In Latvia approximately of 14.6% of unfarmed agricultural land can be used for herbaceous energy crop growing. Herbaceous energy crops would be as the main basis for solid biofuel production in agricultural ecosystem in future. Herbaceous energy crops as hemp (Cannabis sativa) are grown in recent years and can be used for solid biofuel production. Experimentally stated hemp stalk material ultimate tensile strength the medium value is 85 ± 9 N mm-2. The main conditioning operation before preparation of herbaceous biomass compositions for solid biofuel production is shredding. Therefore hemp stalks were used for cutting experiments. Cutting using different types of knives mechanisms had been investigated. Specific shear cutting energy for hemp samples were within 0.02 – 0.04 J mm-2. Hemp stalk material density was determined using AutoCAD software for cross-section area calculation. Density values are 325 ± 18 kg m-3 for hemp stalks. Specific cutting energy per mass unit was calculated on basis of experimentally estimated values of cutting energy and density.

The main task of this investigation is evaluation of patented (LV 14604 B) biomass briquetting mechanism. Theoretical relationship between necessary drive force and resistance force during pressing in die was determined. Briquettes from grinded common reed (Phragmites Australis) or common reed-peat mixture were produced with designed experimental briquetting press. Density of common reed briquettes depending on the size of particles was stated. Density of briquettes obtained during compacting was from 826.3±16.4 to 934.5±35.1 kg m-3. The minimum of density 826.3±16.4 kg m-3 had briquettes with particles from 6 mm grinding screen, but maximum density 934.5±35.1 kg m-3 had briquettes, when particles from 1.5 mm grinding screen had been used. Compositions of reed particles with peat allow obtaining briquettes density > 1000 kg m-3 if peat proportion in mixture is 30%. Results of theoretical and experimental investigation show that the designed pressing mechanism can be recommended for mobile biomass briquetter design.

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