Future perspective of the research is the production of fuel pellets from energy plant (Phalaris arundinacea L., Festuca arundinacea, etc.) biomass, because it can be better burnt in granule burners and is more environmentally friendly, if compared to the fossil mineral resources (coal, oil, gas), moreover it has low moisture content (70 – 90 g kgE-1) and correspondingly it produces higher combustion energy. The research covered preparation of various content tablets from reed canary grass (Phalaris arundinacea L.) variety ’Marathon’ (N fertilizer rate on the N-90 kg haE-1), energy wood - osier (Salix viminalis L) and poplar (Populus tremula L.) with N fertilizer norms N-0 and N-120 kg haE-1, and afterwards research of the combustion ability of and ash content in these tablets. Combustion ability of reed canary grass (Phalaris arundinacea L.) variety ‘Marathon’ reached 17.48 MJ kgE-1. The highest average combustion ability with different pellet content was found for the fast-growing poplar both with doses of N fertilizer - 18.55 MJ kgE-1 and without N fertilizer - 18.49 MJ kgE-1. Optimum content of various component pellets for biomass was a mixture of components 1/3 (reed canary grass/osier or poplar). The lowest indicators in respect to the ash content were observed for osier (Salix viminalis L.) - 27.9 g kgE-1. The best ash content indicators for a mixture of granular composition was in a mixture of components one-fourth of the reed canary grass with three parts of osier - 34.3 g kgE-1 or with poplar - 41.8 g kgE-1.

The study aims to find productivity of biofuel production in pre-commercial thinning, depending on the structure of assortments and to identify factors that influence the cost of mechanized tending of young stands. Five work methods were compared in the study, starting from standard thinning (production of sawn timber, pulpwood and firewood) with no use of accumulating device and finalizing with the biofuel method – no other assortments except biofuel are produced and the most intense use of accumulating device is considered. Accumulating device is not used for production of standard round-wood assortments. The experiments were implemented in February – March, 2013. The material produced in the study was used by ‘Graanul Pellets’ company to evaluate possibilities to use timber extracted in pre-commercial thinning of coniferous stands in production of premium class pellets. The average productivity in different stands is statistically different. The study shows that productivity of harvesting is 3.7 … 5.1 m**3 hE-1, which can be increased by more intensive use of accumulation. No difference found between work methods in forwarding trials, but productivity grows with increase of share of firewood. Average loading time 26 min, unloading 3.6 min, average load 6.0 m**3 . Prime-cost calculation shows that harvesting costs depending on the working method is in the range of 22.4 … 26.5 EUR mE-3. Comparison of potential expenses and incomes demonstrates that economically the most efficient is production of traditional assortments (sawn wood, small size sawn wood, pulp wood and firewood) with an active use of accumulating function.

This paper describes the use of Scots pine (Pinus sylvestris L) bark humus and fine fractions for animal litter pellet manufacture, and the efficacy of various additives in improving absorbency. In Latvia is no researches about litter pellet manufacture of pine bark, and possibilities of increasing water absorbency; in internationals research papers there is also no information about the possibilities of improving water absorbency of pine bark pellets with various additives. The additives tested were fresh and fallen leaves, tree needles, dried hogweed and sawdust. Pellets were manufactured with a ZLSP200B granulator at Adazi city, Latvia, in 2014. The results indicated that production of small diameter pine bark pellets could be problematic. Absorbency of the pellets was tested both by rinsing and soaking the pellets, and results were compared to woodchip particle litter pellets. It was found that the best absorbency was achieved with adding up to 30% sawdust, which increased pellet absorbency both by rinsing and soaking. The results indicate that it is possible to manufacture pellets using Scots pine (Pinus sylvestris L.) bark humus and fine fraction with good absorbency which can be disposed of in sewerage systems.