, which is included in renewable energy sources, including solar, geothermal, wind and river energy, agricultural biogas, and landfill and sewage treatment plants (Demirbas, 2004; Dreszer et al., 2003). Poland is characterized by the high potential of biomass used for energy purposes. It has considerable potential for development of agro-energy, especially based on the production of perennial energy crops. Hence, most biomass used for power generation is produced in the country (Kołodziej & Matyka, 2012; Niedziółka, 2014).