Potential of wild growing Japanese knotweed (Reynoutria japonica) for briquette production

Abstract

Popularity of renewable energies and their competitiveness with fossil fuels are rapidly increasing also due public interest in such topic as biomass, which represents 75 % of all renewable resources. Therefore, much of the current literature pays particular attention to variety of biomasses, which are not publicly well-known yet. Japanese knotweed (Reynoutria japonica) is a hardy plant with outstanding biomass yield up to 30 t•ha-1 of dry matter (i.e. 583.32 GJ•h-1), however, it belongs to invasive plants, which spread rapidly (>200 stalks•m-1), form dense monocultures and replace native vegetation. Thus, there is intensive effort to reduce its population and to prevent further spread. Considering that, a great amount of biomass with extremely high yield can be produced and utilized for energy production. The aim of the present study was to determine the potential of Japanese knotweed as a feedstock material for briquette production within its chemical, mechanical and microscopic properties. Within the chemical analysis a satisfactory level of moisture content (8.84 %), ash content (1.14 %), gross calorific value (19.43 MJ-kg-1) and net calorific value (17.71 MJ-kg-1) were proved. The mechanical analysis of the produced briquette samples also proved a high level of biofuel quality; mechanical durability was determined equal to 95.1 %, volume density equal to 989.1 kg-m'3and rupture force was 112.1 N-mm-1. The microscopic analysis described the surface of the material and dimensions of the particle size within what it proved that 68 % of the particles had the surface area <2 mm2 and average length of the fraction size <5 mm was observed in 35 %.Overall evaluation of all investigated parameters of Japanese knotweed exhibited more than satisfactory results. The results of this study indicate that Japanese knotweed is a crop with high energy potential.