The great potential of cereal lignocelluloses for use as energy or as an industrial raw material source determines the necessity to investigate the mechanical properties of stalks, as the main parts of any herbaceous material. Annual world production of cereal straw is approximately of the same amount (around 2 billion tons) as wood material production. Latvia as a country with more than 2000 lakes has wide areas, covered with reeds, which are also an important stalk material resource. Stalk cross section and structural studies show that it is a complicated structure. Special test piece preparation and clamping methods, measuring devices, testing procedure for stalk material strength testing have been worked out. Ultimate tensile (118.7 +/- 8.63 N/mm(2)) and shear (8.47 +/- 0.56 N/mm(2)) strength, modulus of elasticity (13.1 +/- 1.34 GPa) and shear modulus (0.643 +/- 0.043 GPa) had been experimentally determined for wheat stalks in order to find methods for mechanical conversion with minimum energy consumption. Stalk biomass compacting methods and energy requirement for that are analysed on the basis of the results from the experiments. It has been stated, that energy for wheat straw pressing ( approximate to 40 kJ/kg up to pressure 160 MPa) is one order of magnitude less than that for heating of the same mass up to 200 degrees C in the briquetting process ( approximate to 360 kJ/kg), if solid material has to be obtained. Depending on the target goals for usage, different energy saving compacting technologies can be developed. Thus the analysis of mechanical and physical properties of the stalk materials determines the profit of biomass usage. (C) 2000 Elsevier Science B.V. All rights reserved.
