The world energy demand and declining fossil fuel resources make renewable energy resources to receive increased attention. Lithuania is sufficiently rich in renewable natural resources, and energy can be used from various types of solid biofuels, without being tied to fossil fuels, which have to be imported from other countries. Osier willows (Salix vinimalis) are one of the most cultured short rotations sprouts in the energetic plantations. These sprouts are willows which grow as bushes and have almost equal diameter and height of perennial stems. Preparing osier willows for fuel, the trunks of the trees are felled every four years, usually in the cold season. Osier willows are chopped by various shredders in the process after the removal of branches and leaves. Cutting willows in other seasons leads to the high moisture content and the biological activity of carving and other significant features: density, porosity, thermal conductivity, self-heating and other properties. According to the experiments, the highest biological activity (747 ± 43.5-379 ± 34.7 W·t -1 ) is characterized by willow chaff from 50.4 ± 0.14 % to 30.0 ± 0.075 % humidity. When the humidity reaches 11.6 ± 0.11 %, the wood carving becomes biologically inactive. It was found that the thermal and temperature conductivity of wood carving differ based on the difference in moisture. The maximum values of the temperature field (21.56 m 2 ·s -1 and 19.39 m 2 ·s -1 ) were fixed, when the chopped osier willow moisture was 30.0 ± 0.075 % and 38.4 ± 0.088 % respectively. Moreover, it is observed that, when the osier willow dries from 50.4 ± 0.14 % to 11.6 ± 0.11 % of moisture, its true wood density decreases by 21.2 % -from 808 ± 11.25 kg·m -3 to 637 ± 63.5 kg·m -3 . The density of the chopped osier willow decreased by 28.1 % -from 433 ± 5.13 kg·m -3 to 311 ± 3.05 kg·m -3 .